There are several rationales for the study of biology in micro gravity. First, biologists are interested in gravity's role in normal development. Some organisms' eggs display a natural orientation response to the earth's gravity. Second, biologists may use micro gravity experiments to generate new information about basic cellular processes. Third, future permanent manned space endeavors may require multiple generations of plants and animals for food and waste recycling.
GAS canisters are payloads mounted inside the shuttle bay.
Conducting research in the GAS program requires designing your experiment within tight parameters . First, the shuttle will only be in space for seven to ten days, depending on the mission plan and resources. Another parameter that must be overcome is the time, before and after the shuttle flight. GAS experiments are loaded on the shuttle up to three months before it launches. Then following the return of the shuttle to Earth it is another month before the payload is returned.