Space shuttle

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Space shuttle
The Atlantis takes off on the STS-115 mission
The Atlantis takes off on the STS-115 mission
Orbiter
length 37.24 m
span 23.79 m
Wing area 249.9 m²
Takeoff mass (maximum) 109,000 kg
Payload in low orbit 24,500 kg
Payload to the ISS 16,400 kg
maximum thrust at sea level 3 x 1.76 = 5.27 MN
maximum thrust in vacuum 3 x 2.09 = 6.27 MN
Control range of the main engines 65-109%
Bet height 185-643 km
crew 8 people maximum
Outside tank
length 46.88 m
diameter 8.41 m
volume 2,030 m³
Empty mass 26,556 kg
Takeoff mass 757,000 kg
Booster (2 pieces)
length 45.6 m
diameter 3.71 m
Starting mass (1 booster) 590,000 kg
Start boost (1 booster) 12.46 MN
Overall system
Takeoff mass 2,046,000 kg
Start thrust 30.16 MN
Ratio of take-off thrust / take-off mass 1.5: 1
Acceleration when taking off 4.93 m / s² = 0.5 g
maximum acceleration
before burnout
limited to 3 g
NASA's emblem in memory of the space shuttle program

The space shuttle (also known as the shuttle ) was the only space shuttle type used for manned space flights . The system has been developed for the US space agency NASA since the 1970s ; the first STS-1 mission started on April 12, 1981. By reusing the parts of the system, flights into space should be significantly more cost-effective than with non-reusable launch vehicles become. This expectation was not fulfilled due to the high repair costs. The last flight took place in 2011.

In addition to the orbiter , the components were divided into the external fuel tank and two solid rocket rockets . This system was called the Space Transportation System ( STS for short ). Experts only ever called the orbiter the space shuttle. First of all, the test shuttle Enterprise was built to test the flight characteristics in the earth's atmosphere . Then five orbiters were built for use in space, these were called Columbia , Challenger , Discovery , Atlantis and Endeavor . Two of these space shuttles were destroyed by disasters. All seven crew members were killed in each case.

A space shuttle could bring up to eight astronauts and at the same time 24.5 tons of payload into low earth orbit (between about 200 and 650 kilometers orbit height). In addition, the shuttle coupled several times to space stations (initially the Russian Mir , later the ISS ) with the help of docking adapters . The ability to transport crew and cargo at the same time made the shuttle very versatile. Satellites could be repaired or brought back to earth, but the construction and supply of Mir and ISS were also a central part of the shuttle missions.

After the last flight of the Apollo spacecraft in 1975, the shuttle was NASA's workhorse from 1981. A total of 135 flights were carried out. The last shuttle flight STS-135 took off on July 8, 2011. With the landing of Atlantis on July 21, 2011, the era of the space shuttles came to an end.

The most important successes include the launching of several space probes and the Hubble space telescope , various flights with built-in laboratories and the flights to the Mir and the ISS.

history

First concepts

Some concept studies for the space glider from the late 1960s

In the 1950s, the Air Force worked on a space glider as part of the Dyna-Soar project - from 1958 with NASA as a partner. Although the project was discontinued in 1963 due to the priority of the Gemini program , among other things for cost reasons, new materials and alloys had been tested in re-entry tests shortly before in September 1963, and the Air Force continued tests for materials and re-entry. In 1957, the Air Force commissioned a concept study for reusable boosters that could start horizontally, which gave rise to the concept of the three-stage "Recoverable Orbital Launch System", which, however, turned out to be technically too demanding. Instead, the two-stage design of an "aerospace plane" was turned to in 1962, but work on it was discontinued because of the need for more conventional research. At NASA, a committee had called for a reusable two-stage concept in June 1964. In August 1965, the Air Force and NASA formed a joint committee that concluded in September 1966 that numerous technical and financial problems had to be overcome, but that manned spaceflight in low earth orbits had a great future. The main idea behind this was to drastically reduce the costs of space transport and thus initiate the commercialization of space travel.

In 1969, the year of the first moon landing , NASA commissioned a study, whereupon the four major US space companies ( Lockheed , Grumman , McDonnell Douglas and North American Rockwell ) each submitted a concept.

The program was in the concept phase for a number of years. Progress, however, was hampered by adverse political sentiment in the White House and NASA's tight budget towards the end of the Apollo program . President Richard Nixon , “not a great fan of space travel […], thought of his re-election, for which he had to create jobs in the populous states of Texas and California - traditionally important centers of space travel. Nixon therefore decided (1972) for the obvious: The space shuttle should be built. And only the space shuttle. "

The project also got a breath of fresh air in 1971 when the US Air Force also expressed interest in a reusable spacecraft. As a result, attempts were made at NASA to integrate the additional requirements of the Air Force into the design. The main focus was on an enlarged payload bay to be able to transport large spy satellites and the ability of the shuttle to return to the launch site after a single orbit in a polar orbit. This required a so-called cross-range (deviation from the orbit to the landing site) of almost 1,800 kilometers, which could only be achieved with larger delta wings and an improved heat shield.

Wernher von Braun demonstrated the idea of ​​a reusable ship with the help of a shuttle , which is known in English as a "shuttle".

The designs of the industry also changed. Some provided for manned lower stages or external tanks with wings. Most of the concepts failed because of weight problems. Eventually, the problem seemed to be solved by putting a small orbiter on a large tank, compared to other studies that assumed a huge spacecraft with space for up to 20 people, and equipping it with solid rocket rockets . Although this did not achieve 100% reusability, other important requirements could be met.

development

The three-part concept of the shuttle with the division into orbiter, external tank and booster was officially established by NASA on March 15, 1972. On August 9 of the same year, North American Rockwell (now Boeing ) received the order to build the orbiter. The contract was worth $ 2.6 billion. The contract for the construction of the solid fuel booster went to Morton Thiokol (now Alliant Techsystems ), the outer tank was to be manufactured by Martin Marietta (now Lockheed Martin ).

A year later, the first more detailed plans were available. From today's perspective, these contained completely utopian figures. The first flight was estimated in 1978 and the market for scientific, commercial and military missions was estimated at 50 flights per year. The aim was to put enough commercial payloads into orbit that the shuttle program should finance itself.

At that time, it was estimated at 10.5 million US dollars per start. In the course of development, however, these costs increased considerably - in 1977 it was estimated at around $ 24 million. As a result, the number of planned flights also had to be drastically reduced. Development costs rose steadily and soon reached over $ 12 billion.

In 1978, the year in which the first flight of the shuttle should actually have taken place, the program was about to end. Again, it was the US Air Force who put pressure on Congress to approve more funding for the shuttle program. The shuttle had been expected and several heavy spy satellites had been developed that could only be brought into orbit by the space shuttle. This intervention prevented the space shuttle program from ending prematurely.

testing

The Enterprise during a free flight test with an aerodynamic engine cowling
Dropping the Enterprise from the SCA to the free flight test

The first airworthy space shuttle, the Enterprise , was completed in September 1976. However, this orbiter was not capable of space flight and was only used for atmospheric flight tests .

The first free flight took place on August 12, 1977. The Enterprise was brought into the air with a modified Boeing 747 - the Shuttle Carrier Aircraft - and released there. Then, just like after a space flight, the space shuttle slid without propulsion to the runway. A total of five such free flight tests were carried out.

As it turned out, the main engines were the most difficult components of the shuttle. The first test run took place on October 17, 1975. During the tests, there were repeated setbacks. A particularly violent explosion even destroyed an entire test stand. The problems could not be fully resolved until 1979 after more than 700 test runs. The main engines completed their final test before the first flight a few weeks before take-off, when the FRF (Flight Readiness Firing) test was carried out with the Columbia, which was already on the launch pad, in which all three engines were run up to full power for 20 seconds. without the space shuttle taking off.

First flight and the first five years

The Columbia takes off on its maiden flight

The Columbia, the first space flight capable orbiter, was delivered to NASA in March 1979. The space shuttle was then transferred to the Kennedy Space Center (KSC) to be prepared there for its first mission. In November 1980, the Columbia was connected to the outer tank and a month later drove to the launch pad. After several postponements , the launch of the world's first reusable spacecraft took place on April 12, 1981, exactly on the 20th anniversary of Yuri Gagarin's first space flight .

Mission flow

The aim of the first flight was simply to get the Columbia safely into orbit and back again. The flight lasted a little over two days and ended with a landing at Edwards Air Force Base in California. The first flight is still considered a technical masterpiece, because it was the first time in the history of space travel that a launch vehicle was manned on its maiden flight.

