Both missions were in orbit for about two weeks. USML experiment results were recorded with a video camera and the signals were sent to Earth. During USML-1, scientists on the ground had to share the one video channel trom the Spacelab. For USML-2, six video channels gave scientists more time to watch experiments as they happened and to direct the astronauts conducting their experiments. USML-2 also had a live video uplink from the control center to the shuttle so that astronauts watching a scientist perform a procedure on the ground could then mimic that procedure in space.
Proteins serve many important functions in plants and animals, and viruses cause diseases.
Scientists use space-grown crystals to determine the molecular structure of proteins and viruses. The crystals grow larger in microgravity than they do on Earth, which gives scientists better information about their structure. This knowledge contributes to the design of disease-fighting drugs and the engineering of plants with greater nutritional yield. More than 1,500 crystals of proteins and viruses were grown during the USML series. On Earth, combustion, or burning, depends on the flow of air around a flame.