NASA's Long Duration Exposure Facility, or LDEF (acronym pronounced "EL-deaf"), was a school bus-sized cylindrical facility designed to provide long-term experimental data on the outer space environment and its effects on space systems, materials, operations and selected spores' survival. It was placed in low Earth orbit by Space Shuttle Challenger in April 1984. The original plan called for the LDEF to be retrieved in March 1985, but after a series of delays it was eventually returned to Earth by Columbia in January 1990.
It successfully carried science and technology experiments for about 5.7 years, that have revealed a broad and detailed collection of space environmental data. LDEF's 69 months in space provided scientific data on the long-term effects of space exposure on materials, components and systems that has benefited NASA spacecraft designers to this day.
|Long Duration Exposure Facility|
|Mission type||Materials research|
|Mission duration||2076 days|
|Distance travelled||1,374,052,506 km (853,796,644 mi)|
|Launch mass||9,700 kg (21,400 lb)|
|Start of mission|
|Launch date||April 6, 1984, 13:58:00 UTC|
|Rocket||Space Shuttle Challenger|
|Launch site||Kennedy LC-39A|
|End of mission|
|Recovered by||Space Shuttle Columbia|
|Recovery date||January 12, 1990, 15:16 UTC|
|Landing date||January 20, 1990, 09:35:37 UTC|
|Landing site||Edwards Runway 22|
|Perigee||473.0 km (293.9 mi)|
|Apogee||483.0 km (300.1 mi)|
Researchers identified the potential of the planned Space Shuttle to deliver a payload to space, leave it there for a long-term exposure to the harsh outer space environment, and on a separate mission retrieve the payload and return it to Earth for analysis. The LDEF concept evolved from a spacecraft proposed by NASA's Langley Research Center in 1970 to study the meteoroid environment, the Meteoroid and Exposure Module (MEM). The project was approved in 1974 and LDEF was built at NASA's Langley Research Center.
LDEF was intended to be reused, and redeployed with new experiments, perhaps every 18 months. but after the unintended extension of mission 1 the structure itself was treated as an experiment and intensively studied before being placed into storage.
Its shape was a 12 sided prism (to fit the shuttle orbiter payload bay). There were 5 or 6 experiments on each of the 12 long sides and a few more on the ends. It was designed to fly with one end facing earth and the other away from earth. Attitude control of LDEF was achieved with gravity-gradient stabilization and inertial distribution to maintain three-axis stability in orbit. Therefore, propulsion or other attitude control systems were not required, making LDEF free of acceleration forces and contaminants from jet firings. There was also a magnetic/viscous damper to stop any initial oscillation after deployment.
It had two grapple fixtures. An FRGF and an active (rigidize sensing) grapple used to send an electronic signal to initiate the 19 experiments that had electrical systems. This activated the Experiment Initiate System (EIS):1538 which sent 24 initiation signals to the 20 active experiments. There were six initiation indications which were visible to the deploying astronauts :109 next to the active grapple fixture.:111
Engineers originally intended that the first mission would last about one year, and that several long-duration exposure missions would use the same frame. The exposure facility was actually used for a single 5.7-year mission.
The LDEF facility was designed to glean information vital to the development of the Space Station Freedom (that was eventually built as the International Space Station) and other spacecraft, especially the reactions of various space building materials to radiation, extreme temperature changes and collisions with space matter.
There was no telemetry but some active experiments recorded data on a magnetic tape recorder (which was powered by a lithium sulfur dioxide battery). e.g. The Advanced Photovoltaic Experiment (S0014) (recorded data once a day), the German Solar cell study (S1002) also recorded data,:#91 as did the Space Environment Effects on Fiber Optics Systems (M004):#182
Six of the seven active experiments that needed to record data used one or two Experiment Power and Data System (EPDS) modules.:1545 Each EPDS contained a processing and control module, a magnetic tape recorder and two LiSO2 batteries.:1536 One experiment (S0069) used a 4-track magnetic tape module not as part of an EPDS.:1540
Fifty-seven science and technology experiments – involving government and university investigators from the United States, Canada, Denmark, France, Germany, Ireland, the Netherlands, Switzerland, and the United Kingdom – flew on the LDEF mission. A total of 57 experiments were conducted on the LDEF. Interstellar gases also would be trapped in an attempt to find clues into the formation of the Milky Way and the evolution of heavier elements. Some examples are investigation of exposure effects on:
and physics in low gravity – e.g. crystal growth.