The following three flights ( STS-2 to STS-4 ), all of which were carried out with the space shuttle Columbia, were used to test all systems of the shuttle. The system was then declared operational.

In the following 21 missions, which were carried out until January 1986, the satellite transport was in the foreground. There were also some purely scientific flights before the Challenger disaster occurred.

Challenger disaster (1986) and subsequent years

The Challenger's outer tank explodes and the orbiter breaks apart.

On 28 January 1986, the space shuttle Challenger lifted at an unusually low outside temperature of 2 ° C for mission STS-51-L from. NASA had decided to take off, although engineers from the booster manufacturer Morton Thiokol , especially Roger Boisjoly , had warned urgently against a take-off at temperatures below 12 ° C. However, the management of Thiokol eventually overruled its engineers and officially gave its key customer NASA the go-ahead.

A few seconds after take-off, one of the sealing O-rings on the right solid fuel rocket actually failed , and the resulting leak caused hot combustion gas to escape from one side of the booster. The flame hit the outer tank and the attachment of the solid fuel rocket, which destroyed the tank shell. The tank exploded 73 seconds after take-off at a height of 15 kilometers, whereupon the shuttle was destroyed by the enormous aerodynamic forces. The seven astronauts probably survived, but died when the cockpit section hit the surface of the Atlantic at the latest .

After the Challenger accident, on the one hand the solid fuel boosters and the flight abortion options were revised, and on the other hand the management was restructured. Many decision-making paths were changed, and for the sake of safety, engineers were given more decision-making powers.

Two years after the Challenger accident, the shuttle fleet resumed its service, which marked the beginning of the second phase of its use. The shuttle was withdrawn from the commercial satellite business and the focus was now on scientific tasks, state satellite launches and the maintenance of satellites. That remained the area of ​​responsibility of the shuttle until it docked at the Mir space station for the first time in 1995 , which amounted to a third phase of use. The field of tasks of the satellite launches and maintenance missions was gradually restricted in favor of the supply of space stations. With the start of construction of the International Space Station , the purely scientific missions also became less numerous. Instead, the shuttles were used to transport the modules to the station and for their assembly.

Columbia Disaster (2003)

Investigation of the wreckage of Columbia

When STS-107 launched in January 2003, some foam pieces broke off from the outer tank, possibly including pieces of ice. These hit the left wing leading edge and punched a large hole in the heat shield. Although the technicians in the control center noticed the incident, they were not aware of the damage that had occurred. On return of flight (February 1, 2003), however, hot plasma , which is produced upon re-entry , then entered through the hole in the wing structure. Together with the resulting change in the aerodynamics around the wing, this led to the failure of the structure. As a result, the space shuttle broke apart. All 7 astronauts died. At the time of the accident, they were at an altitude of 70 km and moving at 23 times the speed of sound ( Mach 23).

In response to the accident, the precautionary measures for the heat shield were enormously strengthened. The outer tank has been redesigned to minimize foam chipping, and the heat shield has been checked for damage with a special robotic arm extension ( OBSS ) on every flight since the accident . In addition, a concept for rescuing a shuttle with a damaged heat shield was worked out. Finally, the US government announced that it would decommission the shuttle fleet by September 2010.

With the resumption of regular flight operations in 2006 - apart from STS-125 , the last maintenance flight for the Hubble space telescope - only the construction of the International Space Station remained as a task area. Smaller satellites continued to be carried in the payload bay and were also launched.

Whereabouts

Since the end of the space shuttle program and its retirement, the orbiters and other parts of the program have been exhibited in U.S. facilities:

Training and equipment objects were also presented to the public, for example a simulator in the Adler Planetarium in Chicago, astronaut seats in NASA's Johnson Space Center in Houston, Texas, and space shuttle control engines in museums in Huntsville, Alabama, and Washington , DC

Mission Profile

Preparation and countdown

Atlantis is brought to the launch site by crawler transporter ( STS-117 )

The preparation for a shuttle mission in the narrower sense began with the assembly of the individual elements of the shuttle system. First, the segments of the two solid fuel boosters were put together. This happened in the Vehicle Assembly Building (VAB) on the mobile launch platform with which the shuttle was later driven to the launch pad. Then the external tank, which was brought to the Kennedy Space Center on a special ferry, was connected to the two boosters. Finally, the orbiter was brought into the VAB and mounted on the external tank. Shortly afterwards the whole system was driven to one of the two launch ramps, LC-39A or LC-39B.

The final preparations were carried out on the launch pad . Usually the main payload was only installed here in the cargo hold of the orbiter.

About 70 hours before the scheduled start time, the countdown began at the T-43 hour mark. As planned, the countdown was interrupted several times - that explained the difference of around 27 hours. This achieved a certain standardization of the countdown procedure: the same work was always carried out at the same countdown time.

The shuttle behind the closed work platform
STS-135 rocket launch (slow motion)

During the entire time on the ramp, which usually lasted several weeks, the shuttle was protected from the weather by the swiveling RSS working platform (Rotating Service Structure). The RSS also contains the Payload Changeout Room , a clean room in which the payload was temporarily stored before it was installed in the space shuttle's loading bay. This structure was only swung away on the day before the launch.

About ten hours before the start, the filling of the external tank with liquid hydrogen (−252 ° C) and liquid oxygen (−183 ° C) began. This procedure took three hours. Then, about four hours before take-off, the crew went into the orbiter.

From nine minutes before take-off, all processes were monitored by the computers in the launch control center, the Ground Launch Sequencer . It was still possible to manually intervene in the countdown up to 31 seconds before take-off. After that, the start could only be canceled from the Space Shuttle's on-board computer.

Start and ascent

Start of Discovery for mission STS-114 from KSC

The Sound Suppression Water System was activated 16 seconds before take-off. This device poured 1,135 cubic meters of water onto the area under the main engines and boosters within 20 seconds to protect the shuttle and payload from damage from the enormous sound waves. In order to prevent escaping hydrogen from generating oxyhydrogen gas explosions and affecting the sensitive computer control of the engines, the electrical spark spray system (main engine hydrogen burnoff system) was activated 10 seconds before take-off. In addition, the combustion chambers of the engines were filled and pressurized by the turbo pumps.

The actual start sequence was then initiated with the ignition of the three main engines offset by 140 milliseconds 6.6 seconds before take-off. The engines were cooled with liquid hydrogen during operation.

After the main engines were ignited, the entire shuttle (with tank and boosters) swayed about 3 meters forward at the top because the orbiter's engines were slightly behind the center of gravity of the entire shuttle. Then it swung back again. During this time, the correct start-up of the main engines was checked, because they could still be switched off. When the shuttle was exactly upright again, the two solid rocket boosters (SRB, Solid Rocket Booster ) fired . Up to this point in time, the boosters were held in place by bolts on the launch pad. A few fractions of a second after the SRBs were ignited, these were partially blown up, slipping out of the holder and releasing the entire shuttle for take-off. Then the space shuttle took off.

Launch of the STS-117 mission . The smoke trail comes from the solid fuel boosters.

The two SRBs had a burn time of around 2 minutes and produced around 80 percent of the total thrust. They burned around 4 tons of solid fuel per second. A total of 10 to 12 tons of fuel and oxygen per second drove the shuttle upwards. The tank contents of a Boeing 737 would be used up in 2 seconds. After they were burned out, they were separated at an altitude of around 50 km, but their high speed increased them to 70 km. Only then did they fall back and reach a rate of descent of 370 km / h. Before the SRBs hit the surface of the sea, three parachutes were activated in each of the noses at a height of almost 2 kilometers. The boosters finally fell into the Atlantic Ocean at around 80 km / h . Two NASA salvage ships (the Liberty Star and the Freedom Star ) picked up the empty shells and towed them back to the Kennedy Space Center, where they were prepared for reuse.

The outer tank falls back into the earth's atmosphere before it burns up on re-entry

After the booster was disconnected, the space shuttle flew only with the help of its main engines. After about 8.5 minutes of burning, shortly before reaching orbital speed (at approx. 7700 m / s), the external tank was dropped at an altitude of around 110 km. Most of it burned up in the atmosphere after completing half a orbit around the world. The remaining parts of the tank fell into the Pacific .

