Space Shuttle Program

Space Shuttle Program

Conceived as a means to reduce the cost of space flights, NASA's Shuttle Program originally was supposed to produce completely reusable vehicles, which would make launches routine and relatively cheap. In semi-reusable form, the shuttle has completed dozens of successful missions, but two disasters have been etched into the nation's collective memory.

The original idea of reaching space in vehicles that resembled airplanes rather than rockets dates to before World War II. In 1951, Collier's printed a series of articles that popularized the possibility of manned exploration of space. The articles were the result of collaboration between Collier's editors and Wernher von Braun, who suggested that the United States should build a permanent space station and supply it with a vehicle that looked somewhat like the eventual space shuttle.

By the late 1960s, NASA began to worry about its future after the completion of the Apollo Mission. Budgets had already peaked and von Braun worried about staff reductions if no new projects appeared. The space shuttle was conceived as a means to make space exploration economical. The Saturn V rockets required by Apollo cost $185 million each, back when $185 million was a lot of money. The sum of all National Science Foundation grants at the time was around $440 million a year. Reducing the cost of launches was an obvious objective.

The shuttle project was proposed and discussed extensively. Finally, on January 5, 1972, President Richard M. Nixon authorized the development of reusable vehicles for space exploration. The project became known officially as the Space Transportation System, and unofficially as the Space Shuttle Program.

The goal of 100-percent re-usability had been abandoned. The delta-winged Orbiter, which would contain a cargo bay and a crew compartment, would be put into orbit by its own rockets, assisted by two Solid Rocket Boosters (SRBs). In addition, an external fuel tank for the hydrogen and oxidizer required by the main engines was attached. The fuel tank would be jettisoned after use; the other components would be reused.

Work on the first orbiter began in mid-1974 by North American Rockwell (now owned by Boeing Company) and was completed in September 1976. North American Rockwell also produced the Apollo Spacecraft. The shuttle was designed for 100 launches, or 10 years of operation. As a result of requests by many Star Trek fans, it was named the Enterprise. It was used solely for testing and never completed an actual mission.

The first operational shuttle was the Columbia. Between April 21, 1981, and July 4, 1982, it performed four missions to demonstrate that the vehicle could be put into space, perform useful work, and return safely to Earth. After the fourth landing, NASA declared the shuttle ready for operation. In July 1982, the Challenger was added to the shuttle fleet. Later additions were the Discovery in 1983, Atlantis in 1985, and Endeavour in 1991.

In the first three-and-a-half years of shuttle operation, only 24 flights were completed, a figure below what NASA had estimated for each year when the project began. Nevertheless, the shuttle program accomplished a number of achievements during that period. In June 1983, Sally Ride became the first American woman in space and two months later, Guion S. Buford Jr. became the first African-American astronaut. The first American government official to reach space was U.S. Senator Jake Garn of Utah, who made the trip in April 1985 as a payload specialist. In January 1986, U.S. Congressman Bill Nelson flew on the Columbia, also as a payload specialist.

Disaster struck the space shuttle program on January 28, 1986. The Challenger disaster claimed the lives of all seven of its crew, including Christa McAuliffe, who was to be the first teacher in space. The repercussions of the Challenger loss brought the shuttle program to a halt for two and a half years. With a revamped design and solid-fuel rockets, the Discovery took off on September 28, 1988, marking the resumption of regular shuttle flights.

Following the Challenger disaster, the U.S. military dropped plans to use shuttles for military missions, and shuttles no longer launched commercial satellites. Despite those terminations, the shuttle has continued to play a central role in space exploration. Since 1986, the shuttle has launched the Magellan spacecraft to Venus, the Galileo spacecraft to Jupiter, and the Ulysses spacecraft to study the sun. The shuttle also deployed the Hubble Space Telescope, Gamma Ray Observatory, and Upper Atmosphere Research Satellite.

Astronaut John Glenn, the first American to orbit the Earth, returned as the oldest man to reach space as a member of the crew of Discovery on a nine-day mission in late 1998. The 77-year-old astronaut helped deploy the Spartan solar-observing spacecraft, the Hubble Space Telescope Orbital Systems Test Platform, and perform investigations on the aging process and on space flight.

In 1990, Discovery launched the Hubble Space Telescope, or HST. It was soon learned that a tiny flaw in the mirror was preventing the telescope from sending back completely clear images. A servicing flight by Endeavour in 1993 provided Hubble with corrective "eyeglasses," allowing the telescope to begin transmitting images of unprecedented quality. The Discovery returned in 1997 and 1999 to replace worn and outdated instruments. In March 2002, Columbia performed a similar mission.

On February 1, 2003, Columbia broke apart during re-entry. All seven crew members were killed in the accident. Once again, the space shuttle program came to a thunderous halt. An investigation determined that one of the shuttle's thermal tiles had been damaged during takeoff, resulting in the failure of the protective shield when the shuttle returned to the atmosphere. Equipment and procedures were again modified and shuttle flights were scheduled to resume in the spring of 2005. Although Discovery would deliver supplies and cargo to the International Space Station in a new Italian-built Multi-Purpose Logistics Module, its main mission would be to test and evaluate the shuttle’s new safety procedures.

Even though the shuttle program has suffered two tremendous disasters, its dozens of successful missions have made great strides in space travel and exploration during its short history. The future of space exploration through the Space Shuttle Program may provide humanity with the answers to questions of their past and destiny. That future may include humans landing on Mars and perhaps even the establishment of colonies there.


Space shuttle

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space shuttle, also called Space Transportation System, partially reusable rocket-launched vehicle designed to go into orbit around Earth, to transport people and cargo to and from orbiting spacecraft, and to glide to a runway landing on its return to Earth’s surface that was developed by the U.S. National Aeronautics and Space Administration (NASA). Formally called the Space Transportation System (STS), it lifted off into space for the first time on April 12, 1981, and made 135 flights until the program ended in 2011.

The U.S. space shuttle consisted of three major components: a winged orbiter that carried both crew and cargo an external tank containing liquid hydrogen (fuel) and liquid oxygen (oxidizer) for the orbiter’s three main rocket engines and a pair of large, solid-propellant, strap-on booster rockets. At liftoff the entire system weighed 2 million kilograms (4.4 million pounds) and stood 56 metres (184 feet) high. During launch the boosters and the orbiter’s main engines fired together, producing about 31,000 kilonewtons (7 million pounds) of thrust. The boosters were jettisoned about two minutes after liftoff and were returned to Earth by parachute for reuse. After attaining 99 percent of its orbital velocity, the orbiter had exhausted the propellants in the external tank. It released the tank, which disintegrated on reentering the atmosphere. Although the orbiter lifted off vertically like an expendable rocket launcher, it made an unpowered descent and landing similar to a glider.

The space shuttle could transport satellites and other craft in the orbiter’s cargo bay for deployment in space. It also could rendezvous with orbiting spacecraft to allow astronauts to service, resupply, or board them or to retrieve them for return to Earth. Moreover, the orbiter could serve as a space platform for conducting experiments and making observations of Earth and cosmic objects for as long as about two weeks. On some missions it carried a European-built pressurized facility called Spacelab, in which shuttle crew members conducted biological and physical research in weightless conditions.

Designed to be reflown as many as 100 times, the U.S. space shuttle originally had been expected to reduce the high cost of spaceflight into low Earth orbit. After the system became operational, however, the vehicle’s operating costs and the time needed for refurbishment between flights proved to be significantly higher than early projections. Between 1981 and 1985 a fleet of four orbiters— Columbia (the first to fly in space), Challenger, Discovery, and Atlantis—was put into service.

On January 28, 1986, Challenger, carrying seven astronauts, exploded shortly after liftoff, killing all aboard including a private citizen, schoolteacher Christa McAuliffe. The presidential commission appointed to investigate the accident determined that a joint seal in one of the solid rocket boosters had failed as a result of mechanical design problems, which were exacerbated by the unusually cold weather on the morning of the launch. Hot gases leaking from the joint eventually ignited the fuel in the shuttle’s external tank, causing the explosion. After the accident, the shuttle fleet was grounded until September 1988 to allow NASA to correct the design flaws and implement associated administrative changes in the shuttle program. In 1992, Endeavour, a replacement orbiter for the destroyed Challenger, flew its first mission.

Between 1995 and 1998, NASA conducted a series of shuttle missions to the orbiting Russian space station Mir to give the agency experience in station operations in anticipation of the construction of the modular International Space Station (ISS). Beginning in 1998, the shuttle was used extensively to take components of the ISS into orbit for assembly and to ferry astronaut crews and supplies to and from the station.

On February 1, 2003, Columbia broke up catastrophically over north-central Texas at an altitude of about 60 km (40 miles) as it was returning from an orbital mission. All seven crew members died, including Ilan Ramon, the first Israeli astronaut to go into space. (See Columbia disaster.) Once again the shuttle fleet was immediately grounded. The accident investigation board concluded that, during the launch of the shuttle, a piece of insulating foam had torn from the external tank and struck the orbiter’s left wing, weakening its thermal protection ability. When the orbiter later reentered the atmosphere, it was unable to withstand the superheated air, which penetrated the wing and destroyed it, leading to the vehicle’s breakup. As in the analysis of the Challenger disaster, the Columbia accident was seen as the result of both mechanical and organizational causes that needed to be addressed before shuttle flights could resume.

Space shuttle flights resumed on July 26, 2005, with the launch of Discovery. The last space shuttle flight, the 135th, was launched on July 8, 2011. NASA announced that subsequent crewed missions would use the Russian Soyuz spacecraft as well as spacecraft built by American companies. The three remaining orbiters, as well as Enterprise (which did not fly into space but was only used in landing tests in 1977), were placed in museums across the United States. (For additional information on the space shuttle, see space exploration.)


The Sad History of Russia's Forgotten Space Shuttle Program

Key Point: The Buran is now little more than a footnote in space history.

The intense rivalry between the United States and the Soviet Union pushed the two countries to compete, not only on Earth but throughout the solar system. Good ideas, or perhaps more accurately good ideas at the time, were frequently imitated as long as they garnered prestige for Washington or Moscow. Of all the ideas that were copied during the Space Race, none were as curious—and blatant—as the Soviet Space Shuttle.

The American Space Shuttle program was designed to create a spacecraft that could act as an inexpensive, reusable connector between Earth and low Earth orbit. The shuttle was capable of carrying military and civilian payloads into space, acting as a laboratory for science experiments, and ferrying crews and visitors to orbiting space stations. The reusable nature of the shuttle program, which had named spaceships that carried out dozens of missions during their lifetimes, was a source of great pride for the United States and an example of American “soft” power.

The temptation for the Soviet Union to create a shuttle system of its own was too great, and work began in the mid 1970s, before the American spaceplane even flew. Moscow also had a practical, direct reason to build a reusable space plane: its Salyut series of space stations, and later the Mir space station, would benefit from having an inexpensive transport system capable of resupplying and even expanding the country’s semipermanent outposts in space.

Moscow had known for years that Washington had been tinkering with winged, reusable spacecraft. Designs such as the X-20 Dyna-Soar had tipped America’s hand. The Space Shuttle project was approved in 1969, boosted by NASA’s success with the Apollo moon landing. That the Soviet space program didn’t immediately embark on its own shuttle program is curious it may have had reservations about the technical feasibility of a reusable space plane.

By 1976, the Americans already had two shuttles under construction—the prototype Enterprise and the first fully operational shuttle, Columbia. The Soviet leadership, perhaps buoyed by American confidence in the project, authorized the Buran (“Snowstorm”) program in February 1976. The Buran program was actually a two-part program, to develop the space plane itself—also named Buran—and a new booster, Energia, that would carry it into space. The Energia rocket was designed by NPO Energia to function as both a heavy lifter and carry the spaceplane into orbit.

Energia was designed to be a two stage rocket, with the first stage consisting of four RD-170 booster rockets and a core stage of four RD-0120 engines. The rocket had an overall mass of 5.3 million pounds, and could lift an amazing (at the time) 110 tons into low earth orbit. Energia’s first flight, on March 15, 1987 was to carry the Polyus-Skif experimental laser weapon into space. While the launch itself was successful, Polyus-Skif inadvertently pitched itself in the wrong direction, crashing back into the Pacific Ocean.

Meanwhile, engineers proceeded with work on the Soviet shuttle. The two spacecraft were externally identical, both in dimensions and key features. Buran had the same delta wing at the same angle, the same shaped nose and the same orbital thrusters in the nose and other key locations. The Soviet program had the benefit of American shuttle blueprints obtained by the KGB. At its peak, more than 150,0000 engineers, scientists and others worked on the Buran project.