In the German experiment EXOSTACK, 30% of Bacillus subtilis spores survived the nearly 6 years exposure to outer space when embedded in salt crystals, whereas 80% survived in the presence of glucose, which stabilize the structure of the cellular macromolecules, especially during vacuum-induced dehydration.
If shielded against solar UV, spores of B. subtilis were capable of surviving in space for up to 6 years, especially if embedded in clay or meteorite powder (artificial meteorites). The data may support the likelihood of interplanetary transfer of microorganisms within meteorites, the so-called lithopanspermia hypothesis.
The Space Exposed Experiment Developed for Students (SEEDS) allowed students the opportunity to grow control and experimental tomato seeds that had been exposed on LDEF comparing and reporting the results. 12.5 million seeds were flown, and students from elementary to graduate school returned 8000 reports to NASA. The L.A. Times reported that a DNA mutation from space exposure could yield a poisonous fruit, and the report served to raise awareness of the experiment and generate discussion. Space seeds germinated sooner and grew faster than the control seeds. Space seeds were more porous than terrestrial seeds.
At LDEF's launch, retrieval was scheduled for March 19, 1985, eleven months after deployment. Schedules slipped, postponing the retrieval mission first to 1986, then indefinitely due to the Challenger disaster. After 5.7 years its orbit had decayed to about 175 nautical miles and it was likely to burn up on reentry in a little over a month.:15
It was finally recovered by Columbia on mission STS-32 on January 12, 1990. Columbia approached LDEF in such a way as to minimize possible contamination to LDEF from thruster exhaust. While LDEF was still attached to the RMS arm, an extensive 4.5 hour survey photographed each individual experiment tray, as well as larger areas. Nevertheless, shuttle operations did contaminate experiments when concerns for human comfort out-weighed important LDEF mission goals.
Columbia landed at Edwards Air Force Base on January 20, 1990. With LDEF still in its bay, Columbia was ferried back on the Shuttle Carrier Aircraft to the Kennedy Space Center on January 26. Special efforts were taken to ensure protection against contamination of the payload bay during the ferry flight.
Between January 30 and 31, LDEF was removed from Columbia's payload bay in KSC's Orbiter Processing Facility, placed in a special payload canister, and transported to the Operations and Checkout Building. On February 1, 1990, LDEF was transported in the LDEF Assembly and Transportation System to the Spacecraft Assembly and Encapsulation Facility – 2, where the LDEF project team led deintegration activities.
During the Space Shuttle program, several missions were canceled. Many were canceled as a result of the Challenger and the Columbia disasters. Many early missions were canceled due to delays in the development of the shuttle. Others were canceled because of changes in payload and missions requirements.European Retrievable Carrier
The European Retrievable Carrier (EURECA) was an unmanned 4.5-tonne satellite with 15 experiments. It was a European Space Agency (ESA) mission and the acronym was derived from Archimedes' bathtub revelation "Eureka!".
It was built by the German MBB-ERNO and had automatic material science cells as well as small telescopes for solar observation (including x-ray).
It was launched 31 July 1992 by Space Shuttle Atlantis during STS-46, and placed into an orbit at an altitude of 508 km (316 mi). EURECA was retrieved on 1 July 1993 by Space Shuttle Endeavour during STS-57 and returned to Earth. It was designed to fly five times with different experiments but the following flights were cancelled.
EURECA is one of the few unmanned space vehicles that have been returned to the Earth unharmed. It has been on display at the Swiss Museum of Transport in Lucerne since 2000.G. David Low
George David Low (February 19, 1956 – March 15, 2008) was an American aerospace executive and a NASA astronaut. He was born in 1956 to Dr. George Low, the Manager of the Apollo Spacecraft Program Office. With undergraduate degrees in physics and mechanical engineering and a master's degree in aeronautics and astronautics, he worked in the JPL at the California Institute of Technology in the early 80's, before being picked as an astronaut candidate by NASA in 1984. In addition to holding some technical assignments, he logged more than 700 hours in space (including stints on the Columbia, the Atlantis and the Endeavour), before he left NASA in 1996 to pursue a career in the private sector.George Nelson (astronaut)
George Driver "Pinky" Nelson (born (1950-07-13)July 13, 1950) is an American physicist, astronomer, science educator, and a former NASA astronaut.Grapple fixture
Grapple fixtures are used on spacecraft or other objects to provide a secure connection for a robotic arm.Gravity-gradient stabilization
Gravity-gradient stabilization (a.k.a. "tidal stabilization") is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction wheels is the low use of power and resources.
