The vast majority of satellites which re-enter the earth's atmosphere burn up, of course. However, ground controllers occasionally want to recover them for reasons of cost, military security, or for the simple fact that humans are on board; and for these reasons satellite recovery has become an important part of space technology.

Discoverer

Discoverer 2 (1959) was the first recoverable space capsule launched, but errors caused by ground control meant that it crashed into ice near Spitzbergen. This was only the first of many such failures. Discoverer 13 almost made it: circling U2 spyplanes and radar aircraft tracked it on its way down through the atmosphere, but the mid-air retrieval failed, and it landed in the sea. On 18 August 1960 Discoverer 14 was launched, and was later successfully snatched in mid-air by a C-119 skimming across the top of its parachute and catching the capsule by a line stretched from the cargo door. (The pilot was awarded the DFC for this, and the capsule was put on display in a museum.)

The USAF was eager to perfect this technique at night, and over the course of time the Americans put brilliant strobe-lights and telemetry packages on Discoverers.

However the overall success rate was not improving, and the adverse comment attracted by continuing failures led the military to classify all its satellite launches from 1961 onwards.

Originally the capsules were collected by ship if the mid-air pick-ups failed. The last three ships were retired in 1974, and helicopters have been used since then.

Space shuttle rocket boosters

Few civilian space objects are designed to be retrieved, but one example is the pair of rocket boosters which help the shuttle for the first few seconds of its launch. (It was an O-ring failure on one of these boosters which caused the Challenger explosion in 1986). Once ejected from the ascending shuttle, the boosters reach 4650 km/h before being slowed by atmospheric drag. A barometric switch deploys the pilot parachute at an altitude of 4,694 m, and then the drogue follows; the main parachutes come on at 2,012 m, slowing the booster's fall to about 376 km/m (about 233 mph). They only fully inflate at 670 m and the vehicle decelerates to 111 km/h (69 mph) before hitting the water. On splashdown an impact switch separates the parachutes so that the booster is not dragged underwater. The space shuttle boosters are of course far too large for a mid-air recovery to be contemplated.

Soviet recoveries

Russian Cosmos satellites of the early 1980s were often low altitude spysats like Big Bird, although of a much simpler design (see Soviet satellites), and they too were expected to re-enter and be recovered. The Soviets, however, relied on land recovery. C1227, for instance, re-entered at the same time as the Rendlesham Forest incident, landing by parachute in Kazakhstan on 28 December 1980, and emitting a "two-tone" recovery beacon so that the Russian military could find it (ie. alternately transmitting a brief signal on two separate frequencies). More advanced satellites sent telemetry. Most Russian military satellites, however, were detonated at the end of their missions so none of it could be recovered by the West.

In October 1976 a Soyuz manned capsule accidentally landed in Lake Tengiz. "The main parachute dragged the capsule over the water for some time. Some electrical connectors corroded in the salty water of Lake Tengiz and the reserve parachute was deployed due to an electrical short. This reserve parachute became filled with water and sunk to the bottom of the lake. Had the lake not been shallow the reserve parachute may have pulled the capsule below the water..." (Haeseler 1995). The two cosmonauts were eventually rescued after 11 hours in the airtight capsule.

On to RAF Woodbridge and Bentwaters

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