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AsiaSat 3

AsiaSat 3 → HGS-1 → PAS-22
Mission type Communications
Operator
COSPAR ID 1997-086A
Mission duration
  • 15 years (planned)
  • 4 years (achieved)
Spacecraft properties
Bus HS-601HP
Manufacturer Hughes
Launch mass 3,400 kilograms (7,500 lb)
Start of mission
Launch date 24 December 1997, 23:19 (1997-12-24UTC23:19Z) UTC
Rocket Proton-K/DM3
Launch site Baikonur 81/23
Contractor ILS
End of mission
Disposal Decommissioned
Deactivated July 2002 (2002-08)
Orbital parameters
Reference system Geocentric
Regime
Longitude
  • 105.5° East (intended)
  • 158° West (1998)
  • 62° West (1999-2002)
Flyby of the Moon
Closest approach 13 May 1998, 19:00 UTC
Distance 6,200 kilometres (3,900 mi)
Flyby of the Moon
Closest approach 6 June 1998, 16:30 UTC
Distance 34,300 kilometres (21,300 mi)
Transponders
Band

PAS-22, previously known as AsiaSat 3 and then HGS-1, was a geosynchronous communications satellite which was salvaged from an unusable geosynchronous transfer orbit by means of the Moon's gravity.

AsiaSat 3 was launched by AsiaSat Ltd of Hong Kong to provide communications and television services in Asia by a Proton booster on 24 December 1997, destined for an orbit slot at 105.5° E. However, a failure of the Blok DM3 fourth stage left it stranded in a highly inclined (51 degrees) and elliptical orbit, although still fully functional. It was declared a total loss by its insurers. The satellite was transferred to Hughes Global Services, Inc., with an agreement to share any profits with the insurers.

Edward Belbruno and Rex Ridenoure heard about the problem and proposed a 3–5 month low energy transfer trajectory that would swing past the moon and leave the satellite in geostationary orbit around the earth. Hughes had no ability to track the satellite at such a distance, and considered this trajectory concept unworkable. Instead, Hughes used an Apollo-style free return trajectory that required only a few days to complete, a trajectory designed and subsequently patented by Hughes Chief Technologist Jerry Salvatore. This maneuver removed only 40 degrees of orbital inclination and left the satellite in a geosynchronous orbit, whereas the Belbruno maneuver would have removed all 51 degrees of inclination and left it in geostationary orbit.

Although Hughes did not end up using the low-energy transfer trajectory, the insight to use a lunar swingby was key to the spacecraft rescue. According to Ocampo, Hughes had not considered this option until it was contacted by Ridenoure, although the Hughes engineers involved in the lunar flyby operations have stated that they were already working on the lunar swingby mission design before being contacted by him.


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