REX (Radiation Experiment)
REX (Radiation Experiment) were United States Air Force satellites designed to study scintillation effects of Earth's atmosphere on radio transmissions. REX 2 was also the first spacecraft to successfully employ GPS (Global Positioning System) navigation for full closed-loop attitude control.
| spacecraft | launch date | launch vehicle | launch site | orbit | mass (kg) | size (m) |
| REX 1 | Jun 29, 1991 | Scout G | Vandenberg | 766 × 869 km × 89.6° | 85 | 0.6 × 0.8 |
| REX 2 | Mar 9, 1996 | Pegasus XL | Vandenberg | 799 × 835 km × 90.0° | 0.6 × 0.8 |
