To assure that diverse groups have access to space, NASA rotated payload assignments among three major categories of users: educational, foreign and commercial, and U.S. government. GAS payloads had to fit NASA standard containers and weigh no more than 90 kg. The payload had to be self-powered and not draw on the shuttle orbiter's electricity. The crew's involvement with GAS payloads was limited to six simple activities (such as turning on and off up to three payload switches). Crew activity schedules did not provide opportunities to either monitor or service GAS payloads in flight.
Since the program was first announced in the fall of 1976, payloads were reserved by foreign governments and individuals; U.S. industrialists, foundations, high schools, colleges and universities; professional societies; service clubs; and many others. Although persons and groups involved in space research obtained many of the reservations, a large number of spaces were reserved by persons and organizations outside the space community.
There were no stringent requirements to qualify for space flight. However, each payload had to meet specific safety criteria and be screened for its propriety as well as its educational, scientific or technological objectives. These guidelines precluded commemorative items, such as medallions, that were intended for sale as objects that had flown in space.
GAS requests were first be approved at NASA Headquarters in Washington, DC, by the director of the Transportation Services Office. At that point NASA screened the propriety and objectives of each request. To complete the reservation process for GAS payloads, each request had to be accompanied or preceded by the payment of $500 earnest money.
Approved requests were assigned an identification number and referred to the GAS team at the Goddard Space Flight Centre in Greenbelt, Md., the designated lead centre for the project. The GAS team screened the proposals for safety and provided advice and consultation on payload design. It certified that proposed payloads were safe and would not harm or interfere with the operations of the space shuttle, its crew or other experiments on the flight. The costs of any physical testing required to answer safety questions before launch were borne by the GAS customer.
The cost of the service depended on the size and weight of the experiment. Getaway specials of 90 kg pounds and 0.14 cubic m cost $10,000; 45 kg and .07 cubic m, $5,000; and 27 kg and 0.07 cubic m, $3,000. The weight of the GAS container, experiment mounting plate and its attachment screws, and all hardware regularly supplied by NASA was not charged to the experimenter's weight allowance.
The GAS container provided internal pressure, which could be varied from near vacuum to about one atmosphere. The bottom and sides of the container were always thermally insulated, and the top could be insulated or not, depending on the specific experiment. A lid that could be opened or one with a window were offered as options at additional cost.
The GAS container was made of aluminum, and the circular end plates were 1.6 cm-thick aluminum. The bottom 7 cm of the container were reserved for NASA interface equipment, such as command decoders and pressure regulating systems. The container was a pressure vessel that could be evacuated before or during launch or on orbit and could be repressurized during re-entry or on orbit, as required by the experimenter.
The getaway bridge, which was capable of holding 12 canisters, made its maiden flight on STS 61-C. The aluminum bridge fitted across the payload bay of the orbiter and offered a convenient and economic way of flying several GAS canisters.
AKA: GetAway Special; Small Self-Contained Payloads.
Gross mass: 90 kg (198 lb).