Transfer to final orbit

The space shuttle was then accelerated by the two engines of the OMS (Orbital Maneuvering System) into an elliptical orbit with a lowest point ( perigee ) of about 110 km and a highest point ( apogee ) of 185 km above the earth's surface. After half-orbiting the earth, the orbiter's thrusters fired at the highest point to transform the orbit into an ellipse with a perigee of 185 km and an apogee at the level of the target orbit (for example, about 380 km for a flight to the ISS ). When the orbiter reached the highest point again, it fired the maneuvering thrusters one more time to enter a circular orbit at that height. The orbiter thus reached its target orbit. For complex missions that require a special orbit or have to fly to a specific destination, the orbit was adjusted several times over the course of the first days of flight. This was necessary , for example, to reach the ISS or the Hubble space telescope .

Work in orbit

The Challenger space shuttle during the STS-7 mission, June 1983

The work in orbit, the so-called on-orbit operations , began with the opening of the cargo bay doors. This was absolutely necessary because radiators were installed on the inside of these gates, which ensured the cooling of the orbiter. If the gates could not be opened, the mission had to be stopped immediately.

Sectional view of the shuttle with the Spacelab

The space shuttle could be used in a wide variety of ways. Typical tasks for a mission consisted of launching or capturing satellites, carrying out scientific experiments or carrying out construction work on a space station, such as the ISS or earlier the Mir . A laboratory such as Spacelab or Spacehab could be carried along for scientific work . Depending on their configuration, these laboratories offered possibilities for experiments in free space or in a manned module.

In addition, the crew was often busy with physical training to take account of the muscle regression in weightlessness. A considerable part of the astronauts' working time was also used to look after and operate the many systems of the space shuttle.

landing

Landing of the Columbia on the STS-1 mission on the EAFB

To leave the orbit, the space shuttle was rotated against the direction of orbit. The OMS engines were ignited for about three minutes (so-called deorbit burn ), which slowed the space shuttle down by about 300 km / h. Then the space shuttle was turned back in the direction of flight with its nose. Due to the braking maneuver, the orbiter left its previous orbit and changed from its circular orbit to an elliptical orbit with a perigee of 80 km. After almost another half orbit around the earth, it entered the outer layers of the atmosphere and was further braked aerodynamically there. Due to the dimensions and the relatively flat entrance, the shuttles were not completely enveloped by the plasma, which means that since 1988 a continuous radio connection via TDRS without blackout has been possible for them using the S-band . The attitude control engines (RCS) were deactivated at an altitude of about 15,000 meters; Approach and landing took place without any propulsion, so there was only one attempt.

When it re- entered the earth's atmosphere, the space shuttle was protected from the extreme heat of the pressure front of up to 1650 ° C by special heat protection tiles on the front and underside. Shortly after re-entry, several hundred kilometers away, it received guidance signals from the intended runway. The aerodynamic landing phase began at an altitude of around 13 km, in which the orbiter gradually reduced the remaining energy in unpowered flight ( gliding flight with a glide ratio of 4.5). The rate of descent was regulated in this phase by alternating rolling movements of the shuttle around its longitudinal axis, which led to a serpentine flight path.

The last part of the approach consisted of three phases:

  1. Alignment with the runway in the Heading Alignment Circle (12.8 km before the runway, final height 3660 m)
  2. Steep final approach (up to 610 m altitude)
  3. Flattening of the glide angle with landing

At the end of the first phase, the attitude, direction, altitude and speed were optimized for the landing. Up to phase three, the glide angle was around 17 to 18 ° (compared to 2 to 3 ° for commercial aircraft) at a speed of around 500 km / h. In the third phase, the glide angle was reduced to 1.5 ° by changing the angle of attack , so that the shuttle had deployed 30 seconds earlier at a speed of around 340 km / h, about one and a half times that of a commercial aircraft (“preflare” phase) Landing gear touched down on the runway. To shorten the braking distance was a drag parachute used. The brakes of the chassis were only used when a lower speed was reached. The pilot was allowed to fly the shuttle himself for a short time, but then had to hand it over to the commander, who carried out the landing. However, the pilot was responsible for extending the landing gear and releasing the parachute.

A braking parachute has been used on landing since 1992 .

Bad weather conditions at the main landing site sometimes made it necessary to switch to cheaper locations. Since 1991, the Kennedy Space Center in Florida has been the primary landing target. There is the so-called Shuttle Landing Facility , a 4.5 km long and 90 m wide runway that was built especially for the return of the orbiters from space. When the weather made it impossible to land in Florida, NASA had two alternatives. The first alternative airport was the Edwards Air Force Base ( California ), where the testing of the then newly developed space shuttle had also been carried out, the second alternative location was White Sands ( New Mexico ) (only one landing, STS-3 1982).

Return transport with the Shuttle Carrier Aircraft

In addition, there were other emergency landing sites around the world for the start phase and the further course of the mission. A distinction was made between East Coast Abort Landing Sites (ECAL) in the USA and Canada and Transoceanic Abort Landing Sites (TAL) . The latter included the Istres Air Base in France and Zaragoza Air Base and Moron Air Base in Spain. Another airport that was certified for a landing of the space shuttle was, among others. the German airport Cologne / Bonn .

If the shuttle needed to land somewhere other than Florida, it was piggybacked back there on a modified Boeing 747 (the so-called Shuttle Carrier Aircraft , SCA). In order to improve the aerodynamics during this overflight, a cover tapering towards the rear was attached to the rear of the shuttle to be transported, which concealed the shuttle's engines.

use

A chronological list and a tabular overview of all missions flown can be found under List of Space Shuttle Missions .

Due to its design as a space shuttle, the space shuttle was extremely flexible in use. It was the only delivery system that was able to bring several tons of payload from space to Earth. In addition, due to their dimensions, some components of the ISS space station could only be brought into space by shuttle. This fact and the resulting contracts with the partner countries were also one of the main reasons why the space shuttle program was maintained despite massive cost overruns. In the course of the shuttle program, the tasks of the system changed considerably. The following is an overview of the most important tasks of the shuttle.

Satellite transport

The SBS-C satellite was deployed during STS-5

At the beginning of the shuttle program, the main task of the orbiter was to launch satellites into space. It was hoped that the reusability would generate enormous savings. The first operational flights of the Space Shuttle were also dedicated to this task. During the STS-5 mission , the two communications satellites Anik C-3 and SBS-C were launched into space. The three subsequent missions were also used for satellite transport.

Working on the Hubble Telescope during STS-103

In addition, the shuttle had the unique ability to bring satellites back from space to earth. This happened for the first time on the STS-51-A mission , when two satellites that had previously been placed in orbit too low were recaptured. The shuttle could also be used to capture satellites so that they could be repaired by astronauts. This was done, for example, during the STS-49 mission when the upper stage of the Intelsat IV satellite was replaced.

Another example was the Hubble Space Telescope , which was approached five times by a space shuttle for repairs. The telescope was last visited in 2009 by the STS-125 mission .

Since the Challenger disaster in 1986, the shuttle has been withdrawn from the commercial satellite business. Since then, only military, scientific or government payloads have been put into orbit. The last shuttle mission primarily devoted to the transport of a satellite was STS-93 in the summer of 1999. During this mission, the Chandra X-ray telescope was launched .

science

Another important area of ​​application for the shuttle was weightless science. The space shuttle offered a very flexible platform for experiments of all kinds. First of all, there is the Spacelab , a laboratory that could be carried in the payload bay. The first Spacelab flight was STS-9 in November 1983. By the last flight in 1998 on board STS-90 , 22 Spacel departures had been made.

The Spacelab can be seen in the payload bay of a space shuttle

The successor to the Spacelab was the Spacehab . This could be used in a more versatile way than the Spacelab - for example, it could also be used to bring cargo to the ISS, as was the case on flight STS-105 . The last pure research mission of the shuttle program was STS-107 from Columbia, which then broke apart when re-entering the atmosphere and partially burned up, killing the seven astronauts on board. The last flight of a Spacehab logistics module was the STS-118 mission .

The LDEF satellite contained over 50 experiments

On other missions, for example during STS-7 , research platforms were carried in the payload bay, which were then released into space for several hours during the mission, only to be captured again with the robotic arm. Still other such platforms remained in space for several months or years and were overtaken by a later shuttle mission.

In principle, most of the shuttle missions had some scientific objectives. So-called get-away containers with automatically running experiments were often carried in the payload bay, or so-called middeck payloads , i.e. middle deck payloads, were carried with them, which were also looked after by the shuttle crew. This was still partly the case with ISS flights.