The idea is to use the Earth's gravitational field and tidal forces to keep the spacecraft aligned in the desired orientation. The gravity of the Earth decreases according to the inverse-square law, and by extending the long axis perpendicular to the orbit, the "lower" part of the orbiting structure will be more attracted to the Earth. The effect is that the satellite will tend to align its axis of minimum moment of inertia vertically.
The first experimental attempt to use the technique on a human spaceflight was performed on September 13, 1966, on the US Gemini 11 mission, by attaching the Gemini spacecraft to its Agena target vehicle by a 100-foot (30 m) tether. The attempt was a failure, as insufficient gradient was produced to keep the tether taut.The technique was first successfully used in a near-geosynchronous orbit on the Department of Defense Gravity Experiment (DODGE) satellite in July 1967.It was first used for low Earth orbit and tested unsuccessfully for geosynchronous orbit in the Applications Technology Satellites ATS-2, ATS-4 and ATS-5 from 1966 until 1969.The lunar orbiter Explorer 49 launched in 1973 was gravity gradient oriented (Z axis parallel to local vertical).Long Duration Exposure Facility (LDEF) used this method for 3-axis stabilization; yaw about the vertical axis was stabilized.An example of gravity-gradient stabilization was attempted during NASA's TSS-1 mission in July, 1992. The project failed because of tether deployment problems. In 1996 another mission, TSS-1R, was attempted but failed when the tether broke. Just prior to tether separation, the tension on the tether was about 65 N (14.6 lbs).James van Hoften
James Dougal Adrianus "Ox" van Hoften, Ph.D. (born June 11, 1944) is an American civil and hydraulic engineer, retired U.S. Navy officer and aviator, and a former astronaut for NASA.Marsha Ivins
Marsha Sue Ivins (born April 15, 1951) is an American former astronaut and a veteran of five space shuttle missions.Materials International Space Station Experiment
The Materials International Space Station Experiment (MISSE) is a series of experiments mounted externally on the International Space Station (ISS) that investigates the effects of long-term exposure of materials to the harsh space environment.
The MISSE project evaluates the performance, stability, and long-term survivability of materials and components planned for use by NASA, commercial companies and the Department of Defense (DOD) on future low Earth orbit (LEO), synchronous orbit and interplanetary space missions. The Long Duration Exposure Facility (LDEF), which was retrieved in 1990 after spending 68 months in LEO, revealed that space environments are very hostile to many spacecraft materials and components. Atomic oxygen, which is the most prevalent atomic species encountered in low earth orbit, is highly reactive with plastics and some metals, causing severe erosion.
There is also extreme ultraviolet radiation due to the lack of an atmospheric filter. This radiation deteriorates and darkens many plastics and coatings. The vacuum in space also alters the physical properties of many materials. Impacts of meteoroids and orbiting man-made debris can damage all materials exposed in space. The combined effects of all of these environments on spacecraft can only be investigated in space. MISSE evaluates materials currently being used and those planned for use in future space missions.The MISSE program is a direct successor to the Mir Environmental Effects Payloads (MEEPs) that were attached for over a year to the Mir Docking Module of the space station Mir between shuttle flights STS-76 and STS-86; and is a descendant of the Long Duration Exposure Facility. Also MEEPS can trace their inception to the Passive Optical Sample Array (POSA) sample trays flown on STS-1 and STS-2, and their successor Effects of Oxygen Interaction with Materials (EOIM) on STS-3 and STS-5.Mir Environmental Effects Payload
The Mir Environmental Effects Payload (MEEP) was a set of four experiments installed on the Russian space station Mir from March 1996 to October 1997 to study the effects of space debris impacts and exposure to the space environment on a variety of materials. The materials used in the experiments were being considered for use on the International Space Station, and by exposing them at a similar orbital altitude to that flown by the ISS, the experiments provided an assessment of the performance of those materials in a similar space environment. MEEP also fulfilled the need to examine the occurrence and effects of man-made debris and natural micrometeoroids through capture and impact studies. The experiments were installed on the Mir docking module during STS-76, and retrieved during STS-86.NASA Astronaut Group 10
NASA Astronaut Group 10 (nicknamed "The Maggots") was a group of 17 astronauts that were selected in 1984 and consisted of seven pilots and ten mission specialists. Although selected in 1984, no member of the group would fly until 1988 (William Shepherd on STS-27) due to the Challenger disaster and the resulting grounding of the Space Shuttle fleet.NASA Astronaut Group 7
