Discoverer As American space launches were not classified until late 1961, There were three camera-less test launches in the first half of 1959, none of them entirely successful.
Discoverer 1 was a test vehicle carrying no SRV nor camera. Launched on 28 February 1959, it was the first man-made object put into a polar orbit, but only sporadically returned
telemetry.
Discoverer 2 (14 April 1959) carried a recovery capsule for the first time but no camera. The main bus performed well, but the capsule recovery failed, the SRV coming down over
Spitzbergen rather than
Hawaii. The capsule was never found.
Discoverer 3 (3 June 1959), the first Discoverer to carry a biological package (four black mice in this case) failed to achieve orbit when its
Agena crashed into the
Pacific Ocean. The pressure to orbit a photographic surveillance satellite to succeed the
Lockheed U-2 was so great that operational, camera-equipped KH-1 launches began 25 June 1959 with the (unsuccessful) launching of
Discoverer 4, despite there not having been a successful test of the life-support unit for biological passengers. This proved to be a moot point by this time as the link between the Discoverer series and living payloads had been established by the attempted flight of Discoverer 3. This was the first recovery of a man-made object from orbit, beating the Soviet
Korabl Sputnik 2 by nine days. Discoverer 13 is now on display in the "Milestones of Flight" hall in the
National Air and Space Museum in
Washington, D.C. Two days after the 18 August 1960 launch of Discoverer 14, its film bucket was successfully retrieved in the Pacific Ocean by a
Fairchild C-119 Flying Boxcar transport plane. This was the first successful return of a payload from orbit, occurring just one day before the launch of
Korabl-Sputnik 2, a
biosatellite that took into orbit the two Soviet space dogs,
Belka and Strelka, and safely returned them to
Earth. The impact of CORONA on American intelligence gathering was tremendous. With the success of
Discoverer 14, which returned of film and provided more coverage of the Soviet Union than all preceding U2 flights, for the first time the United States had a clear picture of the USSR's strategic nuclear capabilities. Before CORONA, the
National Intelligence Estimates (NIE) of CIA were highly uncertain and strongly debated. Six months before Discoverer 14, an NIE predicted that the Soviets would have 140–200
ICBMs deployed by 1961. A month after the flight of Discoverer 14, that estimate was refined to just 10–25.
Later KH Series In 1963, the KH-4 system was introduced with dual cameras and the program made completely secret by then president, John Kennedy. The Discoverer label was dropped and all launches became classified. Because of the increased satellite mass, the basic
Thor-Agena vehicle’s capabilities were augmented by the addition of three
Castor solid-fueled strap-on motors. On 28 February 1963, the first Thrust Augmented Thor lifted from
Vandenberg Air Force Base at Launch Complex 75 carrying the first KH-4 satellite. The launch of the new and unproven booster went awry as one SRB failed to ignite. Eventually the dead weight of the strap-on motor dragged the Thor off its flight path, leading to a Range Safety destruct. It was suspected that a technician had not attached an umbilical on the SRB properly. Although some failures continued to occur during the next few years, the reliability rate of the program significantly improved with KH-4. Maneuvering rockets were also added to the satellite beginning in 1963. These were different from the attitude stabilizing thrusters which had been incorporated from the beginning of the program. CORONA orbited in very low orbits to enhance resolution of its camera system. But at
perigee (the lowest point in the orbit), CORONA endured drag from the
atmosphere of Earth. In time, this could cause its orbit to decay and force the satellite to re-enter the atmosphere prematurely. The new maneuvering rockets were designed to boost CORONA into a higher orbit, and lengthen the mission time even if low perigees were used. For use during unexpected crises, the
National Reconnaissance Office (NRO) kept a CORONA in "R-7" status, meaning ready for launch in seven days. By the summer of 1965, NRO was able to maintain CORONA for launch within one day. Nine of the KH-4A and KH-4B missions included
ELINT subsatellites, which were launched into a higher orbit. Some P-11 reconnaissance satellites were launched from KH-4A. At least two launches of Discoverer were used to test satellites for the
Missile Defense Alarm System (MIDAS), an early missile-launch-detection program that used infrared cameras to detect the heat signature of launch vehicles launching to orbit. The last launch under the Discoverer cover name was
Discoverer 38 on 26 February 1962. Its bucket was successfully recovered in midair during the 65th orbit (the 13th recovery of a bucket; the ninth one in midair). Following this last use of the Discoverer name, the remaining launches of CORONA satellites were entirely
TOP SECRET. The last CORONA launch was on 25 May 1972. The project ended when CORONA was replaced by the
KH-9 Hexagon program. == Technology ==