Attached to the International Space Station’s doorway, the Quest
Airlock, a square suitcase-sized package holds hundreds of materials.
The Materials International Space Station Experiment, or MISSE,
includes samples of materials used for solar power cells, spacecraft
shielding, thermal control, optics and other purposes. MISSE was
delivered last summer and will be exposed to the space environment for
about nine more months. Then, the samples will be returned to Earth so
that engineers can determine how the space environment affects
materials needed to build advanced spacecraft of the future.

Three samples being tested as part of MISSE – all ultra-thin tether
materials – are of particular interest to materials scientists in the
Engineering Directorate at NASA’s Marshall Space Flight Center in
Huntsville, Ala. Similar tethers have been tested in Marshall’s
materials laboratory and will be used on the June flight of the
Propulsive Small Expendable Deployer System – called ProSEDS. This
flight — managed by the Marshall Center’s Space Transportation
Directorate — will mark the first time a tether system is used to
change the orbital altitude of a satellite.

Electrodynamic tether propulsion systems are propellant-free. They
draw power from Earth’s electrically charged atmosphere and transfer
this energy to satellites or other objects to raise or lower their

The ProSEDS tether mission will last no longer than three weeks, but
,hÓmethers used as permanent space tugboats would be expected to be
durable, reusable systems in service for long periods. The MISSE
materials tests will give engineers data on how the tether material
fares when exposed to the harsh space environment for a year.