One key difference: while the American Space Shuttle had three Space Shuttle main engines that would provide thrust at liftoff, Buran lacked main engines altogether. The Space Shuttle used a combination of these three engines and a pair of solid rocket boosters to achieve orbit. Buran, on the other hand, relied upon Energia to do all the heavy lifting. Buran was, for all intents and purposes, an unpowered glider, with only small thrusters to adjust its orbit in space.

Another difference between the two craft was that while the American shuttle would actually be flown by an astronaut pilot during reentry, the Soviet Shuttle would land entirely on autopilot.

The first Buran launch was scheduled for October 29, 1988. It being a test flight, Buran didn’t carry any cosmonauts on board. A launch pad gantry failed to retract in time, causing the rocket computer to cancel the launch. The second attempt on November 15 was a success, and after a brief one-hour orbit, it successfully landed back in the Soviet Union—one second later than planned.

The Buran program was judged a success and would likely have continued had the Cold War carried on. Unfortunately it suffered from poor timing: the Soviet Union had already begun a serious, ultimately fatal economic decline, and Buran never flew again. NPO Energia did not survive the collapse of the USSR, and the remaining three shuttles were abandoned. Buran itself was destroyed at the Baikonur Cosmodrome in 2002 when the hangar housing it collapsed. Another shuttle is also located at Baikonur, and a third rests at Zhukovsky Air Base near Moscow. The Buran program, which once involved the hard work of so many talented individuals and so much of the USSR’s treasure, is now a footnote in space history.

Kyle Mizokami is a defense and national-security writer based in San Francisco who has appeared in the Diplomat, Foreign Policy, War is Boring and the Daily Beast. In 2009 he cofounded the defense and security blog Japan Security Watch. You can follow him on Twitter: @KyleMizokami.


Space Shuttle Program - History

Computers in Spaceflight: The NASA Experience

- Chapter Four - - Computers in the Space Shuttle Avionics System - Developing software for the space shuttle [ 108 ] During 1973 and 1974 the first requirements began to be specified for what has become one of the most interesting software systems ever designed. It was obvious from the very beginning that developing the Shuttle's software would be a complicated job. Even though NASA engineers estimated the size of the flight software to be smaller than that on Apollo, the ubiquitous functions of the Shuttle computers meant that no one group of engineers and no one company could do the software on its own. This increased the size of the task because of the communication necessary between the working groups. It also increased the complexity of a spacecraft already made complex by flight requirements and redundancy. Besides these realities, no one could foresee the final form that the software for this pioneering vehicle would take, even after years of development work had elapsed, since there continued to be both minor and major changes. NASA and its contractors made over 2,000 requirements changes between 1975 and the first flight in 1981 80 . As a result, about $200 million was spent on software, as opposed to an initial estimate of $20 million. Even so, NASA lessened the difficulties by making several early decisions that were crucial for the program's success. NASA separated the software contract from the hardware contract, closely managed the contractors and their methods, chose a high-level language, and maintained conceptual integrity. NASA awarded IBM Corporation the first independent Shuttle software contract on March 10, 1973. IBM and Rockwell International had worked together during the period of competition for the orbiter contract 81 . Rockwell bid on the entire aerospacecraft, intending to subcontract the computer hardware and software to IBM. But to Rockwell's dismay, NASA decided to separate the software contract from the orbiter contract. As a result, Rockwell still subcontracted with IBM for the computers, but IBM hand a separate software contract monitored closely by the Spacecraft Software Division of the Johnson Space Center. There are several reasons why this division of labor occurred. Since software does not weigh anything in and of itself, it is used to overcome hardware problems that would require extra systems and components (such as a mechanical control system) 82 . Thus software is in many ways the most critical component of the Shuttle, as it ties the other components together. Its importance to the overall program alone justified a separate contract, since it made the contractor directly accountable to NASA. Moreover, during the operations phase, software underwent the most changes, the hardware being essentially fixed 83 . As time went on, Rockwell's responsibilities as [ 109 ] prime hardware contractor were phased out, and the shuttles were turned over to an operations group. In late 1983, Lockheed Corporation, not Rockwell, won the competition for the operations contract. By keeping the software contract separate, NASA could develop the code on a continuing basis. There is a considerable difference between changing maintenance mechanics on an existing hardware system and changing software companies on a not yet perfect system because to date the relationships between components in software are much harder to define than those in hardware. Personnel experienced with a specific software system are the best people to maintain it. Lastly, Christopher Kraft of Johnson Space Center and George Low of NASA Headquarters, both highly influential in the manned spacecraft program during the early 1970's, felt that Johnson had the software management expertise to handle the contract directly 84 . One of the lessons learned from monitoring Draper Laboratory in the Apollo era was that by having the software development at a remote site (like Cambridge), the synergism of informally exchanged ideas is lost sometimes it took 3 to 4 weeks for new concepts to filter over 85 . IBM had a building and several hundred personnel near Johnson because of its Mission Control Center contracts. When IBM won the Shuttle contract, it simply increased its local force. The closeness of IBM to Johnson Space Center also facilitated the ability of NASA to manage the project. The first chief of the Shuttle's software, Richard Parten, observed that the experience of NASA managers made a significant contribution to the success of the programming effort 86 . Although IBM was a giant in the data processing industry, a pioneer in real time systems, and capable of putting very bright people on a project, the company had little direct experience with avionics software. As a consequence, Rockwell had to supply a lot of information relating to flight control. Conversely, even though Rockwell projects used computers, software development on the scale needed for the Shuttle was outside its experience. NASA Shuttle managers provided the initial requirements for the software and facilitated the exchange of information between the principal contractors. This situation was similar to that during the 1960s when NASA had the best rendezvous calculations people in the world and had to contribute that expertise to IBM during the Gemini software development. Furthermore, the lessons of Apollo inspired the NASA managers to push IBM for quality at every point 87 . The choice of a high level language for doing the majority of the coding was important because, as Parten noted, with all the changes, "we'd still be trying to get the thing off the ground if we'd used assembly language" 88 . Programs written in high level languages are far easier to modify. Most of the operating system software, which is rarely changed, is in assembler, but all applications software and some of the interfaces and redundancy management code is in HAL/S 89 . [ 110 ] Although the decision to program in a high-level language meant that a large amount of support software and development tools had to be written, the high-level language nonetheless proved advantageous, especially since it has specific statements created for real-time programming. Defining the Shuttle Software In the end, the success of the Shuttle's software development was due to the conceptual integrity established by using rigorously maintained requirements documents. The requirements phase is the beginning of the software life cycle, when the actual functions, goals, and user interfaces of the eventual software are determined in full detail. If a team of a thousand workers was asked to set software requirements, chaos would result 90 . On the other hand, if few do the requirements but many can alter them later, then chaos would reign again. The strategy of using a few minds to create the software architecture and interfaces and then ensuring that their ideas and theirs alone are implemented, is termed "maintaining conceptual integrity," which is well explained in Frederick C. Brooks' The Mythical Man Month 91 . As for other possible solutions, Parten says, "the only right answer is the one you pick and make to work" 92 . Shuttle requirements documents were arranged in three Levels: A, B, and C, the first two written by Johnson Space Center engineers. John R. Garman prepared the Level A document, which is comprised of a comprehensive description of the operating system, applications programs, keyboards, displays, and other components of the software system and its interfaces. William Sullivan wrote the guidance, navigation and control requirements, and John Aaron, the system management and payload specifications of Level B. They were assisted by James Broadfoot and Robert Ernull 93 . Level B requirements are different in that they are more detailed in terms of what functions are executed when and what parameters are needed 94 . The Level Bs also define what information is to be kept in COMPOOLS, which are HAL/S structures for maintaining common data accessed by different tasks 95 . The Level C requirements were more of a design document, forming a set with Level B requirements, since each end item at Level C must be traceable to a Level B requirement 96 . Rockwell International was responsible for the development of the Level C require ments as, technically, this is where the contractors take over from the customer, NASA, in developing the software. Early in the program, however, Draper Laboratory had significant influence on the software and hardware systems for the Shuttle. Draper was retained as a consultant by NASA and contributed two [ 111 ] key items to the software development process. The first was a document that "taught" NASA and other contractors how to write require ments for software, how to develop test plans, and how to use func tional flow diagrams, among other tools 97 . It seems ironic that Draper was instructing NASA and IBM on such things considering its difficulties in the mid-1960s with the development of the Apollo flight software. It was likely those difficult experiences that helped motivate the MIT engineers to seriously study software techniques and to become, within a very short time, one of the leading centers of software engineering theory. The Draper tutorial included the concept of highly modular software, software that could be "plugged into" the main circuits of the Shuttle. This concept, an application of the idea of interchangeable parts to software, is used in many software systems today, one example being the UNIX *** operating system developed at Bell Laboratories in the 1970s, under which single function software tools can be combined to perform a large variety of functions. Draper's second contribution was the actual writing of some early Level C requirements as a model 98 . This version of the Level C documents contained the same components as in the later versions delivered by Rockwell to IBM for coding. Rockwell's editions, however, were much more detailed and complete, reflecting their practical, rather than theoretical purpose and have been an irritation for IBM. IBM and NASA managers suspect that Rockwell, miffed when the software contract was taken away from them, may have delivered incredibly precise and detailed specifications to the software contractor. These include descriptions of flight events for each major portion of the software, a structure chart of tasks to be done by the software during that major segment, a functional data flowchart, and, for each module, its name, calculations, and operations to be performed, and input and output lists of parameters, the latter already named and accompanied by a short definition, source, precision, and what units each are in. This is why one NASA manager said that "you can't see the forest for the trees" in Level C, oriented as it is to the production of individual modules 99 . One IBM engineer claimed that Rockwell went "way too far" in the Level C documents, that they told IBM too much about how to do things rather than just what to do 100 . He further claimed that the early portion of the Shuttle development was "underengineered" and that Rockwell and Draper included some requirements that were not passed on by NASA. Parten, though, said that all requirements documents were subject to regular review by joint teams from NASA and Rockwell 101 . The impression one gains from documents and interviews is that both Rockwell and IBM fell victim to the "not invented here" [ 112 ] syndrome: If we didn't do it, it wasn't done right. For example, Rockwell delivered the ascent requirements, and IBM coded them to the letter, thereby exceeding the available memory by two and a third times and demonstrating that the requirements for ascent were excessive. Rockwell, in return, argued for 2 years about the nature of the operating system, calling for a strict time-sliced system, which allocates predefined periods of time for the execution of each task and then suspends tasks unfinished in that time period and moves on to the next one. The system thus cycles through all scheduled tasks in a fixed period of time, working on each in turn. Rockwell's original proposal was for a 40-millisecond cycle with synchronization points at the end of each 102 . IBM, at NASA's urging, countered with a priority-interrupt-driven system similar to the one on Apollo Rockwell, experienced with time-slice systems, fought this from 1973 to 1975, convinced it would never work l03 . The requirements specifications for the Shuttle eventually contained in their three levels what is in both the specification and design stage of the software life cycle. In this sense, they represent a fairly complete picture of the software at an early date. This level of detail at least permitted NASA and its contractors to have a starting point in the development process. IBM constantly points to the number of changes and alterations as a continuing problem, partially ameliorated by implementing the most mature requirements first 104 . Without the attempt to provide detail at an early date, IBM would not have had any mature requirements when the time came to code. Even now, requirements are being changed to reflect the actual software, so they continue to be in a process of maturation. But early development of specifications became the means by which NASA could enforce conceptual integrity in the shuttle software. Architecture of the Primary Avionics Software System The Primary Avionics Software System, or PASS, is the software that runs in all the Shuttle's four primary computers. PASS is divided into two parts: system software and applications software. The system software is the Flight Computer Operating System (FCOS), the user interface programming, and the system control programs, whereas the applications software is divided into guidance, navigation and control, orbiter systems management, payload and checkout programs. Further divisions are explained in Box 4-3. [ 113 ] Box 4-3: Structure of PASS Applications Software The PASS guidance and navigation software is divided into major functions, dictated by mission phases, the most obvious of which are preflight, ascent, on-orbit, and descent. The requirements state that these major functions be called OPS, or operational sequences. (e.g., OPS-1 is ascent OPS-3, descent.) Within the OPS are major modes. In OPS-1, the first-stage burn, second-stage burn, first orbital insertion burn, second orbital insertion burn, and the initial on-orbit coast are major modes transition between major modes is automatic. Since the total mission software exceeds the capacity of the memory, OPS transitions are normally initiated by the crew and require the OPS to be loaded from the MMU. This caused considerable management concern over the preservation of data, such as the state vector, needed in more than one OPS 105 . NASA's solution is to keep common data in a major function base, which resides in memory continuously and is not overlaid by new OPS being read into the computers. Within each OPS, there are special functions (SPECs) and display functions (DISPs). These are available to the crew as a supplement to the functions being performed by the current OPS. For example, the descent software incorporates a SPEC display showing the horizontal situation as a supplement to the OPS display showing the vertical situation. This SPEC is obviously not available in the on-orbit OPS. A DISP for the on-orbit OPS may show fuel cell output levels, fuel reserves in the orbital maneuvering system, and other such information. SPECs usually contain items that can be selected by the crew for execution. DISPs are just what their name means, displays and not action items. Since SPECs and DISPs have lower priority than OPS, when a big OPS is in memory they have to be kept on the tape and rolled in when requested 106 . The actual format of the SPECs, DISPs, OPS displays, and the software that interprets crew entries on the keyboard is in the user interface portion of the system software.

