November 12, 2010

First Salvage Operation in Space – 1984

On this date in 1984, U. S. astronauts Joseph Allen, Dale Gardner, and Anna Fisher were able to successfully salvage a satellite that had not reached its proper orbit.

During the fourteenth flight of the Space Shuttle program, STS-51A, two satellites were deployed (one Canadian and one American). Then astronauts Allen and Gardner performed an EVA (Extra-Vehicular Activity) space walk to retrieve an Indonesian satellite, Palapa B-2. The satellite had been deployed by a Space Shuttle mission earlier that year but had not reached geostationary orbit because its kick motor had malfunctioned.

This photo shows the "cradles" for the Palapa B-2 and the Westar 6 satellites.

Allen inserted a device known as a “Stinger” into one of the motor nozzles, and the rotation of the satellite was slowed down to 1 RPM. At this point Fisher tried to use the Shuttle's robotic arm to grapple the satellite. The attempt failed. Allen succeeded where the robot had failed and, with the help of Gardner and Fisher via the robotic arm, was able to maneuver the satellite into the cradle.

The photo below shows Allen manhandling the satellite. Remember, no gravity means no weight--but the mass of the satellite means that there is still plenty of inertia. It's hard to get big things moving, and it's hard to get them to stop moving, too!

The next day the shuttle crew salvaged another satellite, Westar 6, that had the same deployment date and the same kick motor malfunction. This salvage effort went more smoothly and quickly, although Gardner used the same muscle power technique to capture the satellite.

The picture above shows Dale Gardner cracking a joke during his space walk, holding up a “For Sale” sign in front of the salvaged goods. Indeed, Westar 6 was sold to China for relaunch, and Palapa B-2 was also later relaunched on behalf of Indonesia.

What is a geostationary orbit? And what about a geosynchronous orbit?

A geosynchronous orbit is an orbit that matches the Earth's rotation, so that it always returns to the exact same spot in the sky at exactly the same time in the day.

A geostationary orbit is a geosynchronous orbit that is circular and positioned above the equator. This kind of orbit insures that the satellite is always in one fixed location above the Earth's surface. Communications satellites are often placed in geostationary orbits so that the antennas that communicate with them do not have to move.

A geostationary orbit is sometimes called a Clarke orbit because author Arthur C. Clarke first proposed the notion of using such an orbit for communications satellites. If you have satellite TV, your television probably communicates with a geostationary satellite.

Funny photos in space?

Gardner isn't the only astronaut to joke around from on high. NASA astronaut Garrett Reisman filmed an interview with comedian Stephen Colbert from the International Space Station,  Alan Shepard hit some golf balls on the moon and joked that they went miles and miles and miles  , and astronauts routinely have fun in zero-G.