|Launch vehicle.||ATLAS Agena D rocket.|
|Launch site.||Vandenberg Air Force Base.|
|Ceased operations.||It had shut down after 43 days due to a non-nuclear malfunction caused by a broken on-board (carried inside) voltage regulator within the spacecraft.|
|Owner(s).||U.S. Atomic Energy Commission.|
|Major contractor(s).||Atomics International had primary responsibility and Sandia National Laboratories.|
|Is it still in orbit.||Yes, until circa ~5,965. Some minor bits stared coming off since the November of 1979 after a collision and radiation is leaking out. The main parts and the reactor core are still safely in orbit.|
|Launch mass.||440 kg (970 lb).|
|Satellite type.||Systems Nuclear Auxiliary Power Program (SNAP) [fusion] reactor test bed satellite.|
|Links.||http://www.astronautix.com/s/snapshot.html, http://arc.aiaa.org/doi/abs/10.2514/3.28260?journalCode=jsr, http://www.space4peace.org/ianus/npsm3.htm, http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=32899.0;attach=543853, http://adsabs.harvard.edu/abs/2008AdSpR..41.1004S, http://uk.businessinsider.com/nuclear-powered-satellites-space-2016-3?r=US&IR=T, https://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_Power and https://en.wikipedia.org/wiki/SNAP-10A|
The plan was tn the 1950s and early 1960s. The Systems Nuclear Auxiliary Power Program (SNAP) reactor was developed i as part of the SNAPSHOT program overseen by the U.S. Atomic Energy Commission.
Idaho National Laboratory conducted 3 pre-launch destructive tests in Test Area North, including the SNAPTRAN-3 destructive experiment, on April 1, 1964. The test simulated a rocket crash into the ocean, radiating part of the Idaho desert in a deliberate fire ball.
The plan was to create an endless or near endless power-supply for space vessels and satellites, since solar panels only worked in star-light and batteries would eventually run out.