The most critical part of the system software is the FCOS. NASA, Rockwell, and IBM solved most of the grand conceptual problems, such as the nature of the operating system and the redundancy management scheme, by 1975. The first task was to convert the FCOS from the proposed 40-millisecond loop operating system to a priority-driven [113] system 107 . Priority interrupt systems are superior to time-slice systems because they degrade gracefully when overloaded 108 . In a time-slice system, if the tasks scheduled in the current cycle get bogged down by excessive I/O operations, they tend to slow down the total time of execution of processes. IBM's version of the FCOS actually has cycles, but they are similar to the ones in the Skylab system described in the previous chapter. The minor cycle is the high-frequency cycle tasks within it are scheduled every 40 milliseconds. Typical tasks in this cycle are those related to active flight control in the atmosphere. The major cycle is 960 milliseconds, and many monitoring and system management tasks are scheduled at that frequency 109 . If a process is still running when its time to. [ 114 ] Figure 4-6. A block diagram of the Shuttle flight computer software architecture. (From NASA, Data Processing System Workbook) . restart comes up due to excessive I/O or because it was interrupted, it cancels its next cycle and finishes up 110 . If a higher priority process is called when another process is running, then the current process is interrupted and a program status word (PSW) containing such items as the address of the next instruction to be executed is stored until the interruption is satisfied. The last instruction of an interrupt is to restore the old PSW as the current PSW so that the interrupted process can continue 111 . The ability to cancel processes and to interrupt them asynchronously provides flexibility that a strict time-slice system does not. A key requirement of the FCOS is to handle the real-time statements in the HAL/S language. The most important of these are SCHEDULE, which establishes and controls the frequency of execution of processes TERMINATE and CANCEL, which are the opposite of SCHEDULE and WAIT, which conditionally suspends execution 112 . The method of implementing these statements is controlled [ 115 ] by a separate interface control document 113 . SCHEDULE is generally programmed at the beginning of each operational sequence to set up which tasks are to be done in that software segment and how often they are to be done. The syntax of SCHEDULE permits the programmer to assign a frequency and priority to each task. TERMINATE and CANCEL are used at the end of software phases or to stop an unneeded process while others continue. For example, after the solid rocket boosters burn out and separate, tasks monitoring them can cease while tasks monitoring the main engines continue to run. WAIT, although handy, is avoided by IBM because of the possibility of the software being "hung up" while waiting for the I/O or other condition required to continue the process 114 . This is called a race condition or "deadly embrace" and is the bane of all shared resource computer operating systems. The FCOS and displays occupy 35K of memory at all times 115 . Add the major function base and other resident items, and about 60K of the 106K of core remains available for the applications programs. Of the required applications programs, ascent and descent proved the most troublesome. Fully 75% of the software effort went into those two programs 116 . After the first attempts at preparing the ascent software resulted in a 140K load, serious code reduction began. By 1978, IBM reduced the size of the ascent program to 116K, but NASA Headquarters demanded it be further knocked down to 80K 117 . The lowest it ever got was 98,840 words (including the system software), but its size has since crept back up to nearly the full capacity of the memory. IBM accomplished the reduction by moving functions that could wait until later operational sequences 118 . The actual figures for the test flight series programs are in Table 4-1 119 . The total size of the flight test software was 500,000 words of code. Producing it and modifying it for later missions required the development of a complete production facility.

[ 116 ] TABLE 4-1: Sizes of Software Loads in PASS.

On-orbit system management

Note: Payload and rendezvous software was added later during the operations phase. Implementing PASS NASA planned that PASS would be a continuing development process. After the first flight programs were produced, new functions needed to be added and adapted to changing payload and mission requirements. For instance, over 50% of PASS modules changed during the first 12 flights in response to requested enhancements 120 . To do this work, NASA established a Software Development Laboratory at Johnson Space Center in 1972 to prepare for the implementation of the Shuttle programs and to make the software tools needed for efficient coding and maintenance. The Laboratory evolved into the Software Production Facility (SPF) in which the software development is carried on in the operations era. Both the facilities were equipped and managed by NASA but used largely by contractors. The concept of a facility dedicated to the production of onboard software surfaced in a Rand Corporation memo in early 1970 121 . The memo summarized a study of software requirements for Air Force space missions during the decade of the 1970s. One reason for a government-owned and operated software factory was that it would be easier to establish and maintain security. Most modules developed for [ 117 ] the Shuttle, such as the general flight control software and memory displays, would be unclassified. However, Department of Defense (DoD) payloads require system management and payload management software, plus occasional special maneuvering modules. These were expected to be classified. Also, if the software maintenance contract moved from the original prime contractor to some different operations contractor, it would be considerably simpler to accomplish the transfer if the software library and development computers were government owned and on government property. Lastly, having such close control over existing software and new development would eliminate some of the problems in communication, verification, and maintenance encountered in the three previous manned programs. Developing the SPF turned out to be as large a task as developing the flight software itself. During the mid-1970s, IBM had as many people doing software for the development lab as they had working on PASS 122 . The ultimate purpose of the facility is to provide a programming team with sufficient tools to prepare a software load for a flight. This software load is what is put on to the MMU tape that is flown on the spacecraft. In the operations era of the 1980s, over 1,000 compiled modules are available. These are fully tested, and often previously used, versions of tasks such as main engine throttling, memory modification, and screen displays that rarely change from flight to flight. New, mission-specific modules for payloads or rendezvous maneuvers are developed and tested using the SPF's programming tools, which themselves represent more than a million lines of code 123 . The selection of existing modules and the new modules are then combined into a flight load that is subject to further testing. NASA achieved the goal of having such an efficient software production system through an 8-year development process when the SPF was still the Laboratory. In 1972, NASA studied what sort of equipment would be required for the facility to function properly. Large mainframe computers compatible with the AP-101 instruction set were a must. Five IBM 360/75 computers, released from Apollo support functions, were available 124 . These were the development machines until January of 1982 125 . Another requirement was for actual flight equipment on which to test developed modules. Three AP-101 computers with associated display electronics units connected to the 360s with a flight equipment interface device (FEID) especially developed for the purpose. Other needed components, such as a 6-degree-of-freedom flight simulator, were implemented in software 126 . The resulting group of equipment is capable of testing the flight software by interpreting instructions, simulating functions, and running it in the actual flight hardware 127 . In the late 1970s, NASA realized that more powerful computers were needed as the transition was made from development to operations. The 360s filled up, so NASA considered the Shuttle Mission [ 118 ] Simulator (SMS), the Shuttle Avionics Instrumentation Lab (SAIL), and the Shuttle Data Processing Center's computers as supplementary development sites, but this idea was rejected because they were all too busy doing their primary functions 128 . In 1981, the Facility added two new IBM 3033N computers, each with 16 million bytes of primary memory. The SPF then consisted of those mainframes, the three AP-101 computers and the interface devices for each, 20 magnetic tape drives, six line printers, 66 million bytes of drum memory, 23.4 billion bytes of disk memory, and 105 terminals 129 . NASA accomplished rehosting the development software to the 3033s from the 360s during the last quarter of 1981. Even this very large computer center was not enough. Plans at the time projected on-line primary memory to grow to 100 million bytes 130 , disk storage to 160 billion bytes 131 , and two more interface units, display units, and AP-101s to handle the growing DOD business 132 . Additionally, terminals connected directly to the SPF are in Cambridge, Massachusetts, and at Goddard Space Flight Center, Marshall Space Flight Center, Kennedy Space Center, and Rockwell International in Downey, California 133 . Future plans for the SPF included incorporating backup system software development, then done at Rockwell, and introducing more automation. NASA managers who experienced both Apollo and the Shuttle realize that the operations software preparation is not enough to keep the brightest minds sufficiently occupied. Only a new project can do that. Therefore, the challenge facing NASA is to automate the SPF, use more existing modules, and free people to work on other tasks. Unfortunately, the Shuttle software still has bugs, some of which are no fault of the flight software developers, but rather because all the tools used in the SPF are not yet mature. One example is the compiler for HAL/S. Just days before the STS-7 flight, in June, 1983, an IBM employee discovered that the latest release of the compiler had a bug in it. A quick check revealed that over 200 flight modules had been modified and recompiled using it. All of those had to be checked for errors before the flight could go. Such problems will continue until the basic flight modules and development tools are no longer constantly subject to change. In the meantime, the accuracy of the Shuttle software is dependent on the stringent testing program conducted by IBM and NASA before each flight. Verification and Change Management of the Shuttle Software IBM established a separate line organization for the verification of the Shuttle software. IBM's overall Shuttle manager has two managers reporting to him, one for design and development, and one for verification and field operations. The verification group has just [ 119 ] less than half the members of the development group and uses 35% of the software budget 134 . There are no managerial or personnel ties to the development group, so the test team can adopt an "adversary relationship" with the development team. The verifiers simply assume that the software is untested when received 135 . In addition, the test team can also attempt to prove that the requirements documents are wrong in cases where the software becomes unworkable. This enables them to act as the "conscience" of the entire project 136 . IBM began planning for the software verification while the requirements were being completed. By starting verification activity as the software took shape, the test group could plan its strategy and begin to write its own books. The verification documentation consists of test specifications and test procedures including the actual inputs to be used and the outputs expected, even to the detail of showing the content of the CRT screens at various points in the test 137 . The software for the first flight had to survive 1,020 of these tests 138 . Future flight loads could reuse many of the test cases, but the preparation of new ones is a continuing activity to adjust to changes in the software and payloads, each of which must be handled in an orderly manner. Suggestions for changes to improve the system are unusually welcome. Anyone, astronaut, flight trainer, IBM programmer, or NASA manager, can submit a change request 139 . NASA and IBM were processing such requests at the rate of 20 per week in 1981 140 . Even as late as 1983 IBM kept 30 to 40 people on requirements analysis, or the evaluation of requests for enhancements 141 . NASA has a corresponding change evaluation board. Early in the program, it was chaired by Howard W. Tindall, the Apollo software manager, who by then was head of the Data Systems and Analysis Directorate. This turned out to be a mistake, as he had conflicting interests 142 . The change control board moved to the Shuttle program office. Due to the careful review of changes, it takes an average of 2 years for a new requirement to get implemented, tested, and into the field 143 . Generally, requests for extra functions that would push out current software due to memory restrictions are turned down 144 .

[ 120 ] Box 4-4: How IBM Verifies the Shuttle Flight Software The Shuttle software verification process actually begins before the test group gets the software, in the sense that the development organization conducts internal code reviews and unit tests of individual modules and then integration tests of groups of modules as they are assembled into a software load. There are two levels of code inspection, or "eyeballing" the software looking for logic errors. One level of inspection is by the coders themselves and their peer reviewers. The second level is done by the outside verification team. This activity resulted in over 50% of the discrepancy reports (failures of the software to meet the specification) filed against the software, a percentage similar to the Apollo experience and reinforcing the value of the idea 145 . When the software is assembled, it is subject to the First Article Configuration Inspection (FACI), where it is reviewed as a complete unit for the first time. It then passes to the outside verification group. Because of the nature of the software as it is delivered, the verification team concentrates on proving that it meets the customer's requirements and that it functions at an acceptable level of performance. Consistent with the concept that the software is assumed untested, the verification group can go into as much detail as time and cost allow. Primarily, the test group concentrates on single software loads, such as ascent, on-orbit, and so forth 146 . To facilitate this, it is divided into teams that specialize in the operating system and detail, or functional verification teams that work on guidance, navigation, and control and teams that certify system performance. These groups have access to the software in the SPF, which thus doubles as a site for both development and testing. Using tools available in the SPF, the verification teams can use the real flight computers for their tests (the preferred method). The testers can freeze the execution of software on those machines in order to check intermediate results, alter memory, and even get a log of what commands resulted in response to what inputs 147 . After the verification group has passed the software, it is given an official Configuration Inspection and turned over to NASA. At that point NASA assumes configuration control, and any changes must be approved through Agency channels. Even though NASA then has the software, IBM is not finished with it 148 . [ 121 ] The software is usually installed in the SAIL for prelaunch, ascent, and abort simulations, the Flight Simulation Lab (FSL) in Downey for orbit, de-orbit, and entry simulations, and the SMS for crew training. Although these installations are not part of the preplanned verification process, the discrepancies noted by the users of the software in the roughly 6 months before launch help complete the testing in a real environment. Due to the nature of real-time computer systems, however, the software can never be fully certified, and both IBM and NASA are aware of this 149 . There are simply too many interfaces and too many opportunities for asynchronous input and output.

