Discoverer 31, also known as Corona 9024, was an American optical reconnaissance satellite which was launched in 1961. It was a KH-3 Corona''' satellite, based on an Agena-B.
The launch of Discoverer 31 occurred at 21:00 UTC on 17 September 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-1-1 at the Vandenberg Air Force Base. Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Alpha Beta 1.
Discoverer 31 was operated in a low Earth orbit, with a perigee of 233 kilometres (Template:Convert/round mi), an apogee of 380 kilometres (Template:Convert/round mi), 82.7 degrees of inclination, and a period of 90.7 minutes. The satellite had a mass of 1,150 kilograms (Template:Convert/round lb), and was equipped with a panoramic camera with a focal length of 61 centimetres (Template:Convert/round in), which had a maximum resolution of 7.6 metres (Template:Convert/round ft). Images were recorded onto 70-millimeter (Template:Convert/LoffAonSon) film, and were to have been returned in a Satellite Recovery Vehicle. The Satellite Recovery Vehicle carried aboard Discoverer 31 was SRV-552. During the spacecraft's thirty-third orbit, the attitude control and power systems malfunctioned, and as a result Discoverer 31 was unable to complete its mission or return images. It decayed from orbit on 26 October 1961.