Operation of space stations

Due to its incomparable flexibility, the shuttle was an ideal workhorse for building and maintaining a large space station. Many of the ISS modules were so large that they could not be brought into space with other carriers. In addition, the shuttle with its robotic arm offered the option of mounting the modules directly on the station. This was inevitable, as most of the ISS modules do not have their own drive and position control systems and so autonomous docking was not possible. Crew transport has also been simplified with the shuttle; theoretically up to 5 crew members could be exchanged per flight.

Because of this critical role of the shuttle, the ISS program was then set back by several years when the shuttle fleet was banned from flying after the Columbia crash in February 2003. Some experiments even had to be canceled as a result.

Before the time of the ISS, the shuttle was also used on several flights to the Russian Mir space station . Between 1995 and 1998 a space shuttle docked at the station a total of nine times. It was also about a political sign - it was the first significant joint operation of the two superpowers in space since the Apollo-Soyuz test project in 1975. The first such flight was STS-71 in the summer of 1995.

technology

Solid fuel booster

Diagram of a booster
The Freedom Star tows a booster back to KSC

Over three quarters of the thrust required to start a shuttle was provided by the two solid fuel boosters. The two white, 45-meter-long rockets were the most powerful engines of their kind ever built. Each of these boosters contained over 500 tons of APCP , a solid fuel based on ammonium perchlorate and aluminum . This mixture gave the boosters a burn time of a good two minutes and a specific pulse (ISP) at sea level of 242 s (based on the mass of the fuel). The boosters were equipped with swiveling nozzles for position control. In addition, several cameras were housed in the upper part, which provided a large number of images during the ascent.

At an altitude of about 45 km above ground, the almost burned-out boosters were cut off and pushed away from the external tank by small rocket engines. This prevented a collision between the falling boosters and the tank. The boosters then continued to climb along a ballistic path up to about 65 km, in order to then initiate the descent. First, smaller stabilization screens were ejected, which slowed the boosters down a bit. Eventually the main parachutes were deployed, the boosters slid back to earth and fell into the sea about 230 km from the KSC at a speed of 80 km / h. Just a few hours after taking off, they were recovered by two ships and towed back to Florida. There they were cleaned, checked and prepared and refilled for another flight.

Outside tank

Diagram of the external tank

The largest component of the shuttle system was the external tank ( English External Tank , ET ). In fact, the orange cylinder contained two tanks, a larger hydrogen tank in the lower part and a smaller oxygen tank in the upper part of the tank. In between was the so-called intertank section ; this was not under pressure and contained a large part of the electronics of the outer tank. Since the two gases hydrogen and oxygen were in liquid state and therefore very cold (below −200 ° C), the tank was insulated with a special foam. This gave it its characteristic orange color. Only on the first two flights was the tank coated with an additional layer of white paint, but this was no longer used for weight reasons from the next mission onwards.

The tank on a special transporter

The shuttle was attached to the external tank at one point at the front and at two points at the rear. In addition, several lines run on the outside of the tank, including conducted the hydrogen and oxygen into the orbiter, where the liquids were then burned in the main engines. The tank was the only component of the shuttle that was not reusable. After the main engine cutoff (MECO ) had burned out, the tank was thrown off and entered the atmosphere, where it burned up.

Since the Columbia disaster in 2003, the insulation of the tank had become more and more talked about. At the time, a piece of chipped foam had damaged the shuttle, which caused extremely hot gases to enter the orbiter during the re-entry phase and destroy it. Since then, the tank has been heavily redesigned in places. The tank was also revised several times during the course of the shuttle program. The first tanks, for example, which were painted white to hide the typical orange of the insulation foam, weighed around 35 tons when empty. In the last version it was less than 30 tons.

Orbiter

Atlantis in unpowered flight at the end of STS-30

The main component of the shuttle system was the orbiter. It contained the crew quarters and the cockpit (flight deck) as well as the payload of the respective mission. Its outer shape was characterized by its aerodynamic components, the delta wing and vertical tail unit, which enabled it to land in a classic gliding flight at the end of a mission . A total of five spaceflight orbiters were built, two of which ( Challenger and Columbia) were destroyed by accidents. The orbiter was one of the most complex technical devices ever built by humans. In the start phase it was mounted in a vertical position on the outer tank in order to be transported into orbit. After he had left orbit at the end of a mission, the beginning of the landing was purely ballistic at first before it was concluded with an aerodynamic phase.

Main engine

The main engines of the space shuttle

The orbiter had three large main engines, the Space Shuttle Main Engines , SSMEs for short . The main engines were deployed during the eight-minute ascent into space and supplied with liquid hydrogen and oxygen from the external tank. After switching off and disconnecting the tank, the engines could therefore not be re-ignited during the mission.

They were gimbaled and swiveled hydraulically by 10.5 °. In this way, it was possible to compensate for the torque that occurred due to the change in the center of gravity and the thrust vector after the booster burned out and dropped.

After landing on earth, the engines were removed, checked and prepared for their next use. They should be reusable up to 55 times with a maximum thrust of 109%. However, this number was never reached. The reusability made them technically highly complex systems; at $ 51 million, a single engine cost roughly the same as a complete Delta II rocket . The main engines for the space shuttle program were tested with the Main Propulsion Test Article (MPTA-098) .

Auxiliary power units

Left OMS pod of a space shuttle is dismantled for maintenance work
The Forward Reaction Control System (FRCS) is reinstalled after maintenance work
The radiators can be seen on the inside of the cargo bay doors

In addition to the main engines, the orbiter had 46 medium and smaller engines that were used while in orbit and during the first phase of re-entry. The two largest of these belonged to the Orbital Maneuvering System (OMS). They delivered a thrust of 27 kN each and, like the SSMEs, were housed in the rear of the shuttle. They were used to make changes in orbit, such as zeroing into the definitive orbit or igniting the brakes for re-entry. They were operated with hypergolic fuels, i.e. with two components that ignite when touched.

The 44 smaller engines belonged to the so-called Reaction Control System (RCS). With their help, the position of the shuttle in space was controlled. This was especially important when docking with a space station or when capturing a satellite. The RCS engines were also needed to turn the shuttle with the tail in the direction of flight before the brake ignition. The nozzles were attached to the nose and stern and each had a redundant design. This largely ensured the maneuverability of the shuttle. Like the OMS engines, the RCS nozzles were powered by hypergolic fuel.

Crew quarters

The crew quarters of the space shuttle consisted of the flight deck (Engl. Flightdeck ), the middle deck (Engl. Middeck ) and the airlock (Engl. Airlock ), but this was sometimes counted as middle deck. The entire crew quarters had a volume of 65.8 m³. The flight deck represented the actual cockpit; the pilot and commander's seats were located there during take-off. When the shuttle reached an orbit, all the seats were stowed away to save space. The middle deck was the living and working area of ​​the space shuttle. There was a toilet, sleeping compartments and the necessary equipment for the preparation of meals. In addition, the middle deck offered space for experiments and around 140 liters of storage space for payload. Also in the middle deck was an ergometer , a training device with which the astronauts counteracted the reduction in muscle mass caused by weightlessness.

In order to enable the life of the astronauts on board, a comfortable climate had to be maintained in the cabin at all times. This was by various life support systems (Engl. Environmental Control and Life Support System (ECLS) ) achieved. For example, the temperature and pressure had to stay within a certain range. The biggest challenge was keeping the orbiter from overheating. Two large radiators inside the cargo bay doors were used for this purpose. These radiated heat into space during the entire stay in space. The pressure in the cabin was obtained from several tanks of nitrogen and oxygen. In this way, an atmosphere could be created in the shuttle that was very similar to that on earth.

The water system was also one of the life support systems. Four water tanks were installed in the shuttle, each holding around 75 liters of water. Another 10 liters of water per hour was created as a by-product of electricity generated by fuel cells . Waste water was collected in an appropriate tank and released into space at regular intervals.

Payload Bay

The payload bay and the robotic arm

The payload bay was located in the middle part of the shuttle. Two large gates could be swung upwards to expose the payload bay to free space. This process was carried out on every mission, as the radiators, which ensured the cooling of the orbiter, were on the inside of the payload bay gates. The payload bay was 18.38 m long and had a diameter of 4.57 m. This cylindrical area could be used to the full for payload.

In addition, a robot arm, the Remote Manipulator System (RMS), was installed in the payload bay . Because the system was made in Canada, it was sometimes called Canadarm . The arm had six degrees of freedom and had a gripping mechanism at its end, with which it could move payloads or astronauts, as well as catch satellites. It was 15 m long and weighed 410 kg, but could move masses of up to 29 tons. The control was done by an astronaut who was on the flight deck of the shuttle. In addition to the two rear windows of the flight deck, several cameras were used on the arm and in the payload bay for precise control of the arm.

