On-orbit science investigation continues to be the focus of Columbia’s Microgravity Science Laboratory mission as the seven astronauts work around the clock on two shifts supporting the more than 30 experiments in the Spacelab module.

Janice Voss, Mike Gernhardt and Roger Crouch continue to adjust their sleep schedules each day to prepare for the end of the mission Thursday morning at the Kennedy Space Center in Florida.

Jim Halsell, Susan Still, Don Thomas and Greg Linteris remain on the same schedule throughout the flight, waking up at 11 p.m. each day.

Work today in the laboratory includes plant experiment and protein crystal growth status checks and work in the glovebox on the Coarsening in Solid-Liquid Mixtures experiment. During coarsening, small particles shrink by losing atoms to larger particles, causing the larger particles to grow. In this experiment solid particles of tin will grow, or coarsen, within a liquid lead-tin matrix. By conducting this experiment in space, a greater range of solid volume fractions can be studied without the effects of convection present in Earth-based experiments.

The Observable Protein Crystal Growth Apparatus is being used to characterize proteins and determine the differences that exist in crystal growth processes in microgravity and on the ground. The experiment hopes to ultimately optimize growth procedures and conditions for application in the biochemical field. A major goal of this experiment is to improve the design and loading procedures and to eliminate bubble formation, which interferes with crystal growth.

The dual-shift mission is set to end Thursday morning with favorable weather forecast for the time of landing.

Columbia continues to orbit the Earth at an average altitude of 160 nautical miles. All orbiter systems are in excellent shape.

The next orbiter status report will be issued at approximately 5 p.m. Monday.

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