Discrepancy reports cause changes in software to make it match the requirements. Early in the program, the software found its way into the simulators after less verification because simulators depend on software just to be turned on. At that time, the majority of the discrepancy reports were from the field installations. Later, the majority turned up in the SPF 150 . All discrepancy reports are formally disposed of, either by appropriate fixes to the software, or by waiver. Richard Parten said, "Sometimes it is better to put in an 'OPS Note' or waiver than to fix (the software). We are dependent on smart pilots" 151 . If the discrepancy is noted too close to a flight, if it requires too much expense to fix, it can be waived if there is no immediate danger to crew safety. Each Flight Data File carried on board lists the most important current exceptions of which the crew must be aware. By STS-7 in June of 1983, over 200 pages of such exceptions and their descriptions existed 152 . Some will never be fixed, but the majority were addressed during the Shuttle launch hiatus following the 51L accident in January 1986. So, despite the well-planned and well-manned verification effort, software bugs exist. Part of the reason is the complexity of the real-time system, and part is because, as one IBM manager said, "we didn't do it up front enough," the "it" being thinking through the program logic and verification schemes 153 . Aware that effort expended at the early part of a project on quality would be much cheaper and simpler than trying to put quality in toward the end, IBM and NASA tried to do much more at the beginning of the Shuttle software development than in any previous effort, but it still was not enough to ensure perfection.

[ 122 ] Box 4-5: The Nature of the Backup Flight System The Backup Flight System consists of a single computer and a software load that contains sufficient functions to handle ascent to orbit, selected aborts during ascent, and descent from orbit to landing site. In the interest of avoiding a generic software failure, NASA kept its development separate from PASS. An engineering directorate, not the on-board software division, managed the software contract for the backup, won by Rockwell 154 . The major functional difference between PASS and the backup is that the latter uses a time-slice operating system rather than the asynchronous priority-driven system of PASS 155 . This is consistent with Rockwell's opinion on how that system was to be designed. Ironically, since the backup must listen in on PASS operations so as to be ready for instant takeover, PASS had to be modified to make it more synchronous 156 . Sixty engineers were still working on the Backup Flight System software as late as 1983 157 . *** UNIX is a trademark of AT&T.


Welcome To Spaceline - A Service Of Spaceline, Inc.

Includes fact sheets and brief historical summaries of every rocket and missile program ever flown from Cape Canaveral, with vehicle classification, dimensions, dates of first and last launch, number launched, operational specifications and more.

Cape Canaveral Launch Chronology

Spaceline, Inc. has completed an exclusive Cape Canaveral Launch Chronology for over 3,000 launches from July 24, 1950 to the present, including launch dates, vehicle types, launch sites, payloads and flight results where known.

Cape Canaveral Launch Vehicles Box Score

Includes a complete list of every rocket and missile variant launched from Cape Canaveral presented in an easy-to-read table format, including vehicle type, dates of first and last launch, number launched, sponsors and vehicle type.

Cape Canaveral Launch Facilities

Cape Canaveral Launch Facilities Fact Sheets

Includes fact sheets for every Cape Canaveral launch site, including launch pads, silos, other land sites, aircraft, ships and submarines.

Dates of service, types of vehicles launched and a brief description of each launch site is featured.

Cape Canaveral Launch Sites Box Score

Includes a complete listing of every Cape Canaveral launch site, listed in numerical or alphabetical order, presented in an easy-to-read table format.

Features dates of service plus types and number of vehicles launched.

History Of Cape Canaveral

History Of Cape Canaveral

Tells the story of how 15,000 acres of sand and scrub became America’s gateway to space. Includes an easy-to-read narrative explaining how Cape Canaveral was discovered, settled and developed as a missile test range and spaceport.

History Of The Cape Canaveral Lighthouse

Dedicated to one of the richest historical treasures in the State of Florida, this feature provides a brief account of the history of the Cape Canaveral Lighthouse, explaining why it was constructed in 1868 and how it has survived nearly intact to the present.

History Of Rocketry

This feature presents an easy-to-read overview of the general development of rocketry through the ages, from Chinese fire arrows to the work of rocket pioneers Konstantin Tsiolkovsky, Robert Goddard, Hermann Oberth and Wernher von Braun that led to the rockets and missiles that spurred the development of Cape Canaveral as a missile test range and spaceport.

Spaceline Commemorates The First Rocket Launch From Cape Canaveral

Pieced together in honor of the 50th anniversary of the first rocket launch from Cape Canaveral, this feature provides a factual account and photos of the launch of Bumper #8, serving most of all to clear up many of the myths surrounding this launch.


The History of Space Exploration

During the time that has passed since the launching of the first artificial satellite in 1957, astronauts have traveled to the moon, probes have explored the solar system, and instruments in space have discovered thousands of planets around other stars.

Earth Science, Astronomy, Social Studies, U.S. History, World History

Apollo 11 Astronauts on Moon

A less belligerent, but no less competitive, part of the Cold War between the Soviet Union and the United States was the space race. The Soviet Union bested its rival at nearly every turn, until the United States beat them to the finish line by landing astronauts on the moon. Neil Armstrong and Buzz Aldrin completed that mission in 1969.

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We human beings have been venturing into space since October 4, 1957, when the Union of Soviet Socialist Republics (U.S.S.R.) launched Sputnik, the first artificial satellite to orbit Earth. This happened during the period of political hostility between the Soviet Union and the United States known as the Cold War. For several years, the two superpowers had been competing to develop missiles, called intercontinental ballistic missiles (ICBMs), to carry nuclear weapons between continents. In the U.S.S.R., the rocket designer Sergei Korolev had developed the first ICBM, a rocket called the R7, which would begin the space race.

This competition came to a head with the launch of Sputnik. Carried atop an R7 rocket, the Sputnik satellite was able to send out beeps from a radio transmitter. After reaching space, Sputnik orbited Earth once every 96 minutes. The radio beeps could be detected on the ground as the satellite passed overhead, so people all around the world knew that it was really in orbit. Realizing that the U.S.S.R. had capabilities that exceeded U.S. technologies that could endanger Americans, the United States grew worried. Then, a month later, on November 3, 1957, the Soviets achieved an even more impressive space venture. This was Sputnik II, a satellite that carried a living creature, a dog named Laika.

Prior to the launch of Sputnik, the United States had been working on its own capability to launch a satellite. The United States made two failed attempts to launch a satellite into space before succeeding with a rocket that carried a satellite called Explorer on January 31, 1958. The team that achieved this first U.S. satellite launch consisted largely of German rocket engineers who had once developed ballistic missiles for Nazi Germany. Working for the U.S. Army at the Redstone Arsenal in Huntsville, Alabama, the German rocket engineers were led by Wernher von Braun and had developed the German V2 rocket into a more powerful rocket, called the Jupiter C, or Juno. Explorer carried several instruments into space for conducting science experiments. One instrument was a Geiger counter for detecting cosmic rays. This was for an experiment operated by researcher James Van Allen, which, together with measurements from later satellites, proved the existence of what are now called the Van Allen radiation belts around Earth.

In 1958, space exploration activities in the United States were consolidated into a new government agency, the National Aeronautics and Space Administration (NASA). When it began operations in October of 1958, NASA absorbed what had been called the National Advisory Committee for Aeronautics (NACA), and several other research and military facilities, including the Army Ballistic Missile Agency (the Redstone Arsenal) in Huntsville.

The first human in space was the Soviet cosmonaut Yuri Gagarin, who made one orbit around Earth on April 12, 1961, on a flight that lasted 108 minutes. A little more than three weeks later, NASA launched astronaut Alan Shepard into space, not on an orbital flight, but on a suborbital trajectory&mdasha flight that goes into space but does not go all the way around Earth. Shepard&rsquos suborbital flight lasted just over 15 minutes. Three weeks later, on May 25, President John F. Kennedy challenged the United States to an ambitious goal, declaring: &ldquoI believe that this nation should commit itself to achieving the goal, before the decade is out, of landing a man on the moon and returning him safely to Earth."

In addition to launching the first artificial satellite, the first dog in space, and the first human in space, the Soviet Union achieved other space milestones ahead of the United States. These milestones included Luna 2, which became the first human-made object to hit the Moon in 1959. Soon after that, the U.S.S.R. launched Luna 3. Less than four months after Gagarin&rsquos flight in 1961, a second Soviet human mission orbited a cosmonaut around Earth for a full day. The U.S.S.R. also achieved the first spacewalk and launched the Vostok 6 mission, which made Valentina Tereshkova the first woman to travel to space.

During the 1960s, NASA made progress toward President Kennedy&rsquos goal of landing a human on the moon with a program called Project Gemini, in which astronauts tested technology needed for future flights to the moon, and tested their own ability to endure many days in spaceflight. Project Gemini was followed by Project Apollo, which took astronauts into orbit around the moon and to the lunar surface between 1968 and 1972. In 1969, on Apollo 11, the United States sent the first astronauts to the Moon, and Neil Armstrong became the first human to set foot on its surface. During the landed missions, astronauts collected samples of rocks and lunar dust that scientists still study to learn about the moon. During the 1960s and 1970s, NASA also launched a series of space probes called Mariner, which studied Venus, Mars, and Mercury.

Space stations marked the next phase of space exploration. The first space station in Earth orbit was the Soviet Salyut 1 station, which was launched in 1971. This was followed by NASA&rsquos Skylab space station, the first orbital laboratory in which astronauts and scientists studied Earth and the effects of spaceflight on the human body. During the 1970s, NASA also carried out Project Viking in which two probes landed on Mars, took numerous photographs, examined the chemistry of the Martian surface environment, and tested the Martian dirt (called regolith) for the presence of microorganisms.

Since the Apollo lunar program ended in 1972, human space exploration has been limited to low-Earth orbit, where many countries participate and conduct research on the International Space Station. However, unpiloted probes have traveled throughout our solar system. In recent years, probes have made a range of discoveries, including that a moon of Jupiter, called Europa, and a moon of Saturn, called Enceladus, have oceans under their surface ice that scientists think may harbor life. Meanwhile, instruments in space, such as the Kepler Space Telescope, and instruments on the ground have discovered thousands of exoplanets, planets orbiting other stars. This era of exoplanet discovery began in 1995, and advanced technology now allows instruments in space to characterize the atmospheres of some of these exoplanets.

A less belligerent, but no less competitive, part of the Cold War between the Soviet Union and the United States was the space race. The Soviet Union bested its rival at nearly every turn, until the United States beat them to the finish line by landing astronauts on the moon. Neil Armstrong and Buzz Aldrin completed that mission in 1969.


Program Liftoff

On April 12, 1981, John Young and Robert Crippen launched the space shuttle program by piloting Columbia to space and returning successfully two days later.

In 1983 space shuttle astronaut Sally Ride became the first U.S. woman in space as part of the Challenger crew.

The program was a tremendous success for NASA, but it also endured several tragedies. A string of successful missions was broken in 1986 when Challenger disintegrated seconds after liftoff, killing its seven-person crew.

The space shuttle program was suspended in the wake of the accident, and no shuttles were launched for nearly three years. The program rebounded in April 1990 with the successful mission of Discovery.

Astronauts on this momentous flight placed the Hubble Space Telescope into orbit. This incredible imaging device has subsequently added much to our understanding of the cosmos while returning otherworldly images that bring the universe to life.

In 1995 the space shuttle Atlantis successfully docked at the Russian space station Mir, bringing the two great space programs closer together in an era of cooperation that stood in marked contrast to the early days of the space race.

Tragedy struck again in February 2003 when the program lost its second shuttle: Columbia disintegrated over Texas just 16 minutes before its scheduled landing, and all seven crew members were lost.

