This is a flight spare 32-level digitized grid spark chamber sensitive to gamma rays of energies above 35 mev. It was built for the SAS-B satellite, also known as SAS-2 or Explorer 48, the second spacecraft designed specifically to study gamma rays. The wire grid detector used for this satellite was the precursor for the one used on the highly sucessful EGRET instrument on the Compton Gamma Ray Observatory. SAS-B provided the first full-sky gamma-ray map and identified the gamma-ray behavior of objects such as the Vela Pulsar. This flight spare was used for many years as a laboratory test device at the Goddard Space Flight Center and later at Wallops Island.
NASA's Goddard Space Flight Center transferred this object to the Museum in 1994.
Transferred from NASA, Goddard Space Flight Center.