Second Small Astronomy Satellite
Encyclopedia
The Small Astronomy Satellite 2, also known also as SAS-2, SAS B or Explorer 48, was a NASA
gamma ray telescope. It was launched on 15 November 1972 into low Earth orbit with a periapsis of 443 km and an apoapsis of 632 km. It completed its observations on 8 June 1973.
SAS-2 was launched from the San Marco platform off the coast of Kenya, Africa, into a nearly equatorial orbit. The orbiting spacecraft was in the shape of a cylinder approximately 59 cm in diameter and 135 cm in length. Four solar paddles were used to recharge the 6 amp-h nickel-cadmium battery and provide power to the spacecraft and telescope experiment. The spacecraft was spin stabilized, and a magnetically torqued commandable control system was used to point the spin axis of the spacecraft to any position in space within approximately 1 degree. The experiment axis lay along this axis allowing the telescope to look at any selected region of the sky with its plus or minus 30 degree acceptance aperture. The nominal spin rate was 1/12 rpm. Data were taken at 1000 bps and could be recorded on an onboard tape recorder and simultaneously transmitted in real time. The recorded data were transmitted once per orbit. This required approximately 5 minutes.
The telescope experiment was initially turned on Nov 20 1972, and by Nov 27 1972, the spacecraft became fully operational. The low-voltage power supply for the experiment failed on Jun 8 1973. No useful scientific data were obtained after that date. With the exception of a slightly degraded star sensor, the spacecraft control section performed in an excellent manner.
SAS-2 first detected Geminga
, a pulsar
believed to be the remnant of a supernova that exploded 300,000 years ago.
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
gamma ray telescope. It was launched on 15 November 1972 into low Earth orbit with a periapsis of 443 km and an apoapsis of 632 km. It completed its observations on 8 June 1973.
SAS-2 was launched from the San Marco platform off the coast of Kenya, Africa, into a nearly equatorial orbit. The orbiting spacecraft was in the shape of a cylinder approximately 59 cm in diameter and 135 cm in length. Four solar paddles were used to recharge the 6 amp-h nickel-cadmium battery and provide power to the spacecraft and telescope experiment. The spacecraft was spin stabilized, and a magnetically torqued commandable control system was used to point the spin axis of the spacecraft to any position in space within approximately 1 degree. The experiment axis lay along this axis allowing the telescope to look at any selected region of the sky with its plus or minus 30 degree acceptance aperture. The nominal spin rate was 1/12 rpm. Data were taken at 1000 bps and could be recorded on an onboard tape recorder and simultaneously transmitted in real time. The recorded data were transmitted once per orbit. This required approximately 5 minutes.
The telescope experiment was initially turned on Nov 20 1972, and by Nov 27 1972, the spacecraft became fully operational. The low-voltage power supply for the experiment failed on Jun 8 1973. No useful scientific data were obtained after that date. With the exception of a slightly degraded star sensor, the spacecraft control section performed in an excellent manner.
SAS-2 first detected Geminga
Geminga
Geminga is a neutron star approximately 250 parsecs away from the Sun in the constellation Gemini. Its name is both a contraction of "Gemini gamma-ray source", and gh'è minga "it's not there" in the Lombard dialect of Milan .- Pulsar :...
, a pulsar
Pulsar
A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...
believed to be the remnant of a supernova that exploded 300,000 years ago.