Despite this heartbreaking setback, the space shuttle was flying regularly again by 2006. In February 2008 Atlantis delivered the European Space Agency's Columbus laboratory to the ISS. And in February 2010 Endeavour brought up the Cupola, a robotic control station with seven windows that provides the ISS crew with a 360-degree view.


1983-1986: The Missions and History of Space Shuttle Challenger

25-years ago today, Space Shuttle Challenger was lost with all hands in the bright blue sky over Central Florida. Embarking on her 10th mission on January 28, 1986, Challenger was at the time the most-flown orbiter in NASA’s fleet. Quickly rising to prominence as the fleet leader (in terms of not only the number of missions flown, but also her impressive scientific and technological accomplishments), Challenger was the workhorse of the early days of the Shuttle fleet, setting numerous records and leaving behind a legacy of education, inspiration, and safety.

The History of Space Shuttle Challenger:

The early history of Challenger is arguable the most complex of the six Shuttle orbiters (Enterprise, Columbia, Challenger, Discovery, Atlantis, and Endeavour) constructed by NASA in the 1970s, 80s, and 90s.

Beginning life as STA-099 (Structural Test Article -099), the components that would eventually become the airframe and body for orbiter Challenger were initially used by the Space Shuttle Program (SSP) to test and validate the effects of launch and entry stress (including heating) on a “light weight” Shuttle airframe – a weight reduction savings that would, in turn, allow future orbiters (from Challenger through Endeavour) to have a greater payload weight to orbit capability than pioneer orbiter and older sister Columbia.

Since computer technology in the 1970s was not powerful or advanced enough to accurately calculate/predict the effects a “light weight” airframe would have on an orbiter’s performance and ability during launch and entry ops, NASA opted to build STA-099 and submit the Structural Test Article to a year of intense vibration and thermal testing.

To this end, the contract to begin construction of STA-099 was awarded on July 26, 1972 to Rockwell International. For the next three years, components for STA-099 were manufactured simultaneously with components for what would eventually become orbiter Columbia.

On November 21, 1975, engineers began structural assembly of STA-099’s crew module. This was followed on June 14, 1976 by the start of structural assembly of the aft-fuselage.

STA-099’s tell-tale Delta wings arrived on-dock at the Palmdale, California construction facility on March 16, 1977.

Final assembly began later that year on September 30 and was completed on February 10, 1978. STA-099 rolled out of Palmdale on February 14 (Valentine’s Day), 1978.

For the next year, STA-099 was put through the wringer, with numerous vibration and thermal tests to provide and ground the light weight airframe design planned for future Shuttle orbiters.

As stated by Volume II of the NASA Engineering and Safety Center Technical Report from June 14, 2007, “There was a high probability that performing static strength tests to demonstrate ultimate design limits (1.4 times limit load) would result in deformations and strains that [would] render the vehicle unusable for flight.”

Nonetheless, “it was clear the vehicle must be shown to be acceptable at the design limit loads [ref. 19].”

To this end, “a hybrid qualification program was adopted that combined limited flight hardware testing and the validation of stress predictions through the modeling and testing of prototype hardware assemblies and components. “Qualification” tests on STA-099 were performed at 1.2 times the design limit loads.”

Meanwhile, Rockwell was busy finishing the final year of assembly of orbiter Columbia (OV-102) at Palmdale, and NASA was busy reviewing the wealth of data gathered from orbiter Enterprise’s (OV-101’s) free-flight approach and landing tests in 1977 while taking Enterprise through KSC mating, rollout, and launch pad validation ops.

But behind all this, discussions were beginning to focus on the cost and time that would be required to convert Enterprise into a space-worthy vehicle. As the costs and timelines began to build, NASA realized that it would cost less, and take less time, to convert STA-099 into a space-worthy vehicle than it would Enterprise.

On January 1, 1979, the decision was made official when NASA awarded Rockwell International the contract to convert STA-099 into OV-099 (Orbital Vehicle -099). While the process of converting STA-099 into OV-099 was simpler than converting Enterprise, it still involved intensive work and the disassembly and reconstruction of numerous air frame and flight elements.

With conversion of STA-099 into OV-099, the process began of selecting a name for the now-second orbiter of the Shuttle fleet.

Named after the HMS Challenger – a British corvette which served as the command ship for the Challenger Expedition (a pioneering global marine research expedition from 1872-1876) – and the Apollo 17 lunar module, Challenger is the only Shuttle orbiter to be named in honor of a previously-flown spacecraft that landed on the surface of another celestial body.

In an odd coincidence, crews began the start of structural assembly of Challenger’s flight-worthy crew module on January 28, 1979 – exactly 7 years to the day before she would be lost.

From this point, through Nov. 3, 1980, engineers and technicians disassembled and rebuilt Challenger. On Nov. 3, final assembly began and ran through October 21, 1981.

Workers spent the next year going over Challenger with a fine-toothed comb and completing installation of the vehicle’s Thermal Protection System (TPS) tiles and RCC (Reinforced Carbon-Carbon) WLE (Wing Leading Edge) and nose cap panels.

A major change between the construction of Columbia and Challenger was the replacement of TPS tiles with DuPont white nomex felt insulation on her payload bay doors, upper wing surfaces, and rear fuselage. This move further reduced Challenger’s weight by 2,500 lbs.

On June 30, 1982, Challenger rolled out of her Palmdale assembly facility. She was transported overland to Edwards Air Force Base the following day where she spent four days being mated to the Shuttle Carrier Aircraft for her ferry flight delivery to the Kennedy Space Center.

On the day of the beginning of the ferry flight, sister orbiter Columbia triumphantly returned to Earth on July 4 with an Independence Day landing at Edwards Air Force Base to cap off STS-4 and the orbital test flight phase of the Shuttle Program.

With Columbia on the runway at Edwards, Challenger and the SCA took off on July 4 under the watchful eye of then-U.S. President Ronald Reagan. One day later, Challenger arrived at the Kennedy Space Center.

One day after delivery, Challenger was towed into an OPF (Orbiter Processing Facility), where she underwent initial receiving inspections before being transitioned into pre-mission processing for her maiden flight.

Challenger spent nearly 4 months in the OPF before she was moved to the VAB on Nov. 23 for mating with her External Tank/Solid Rocket Booster (ET/SRB) stack. Seven days later, on November 30, 1982, Challenger and the STS-6 stack was rolled out to LC-39A to undergo both pad processing and the mandatory Flight Readiness Firing (FRF) before a targeted January 20, 1983 launch.

On December 18, 1982, the customary 20-second FRF occurred, revealing a hydrogen leak into SSME-1 (Space Shuttle Main Engine 1). Launch was postponed from January 20 and a second FRF was performed on January 25.

The second FRF confirmed the presence of cracks in SSME-1. To the end, all three SSMEs were removed while Challenger was at Pad-A. This marked the first time in Shuttle Program history that the SSMEs were removed at the launch pad.

The second FRF for Challenger also places her in the record books for being the only Shuttle orbiter to require two FRFs before her maiden flight. However, Challenger is not the only orbiter to have two FRFs to her name. Discovery underwent a second FRF during the Return to Flight launch campaign for STS-26 – the mission which returned the Shuttle fleet to flight following the loss of Challenger.

With the removal of all three of Challenger’s SSMEs, the teams thoroughly tested and analyzed SSMEs 2 and 3 before reinstalling them for flight. SSME-1 was completely replaced.

The launch date was then reset before being pushed back yet again due to the contamination of Challenger’s payload – the first Tracking and Data Relay Satellite (TDRS-1) – during a severe storm at the launch pad.

Once the contamination issue was fixed, the launch was rescheduled for April 4 at 1330 EST. The countdown proceeded on schedule and Challenger lifted off on her maiden voyage right on time on April 4, 1983.

Weighing 256,744lbs at launch, Challenger ushered in a series of firsts for the Shuttle Program STS-6. The maiden flight of Challenger marked the first flight of a Space Shuttle from the new MLP-2 (Mobile Launch Platform 2), the first Shuttle flight to use the Light Weight External Tank, the first flight of new light weight SRB casings, the first afternoon launch of a Space Shuttle, and the first time that a second reusable spacecraft flew into space.

On STS-6, Challenger carried Story Musgrave into space – the only person who would go to fly on all five space-worthy Space Shuttle orbiters.

STS-6 also marked the last time that a Space Shuttle mission would launch with a crew of only four astronauts. (However, if STS-135/Atlantis does indeed become a reality, STS-135 will mark the first time since STS-6 that a Shuttle will launch with only four people onboard.)

Launched into a 28.5 degree 178nm orbit, Challenger’s crew successfully deployed the TDRS-1 satellite from the vehicle’s payload bay. A malfunction of TDRS-1’s Inertial Upper Stage (IUS) initially placed the satellite into an improper but stable orbit. Reserve propellant was used to boost TDRS-1 into its properly circularized orbit over the following months.

Following the deployment of TDRS-1, the Challenger crew turned their attention to performing the Shuttle Program’s first spacewalk, or EVA. Lasting 4 hours 17 minutes, Mission Specialists Story Musgrave and Donald Peterson tested the Shuttle Program’s spacesuits, or EMUs, and demonstrated their ability to perform necessary tasks in a microgravity environment.

After 81 orbits of Earth and 2,094,293 miles, Challenger touched down on Runway 22 at Edwards Air Force Base, CA on April 9 at 10:53:42 PST, bringing her total mission duration for her maiden flight to 5 days 2 hours 14 minutes and 25 seconds.

Challenger then underwent initial post-flight deservicing at Edwards before returning to KSC on the SCA on April 16. She was towed into an OPF on April 17 to undergo post-flight deservicing and pre-flight mission processing for STS-7.

After just over a month in the OPF, Challenger was rolled over to the VAB on May 21 and mated to her ET/SRB stack for STS-7. The entire stack was rolled out to LC-39A on May 26 for a targeted June 18 launch.

Pad processing and the launch countdown proceeded nominal and Challenger lifted off right on time (with no launch delays) on her second flight at 07:33 EDT 18 June 1983. Launch of Challenger on STS-7 marked the first flight of an American woman in space and the first re-flight of an astronaut on the Space Shuttle – with Robert L. Crippen from STS-1 commanding Challenger’s second flight.

Launched into a 28.5 degree 160-170nm orbit, Challenger deployed two communications satellites (ANIK C-2 for Canada and PALAPA-B2) for Indonesia.

Seven Get Away Special canisters were also launched in Challenger’s payload bay, as well as an experiment studying the effects of space on the social behavior of an ant colony. Ten experiments were also mounted on Shuttle Pallet Satellite (SPAS-01), experiments designed to perform research in forming metal alloys in microgravity and the use of remote sensing scanners.

During the flight, Challenger’s crew fired the vehicle’s RCS control thrusters while SPAS-01 was held by SRMS (Shuttle Remote Manipulator System) to test the forces of the RCS firings on the extended arm.

STS-7 also marked the first time that a Shuttle orbiter’s Ku-Band antenna was used to transmit data through the TDRS network to a ground terminal.

STS-7 also holds the distinction of being the first Shuttle flight to carry a planned EOM (End of Mission) landing at the Kennedy Space Center however, poor weather conditions at Kennedy precluded a landing of Challenger at the Florida spaceport.

The mission was extended by two orbits to help facilitate a landing at Edwards. Challenger successfully touched down on Runway 15 at Edwards at 06:56.59 PDT on June 24. Rollout distance was 10,450 feet over 75 seconds. Challenger was returned to the Kennedy Space Center on June 29 to begin processing for STS-8.

Challenger then spent June 30 – July 26 inside an OPF before rolling to the VAB for mating with the STS-8 SRB/ET stack. The entire vehicle was then rolled out to Pad-A on August 2 for an August 30 launch.

Initially, STS-8 had carried a July 1983 launch date for a 3-day 4-person mission to deploy the TDRS-B satellite. However, because of IUS issues during the deployment of TDRS-1, the flight was remanifested and TDRS-B pulled from the flight. (TDRS-B would later be remanifested for launch on Challenger’s STS-51E flight before additional problems with the satellite pushed its launch to the fateful STS-51L/Challenger mission.)

Pad processing for STS-8 was uneventful. In the early evening/night hours of Aug. 29/30, a large thunderstorm complex rolled over the Kennedy Space Center during the final few hours of the STS-8 countdown – providing a spectacular image of lightening arcing around Challenger as she sat on Pad-A.

Due to the inclement weather, launch was delayed 17 minutes. At 02:32 EDT, Challenger lit up the night sky of Florida, embarking on her third flight.

Launch of Challenger on STS-8 marked the first night time launch of the Space Shuttle, the 20th overall mission to launch from pad 39A, and the first flight of an African-American into space.

