|Mission type||Optical reconnaissance|
|Operator||US Air Force/NRO|
|Harvard designation||1961 Pi 1|
|Mission duration||2 days|
|Spacecraft type||Corona KH-2|
|Launch mass||1,150 kilograms (2,540 lb)|
|Start of mission|
|Launch date||7 July 1961, 23:29:48UTC|
|Rocket||Thor DM-21 Agena-B 308|
|Launch site||Vandenberg LC-75-3-5|
|End of mission|
|Decay date||5 December 1961|
|Perigee altitude||229 kilometers (142 mi)|
|Apogee altitude||713 kilometers (443 mi)|
The launch of Discoverer 26 occurred at 23:29:48 UTC on 7 July 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-3-5 at the Vandenberg Air Force Base. Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Pi 1.
Discoverer 26 was operated in a low Earth orbit, with a perigee of 229 kilometres (142 mi), an apogee of 713 kilometres (443 mi), 82.9 degrees of inclination, and a period of 94 minutes. The satellite had a mass of 1,150 kilograms (2,540 lb), and was equipped with a panoramic camera with a focal length of 61 centimetres (24 in), which had a maximum resolution of 7.6 metres (25 ft). Images were recorded onto 70-millimeter (2.8 in) film, and returned in a Satellite Recovery Vehicle, which was deorbited two days after launch. The Satellite Recovery Vehicle used by Discoverer 26 was SRV-511. Once its images had been returned, Discoverer 26's mission was complete, and it remained in orbit until it decayed on 5 December 1961.