STS-75 Mission Insignia 
The STS-75 crew patch depicts the Space Shuttle Columbia and the Tethered Satellite connected by a 21 km electrically conduction tether. The Orbiter/satellite system is passing through the Earth's magnetic field which, like an electric generator, will produce thousands of volts of electricity. Columbia is carrying the United States Microgravity Pallet to conduct microgravity research in material science and thermodynamics. The tether is crossing the Earth's terminator signifying the dawn of a new era for space tether applications and in mankind's knowledge of the Earth's ionosphere, material science, and thermodynamics. The patch was designed for the STS-75 crew by Space Artist Mike Sanni.
Vectorized from a NASA image

http://science.ksc.nasa.gov/shuttle/missions/sts-75/sts-75-patch.jpg
http://nix.larc.nasa.gov/info?id=MSFC-9512547&amp;orgid=11