This would also become the first flight for which concern over potential catastrophic failure of the SRBs during flight would begin to build following discovery of SRB flight malfunction during post-flight casing inspections.

With a liftoff weight of 242,742 lbs, Challenger was inserted into 28.5 degree 191nm orbit. Over the course of the six day mission, Challenger’s crew deployed INSAT-1B for India and pointed the nose of Challenger away from the sun for a total of 14 hours to test the vehicle’s flight deck in extreme cold conditions.

During STS-8, Challenger’s orbit was lowered to 139nm to perform tests on thin atomic oxygen in an effort to understand the cause of a glow that had been observed to surround the orbiter during nighttime orbital passes.

Challenger’s SRMS was tested again on this mission to evaluate joint reactions to higher loads. Ku-Band testing/communication with TDRS-1 also continued on this flight to validate the system’s com connections before STS-9 made heavy use of TDRS-1.

Challenger also carried and tested equipment to allow for encrypted communications on future DoD (Department of Defense) dedicated and classified missions.

After 6 days 1 hour 8 minutes and 43 seconds, Challenger glided to a darkened Runway 22 at Edwards at 00:43:43 PDT on September 5 – thereby performing the first night time landing for the Space Shuttle Program.

Challenger was returned to the Kennedy Space Center on September 9 and moved into an OPF the following day. This time, Challenger spent four months in the OPF undergoing processing for the STS-41B flight. Just prior to OPF rollout, all three of Challenger’s Auxiliary Power Units (APUs) were removed and replaced (R&Red) as a precautionary measure following APU failures on Columbia’s STS-9 mission. As a result, the launch date for this mission was postponed from Jan. 29 to February 3.

On January 6, 1984, Challenger was finally rolled to the VAB. Six days later, the STS-41B stack was rolled out to Pad-A where processing occurred with just a few minor issues/hiccups.

Challenger lifted off right on time at 08:00 EST on February 3 on her fourth launch to begin the 10th Space Shuttle mission and the first under the new flight classification system. Had the previous numerical designation continued, this would have been the STS-11 mission.

(Incidentally, Challenger would be the first Shuttle orbiter to launch under the new classification system as well as the last orbiter to do so. NASA would revert back to the straight up numerical flight designation system following the loss of Challenger on STS-51L.)

Like her three previous missions, Challenger was inserted into a 28.5 degree 189nm orbit. Once in orbit, Challenger’s crew deployed the WESTAR-VI and PALAPA-B2 satellites and Bruce McCandless and Robert L. Stewart performed the first untethered EVA in history using the Manned Maneuvering Unit (McCandless) and the SRMS foot restraint for EVA purposes (Stewart). During this EVA, McCandless became the first human Earth-orbiting satellite when he ventured 320 feet away from Challenger.

Also carried aboard Challenger on this flight was the German-built Shuttle Pallet Satellite – which became the first satellite to be refurbished and re-flown into space following its first flight on STS-7. An electrical problem with SRMS, however, precluded the deployment of the satellite as intended.

After 7 days 23 hours 15 minutes and 55 seconds, Challenger triumphantly reentered Earth’s atmosphere to conduct the first EOM landing of a Space Shuttle at the Kennedy Space Center. Landing occurred on February 11 at 07:15:55 EST on KSC Runway 15. Rollout distance was 10,815 feet over 67 seconds.

Challenger was returned to the OPF later that day where she spent just over a month in pre-flight processing for STS-41C. On March 14, she was moved to the VAB. The STS-41C stack was rolled out to Pad-A on March 19 ahead of an April 6 launch.

Pad processing once again proceeded without issue, and on April 6, 1984 at 08:58 EST, Challenger lifted off right on time on her first attempt to begin her 5th mission.

The launch of STS-41C marked the first direct ascent trajectory for the Space Shuttle Program and the mission itself marked the first time that a Shuttle mission was on orbit on the anniversary of the first Space Shuttle flight (April 12).

Launched into a 28.5 degree 288nm high orbit, Challenger’s crew deployed the Long Duration Exposure Facility into Earth orbit for retrieval on a later Shuttle flight.

After this, Challenger’s orbit was raised to 313nm so that the crew could rendezvous, grapple, repair, and re-deploy the Solar Max satellite. Initial attempts by Mission Specialist George “Pinky” Nelson to manually grapple Solar Max with a special capture tool failed.

Nelson then tried to physically grab the satellite, but that sent the satellite into a multi-axis spin. In the overnight hours, the Goddard Spaceflight Center was able to regain control of the satellite. With the satellite stable, Challenger’s crew grappled the satellite with the SRMS and the crew turned their attention toward using the Manned Maneuvering Unit – tested on the previous flight – to replace the altitude control system and coronagraph/polarimeter electronics box in the Solar Max satellite.

The EVA activities were filmed by an IMAX camera in Challenger’s payload bay. The footage eventually became part of the “The Dream is Alive” documentary.

Challenger landed successfully on April 13 at 05:38:07 PST on Runway 17 at Edwards and was returned to the Kennedy Space Center on April 18. This would mark the final flight of the Shuttle with a fleet of only two orbiters. The next mission, STS-41D, would mark the addition of sister Discovery to the fleet.

However, due to lengthy delays with Discovery’s launch, Challenger ended up spending nearly five months in the OPF for STS-41G – the longest OPF stay for Challenger. On September 8, Challenger rolled to the VAB and out to Pad-A on September 13 ahead of a planned Oct. 5th launch.

Remarkably, pad processing and the launch countdown proceeded nominally with no major issues. At 07:03 EDT on October 5, Challenger lifted off into the morning sky on the 13th Space Shuttle flight.

Unlike all of Challenger’s previous missions, this flight was launched into a 57 degree 218nm orbit. The flight marked the first time a Shuttle carried a crew of seven into space, the first time two women flew into space together (and the first time two women were in space at the same time), the first time a Canadian flew into space, the first time an Australian-born person flew into space, and the first spacewalk to involve a woman.

During the 8-day flight, Challenger’s crew deployed the Earth Radiation Budget Satellite and, through an EVA, connected Components of Orbital Refueling System – thereby demonstrating that it was possible to refuel a satellite in orbit. During this EVA, Kathryn Sullivan became the first woman to perform a spacewalk.

On October 13, Challenger returned to Earth conducting the second landing of the Space Shuttle at the Kennedy Space Center. This flight would go down as Challenger’s longest mission, clocking in at 8 days 5 hours 23 minutes 33 seconds.

Challenger was then returned to the OPF where she began processing for STS-51E to deploy the TDRS-B satellite.

After four months in the OPF, Challenger was rolled over to the VAB on February 10 and then out to Pad-A on February 15. Initially, pad processing went smoothly until timing issues were encountered with TDRS-B.

The issues became severe enough that NASA pulled STS-51E from the launch manifest and cancelled the mission.

Challenger was rolled back from the launch pad on March 4, 1985 and returned to her OPF on March 7. NASA then remanifested Challenger for the STS-51B mission and OPF processing proceeded through April 10.

Challenger was mated to her STS-51B ET/SRB stack on April 10 and rolled out to Pad-A on April 15 ahead of a planned April 29 launch – only 14-days after Challenger arrived at the pad.

Pad processing proceeded smoothly. On April 29 a launch processing system failure forced a 2 minute 18 second delay to launch. At 12:02:18 EDT Challenger left Pad-A on her 7th flight and the Space Shuttle Program’s 17th.

During post-flight inspections of the SRBs for this mission, it was discovered that one of the SRBs suffered from a failure similar to the one that would be experienced on STS-51L.

Sadly, this was the second serious O-ring issue identified in 2.5 months. During the January 24, 1985 launch of Discovery/STS-51C, the primary O-rings in both the Right-Hand and Left-Hand SRBs were found to be severely charred. But it was the discovery of the complete burn-through/penetration of the primary O-ring and heavy charring and degradation of the secondary O-ring in the center field joint of the right STS-51C SRB that caused the greatest concern.

Investigations into the failure of the O-rings on STS-51C led to the understanding that the cold temperatures at the time of Discovery’s launch significantly reduced the sealing power of the O-rings. The temperature at the time of the 51C launch was 53 degrees F.

Sadly, both of these O-ring warnings would be ignored, and temperatures at the time of the 51L/Challenger launch one year later would be nearly 20 degrees colder than during 51C.

Nonetheless, Challenger successful obtained a 57 degree 222nm orbit for STS-51B, where she performed 15 primary experiments divided into five basic disciplines: materials sciences, life sciences, fluid mechanics, atmospheric physics, and astronomy via the European Spacelab-3 – flying here for the first time in a fully operational configuration.

Of the 15 primary experiments, 14 were deemed successful. Challenger landed successfully on May 6 at 09:11:04 PDT at Edwards.

After returning to the Kennedy Space Center, Challenger was in an OPF from May 12 – June 24, before being rolled to the VAB for mating and then out to Pad-A on June 29 ahead of a planned July 12 launch on STS-51F.

Pad processing proceeded nominally, as did the countdown. On July 12, the Ground Launch Sequencer handed off control of the countdown and Challenger’s critical systems to Challenger’s onboard computers at T-31secs.

At T-6.6 seconds, with all systems polling “go,” Challenger’s computers sent the commands to start the SSMEs in a 120-millisecond staggered start sequence beginning with SSME-3.

All three engines came up and began building up to full thrust.

At T-3seconds, Challenger’s computers registered a malfunction in SSME-2’s coolant valve and immediately tripped an RSLS (Redundant Set Launch Sequencer) abort. Commands to shut down SSME-2 were transmitted immediately, as were commands to inhibit the launch sequence, safe the SRB pyros, and shutdown SSMEs 3 and 1.

Thanks to the safety upgrades put in place following the STS-41D/Disocvery post-SSME start RSLS abort, post-abort safing was conducted in a methodical manner.

In the following two weeks, Challenger’s SSMEs were replaced at the launch pad and the launch was reset for July 29, 1985.

On that day, the launch was delayed 1 hour 37 minutes due to a problem with the table maintenance block update uplink. With that issue resolved, the countdown resumed and Challenger launched at 17:00 EDT on her 8th mission.

However, 3mins 13secs into the flight, one of two high pressure fuel turbopump turbine discharge temperature sensors for SSME-1 failed, leaving only one sensor active on the engine. Two minutes 12 seconds later, at Mission Elapsed Time 5mins 43secs, the second sensor failed, triggering the immediate shutdown of SSME-1.

To date, this is the only occurrence of an engine shutdown during launch for the Space Shuttle.

The shutdown of SSME-1 significantly lowered the thrust profile for Challenger and triggered the only in-flight abort in Shuttle Program history: an Abort To Orbit (ATO) which allowed Challenger and her seven-member crew to reach a lower-than-planned but safe and stable orbit.

Nonetheless, before Challenger could complete her prolonged ascent (nearly 9mins 45secs in duration due to the lost thrust from SSME-1), an identical high pressure turbopump temperature sensor failure occurred in SSME-2.

Booster Systems Engineer Jenny M. Howard in Mission Control Houston acted immediately, instructing the crew to inhibit any further automatic SSME shutdowns based on readings from the remaining sensors. This quick action prevented the loss of another engine and a possible abort scenario far more risky or far worse than the already in-progress ATO.

When Challenger finally reached orbit, several aspects of the mission were retooled to account for the lower-than-planned orbital altitude.

The flight’s primary payload was Spacelab-2, with the main mission objectives being the verification of performance of Spacelab systems and the determination of interface capability of the Shuttle orbiter.

STS-51F marked the first time the European Space Agency’s Instrument Point System was tested in orbit… with verification of its accuracy to one arc second.

After 7 days 22 hours 45 minutes and 26 seconds in space, Challenger touched down on Runway 23 at Edwards at 12:45:26 EDT on August 6. She was returned to the Kennedy Space Center on August 11.

Challenger then spent exactly 2 months in the OPF while processing for STS-61A, before rolling to the VAB on Oct. 12. The STS-61A stack was rolled out to Pad-A on Oct. 16 for an October 30 launch.

Yet again, pad processing proceeded nominally and Challenger lifted off right on time on her first attempt at 12-noon EST on October 30.

Launch of STS-61A marked the 22nd flight of the Space Shuttle, the 9th flight of Challenger, and the first and only time in history when eight people launched into space at the same time on the same vehicle.

Launched into a 57 degree 207nm orbit, Challenger’s flight was dedicated entirely to the German Spacelab (D-1) mission. The Spacelab mission encompassed 75 numbered experiments, most of which were performed more than once.

