AsiaSat 3, previously known as HGS-1 and then PAS-22, was a

geosynchronous A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

, which was salvaged from an unusable geosynchronous transfer orbit (GTO) by means of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

's gravity.

Launch of AsiaSat 3

AsiaSat 3 was launched for

AsiaSat Asia Satellite Telecommunications Company Limited (AsiaSat) is a Hong Kong–based commercial operator of communications satellites founded in 1988. It is a wholly-owned subsidiary of Asia Satellite Telecommunications Holdings Limited (AsiaSat ...

Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...

to provide communications and television services in Asia by a Proton-K / DM-2M

launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...

on 24 December 1997, destined for an orbital position at 105.5° East. However, a failure of the Blok DM-2M fourth stage left it stranded in a highly inclined (51.6°) and elliptical orbit, although still fully functional. It was declared a total loss by its insurers.

HGS-1

Animation of PAS-22 trajectory around Earth

The satellite was transferred to Hughes Global Services Inc., which was then a subsidiary of Hughes Space and Communications, with an agreement to share any profits with the consortium of 27 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

and leave the satellite in geostationary orbit around the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. Hughes had no ability to track the satellite at such a distance and considered this trajectory concept unworkable. Instead, Hughes used an

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

-style free-return trajectory that required only a few days to complete, a trajectory designed and subsequently patented Salvatore, Jeremiah O. and Ocampo, Cesar A. (Assignee: Hughes Electronics Corporation) U.S. Patent 6,149,103, "Free return lunar flyby transfer method for geosynchronous satellites having multiple perilune stages", filed May 15, 1998 by Hughes Chief Technologist Jerry Salvatore.J. Fisher
"AsiaSat Rescue: The Real Story, Part 1"
Hughes, July 8, 2013 (accessed 10 December 2014) This maneuver removed only 40° of orbital inclination and left the satellite in a

orbit, whereas the Belbruno maneuver would have removed all 51° 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 Cesar 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.

Rescue of satellite

Using on-board propellant and lunar gravity, the orbit's apogee was gradually increased with several manoeuvres at perigee until it flew by the Moon at a distance of 6,200 km from its surface in May 1998, becoming in a sense the first commercial lunar spacecraft. Another lunar fly-by was performed later that month (6 June 1998) at a distance of 34,300 km to further improve the orbital inclination. These operations consumed most of the satellite's propellant, but still much less than it would take to remove the inclination without the Moon-assist manoeuvres. With the remaining fuel, the satellite could be controlled as a geosynchronous satellite, with half the life of a normal satellite – a huge gain, considering that it had been declared a total loss. The satellite was then maneuvered to geosynchronous orbit at 158° West. Once the satellite was in a stable orbit, it was commanded to release its solar panels, which had been stowed during takeoff and maneuvering. Of the satellite's two solar panels, only one released, and it became apparent that a tether was not operating correctly on board, which engineers attributed to heating and cooling cycles due to the satellite operating outside its design range while traveling to its final orbit.

PAS-22

In April 1999, Hughes filled to request authorization to operate the satellite at 60° West in C-band and in Ku-band. In 1999, HGS-1 was acquired by PanAmSat, and renamed as PAS-22, and moved to 60° West. It was deactivated in July 2002 and moved to a graveyard orbit.

References

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