Spacecraft information: ESIAFI 1
| Launched | 20 February 1981 |
| Flight ended | – |
| Status | Non-operational |
| Launch site | Air Force Eastern Test Range, Florida, USA |
| Owner | United States |
| NORAD ID | 12309 |
| COSPAR ID | 1981-018A |
| Alternative names |
COMSTAR 4 |
| Observing |
Current orbital elements
| Inclination | 8.584° |
| Eccentricity | 0.00022 |
| RA ascending node | 20.722 hr |
| Argument perigee | 90.152° |
| Mean anomaly | 269.930° |
| Orbital period | 1435.988 min |
| Epoch of osculation | 18 Aug 2026, 18:14 |
Derived Quantities
| Min Altitude | 35782.2 km |
| Mean Altitude | 35791.6 km |
| Peak Altitude | 35801.0 km |
Launched alongside
ATLAS CENTAUR R/BOrbital History
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