While Challenger herself was controlled through Mission Control Houston, the scientific operations were controlled from the German Space Operations Center at Oberpfaffenhofen, near Munich

Challenger glided back to Earth on November 6, landing on Runway 17 at Edwards at 09:44:51 PST. Rollout distance was 8,304 feet over 49 seconds.

Challenger was returned to the Kennedy Space Center on November 11, where she began processing for the long-awaited and much anticipated STS-51L mission.

Spending just over a month in the OPF, Challenger was rolled to the VAB on December 16 for mating with her ET and SRB stack.

The entire STS-51L stack was moved to Launch Complex 39B on December 22, 1985. With the rollout of Challenger to Pad-B, it marked the first time a Space Shuttle orbiter graced Pad-B as well as the first of 19 times in SSP history when both Shuttle launch pads at Kennedy were occupied simultaneously. (Columbia was on Pad-A following the mounting delays to her STS-61C mission).

When Challenger arrived at Pad-B, her primary payload, the TDRS-B satellite was loaded into her payload bay, and processing continued toward a targeted launch date of January 22, 1986 at 15:43 EST.

However, due to delays to the STS-61C mission, the launch date was slipped to the January 23, then 24th.

The launch was then moved again to January 25 due to unacceptable weather conditions at the mission’s Transoceanic Abort Landing (TAL) site in Dakar, Senegal. The decision was then made to utilize Casablanca as an alternate TAL site. However, since Casablanca was not equiped to handle a night landing, the launch time on January 25 was moved to the morning.

The launch was then quickly delayed again to January 26 when ground teams were unable to meet the new target launch time. The forecast for unacceptable launch site weather on January 26 then prompted launch personnel to move the launch to January 27.

The weather on January 26 would have been more than acceptable for launch.

On January 27, Challenger’s flight crew boarded the vehicle and all appeared to be going well, with the only concern being winds at the Shuttle Landing Facility (SLF).

However, when the closeout crew went to close and lock Challenger’s hatch for flight, they were unable to remove the locking tool from the hatch. Numerous attempts to the remove the tool failed. Eventually, a saw was delivered to Pad-B and the tool sawed off and the attaching bolt drilled out.

The closeout crew then continued and finished closeout operations. However, during the delay caused by this issue, crosswinds at the SLF exceed RTLS (Return to Launch Site) abort limits and the launch was scrubbed for 24hrs.

In the overnight hours, temperatures at the launch pad dropped into the teens (degrees F). Water pipes at the launch pad were opened to prevent them from freezing and bursting, thus creating icicles of significant length on the launch pad structure.

Fueling of Challenger’s External Tank began in the early morning hours. Launch was delayed by two hours when the hardware interface module in the launch processing system, which monitors fire detection systems, failed during liquid hydrogen loading.

With the resolution of this issue and Challenger’s ET fully fueled, Challenger’s flight crew – Commander Francis R. Scobee, Pilot Michael J. Smith, Mission Specialist 1 (MS 1) Judith A. Resnik, MS2/Flight Engineer Ellison Onizuka, MS3 Ronald E. McNair, Payload Specialist 1 (PS 1) Gregory B. Jarvis, and PS2 Sharon Christa McAuliffe – once again boarded Challenger.

Final polls were conducted and all stations polled “go” for launch.

At 11:38 EST on the dot, Challenger’s SRBs ignited and the Space Shuttle Challenger launched on the 25th Space Shuttle flight, which was her 10th flight and first Space Shuttle flight from Pad-B.

Challenger executed a 90-degree roll off Pad-B, to place her onto the proper alignment for a 28.5 degree inclination orbit, and climbed quickly and gracefully into the crystal clear Florida sky.

At 11:39:13 EST on January 28, 1986, the Space Shuttle Challenger and her seven member crew slipped from view.

Addressing a grieving and disheartened nation that night, President Ronald Reagan stated: “Today is a day for mourning and remembering. Nancy and I are pained to the core by the tragedy of the shuttle Challenger. We know we share this pain with all of the people of our country. This is truly a national loss.

“And perhaps we’ve forgotten the courage it took for the crew of the shuttle. But they, the Challenger Seven, were aware of the dangers, but overcame them and did their jobs brilliantly. We mourn seven heroes: Michael Smith, Dick Scobee, Judith Resnik, Ronald McNair, Ellison Onizuka, Gregory Jarvis, and Christa McAuliffe.

“For the families of the seven, we cannot bear, as you do, the full impact of this tragedy. But we feel the loss, and we’re thinking about you so very much. Your loved ones were daring and brave, and they had that special grace, that special spirit that says, ‘Give me a challenge, and I’ll meet it with joy.’ They had a hunger to explore the universe and discover its truths. They wished to serve, and they did. They served all of us.

“We’ve grown used to wonders in this century. It’s hard to dazzle us. But for twenty-five years the United States space program has been doing just that. We’ve grown used to the idea of space, and, perhaps we forget that we’ve only just begun. We’re still pioneers. They, the members of the Challenger crew, were pioneers.

“And I want to say something to the schoolchildren of America who were watching the live coverage of the shuttle’s take-off. I know it’s hard to understand, but sometimes painful things like this happen. It’s all part of the process of exploration and discovery. It’s all part of taking a chance and expanding man’s horizons. The future doesn’t belong to the fainthearted it belongs to the brave. The Challenger crew was pulling us into the future, and we’ll continue to follow them.

“I’ve always had great faith in and respect for our space program. And what happened today does nothing to diminish it. We don’t hide our space program. We don’t keep secrets and cover things up. We do it all up front and in public. That’s the way freedom is, and we wouldn’t change it for a minute.

“We’ll continue our quest in space. There will be more shuttle flights and more shuttle crews and, yes, more volunteers, more civilians, more teachers in space. Nothing ends here our hopes and our journeys continue.

“I want to add that I wish I could talk to every man and woman who works for NASA, or who worked on this mission and tell them: ‘Your dedication and professionalism have moved and impressed us for decades. And we know of your anguish. We share it.’

“There’s a coincidence today. On this day three hundred and ninety years ago, the great explorer Sir Francis Drake died aboard ship off the coast of Panama. In his lifetime the great frontiers were the oceans, and a historian later said, ‘He lived by the sea, died on it, and was buried in it.’ Well, today, we can say of the Challenger crew: Their dedication was, like Drake’s, complete.

“The crew of the space shuttle Challenger honored us by the manner in which they lived their lives. We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and ‘slipped the surly bonds of earth to ‘touch the face of God.'”

During the course of the planned 6 day mission, Challenger’s crew would have deployed TDRS-B on Flight Day 1 (FD 1).

On Flight Day 2, the Comet Halley Active Monitoring Program (CHAMP) experiment was scheduled to begin. Also scheduled were the initial “teacher in space” video tapings. A firing of the OMS engines to place Challenger at the 152-mile orbital altitude from which the Spartan satellite would be deployed was also scheduled.

On Flight Day 3, the crew was to begin pre-deployment preparations on Spartan before deploying the satellite using the SRMS.

On Flight Day 4, the Challenger was to begin closing on Spartan while Gregory B. Jarvis continued fluid dynamics experiments started on FD-2 and FD-3. Live telecasts were also planned to be conducted by Christa McAuliffe.

On Flight Day 5, the crew was to rendezvous with Spartan and use the SRMS to capture the satellite and re-stow it in the payload bay.

On Flight Day 6, re-entry preparations were scheduled, followed on FD-7 by reentry and landing at the Kennedy Space Center.

Yet, Challenger’s mission objectives – deploying TDRS-B and flying a teaching in space – would be carried our by her sisters. TDRS-B’s replacement was deployed by Discovery during the STS-26 Return to Flight mission in September 1988.

But perhaps most fitting, school teacher Barbara Morgan, Christa McAuliffe’s backup, would realize her and Christa’s dream on August 8, 2007 when she launched as a full Mission Specialist on Space Shuttle Endeavour’s – Challenger’s replacement – STS-118 mission to the International Space Station.

In all, Space Shuttle Challenger deployed 10 satellites in her 10 mission career. She spent a total of 62 days 7 hours 56 minutes and 22 seconds in space, travelling 25,803,936 miles in 995 orbits of Earth.

And as we pause today to remember the Challenger crew, it is of great importance to remember the cause for which they freely served: the pursuit of scientific knowledge, education, and understanding. This is the cause for which we continue to fly, and cause for which we can never forget.


NASA's Actions to Implement the Rogers Commission Recommendations after the Challenger Accident

Editorial Note: This document is taken from Actions to Implement the Recommendations of The Presidential Commission on the Space Shuttle Challenger Accident , Executive Summary, July 14, 1986. Copy available in NASA Historical Reference Collection, History Office, NASA Headquarters, Washington, DC.

On June 13, 1986, the President directed NASA to implement, as soon as possible, the recommendations of the Presidential Commission on the Space Shuttle Challenger Accident. The President requested that NASA report, within 30 days, how and when the recommendations will be implemented, including milestones by which progress can be measured.

In the months since the Challenger accident, the NASA team has spent many hours in support of the Presidential Commission on the Space Shuttle Challenger Accident and in planning for a return of the Shuttle to safe flight status. Chairman William P. Rogers and the other members of the Commission have rendered the Nation and NASA an exceptional service. The work of the Commission was extremely thorough and comprehensive. NASA agrees with the Commission's recommendations and is vigorously pursuing the actions required to implement and comply with them.

As a result of the efforts in support of the Commission, many of the actions required to safely return the Space Shuttle to flight status have been under way since March. On March 24, 1986, the Associate Administrator for Space Flight outlined a comprehensive strategy, and defined major actions, for safely returning to flight status. The March 24 memorandum (Commission Activities: An Overview) provided guidance on the following subjects:

  • actions required prior to next flight,
  • first flight/first year operations, and
  • development of sustainable safe flight rate.

The Commission report was submitted to the President on June 9, 1986. Since that time, NASA has taken additional actions and provided direction required to comply with the Commission's recommendations.

The NASA Administrator and the Associate Administrator for Space Flight will participate in the key management decisions required for implementing the Commission recommendations and for returning the Space Shuttle to flight status. NASA will report to the President on the status of the implementation program in June 1987.

The Commission report included nine recommendations, and a summary of the implementation status for each is provided:

RECOMMENDATION I

Solid Rocket Motor Design :

On March 24, 1986, the Marshall Space Flight Center (MSFC) was directed to form a Solid Rocket Motor (SSRM) joint redesign team to include participation from MSFC and other NASA centers as well as individuals from outside NASA. The team includes personnel from Johnson Space Center, Kennedy Space Center, Langley Research Center,

industry, and the Astronaut Office. To assist the redesign team, an expert advisory panel was appointed which includes 12 people with six coming from outside NASA.

The team has evaluated several design alternatives, and analysis and testing are in progress to determine the preferred approaches which minimize hardware redesign. To ensure adequate program contingency in this effort, the redesign team will also develop, at least through concept definition, a totally new design which does not utilize existing hardware. The design verification and certification program will be emphasized and will include tests which duplicate the actual launch loads as closely as feasible and provide for tests over the full range of operating conditions. The verification effort includes a trade study which has been under way for several weeks to determine the preferred test orientation (vertical or horizontal) of the full-scale motor firings. The Solid Rocket Motor redesign and certification schedule is under review to fully understand and plan for the implementation of the design solutions as they are finalized and assessed. The schedule will be reassessed after the SRM Preliminary Design Review in September 1986. At this time it appears that the first launch will not occur prior to the first quarter of 1988.

In accordance with the Commission's recommendation, the National Research Council (NRC) has established an Independent Oversight Group chaired by Dr. H. Guyford Stever and reporting to the NASA Administrator. The NRC Oversight Group has been briefed on Shuttle system requirements, implementation, and control Solid Rocket Motor background and candidate modifications. The group has established a near-term plan that includes briefings and visits to review inflight loads assembly processing redesign status and other solid rocket motor designs, including participation in the Solid Rocket Motor preliminary design review in September 1986.

RECOMMENDATION II

Shuttle Management Structure:

The Administrator has appointed General Sam Phillips, who served as Apollo Program Director, to study every aspect of how NASA manages its programs, including relationships between various field centers and NASA Headquarters. General Phillips has broad authority from the Administrator to explore every aspect of NASA organization, management and procedures. His activities will include a review of the Space Shuttle management structure.

On June 25, 1986, Astronaut Robert Crippen was directed to form a fact-finding group to assess the Space Shuttle management structure. The group will report recommendations to the Associate Administrator for Space Flight by August 15, 1986. Specifically, this group will address the roles and responsibilities of the Space Shuttle Program Manager to assure that the position has the authority commensurate with its responsibilities. In addition, roles and responsibilities at all levels of program management will be reviewed to specify the relationship between the program organization and the field center organizations. The results of this study will be reviewed with General Phillips and the Administrator with a decision on implementation of the recommendations by October 1, 1986.