The Integrated Cargo Carrier was used on 12 flights to transport non-pressurized external loads in the shuttle's payload bay. About 3 tons of payload could be carried on a transport pallet.

power supply

The electricity for the operation of the electrical systems was generated by fuel cells. These were operated with hydrogen and oxygen. Three fuel cells were installed in the orbiter, each with an output of 7 kW, for a short time even up to 12 kW were possible. In addition, the Orbiter Discovery and Endeavor were equipped with the station-to-shuttle power transfer system . This enabled them to draw power from the ISS to allow them to stay longer.

Additional systems for generating energy were the auxiliary power units (APUs ). These three hydrazine- powered turbines generated mechanical power to operate hydraulic pumps. The hydraulic system was needed for the valve and thrust vector control of the three main engines, the movements of the aerodynamic control surfaces, the closing of the fuel doors on the underside of the orbiter and at various points within the landing gear .

Heat shield for re-entry

HRSI heat protection tile: the yellow marking indicates the exact position on the space shuttle and the part number
Heat protection tiles are attached to the Columbia (1979)
Heat protection tiles and RCC nose on the underside of the Discovery

Various areas of the outer shell of the shuttle were equipped with special heat protection panels . This was essential for re-entry into the atmosphere, as the shock front building up in front of the missile caused enormous temperatures. Without the heat shield, the shuttle would have burned out. The earlier spaceships of the Apollo, Gemini and Mercury programs were also equipped with a heat shield , as were the Russian Soyuz capsules. What was unique about the shuttle's heat shield, however, was its reusability.

The largest part of the heat shield was made up of around 24,300 differently shaped tiles on the underside of the fuselage of the orbiter. The so-called high-temperature reusable surface insulation (HRSI) could withstand up to 1260 ° C. The tiles were a maximum of 12 cm thick and consisted for the most part of cavity (90%) and silicon dioxide (10%). The density was 0.14 and 0.35 g / cm³ ( silica around 2.2 g / cm³).

The highly heated areas on the shuttle as the nose and wing leading edges were with a special material, so-called carbon fiber reinforced carbon (CFC) , in English, the term was Carbon Fiber Reinforced Carbon (CFRC) or carbon-carbon (C / C) , dressed in use, the was largely resistant to temperatures above 1300 ° C and mechanical damage such as cracks. Complete protection against damage was not possible. The 2003 Columbia disaster resulted from a large hole in a CFC panel on the wing leading edge.

Other areas of the shuttle were equipped with what is known as Advanced flexible reusable surface insulation (AFRSI) ; these were tiles that can withstand around 650 ° C. This included the cockpit, the front part of the fuselage and the vertical stabilizer or rudder. The rest of the shuttle (rear fuselage and top) did not have any special heat protection. However, the normal outer skin of the space shuttle could withstand up to 370 ° C.

Data transfer

For data transfer (communication, video, telemetry, experiment data), the shuttle had a. via microwave systems in the S-band and Ku-band . An (almost) uninterrupted data link to the ground was available during the entire orbit via the Tracking and Data Relay satellites (TDRS). The Ku-band antenna was located in the cargo bay so that this most powerful of the systems could only be used in flight phases with the cargo bay open.

Security systems

As with any manned missile system, the safety of the crew came first on the space shuttle. Due to the completely new concept of the space glider, completely new safety concepts had to be developed. A rescue tower like in the Apollo times was out of the question for the orbiter. Before the Columbia disaster, re-entry and landing were seen as the less critical phase of the flight, but later this thinking changed somewhat.

Abort before the start

The Challenger tragedy reignited the security debate

In the event of an aborted take-off before the shuttle took off, it was possible to fall back on a cable car system that already existed in the Apollo program. This could safely transport the astronauts away from the launch system in the event of danger. It was slightly modified so that now seven cable car baskets can carry up to 21 people from the launch system; In the event that, in addition to the astronauts, there were also technicians in the vicinity of the fully fueled space shuttle. It was activated during regular exercises and the Terminal Countdown Demonstration Tests , but never had to be used in an emergency.

A termination very shortly before the start could only be carried out using the Redundant Set Launch Sequencer (RSLS). After starting the main engines (6.6 seconds before take-off), this system checked their function and was able to cancel the imminent take-off. This type of RSLS abortion was carried out a total of five times, the last time during the countdown to the start of STS-68 in August 1994. The engines were switched off 1.9 seconds before the start and the ignition of the solid fuel booster was prevented.

Start aborted in flight

After the shuttle took off, there were several options for bringing the flight to a safe end, depending on the time and severity of an error that occurred between disconnecting the boosters and switching off the main engines. Of these four "intact abort types", only the Abort to Orbit (ATO) was actually carried out. During the STS-51-F , one engine failed after about six minutes. The dropping of unnecessary fuel allowed the Challenger to reach a lower than the planned but stable orbit. Since this was only a minor problem, the mission went ahead as planned.

The switch for preselecting the abort mode in the shuttle cockpit

In the case of more serious problems, such as a leak in the crew cabin, however, it was necessary to bring the mission to a swift end. There were three options open to this during the start-up phase. On the one hand, there was the possibility of bringing the shuttle into an unstable orbit and landing it again after less than one orbit around the earth. This abort once around (AOA) could only be initiated during a very small time window and was never carried out. Another option, the Transatlantic Abort Landing (TAL), would have been to land at a European or African airport. For this scenario, the shuttle would pick up enough speed to reach the targeted landing site, then switch off the engines and eject the tank. A little later, the shuttle would land normally on the target runway. For a shuttle start, at least one of the predetermined landing sites had to be able to show good weather. This option was never used either.

The last and most dangerous type of demolition was Return to Launch Site (RTLS), the return to the launch site. It would only have been used if all other termination modes had been excluded as options, e.g. B. because the space shuttle has not yet reached enough speed and altitude. The scenario envisaged that the shuttle with its engines would be rotated in the direction of flight and these would continue to run until they had reduced the speed they had built up. The flight then proceeds like a TAL abort with the aim of descending at the launch site. This option was never used either.

If more than one engine had failed during the first few minutes of the take-off phase, the only option would have been to splash down in the Atlantic. To do this, the orbiter should be brought to a height from which the astronauts could have jumped, as they would probably not have survived a splash. The orbiter would then have touched down on the surface of the sea by remote control. Before the Challenger accident, such a scenario would have been fatal for the crew in any case, since, apart from the first test flights, they did not have any parachutes with them. A splashdown was never carried out.

Cancellation during flight and re-entry

During the flight, there was still the possibility of dropping the shuttle on an emergency landing site at short notice. This would have been used, for example, if the cargo hold doors with the cooling radiators had not opened and the shuttle threatened to overheat. For flights to space stations, there was also the possibility that the crew stayed on the station in order to be picked up later by another shuttle. This possibility arose as a reaction to the Columbia accident in 2003 under the name CSCS (Contingency Shuttle Crew Support) . For this reason, a second space shuttle that was immediately ready for use had to be available every time the shuttle started. This option was waived for the last flight of a space shuttle, but the crew was reduced to just four people so that they could have been brought to earth with Soyuz spaceships that would then have been launched from Russia.

Once re-entry was initiated, it could not be canceled. For this reason, since STS-114, the heat shield on every shuttle flight has been checked using various methods (see Rendezvous Pitch Maneuver , OBSS ) and, if necessary, repaired in the field before ground control gave permission to return. This should prevent accidents like that of Columbia ( STS-107 ) in the future.

Evacuation of the shuttle in orbit

In the event of damage to the shuttle in orbit around the earth, for example due to a collision with space debris , the astronauts had three complete MMU spacesuits at their disposal. These were regularly used for space walks and field missions by astronauts. However, since there were usually more crew members on board a space shuttle, the remaining ones would have been rescued in personal rescue enclosures . These were balloon-shaped, closed and made of the same material as the spacesuits. The astronauts would have waited outside the shuttle to be rescued by a replacement shuttle.

