Encyclopedia Astronautica
1998.10.20 - USA 140


The orbit at burnout of the Centaur was 286 km x 25866 km x 27.0 degree. Modification of the orbit to a geostationary 38,300 km circular x 0.0 degree inclination was accomplished by the Marquardt R-4D liquid propellant motor on the HS-601 spacecraft. The satellite carried UHF and EHF transponders for naval communications, and a Ka-band Global Broadcast Service video relay package. Launch mass of 3200 kg dropped to 1550 kg once geostationary orbit was reached. UHF F/O F9 was placed over the Atlantic Ocean in geosynchronous orbit at 174 deg W in 1998; 22 deg W in 1999.

Booster engine cut-off (BECO) was at T+2:45, followed 3 seconds later by separation of the booster engines. Sustainer engine cut-off (SECO) was at T+4:35. After separation of the Atlas stage at T+4:37, the Centaur II second stage ignited. At T+9:53 the Centaur shut down, having entered a 168 km x 1090 km x 28.9 degree parking orbit. The Centaur re-ignited at T+22:23 for about one minute until its fuel was depleted, and separated from the UHF satellite at T+27:03.

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