Astronaut Group 7, referred to in some documents as the USAF MOL Transfer, was a group of seven astronauts announced by NASA on August 14, 1969, and was the last group to be selected during the Apollo era. After the USAF Manned Orbiting Laboratory (MOL) project was cancelled, NASA hired seven of the astronauts selected for that program to form this "Group 7", roughly the younger half of the MOL astronauts. By the time they joined NASA, all Apollo flight assignments had been lined up, but four were given non-flying support assignments for Apollo. Others were also given support assignments for Skylab and the Apollo-Soyuz Test Project, with Bobko and Crippen participating in the Skylab Medical Experiment Altitude Test. Group 7 went on to form the core of early Space Shuttle pilots, upgrading to commander after their first flight, flying 17 STS missions between them, plus the Approach and Landing Tests of Enterprise (OV-101).NASA Astronaut Group 8
NASA's Astronaut Group 8 was a group of 35 astronauts announced on January 16, 1978. It was the first selection in nine years of astronaut candidates since Group 7 in August 1969, and also included NASA's first female astronauts. Due to the long delay between the last Apollo lunar mission in 1972 and the first flight of the Space Shuttle in 1981, few astronauts from the older groups stayed with NASA. Since then, a new group of candidates has been selected roughly every two years.In Astronaut Group 8, two different astronaut groups were formed: pilots and mission specialists. (With shuttle classes, NASA stopped sending non-pilots for one year of UPT.) Of the 35 selected, six were women, three were male African Americans, and one was a male Asian American.NASA Astronaut Group 9
NASA Astronaut Group 9 was a group of 19 astronauts announced on May 29, 1980, and completed their training by 1981. This group was selected to supplement the 35 astronauts that had been selected in 1978, and marked the first time that non-Americans were trained as mission specialists with the selections of ESA astronauts Claude Nicollier and Wubbo Ockels. In keeping with the previous group, astronaut candidates were divided into pilots and mission specialists, with eight pilots, eleven mission specialists, and two international mission specialists within the group.STS-32
STS-32 was the 33rd mission of NASA's Space Shuttle program, and the 9th launch of Space Shuttle Columbia. Launched on 9 January 1990, it marked the first use of Launch Pad A at Kennedy Space Center's Complex 39 since 1986; it also marked the first use of Mobile Launcher Platform No. 3 (MLP-3) in the Space Shuttle program. STS-32 was, at the time, the longest shuttle mission yet conducted, with a duration of nearly 11 days. Before STS-32, the only mission of the same duration had been STS-9 in 1983. On 20 January 1990, STS-32 executed the third night landing of the shuttle program.STS-41-C
STS-41-C was NASA's 11th Space Shuttle mission, and the fifth mission of Space Shuttle Challenger. The launch, which took place on April 6, 1984, marked the first direct ascent trajectory for a shuttle mission. During the mission, Challenger's crew captured and repaired the malfunctioning Solar Maximum Mission ("Solar Max") satellite, and deployed the Long Duration Exposure Facility (LDEF) experimental apparatus. STS-41-C was extended one day due to problems capturing the Solar Max satellite, and the landing on April 13 took place at Edwards Air Force Base, instead of at Kennedy Space Center as had been planned. The flight was originally numbered STS-13.Space Shuttle Enterprise
Space Shuttle Enterprise (Orbiter Vehicle Designation: OV-101) was the first orbiter of the Space Shuttle system. Rolled out on September 17, 1976, it was built for NASA as part of the Space Shuttle program to perform atmospheric test flights after being launched from a modified Boeing 747. It was constructed without engines or a functional heat shield, and was therefore not capable of spaceflight.Originally, Enterprise had been intended to be refitted for orbital flight to become the second space-rated orbiter in service. However, during the construction of Space Shuttle Columbia, details of the final design changed, making it simpler and less costly to build Challenger around a body frame that had been built as a test article. Similarly, Enterprise was considered for refit to replace Challenger after the latter was destroyed, but Endeavour was built from structural spares instead.Enterprise was restored and placed on display in 2003 at the Smithsonian's new Steven F. Udvar-Hazy Center in Virginia. Following the retirement of the Space Shuttle fleet, Discovery replaced Enterprise at the Udvar-Hazy Center, and Enterprise was transferred to the Intrepid Sea, Air & Space Museum in New York City, where it has been on display since July 2012.Terry Hart
Terry Jonathan "T.J." Hart (born October 27, 1946, in Pittsburgh, Pennsylvania) is an American mechanical and electrical engineer, a retired United States Air Force lieutenant colonel and pilot, and former NASA astronaut.The Dream Is Alive
The Dream is Alive is an IMAX documentary film, released in June 1985, about NASA's Space Shuttle program. The film was narrated by Walter Cronkite, and directed by Graeme Ferguson.