Maintenance and upgrading

The Atlantis is driven into the
Orbiter Processing Facility by aircraft tug

For reasons of safety and flight technology, all orbiters have been taken out of service for several months for extensive improvements. During this so-called Orbiter Maintenance Down Period (OMDP), which came after about 13 flights, extensive tests and maintenance work were carried out on the space shuttle. In addition, major improvements were made in each case. During the last such revision, the orbiters were equipped with a so-called glass cockpit based on LCD, which replaced the old tube screens and analog instruments. Other improvements included a braking parachute that was used on landing and the station-to-shuttle power transfer system , which enabled the shuttle to draw power from the station when it was at the ISS. Such modifications initially took place at the manufacturing plant in Pasadena, California, but were moved to the Orbiter Processing Facility (OPF) in the late 1990s , where the maintenance and preparation of the space shuttles was also carried out.

Even after the Challenger accident, various improvements were made, in which primarily the booster connections to the external tank were strengthened. The changes following the Columbia disaster mainly affected the foam insulation of the external tank. This should prevent it from flaking off so easily and damaging the shuttle's heat shield. In addition, security conditions and starting criteria have been tightened.

List of space shuttles

Spaceflight orbiters

Since the shuttle flights began in 1981, a total of five different space shuttles had flown into space. Of these, three ( Discovery , Atlantis and Endeavor ) were still in use until the program was discontinued in 2011 . Two space shuttles ( Challenger and Columbia ) were destroyed in disasters in 1986 and 2003.

Surname OV no. First
start / mission
Last
start / mission
Number of
miss.
comment
Columbia OV-102 Apr 12, 1981
STS-1
Jan 16, 2003
STS-107
28 first spaceflight orbiter, destroyed on February 1, 2003 upon re-entry due to defective heat protection cladding. All 7 crew members were killed.
Challenger OV-099 0Apr 4, 1983
STS-6
Jan 28, 1986
STS-51-L
10 Destroyed on January 28, 1986 shortly after the start by a defect in a solid fuel booster. All 7 crew members were killed.
Discovery OV-103 Aug 30, 1984
STS-41-D
Feb 24, 2011
STS-133
39 last landing on March 9, 2011,
exhibit at the Steven F. Udvar-Hazy Center since April 19, 2012
Atlantis OV-104 0Oct 3, 1985
STS-51-J
0Jul 8, 2011
STS-135
33 last landing on July 21, 2011,
exhibit at Kennedy Space Center
Endeavor OV-105 0May 7, 1992
STS-49
May 16, 2011
STS-134
25th last landing on June 1, 2011, replacement orbiter for Challenger, exhibit at California Science Center

Non-space flight prototypes

Inspiration Space Shuttle Mock-Up
  • The inspiration is a model made of wood and plastic, with which North American Rockwell applied for the order to manufacture the orbiters of the space shuttle program with the US government.
  • OV-098 Pathfinder was a non-airworthy handling model made of steel. It was used to test and practice the processes on the ground. Pathfinder did not have an official number, but was sometimes listed as OV-098, as the Main Propulsion Test Article (MPTA-098) was also used to configure the Pathfinder . The Pathfinder is on display at the US Space & Rocket Center in Huntsville.
  • OV-101 Enterprise was a prototype suitable for flight but not for space flight, which was used for gliding tests and for flight tests on the back of the Shuttle Carrier Aircraft. The Enterprise can be viewed at the Intrepid Sea, Air & Space Museum since August 2012 . It was planned to convert the Enterprise later into a spaceflight orbiter, but it turned out to be more cost-effective to upgrade the static test cell STA-099 to the space shuttle Challenger (OV-099).
  • OV-100 Independence , formerly Explorer , is a faithful replica of the space glider. It's in the Johnson Space Center .
  • Until 2009, a replica called America was in the Six Flags Great America amusement park in Gurnee, Illinois.
  • Ambassador: Originally built for a space exhibition sponsored by Pepsi , this model of a space shuttle orbiter can be broken down into segments for easy transport. It has been exhibited in the Kennedy Space Center, Korea, and Peru.

Differences between the individual orbiters

Due to the technical development in the course of the space shuttle program, the five spaceflight-capable orbiters were not exactly identical. Some features have been retrofitted to all orbiters, such as the glass cockpit . Most recently, all orbiters flew with LC displays and modern computers.

Other distinguishing features remained until the end; so the Columbia was over three tons heavier than her sister ships built later. In addition, a modification was installed in the payload bay of the Challenger and Discovery, which would allow an already refueled Centaur upper stage to be carried. But that was never done.

Space Shuttles Columbia, Challenger, Discovery, Atlantis and Endeavor

Origin of the name of the space shuttle

NASA named the shuttles, with the exception of the Enterprise, after famous exploration ships from centuries past.

Shuttle
name
Service life of the
eponymous
ships
Ships that give it its name
Atlantis 1930-1960 Two-masted sailing ship Atlantis used by the Woods Hole Oceanographic Institution .
Challenger 1870s British Navy research vessel HMS Challenger that has toured the Atlantic and Pacific Oceans.
Columbia circa 1790s Small research vessel that was deployed outside of Boston and later discovered the mouth of the Columbia River named after him .
Discovery 1610/11 or 1778 Two famous sailing ships. With the first, Henry Hudson was looking for a northwest passage between the Atlantic and Pacific. With the other, James Cook discovered Hawaii .
Endeavor 1768 The first of the ships led by James Cook . Cook sailed to the South Pacific to observe the passage of Venus in front of the solar disk in Tahiti ( Venus transit of June 3, 1769). On this voyage, Cook also visited New Zealand, explored Australia and sailed to the Great Barrier Reef .
Enterprise fictional spaceships The original name was Constitution ( constitution ), since the 200th anniversary celebrated in 1988.
The Star Trek fan base presented the White House with a collection of signatures. Although the then US President Gerald Ford did not take the action seriously, he ultimately got NASA to use the name Enterprise . He had served on the USS Monterey , which co-operated with the USS Enterprise , during World War II .

Problems and criticism

Falling piece of foam during STS-114
Test result of the accident investigation into the Columbia accident: a foam piece knocks a 41 × 42 cm hole in an RCC panel
Burning up debris from the Columbia

Technical risks

Due to its structure, the space shuttle was exposed to more risks than a space capsule such as that used in the Apollo program. The best known problem has been the heat shield since the Columbia accident at the latest. Unlike the heat shield of a space capsule, this was open during the entire mission and was therefore susceptible to damage from space debris , micrometeorites or pieces of ice or foam falling off the external tank during take-off. Small damage to the heat protection tiles of the shuttle occurred with every take-off, which had no further consequences; however, a larger hole on the leading edge of the wing or the nose of the orbiter could pose a serious hazard. When the Columbia reenters at the end of the STS-107 mission, hot gases penetrated through such a hole and led to structural failure on the left wing and ultimately to the destruction of the entire space shuttle. Just by luck, the STS-27 mission did not end in a similar disaster. According to former NASA flight director Jon Harpold, it was not possible to repair damaged heat shield tiles during a mission. This view was widespread within NASA - and thus also among astronauts.

Missing and damaged heat protection tiles on the OMS pods (left and right of the rudder ) during STS-1

The start-up phase also involved more risks than a capsule system. Although it was possible to rescue the crew using the above methods, the demolition could only be carried out safely if there was no time-critical problem. Thus a termination with return flight to the starting position (left Return to Launch Site , RTLS ) or a transatlantic landing pad initiate only after the dropping of the solid rocket boosters. A time-critical problem before the boosters were dropped led to a high probability of the loss of the crew and the shuttle ( Loss of Crew and Vehicle , LOCV). Jumping off the crew on parachutes only came into question if an RTLS demolition was successfully carried out, but no suitable landing site could be reached. A pyrotechnic rescue system, such as B. a rescue rocket or capsule , in which the crew cabin was separated from the rest of the shuttle and then parachuted down, was considered, but then discarded as well as the ejection seats used in the first test flights for reasons of weight and cost.

John Logsdon, one of the most prominent connoisseurs and critics of the American space program, said in 2011: “... the shuttle turned out to be too complex, too expensive and, above all, too risky: Already in the first years of the program, those responsible recognized that they were dealing with safety issues move very thin ice. But they closed their eyes. And already in 1985 there were ideas for a second, more reliable shuttle generation. But nothing had happened. ”…“ But the USA did not want to afford not to have its own access to space for many years during the Cold War. In addition, an immediate end to the shuttle program would have meant the end of the 'Hubble' space telescope and the Jupiter probe ' Galileo' , the development of which was far advanced, but which could only be started with a shuttle. "

Organizational problems

A space shuttle taking off. The sun is behind the camera, and the column of smoke casts a shadow in the earth's atmosphere in the direction of the moon.

