Discoverer 25


Discoverer 25
Mission typeOptical reconnaissance
OperatorUS Air Force/NRO
Harvard designation1961 Xi 1
COSPAR ID1961-014A
SATCAT no.00108Edit this on Wikidata
Mission duration2 days
Spacecraft properties
Spacecraft typeCorona KH-2
Launch mass1,150 kilograms (2,540 lb)
Start of mission
Launch date16 June 1961, 23:02:52 (1961-06-16UTC23:02:52Z) UTC
RocketThor DM-21 Agena-B 303
Launch siteVandenberg LC-75-1-1
End of mission
Decay date12 July 1961 (1961-07-13)
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude223 kilometers (139 mi)
Apogee altitude361 kilometers (224 mi)
Inclination82.1 degrees
Period90.4 minutes

Discoverer 25, also known as Corona 9017, was an American optical reconnaissance satellite which was launched in 1961. It was the fifth of ten Corona KH-2 satellites, based on the Agena-B.[1]

The launch of Discoverer 25 occurred at 23:02 UTC on 16 June 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-1-1 at the Vandenberg Air Force Base.[2] Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Xi 1.

Discoverer 25 was operated in a low Earth orbit, with a perigee of 223 kilometres (139 mi), an apogee of 361 kilometres (224 mi), 82.1 degrees of inclination, and a period of 90.4 minutes.[3] The satellite had a mass of 1,150 kilograms (2,540 lb),[4] 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).[5] Images were recorded onto 70-millimeter (2.8 in) film, and returned in a Satellite Recovery Vehicle two days after launch. The Satellite Recovery Vehicle used by Discoverer 25 was SRV-510. Once its images had been returned, Discoverer 25's mission was complete, and it remained in orbit until it decayed on 12 July 1961.[3]

The Satellite Recovery Vehicle was designed to be recovered in mid-air by a Fairchild C-119J Flying Boxcar aircraft. As SRV-510 descended, the C-119J was unable to capture it, and the capsule had to be recovered at sea after it landed. The film it returned was affected by streaks across images.[4]


  1. ^ Krebs, Gunter. "KH-2 Corona". Gunter's Space Page. Retrieved 23 October 2020.
  2. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 26 June 2010.
  3. ^ a b McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 26 June 2010.
  4. ^ a b Wade, Mark. "KH-2". Encyclopedia Astronautica. Archived from the original on 23 January 2013. Retrieved 26 June 2010.
  5. ^ "Corona". Mission and Spacecraft Library. NASA. Archived from the original on 3 October 2007. Retrieved 26 June 2010.