Rear Admiral Richard Truly, a former astronaut, has been appointed as Associate Administrator for the Office of Space Flight. Several active astronauts are currently serving in management positions in the agency. The Crippen group will address means to stimulate the transition of astronauts into other management positions. It will also determine the appropriate position for the Flight Crew Operations Directorate within the NASA organizational structure.

A Shuttle Safety Panel will be established by the Associate Administrator for Space Flight not later than September 1, 1986, with direct access to the Space Shuttle Program Manager. This date allows time to determine the structure and function of this panel, including an assessment of its relationship to the newly formed Office of Safety, Reliability, and Quality Assurance, and to the existing Aerospace Safety Advisory Panel.

RECOMMENDATION III

Critical Item Review and Hazard Analysis:

On March 13, 1986, NASA initiated a complete review of all Space Shuttle program failure modes and effects analyses (FEMEA's) and associated critical item lists (CIL's). Each Space Shuttle project element and associated prime contractor is conducting separate comprehensive reviews which will culminate in a program-wide review with the Space Shuttle program have been assigned as formal members of each of these review teams. All Criticality 1 and 1R critical item waivers have been cancelled. The teams are required to reassess and resubmit waivers in categories recommended for continued program applicability. Items which cannot be revalidated will be redesigned, qualified, and certified for flight. All Criticality 2 and 3 CIL's are being reviewed for reacceptance and proper categorization. This activity will culminate in a comprehensive final review with NASA Headquarters beginning in March 1987.

As recommended by the Commission, the National Research Council has agreed to form an Independent Audit Panel, reporting to the NASA Administrator, to verify the adequacy of this effort.

RECOMMENDATION IV

The NASA Administrator announced the appointment of Mr. George A. Rodney to the position of Associate Administrator for Safety, Reliability, and Quality Assurance on July 8, 1986. The responsibilities of this office will include the oversight of safety, reliability, and quality assurance functions related to all NASA activities and programs and the implementation of a system for anomaly documentation and resolution to include a trend analysis program. One of the first activities to be undertaken by the new Associate Administrator will be an assessment of the resources including workforce required to ensure adequate execution of the safety organization functions. In addition, the new Associate Administrator will assure appropriate interfaces between the functions of the new safety organization and the Shuttle Safety Panel which will be established in response to the Commission Recommendation II.

RECOMMENDATION V

On June 25, 1986, Astronaut Robert Crippen was directed to form a team to develop plans and recommended policies for the following:

  • Implementation of effective management communications at all levels.
  • Standardization of the imposition and removal of STS launch constraints and other operational constraints.
  • Conduct of Flight Readiness Review and Mission Management Team meetings, including requirements for documentation and flight crew participation.

Since this recommendation is closely linked with the recommendation on Shuttle management structure, the study team will incorporate the plan for improved communications with that for management restructure.

This review of effective communications will consider the activities and information flow at NASA Headquarters and the field centers which support the Shuttle program. The study team will present findings and recommendations to the Associate Administrator for Space Flight by August 15, 1986.

RECOMMENDATION VI

A Landing Safety Team has been established to review and implement the Commission's findings and recommendations on landing safety. All Shuttle hardware and systems are undergoing design reviews to insure compliance with the specifications and safety concerns. The tires, brakes, and nose wheel steering system are included in this activity, and funding for a new carbon brakes system has been approved. Runway surface tests and landing aid requirement reviews had been under way for some time prior to the accident and are continuing. Landing aid implementation will be complete by July 1987. The interim brake system will be delivered by August 1987. Improved methods of local weather forecasting and weather-related support are being developed. Until the Shuttle program has demonstrated satisfactory safety margins through high fidelity testing and during actual landings at Edwards Air Force Base, the Kennedy Space Center landing site will not be used for nominal end-of-mission landings. Dual Orbiter ferry capability has been an issue for some time and will be thoroughly considered during the upcoming months.

RECOMMENDATION VII

Launch Abort and Crew Escape:

On April 7, 1986, NASA initiated a Shuttle Crew Egress and Escape review. The scope of this analysis includes egress and escape capabilities from launch through landing and will provide analyses, concepts, feasibility assessments, cost, and schedules for pad abort, bailout, ejection systems, water landings, and powered flight separation. This review will specifically assess options for crew escape during controlled gliding flight and options for extending the intact abort flight envelope to include failure of 2 or 3 main engines during the early ascent phase. In conjunction with this activity, a Launch Abort Reassessment Team was established to review all launch and launch abort rules to ensure that launch commit criteria, flight rules, range safety systems and procedures, landing aids, runway configurations and lengths, performance versus abort exposure, abort and end-of-mission landing weights, runway surfaces, and other landing-related capabilities provide the proper margin of safety to the vehicle and crew. Crew escape and launch abort studies will be complete on October 1, 1986, with an implementation decision in December 1986.

RECOMMENDATION VIII

In March 1986 NASA established a Flight Rate Capability Working Group. Two flight rate capability studies are under way:

  1. a study of capabilities and constraints which govern the Shuttle processing flows at the Kennedy Space Center and
  2. a study by the Johnson Space Center to assess the impact of flight specific crew training and software delivery/certification on flight rates.

The working group will present flight rate recommendations to the Office of Space Flight by August 15, 1986. Other collateral studies are still in progress which address Presidential Commission recommendations related to spares provisioning, maintenance, and structural inspection. This effort will also consider the National Research Council independent review of flight rate which is under way as a result of a Congressional Subcommittee request.

NASA strongly supports a mixed fleet to satisfy launch requirements and actions to revitalize the United States expendable launch vehicle capabilities.

Additionally, a new cargo manifest policy is being formulated by NASA Headquarters which will establish manifest ground rules and impose constraints to late changes. Manifest control policy recommendations will be completed in November 1986.

RECOMMENDATION IX

A Maintenance Safeguards Team has been established to develop a comprehensive plan for defining and implementing actions to comply with the Commission recommendations concerning maintenance activities. A Maintenance Plan is being prepared to ensure that uniform maintenance requirements are imposed on all elements of the Space Shuttle program. This plan will define the structure that will be used to document

  1. hardware inspections and schedules,
  2. planned maintenance activities,
  3. Maintenance procedures configuration control, and
  4. Maintenance logistics.

The plan will also define organizational responsibilities, reporting, and control requirements for Space Shuttle maintenance activities. The maintenance plan will be completed by September 30, 1986.

A number of other activities are underway which will contribute to a return to safe flight and strengthening the NASA organization. A Space Shuttle Design Requirements Review Team headed by the Space Shuttle Systems Integration Office at Johnson Space Center has been assigned to review all Shuttle design requirements and associated technical verification. The team will focus on each Shuttle project element and on total Space Shuttle system design requirements. This activity will culminate in a Space Shuttle Incremental Design Certification Review approximately 3 months prior to the next Space Shuttle Launch.

In consideration of the number, complexity, and interrelationships between the many activities leading to the next flight, the Space Shuttle Program Manager at Johnson Space Center has initiated a series of formal Program Management Reviews for the Space Shuttle program. These reviews are structured to be regular face-to-face discussions involving the managers of all major Space Shuttle program activities.

Specific subjects to be discussed at each meeting will focus on progress, schedules, and actions associated with each of the major program review activities and will be tailored directly to current program activity for the time period involved. The first of these meetings was held at Marshall Space Flight Center on May 5-6, 1986, with the second at Kennedy Space Center on June 25, 1986. Follow-on reviews will be held approximately every 6 weeks. Results of these reviews will be reported to the Associate Administrator for Space Flight and to the NASA Administrator.

On June 19, 1986, the NASA Administrator announced termination of the development of the Centaur upper stage for use aboard the Space Shuttle. Use of the Centaur upper stage was planned for NASA planetary spacecraft launches as well as for certain national security satellite launches. Majority safety reviews of the Centaur system were under way at the time of the Challenger accident, and these reviews were intensified in recent months to determine if the program should be continued. The final decision to terminate the Centaur stage for use with the Shuttle was made on the basis that even following certain modifications identified by the ongoing reviews, the resultant stage would not meet safety criteria being applied to other cargo or elements of the Space Shuttle System. NASA has initiated efforts to examine other launch vehicle alternatives for the major NASA planetary and scientific payloads which were scheduled to utilize the Centaur upper stage. NASA is providing assistance to the Department of Defense as it examines alternatives for those national security missions which had planned to use the Shuttle/Centaur.

The NASA Administrator has announced a number of Space Station organizational and management structural actions designed to strengthen technical and management capabilities in preparation for moving into the development phase of the Space Station program. The decision to create the new structure is the result of recommendations made to the Administrator by a committee, headed by General Phillips, which is conducting a long range assessment of NASA's overall capabilities and requirements.

Finally, NASA is developing plans for increased staffing in critical areas and is working closely with the Office of Personnel Management to develop a NASA specific proposal which would provide for needed changes to the NASA personnel management system to strengthen our ability to attract, retain, and motivate the quality workforce required to conduct the NASA mission.


Timeline: U.S. Space Program History

Milestones and other notable events in the U.S. history of human space exploration:

— May 5, 1961: U.S. launches first American, astronaut Alan Shepard Jr., into space, on a 15-minute, 22-second suborbital flight.

— May 25, 1961: President Kennedy declares the American national space objective to put a man on the moon.

— Feb. 20, 1962: John Glenn becomes first American to orbit Earth.

— Jan. 27, 1967: Three U.S. astronauts die when a fire sweeps the Apollo I command module during a ground test at Kennedy Space Center.

— Dec. 21, 1968: First manned spacecraft to orbit moon, Apollo 8, comes within 70 miles of lunar surface.

— July 20, 1969: Neil Armstrong and Edwin Aldrin of Apollo XI spend 21 hours on the moon, 2 of those outside the capsule.

— Dec. 7-19, 1972: Apollo 17 mission that includes the longest and last stay of man on the moon — 74 hours, 59 minutes — by astronauts Eugene Cernan and Harrison Schmidt.

— May 14, 1973: Skylab I, first U.S. orbiting laboratory, launched.

— July 17-19, 1975: U.S. astronauts and Soviet cosmonauts participate in Apollo-Soyuz Test Project, docking together in space for two days.

— April 12, 1981: Shuttle Columbia becomes first winged spaceship to orbit Earth and return to airport landing.

— June 18, 1983: Sally Ride becomes first American woman in space.

— Feb. 7, 1984: Astronaut Bruce McCandless performs man's first untethered spacewalk with a Manned Maneuvering Unit off the Challenger space shuttle.

— Jan. 28, 1986: Challenger shuttle explodes 73 seconds after launch, killing its crew of seven.

— March 14, 1995: Norman Thagard becomes first American to be launched on a Russian rocket. Two days later, he becomes first American to visit the Russian space station Mir.

— June 29, 1995: Atlantis docks with Mir in first shuttle-station hookup.

— Sept. 26, 1996: Shannon Lucid returns to Earth after 188-day Mir mission, a U.S. space endurance record and a world record for women.

— Oct. 29, 1998: Glenn, now 77, returns to space aboard shuttle Discovery, becoming the oldest person ever to fly in space.

— May 29, 1999: Discovery becomes first shuttle to dock with the international space station, a multinational, permanent, orbiting research laboratory.

— Nov. 2, 2000: An American and Russian crew begins living aboard the international space station.

— Feb. 1, 2003: Shuttle Columbia breaks apart over Texas, 16 minutes before it was supposed to land in Florida.


Brief History of Endeavour

Built to replace space shuttle Challenger, Endeavour was the final orbiter to join the shuttle fleet. Many newer features were added to Endeavour during construction, such as updated steering mechanisms, upgraded plumbing and electrical connections to allow for longer missions, and a drag chute that reduced wear and tear on the shuttle's brakes and tires. Many of the innovations that were developed for Endeavour were added later to the other shuttles in the fleet.

Endeavour first launched on May 7, 1992 for mission STS-49. The crew's primary goal during that mission was to repair and release a communications satellite (INTELSAT VI) back into orbit. The capture of the satellite did not go as smoothly as planned, but the crew aboard was able to complete the mission through a series of four spacewalks—the most ever completed on a shuttle mission up to that time. One of the spacewalks was the longest ever recorded up to that time, and the second-longest ever—over eight hours! That first mission set a precedent for Endeavour, whose string of 25 missions was marked with ingenuity and success.


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