The investigation of the Columbia accident showed within NASA not only the technical but also organizational deficiencies, similar to earlier in the Challenger disaster . In order to save costs, many activities that were common for manned spaceflight at NASA were discontinued. For example, the drawings of the shuttle were not updated, although significant changes had been made, so that there was no basis for the necessary verification modifications. In general, the devastating investigation report made the entire space shuttle program obsolete and vulnerable because it was too complicated and discredited. In addition, the report showed that ill-considered cost reductions demanded by NASA administrator Daniel Goldin ("faster, better, cheaper") could have serious consequences.

Another problem with the shuttle program was that the maintenance work and the manufacture of spare parts for the Orbiter were almost entirely taken over by Boeing or its subsidiaries. The same applied to the external tank ( Lockheed Martin ) and the solid fuel boosters ( ATKs Launch Systems ). Since tens of thousands of people therefore depended on the space shuttle program, so the critics, it seemed politically inopportune for a long time to stop the program entirely in favor of better technology. However, this also applied to previous programs (for example the Apollo program ) or future programs with the aim of a manned flight to Mars. You need enormous financial resources, most of which flow directly or indirectly to aerospace companies and create dependencies there.

In addition, the space shuttle could partly be viewed as a bad plan: Congress decided to develop a joint launch system for both the US Air Force and NASA that was to replace all previous launch vehicles. This combined not only civil but also military targets with the space shuttle. Because the space shuttle should be sufficient for both partners, the space shuttle represents a suboptimal product for the last only operator, NASA, which meets some Air Force requirements, but which are unnecessary in the civilian sector. For example, the Air Force required the ability to enter a polar orbit (see for example the planned STS-62-A mission ), and even the possibility of landing after just one polar orbit and taking an enemy satellite on board beforehand.

costs

Repair work on the lower heat shield
Maintenance work on a removed RS-25 engine
The original idea of ​​reprocessing a space shuttle after a flight ...
... and the actual, more complicated, slower and therefore more expensive reprocessing

Another point of criticism was that the hoped-for transport prices for "space goods" never reached the targeted 200 US dollars per kilogram - the price was recently around 16,000 US dollars, which was not only due to inflation. There were several technical reasons for the misjudgment.

The space shuttle had around 24,300 heat protection tiles. Every single tile was custom-made due to its individual shape and had to be checked after every mission. In addition, the delta wing protected by the tiles increased the weight and air resistance .

The space shuttle used three main RS-25 engines . This engine is extremely complex and correspondingly expensive at around 50 million US dollars each. After each mission, each engine was removed and checked.

The Vandenberg AFB Space Launch Complex 6 has been extensively rebuilt as a take-off and landing site for the space shuttle. However, the project was discontinued and a shuttle never started or landed there.

After the loss of the Challenger in 1986, a new shuttle, the Endeavor , had to be commissioned. This originally unplanned new shuttle construction cost the program over two billion US dollars, even though the Endeavor was partially assembled from replacement parts from the other shuttles. The loss of the Challenger and later the Columbia cost the program not only money, but also time, as the remaining shuttles were banned from starting for several years. During this time they could not carry out any commercial projects. The separate check was also expensive. At the same time, there was no shuttle that could do its job, as a fleet of four shuttles had been calculated.

Competition in the commercial space transportation business also increased steadily. As was the shuttle developed his only competition was the Ariane rocket the ESA , which at that time was still in its infancy, so commercial satellite launches in the Western world only through the NASA could be carried out. In the meantime, however, there were numerous other competitors:

The rapid development of hardware and software over the past 30 years has led NASA to retrofit the space shuttles several times. The supply of spare parts for computer hardware (e.g. the Intel 8086 ) was sometimes so bad that they were looked for on eBay . In addition, structural problems that had been overlooked or ignored in the original planning had to be remedied at great expense. In addition, it was necessary to make special modifications to the space shuttles for the Shuttle Mir program , which is why only a lower payload could be transported into space over the long term. A NASA space station was in the planning stage, but far from being realized. The savings from the further development of a space station were at the expense of the transport prices of the shuttles, which could therefore be used less commercially.

When the ISS was built, it was necessary to use the shuttle fleet to transport the largest and heaviest loads into space. No or only small commercial payloads could be transported on these flights, as the shuttles' carrying capacity was largely exhausted.

Further developments and successor program

Start of the Shuttle-C (graphic representation)

Shuttle-C

Between 1984 and 1995 a large number of concepts were developed for an unmanned cargo version of the space shuttle. These studies took place under the name Shuttle-C (C stands for Cargo). The advancing automation technology should make it possible to start the Shuttle-C without a crew and the crew rooms and life support systems that this entails. In addition, only the solid fuel boosters and not the entire space shuttle, as with the shuttle, were designed to be reusable. It was hoped that this would result in significant savings in flight costs, especially for satellite launches. The payload should also increase due to the weight savings, it was assumed that 50 to 75 tons. In addition, the existing hardware wanted to save development costs for a new heavy-duty carrier. In the early 1990s, some concepts for manned Mars flights based on the Shuttle-C were also developed. None of the Shuttle-C designs ever got beyond the concept phase.

X-33 / VentureStar

Computer rendering of the X-33 in orbit

The VentureStar was a planned successor to the space shuttle. It should contain some trend-setting innovations, such as a completely new heat shield and a new type of drive. In 1996 Lockheed Martin was awarded the contract to build a 1: 3 scale prototype . However, due to technical problems and budget overruns, this prototype, the X-33, was never completed. In the spring of 2001, the project was abandoned, although the X-33 was already 85 percent ready and over a billion US dollars had been invested in the project.

Constellation program

Concepts of the light (left) and heavy (right) Ares wearer

After the loss of Columbia, then US President George W. Bush launched the Vision for Space Exploration on January 14, 2004, a new, long-term space program that called for the space shuttle to be decommissioned on September 30, 2010. The program also included manned flights to the moon from 2018 and even manned flights to Mars from the middle of the century. For this reason, conventional rockets and space capsules were used again for the Constellation program, but these should continue to use the proven technology of the space shuttle. So the development of the Ares rocket family , which consisted of two models, was started. The Ares I was supposed to move the Orion spaceship into low Earth orbit from 2014 . For lunar missions, the Ares V would have brought the Altair landing module and the Earth Departure Stage into low earth orbit from 2018 , where it would have expected the arrival of the crew capsule.

The Constellation program (Ares I, Ares V, Orion) was discontinued in February 2010. According to US President Obama, it was neither time nor financially sustainable. In May 2011, however, Obama announced the continuation of the development of the Orion spaceship.

Space Launch System (SLS)

After the end of the Constellation program, the US Senate and the US Congress commissioned NASA to develop a new heavy-lift rocket, which is partly based on space shuttle technology and which can carry out both manned and unmanned launches with the Orion spacecraft . The engines of the Shuttles Discovery , Atlantis and Endeavor were removed to use them in the SLS first stage; Instead, dummy nozzles were built into the museum pieces. The tank of the SLS first stage and the SLS solid fuel booster are also derived from the shuttle system.

After numerous delays, the first SLS flights are planned for the early 2020s.

COTS, CRS and CCDev

Since 2006, NASA has initiated the transportation of equipment and people to the ISS by privately operated spacecraft and launch systems as part of the Commercial Orbital Transportation Services (COTS), Commercial Resupply Services (CRS) and Commercial Crew Development (CCDev) programs. In addition to the new launchers Falcon 9 and Antares, the transport spaceships Dragon (first flight 2010; transport missions to the ISS 2012-2020) and Cygnus (in use since 2013) as well as the unmanned versions of the Dragon 2 (in use since 2020) and the Dream Chaser ( planned from 2022). The manned CCDev program led to the development of the manned Dragon 2 ( Crew Dragon , first manned mission SpX-DM2 in May 2020), the CST-100 Starliner (manned first flight Boe-CFT not earlier than 2021) and a manned option for the Dream Chaser.

Similar projects

The space shuttle was the only reusable manned spacecraft that was ever in regular use. However, there have been a number of similar programs run by different space agencies. Some of these are still ongoing.

