Discoverer 8

Image:Thor Agena A with Discoverer 8, 20 November 1959.gif

"Discoverer" was the civilian designation and cover for the Corona satellite photo-reconnaissance series of satellites managed by the Advanced Research Projects Agency of the Department of Defense and the U.S. Air Force. The primary goal of the satellites was to replace the U-2 spyplane in surveilling the Sino-Soviet Bloc, determining the disposition and speed of production of Soviet missiles and long-range bombers assess. The Corona program was also used to produce maps and charts for the Department of Defense and other US government mapping programs.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-002A|title=Discoverer 1|publisher=NASA Space Science Data Coordinated Archive|access-date=24 October 2020}}

The first series of Corona satellites were the Keyhole 1 (KH-1) satellites based on the Agena-A upper stage, which not only offered housing but whose engine provided attitude control in orbit. The KH-1 payload included the C (for Corona) single, vertical-looking, panoramic camera that scanned back and forth, exposing its film at a right angle to the line of flight.{{cite web |title=Corona: America's First Satellite Program |url=https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/corona.pdf |archive-url=https://web.archive.org/web/20070612220818/https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/corona.pdf |url-status=dead |archive-date=June 12, 2007 |publisher=Central Intelligence Agency |access-date=25 January 2020 |date=1995}}{{rp|26}} The camera, built by Fairchild Camera and Instrument with a f/5.0 aperture and {{convert|61|cm}} focal length, had a ground resolution of {{convert|12.9|m}}. Film was returned from orbit by a single General Electric Satellite Return Vehicle (SRV) constructed by General Electric. The SRV was equipped with an onboard small solid-fuel retro motor to deorbit at the end of the mission. Recovery of the capsule was done in mid-air by a specially equipped aircraft.{{cite web|url=https://space.skyrocket.de/doc_sdat/kh-1.htm|title=KH-1 Corona|first=Gunter|last=Krebs|publisher=Gunter's Space Page|accessdate=7 November 2020}}

Discoverer 8 was preceded by four operational missions, as well as three test flights whose satellites carried no cameras, all launched in 1959.{{rp|51–56}}

The battery-powered Discoverer 8 was a cylindrical satellite {{convert|1.5|m}} in diameter, {{convert|5.85|m}} long and had a mass after second stage separation, including propellants, of roughly {{convert|3850|kg}}.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-011A|title=Discoverer 8|publisher=NASA Space Science Data Coordinated Archive|access-date=31 October 2020}} After orbital insertion, the satellite and SRV together massed {{convert|835|kg}}.{{rp|236}} The capsule section of the reentry vehicle was {{convert|84|cm}} in diameter and {{convert|69|cm}} long.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-010A|title=Discoverer 7|publisher=NASA Space Science Data Coordinated Archive|access-date=31 October 2020}} Like its operational predecessors, Discoverers 4–7, Discoverer 8 carried the C camera for its photosurveillance mission.

The capsule was designed to be recovered by a specially equipped aircraft during parachute descent, but was also designed to float to permit recovery from the ocean. The main spacecraft contained a telemetry transmitter and a tracking beacon.

Discoverer 8 was launched on 20 November 1959 at 19:25:24 GMT from Vandenberg LC 75-3-5{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=24 October 2020}} into a {{convert|187|km}} x {{convert|1679|km}} polar orbit by a Thor-Agena A booster. Overburn of the Agena caused the satellite to end up in a much more eccentric, higher apogee orbit than its predecessors. As had happened with Discoverers 5 and 6, the camera film snapped on its way from its supply container. Due to Discoverer 8's eccentric orbit, the onboard ejection timer was unable to properly determine time of SRV separation,{{cite web|url=https://www.nro.gov/Portals/65/documents/foia/declass/WS117L_Records/168.PDF|title=DISCOVERER INFO ON DISCOVERER VIII, DISCOVERER VEHICLES REVIEW OF PROGRESS|access-date=15 February 2021}} and after 15 orbits, a manual command was given from the ground to separate the SRV from the satellite bus for deorbit and recovery, which occurred on 21 November at 21:20 GMT. Telemetry from the capsule was received by the telemetry ship, USNS PVT. Joe E. Mann (positioned between the tracking stations at Kaena Point, Hawaii and Kodiak, Alaska){{cite book|title=CORONA Star Catchers|editor=Robert D. Mulcahy, Jr.|date=June 2012|publisher=Center for the Study of National Reconnaissance|location=Washington D.C.|oclc=811073783|url=https://www.nro.gov/Portals/65/documents/history/csnr/corona/StarCatchersWeb.pdf|access-date=15 February 2020}}{{rp|96}} until ionization blackout. This data suggested the capsule was off course, and the recovery fleet was diverted southward {{convert|200|nmi}} to the expected landing place. The ships arrived in time to see Discoverer 8's capsule hit the water, its parachute undeployed. Later analysis determined that the ceramic reentry heat shield had failed to detach from the SRV, causing a faster than normal descent, in turn preventing the parachute from deploying.{{rp|85}}

The satellite bus reentered on 8 March 1960.{{Cite web|url=https://www.planet4589.org/space/log/satcat.txt|title=Satellite Catalog|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=9 April 2020}}

File:USNS Private Joe. E. Mann 1960.jpg

CORONA achieved its first fully successful flight with the mission of Discoverer 14, launched on August 18, 1960.{{rp|59}} The program ultimately comprised 145 flights in eight satellite series, the last mission launching on 25 May 1972.{{rp|245}} CORONA was declassified in 1995,{{rp|14}} and a formal acknowledgement of the existence of US reconnaissance programs, past and present, was issued in September 1996.{{rp|4}}

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{{Orbital launches in 1959}}

Category:Spacecraft launched in 1959

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