1992-006A
For the second series of DSCS III launches, the USAF let a commercial launch contract for the Medium Launch Vehicle 2, won by General Dynamics (later Lockheed Martin) who proposed their Atlas II launch vehicle. The Atlas II required an apogee engine to deliver the DSCS into stationary orbit; GE Astro Space made the Integrated Apogee Boost Subsystem (IABS) using two R4D liquid engines. IABS was controlled by a new gyro unit on the DSCS spacecraft that also is used for on-orbit DSCS operations. DSCS III B-14 was given the designation USA 78 on reaching orbit.
The IABS carried solar arrays and attiude sensors. IABS LAE firing is controlled by the DSCS payload. IABS burn is at apogee 5, with a planned trim burn at apogee 7. IABS then separates in a 3 deg/day 23 hr drift orbit. However, a problem with IABS prevented the second burn, which had to be done with the DSCS’ onboard RCS engines.
| DSCS III B-14 | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1992 Feb 11 | 0041:02 | Launch by Atlas II | CC LC36A |
| 0043 | Booster sep (T+2:49) | ||
| 0046 | Centaur MES1 (T+5:00) | ||
| 0052 | Centaur MECO1 (T+11:20) | 148 x 522 x 28.3 | |
| 0105 | Centaur MES2 (T+24:00, burn 1:50) | ||
| 0107 | Centaur MECO2 | ||
| 0108 | DSCS/IABS sep from Centaur | 173 x 35710 x 26.5 | |
| 1992 Feb 12 | 2230 | IABS burn (60min) | |
| 1992 Feb 13 | 0145 | IABS trim burn cancelled, 80s | |
| 0150 | IABS sep | ||
| 1995 Jul | EPAC Prime | GEO 135.0W | |
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