|Operator||US Air Force/NRO|
|Mission type||Optical reconnaissance|
|Launch date||7 December 1960
|Carrier rocket||Thor DM-21 Agena-B 296|
|Launch site||Vandenberg LC-75-3-4|
|Orbital decay||2 April 1961|
|COSPAR ID||1960 Sigma 1|
|Mass||1,240 kilograms (2,700 lb)|
|Apoapsis||535 kilometres (332 mi)|
|Periapsis||272 kilometres (169 mi)|
|Orbital period||92.6 minutes|
The launch of Discoverer 18 occurred at 20:20:58 UTC on 7 December 1960. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-3-4 at the Vandenberg Air Force Base. Upon successfully reaching orbit, it was assigned the Harvard designation 1960 Sigma 1.
Discoverer 18 was operated in a low Earth orbit, with a perigee of 272 kilometres (169 mi), an apogee of 535 kilometres (332 mi), 81.4 degrees of inclination, and a period of 92.6 minutes. The satellite had a mass of 1,240 kilograms (2,700 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-millimetre (2.8 in) film, and returned in a Satellite Recovery Vehicle, which was recovered three days after the launch. The Satellite Recovery Vehicle used by Discoverer 18 was SRV-508. Following the return of its images, Discoverer 18 remained in orbit until it decayed on 2 April 1961. It was the first KH-2 satellite to complete its mission successfully.
- Krebs, Gunter. "KH-2 Corona". Gunter's Space Page. Retrieved 26 June 2010.
- McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 26 June 2010.
- McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 26 June 2010.
- Wade, Mark. "KH-2". Encyclopedia Astronautica. Retrieved 26 June 2010.
- "Corona". Mission and Spacecraft Library. NASA. Retrieved 26 June 2010.
- Pike, John (9 September 2000). "KH-2 Corona". Federation of American Scientists. Retrieved 26 June 2010.
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