Minispacelab Mission

''Now we've got to get down to work,'' said David Low on 13 January. ''This is the second-longest Shuttle mission we've had so far, so we can do some good science experiments up here and get some very good medical data.'' His words would prove ironic, if not a little prophetic, for Columbia would break her own endurance record set during STS-9 over six years earlier. One avenue of study for the astronauts was materials processing in microgravity and Dunbar spent a great deal of her time tending to the Fluids Experiment Apparatus (FEA) in one of Columbia's middeck lockers.

This device was capable of heating, cooling, mixing, stirring or imposing centrifugal forces on gaseous, liquid or solid material samples, and had been carefully designed to meet industrial requirements. Dunbar supervised the processing of seven samples of indium - chosen because it was a well-characterised material with a relatively low melting point - to assess disturbances caused by Shuttle thruster firings or the movement of crew members. It was anticipated that results from the experiments could lead to more advanced, industrial-standard versions for the planned space station.

The FEA was switched on a few hours after Columbia reached orbit on 9 January and ran successfully for almost a week, until a sensor indication showed that it had exceeded its touch-temperature limit. The unit deactivated itself as programmed, but the astronauts reported that its front surface was not hot. Nevertheless, after six days of operations, it achieved more than three-quarters of its objectives.

Ivins and Low, meanwhile, tended to the Protein Crystal Growth (PCG) experiment - by now a frequent flier on board the Shuttle - which was part of an ongoing effort to 'grow' crystals in space of key proteins which could some day be used in the production of new drugs to combat AIDS, cancer, high blood pressure, organ-transplant rejection, rheumatoid arthritis and other diseases. However, as biochemist and crystal-growth researcher Larry DeLucas - who would fly on Columbia in June 1992 - has said, such experiments are part of a long process and their benefits would probably not be seen for a decade or more.

Like snowflakes, protein crystals are structured in a regular pattern; by closely examining this pattern under powerful scanning microscopes, scientists have been able to better study their molecular architecture and design drugs to either block or enhance their normal functions in the human body. The main problem with such

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