Boeing X-37
The unmanned X-37 operated by the United States Space Force (formerly the Air Force) is the only space glider that has been used several times alongside the space shuttle. Two copies were built and have completed a total of six space flights since 2010 (as of spring 2021).
Buran (Soviet Union)
The Russian counterpart to the space shuttle, the space shuttle Buran, was the only manned space glider project, besides the shuttle, that got beyond the design phase and was tested with an unmanned test flight. The program was stopped after the dissolution of the Soviet Union in the early 1990s and the remaining ferries were used for exhibitions. See also comparison of Buran and Space Shuttle .
LKS (Soviet Union)
The LKS was a project led by Vladimir Nikolayevich Chelomei as a smaller and cheaper answer by the Soviet Union to the space shuttle.
Singer and Singer II (Germany)
The German engineer Eugen Sänger developed concepts for a reusable space glider at Junkers from 1961 , which was worked on until 1974, but which never got beyond the concept phase.
Hermes (ESA)
In 1987, ESA began developing a space shuttle that was to be launched into space at the tip of an Ariane rocket. The program was stopped in 1993.
Kliper (Russia)
The Kliper was a concept for a partially reusable spaceship designed to replace the Soyuz. Development began in 2000 and was finally discontinued in 2007.
Skylon (Great Britain)
Design for an unmanned space shuttle for the British company Reaction Engines Limited (REL).

Space shuttles in the film

Numerous documentaries for television and cinemas (especially IMAX films) were made about the space shuttle program and the missions associated with it , for example about the first shuttle mission, the Hubble telescope repair, missions to the MIR and the ISS. This also included films in 3D format.

Space Shuttles starred in the following IMAX documentaries:

  • Hail Columbia (1982), about the first flight of the Columbia shuttle.
  • Destiny in Space (1994) in particular about the Hubble telescope.
  • Mission to Mir (1997) about the Shuttle Mir missions.
  • Space Station 3D (2002 in 3D format) on the structure of the ISS.
  • The Dream Is Alive (1985) about everyday life on a space shuttle.

Space Shuttles also played major and minor roles in feature films (and TV series):

  • Star Trek: The film from 1979 shows the first Space Shuttle Enterprise in several scenesin a picture gallery on board the fictional USS Enterprise NCC-1701 ; The five gallery pictures show from left to right: Naval ship USS Enterprise from 1775, aircraft carrier USS Enterprise (CVN-65) , space shuttle Enterprise and two fictitious predecessors of USS Enterprise NCC-1701 .
  • In the James Bond film Moonraker from 1979, a spacecraft is stolen.
  • In the film, the secret thing Hangar 18 , the astronauts of a space shuttle encounter an alien spaceship while launching a satellite.
  • In Starflight One from 1983, a modern supersonic aircraft makes its maiden flight from the earth's atmosphere into space. The space shuttle Columbia is sent into space several times within hours to rescue passengers, which in reality was technically and temporally impossible.
  • In Roland Emmerich's debut film The Noah's Ark principle from 1984, an unnamed shuttle is used to pick up an astronaut from the fictional space station Florida Arklab .
  • An incident occurs aboard the space shuttle Atlantis in Space Camp from 1985.
  • In the television series Ein Colt for all cases (season 4, episode 17, "Two stuntmen for space", 1985), the prototype of a computer chip is stolen from the prototype space shuttle Enterprise (which is subsequently regarded as a space-suitable shuttle). Astronauts Scott Carpenter , Michael Collins and Buzz Aldrin make cameos.
  • In Armageddon - The Last Judgment from 1998, the space shuttle Atlantis is destroyed by a meteor shower at the beginning of the film ; in the further course, two experimental shuttles named Freedom and Independence , which are said to have been developed by NASA together with the US military, play a role .
  • In the 1998 film Deep Impact , the front part of a shuttle is assembled next to the booster rockets to form a new spaceship called Messiah ; Docked to a space station, the Atlantis shuttle and its start-up can be seen in the film.
  • The 1998 US television film Max Q shows the emergency landing of the Endeavor shuttle after an explosion on board. It lands on a country road.
  • In episode 19 of the television series Cowboy Bebop , one of the main characters, Spike Spiegel, is rescued using the space shuttle Columbia.
  • In the 2000 feature film Space Cowboys , a space shuttle named Daedalus is used on a mission # STS-200 (the real missions ended with # STS-135).
  • In the feature film Mission to Mars, also from 2000, flashbacks show a landed shuttle in the background of the protagonist. Apparently this should have been a shuttle pilot earlier.
  • The 2001 US film Space Oddity shows the emergency landing of a shuttle on a boulevard in Cape Town.
  • In the television series Star Trek: Enterprise from 2001-2005, the space shuttle Enterprise is shown in the opening credits , which is a forerunner of the spaceship that gives it its name.
  • In the remake of the novel Die Zeitmaschine , the feature film The Time Machine from 2002, a space shuttle is shown approaching a moon base.
  • In the 2003 feature film The Core , the shuttle Endeavor deviates from course as a result of changes in the Earth's magnetic core and has to make an emergency landing in the channel bed of the Los Angeles River .
  • In the 2013 film Gravity , a shuttle named Explorer is destroyed by satellite debris while attempting to repair the Hubble telescope on the fictional STS-157 mission .
  • The 2013 feature film The Challenger explores the difficulties of investigating the Challenger disaster of 1986.
  • In the Russian feature film Salyut-7 from 2017 (the action takes place in 1985), the Shuttle Challenger meets the cosmonauts of the Salyut 7 space station .
  • In the 2019 feature film X-Men: Dark Phoenix , the eponymous mutants save the crew of the wrecked Endeavor .
  • In the second season of the TV series For All Mankind (from 2020) (which is set in an alternative reality from the 1980s), the space shuttles transport the astronauts to a lunar base. A further development of a nuclear powered shuttle called Pathfinder also plays a role.

See also

literature

  • David Baker: The New Space Shuttles - Columbia, Enterprise & Co. Arena, 1979, ISBN 3-401-03882-6
  • Dennis R. Jenkins: Space Shuttle: The History of the National Space Transportation System. Midland Publishing, 2006, ISBN 978-1-85780-116-3
  • Pat Duggins: Final Countdown: NASA and the End of the Space Shuttle Program University Press of Florida, 2009, ISBN 978-0-8130-3384-6
  • Space Shuttle Geo 2/1978, pages 104–120 Verlag Gruner + Jahr, Hamburg, report by Michael Collins, who, as the helmsman of the Apollo 11 company, first brought people to the moon on July 21, 1969.
  • Space shuttle. In: Bernd Leitenberger: US-Trägerraketen , Edition Raumfahrt, 2nd edition from 2016, ISBN 978-3-7392-3547-9 , pp. 629–691

Web links

Commons : Space Shuttle  - collection of pictures, videos and audio files

swell

Individual evidence

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  6. ^ Roger D. Launius, Dennis R. Jenkins: Coming Home: Reentry and Recovery from Space , National Aeronautics and Space Administration, Government Printing Office, 2012, ISBN 9780160910647 , p. 140
  7. Exploring the Unknown - Selected Documents in the History of the US Civil Space Program, Volume IV: Accessing Space , NASA, 1999, therein: Ray A. Williamson: “Developing the Space Shuttle”, p. 163
  8. Shattered dream. The 'Challenger' space shuttle exploded 25 years ago - and with it the utopia of simple space travel. In: Süddeutsche Zeitung No. 22, Friday, January 28, 2011, p. 16
  9. a b Columbia Accident Investigation Board: CAIB Report, Vol.1 ( Memento of June 30, 2006 in the Internet Archive ) (2003), p. 22 (English)
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  22. Entry, TAEM, and Approach / Landing Guidance Workbook 21002 Chapter 2.8.1
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  24. NASA: Shuttle Entry
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  37. NASA: NASA Orbiter Fleet. Retrieved May 25, 2011 : "Space Shuttle orbiter Challenger was named after the British Naval research vessel HMS Challenger that sailed the Atlantic and Pacific oceans during the 1870s. The Apollo 17 lunar module also carried the name of Challenger. Like its historic predecessors, Challenger and her crews made significant scientific contributions in the spirit of exploration. "
  38. NASA: NASA Orbiter Fleet. Retrieved May 25, 2011 : "Columbia was named after a small sailing vessel that operated out of Boston in 1792 and explored the mouth of the Columbia River. One of the first ships of the US Navy to circumnavigate the globe was named Columbia. The command module for the Apollo 11 lunar mission was also named Columbia. "
  39. NASA: NASA Orbiter Fleet. Retrieved May 25, 2011 (English): “Discovery is named for two famous sailing ships; one sailed by Henry Hudson in 1610-11 to search for a northwest passage between the Atlantic and Pacific Oceans, and the other by James Cook on a voyage during which he discovered the Hawaiian Islands. "
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