Long Duration Exposure Facility
A long-duration orbital facility for space exposure experiments.
The Long Duration Exposure Facility (LDEF, pronounced 'eldef') was a cylindrical, 12-sided prism facility built by NASA's Langley Research Center 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 and, after a series of delays, was retrieved by Space Shuttle Columbia in January 1990, having spent 69 months in space. LDEF successfully carried 57 science and technology experiments from investigators in the United States, Canada, Denmark, France, Germany, Ireland, the Netherlands, Switzerland, and the United Kingdom, revealing a broad and detailed collection of space environmental data that has benefited NASA spacecraft designers to this day.
- Launch date
- April 7, 1984
- Retrieval date
- January 12, 1990
- Time in orbit
- 5.7 years (69 months)
- Orbit altitude at deployment
- 257 nautical miles
- Structure
- 12-sided stainless steel prism
- Number of experiments
- 57
- Countries involved
- 9 (United States, Canada, Denmark, France, Germany, Ireland, Netherlands, Switzerland, United Kingdom)
Quick Facts
- Mission Type
- Materials research
- Operator
- NASA
- Website
- https: · crgis.ndc.nasa.gov/historic/Long_Duration_Exposure_Facility_(LDEF)
- Satcat
- 14898
- Mission Duration
- 2076 days
- Orbits Completed
- 32,422
- Distance Travelled
- 1374052506 km
- Manufacturer
- Langley
- Dry Mass
- 3629 kg
- Launch Mass
- 9724 kg
- Launch Date
- April 6, 1984, 13:58:00 · timezone=yes UTC
- Launch Rocket
- 099 / STS-41-C
Facts from the source article.
Lore & Background
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. It was intended to be reused and redeployed with new experiments every 18 months, but after the unintended extension of the first mission, the structure itself was treated as an experiment and intensively studied before being placed into storage. Attitude control was achieved with gravity-gradient stabilization and inertial distribution, requiring no propulsion or other attitude control systems, making LDEF free of acceleration forces and contaminants from jet firings. It had two grapple fixtures, including an active grapple that sent an electronic signal to initiate 19 experiments with electrical systems via the Experiment Initiate System (EIS).
Reader's Guide
The Long Duration Exposure Facility holds significance as a unique platform for gathering long-term data on the effects of the space environment on materials, components, and systems. Its 5.7-year mission provided information vital to the development of the Space Station Freedom, the International Space Station, and other spacecraft, especially regarding reactions to radiation, extreme temperature changes, and collisions with space matter. Experiments included studies of materials, coatings, thermal systems, power and propulsion, optical fibers, electronics, and the survival of tomato seeds and bacterial spores. Notably, the German EXOSTACK experiment found that 30% of Bacillus subtilis spores survived nearly six years in space when embedded in salt crystals, and up to 80% survived in the presence of glucose, supporting the lithopanspermia hypothesis. The Space Exposed Experiment Developed for Students (SEEDS) flew 12.5 million tomato seeds, with students reporting that space seeds germinated sooner and grew faster than controls. LDEF's retrieval was delayed by the Challenger disaster, and by the time Columbia recovered it in January 1990, its orbit had decayed to about 175 nautical miles and it was likely to burn up within a month.
Did You Know?
- LDEF was originally scheduled for retrieval in March 1985, but was not recovered until January 1990 due to delays and the Challenger disaster.
- The German EXOSTACK experiment showed that 30% of Bacillus subtilis spores survived nearly 6 years in space when embedded in salt crystals.
- LDEF carried 12.5 million tomato seeds for the SEEDS experiment, which germinated sooner and grew faster than control seeds.
- LDEF had no telemetry; some active experiments recorded data on magnetic tape recorders powered by lithium sulfur dioxide batteries.
Frequently Asked Questions
What is the Long Duration Exposure Facility?
LDEF was a 12-sided cylindrical prism built by NASA's Langley Research Center to study how the outer space environment affects materials, systems, and even biological spores over extended periods. It carried 57 science and technology experiments from researchers across multiple countries.
When was LDEF launched and brought back to Earth?
Space Shuttle Challenger deployed LDEF into low Earth orbit on April 7, 1984, at an altitude of 257 nautical miles. After a series of delays, Space Shuttle Columbia retrieved it on January 12, 1990.
How long did LDEF spend in space?
The facility orbited Earth for 69 months, roughly 5.7 years, before its retrieval. This extended duration allowed researchers to gather long-term exposure data that shorter missions simply could not provide.
What did LDEF look like structurally?
It was a 12-sided stainless steel prism, essentially a cylindrical facility with flat faces rather than a smooth curve. This design provided multiple external surfaces for mounting the 57 experiments it carried.
Why is LDEF important for astrobiology?
Among its 57 experiments, LDEF included studies on the survival of selected spores in the space environment, making it a key data source for understanding how biological material endures prolonged orbital exposure. The 69-month duration gave astrobiologists a rare long-term dataset on spore viability outside Earth's atmosphere.
More in Astrobiology space missions 1-24
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