A series of experiments, called the Materials International Space Station Experiments (MISSE), are being conducted jointly by NASA and the Department of Defense (DOD) to investigate the effects of long-term exposure of materials to the harsh space environment.
Image to right: NASA Langley Research Center’s William Kinard, MISSE chief scientist and principal investigator, displays a half-scale model of a MISSE Passive Experiment Container. The MISSE project was created to verify the durability of new materials and devices in space.
Credit: NASA/Jeff Caplan
The only way to be sure how different materials and devices will perform in space is to test them in that environment. Laboratories can simulate just one or two space environments at a time.
Making history as the first experiment to be mounted externally on the International Space Station (ISS), MISSE was created to verify the durability of new materials and devices in space.
The research from MISSE will evaluate the performance, stability and long-term survivability of materials and components planned for use by NASA, DOD, and commercial companies on future Low-Earth Orbit (LEO), synchronous orbit and interplanetary space exploration missions.
Image to right: An astronaut installs one of the MISSE "suitcases" (or Passive Experiment Containers) on the exterior of the International Space Station during a spacewalk in 2001.
MISSE will evaluate materials currently being used and those planned for future space missions.
The Long Duration Exposure Facility (LDEF), which was retrieved in 1990 after spending 69 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 LEO, 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.
Image to right: Researchers examine the materials of a MISSE Passive Experiment Container in a clean room at NASA Langley Research Center. The test devices include ultra-light membranes, composites, ceramics, polymers, coatings, radiation shielding, switches, solar cells, sensors and mirrors.
Credit: NASA/Jeff Caplan
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.
On Earth, a material can only be subjected to one environment at a time for testing. The combined effects of all of these environments on spacecraft can only be investigated in space.
The MISSE project is testing approximately 1,500 technology test specimens in space. Samples range from components such as switches, sensors and mirrors to materials like polymers, coatings and composites. There are also biological materials such as seeds, spores and various types of bacteria being evaluated.
MISSE tests coatings used to control heat absorption and emission temperatures of satellites. The hostile environment of space limits the useful life of currently used coatings. New coatings, which are expected to be much more stable in space and therefore have longer useful lives, are being tested.
MISSE is also addressing a major problem for manned exploration of Mars–shielding the crew from the very energetic cosmic rays found in interplanetary space. New concepts for lightweight shields will be tested on MISSE. Ultra-light membrane structures are planned for solar sails, large inflatable mirrors and lenses. The effects of micrometeoroid impacts on these materials will also be investigated.
MISSEs 1 and 2 were packed on STS-105 when it lifted off from Kennedy Space Center, Fla., on Aug. 10, 2001. While on orbit, the STS-105 crew attached these MISSEs to the exterior of the ISS. At that time, it was planned that MISSEs 1 and 2 would be returned to Earth approximately one year later and that two new MISSEs (3 and 4) would be deployed in their place to be retrieved after a three-year exposure in spa