FAST (Fast Auroral Snapshot Explorer) is a NASA satellite designed to observe and measure rapidly-varying electric and magnetic fields and the flow of electrons and ions above aurorae; it was the second SMEX (Small Explorer) mission. FAST's data is complemented by those from other spacecraft, which observe fields and particles and photograph the aurora from higher altitudes. At the same time, auroral observatories and geomagnetic stations on the ground supply measurements on how the energetic processes FAST observes affect Earth. Although made ready for a mid-1994 launch date, FAST was put in storage for a couple of years until a series of problems with the Pegasus launch vehicle could be corrected.

 

launch date	Aug 21, 1996
launch vehicle	Pegasus XL
launch site	Vandenberg Air Force Base
orbit	353 × 4,163 km × 83.0°
size	1.8 × 1.2 m
mass	187 kg