Once in orbit, Payload Commander Kathryn C. Thornton will activate the USML-2 Spacelab habitation long module and the onboard experiments. From then on, the crew will work around the clock, with the four-member Red Team taking the first 12-hour shift while the three-member Blue team begins their sleep period. The two teams will rotate work periods throughout the mission.

The STS-73 mission is scheduled to end when Columbia touches down at KSC’s Shuttle Landing Facility.

The Crew
The STS-73 crew is made up of two space veterans and five first-timers. Mission Commander Kenneth D. Bowersox (Cdr., USN) is on his third space flight, having served as pilot on both STS-50 in 1992 and STS-61. Pilot Kent V. Rominger (Lt. Cdr., USN) has over 3,000 hours of flight time in 35 types of aircraft. Payload Commander Kathryn C. Thornton (Ph..D.) has served as mission specialist on three space flights; STS-33, STS-49 and STS-61. Mission Specialist Michael E. Lopez-Alegria (Lt. Cdr., USN) has been both an instructor and engineering test pilot. Mission Specialist Catherine G. "Cady" Coleman (Ph.D., Captain, USAF) has worked as a research chemist for the Air Force. Payload Specialist Albert Sacco Jr. (Ph.D.) is a principal investigator for the crystal growth experiments. Payload Specialist Fred W. Leslie (Ph.D.) is a co-investigator on the USML-2 Geophysical Fluid Flow Cell experiment.

The Mission
Throughout the flight, the crew will continue the microgravity research in fluid physics, combustion science, materials science and biotechnology that was conducted during the STS-50/USML-1 mission that lifted off from KSC in June 1992. Analyses of the data from that space flight has lead to new insights into the behavior of fluids, significant findings for research into spacecraft safety, new fundamental information on the role of gravity in the formation of material and protein crystals, and the demonstration of an important operational concept for materials science experiments on the international space station. The extended duration USML-2 mission will provide and opportunity to validate this information and tohelp understand the effects of microgravity over a longer period of time.

The USML-2 experiments are designed to help lead to new discoveries in the fields of fluid physics, combustion science, materials science and biotechnology, as well as providing technology demonstrations to help develop the hardware necessary for future microgravity research. The experiments are housed in Spacelab racks and in the crew cabin middeck locker area.

Throughout the mission, telemetry data will be relayed from the instruments to NASA research personnel, as well as those from industry and academia, located at Marshall Space Flight Center’s Spacelab Mission Operations Center in Huntsville, Ala. A new Hi-Pac video downlink system that is designed to increase the amount and quality of downlink video available to these scientists will make its first flight on this mission.

USML-2 Experiments
Spacelab USML-2 Payloads
The Surface Tension Driven Convection Experiment apparatus will be used to study basic fluid mechanics and the heat transfer of thermocapillary flows in the microgravity environment. These flows play an important role in many industrial and materials processing methods. In space, they also affect spacecraft fuel management and life support systems.

The Drop Physics Module (DPM) will be used for two experiments. The Drop Dynamics Experiment will gather data on the dynamics of liquid drops to provide information that could lead to containerless processing of materials and polymer encapsulation of living cells. The second experiment will examine the influence of surfactants on the behavior of drops.

The Geophysical Fluid Flow Cell Experiment will study how fluids move in microgravity to help researchers understand the large-scale fluid dynamics of planetary and stellar atmospheres. The four experiments to be conducted in the Crystal Growth Furnace (CGF) will involve the high- temperature growth of cadmium zinc telluride, mercury cadmium telluride, and gallium arsenide crystal semiconductor materials, as well as mercury zinc telluride alloy crystals.

The European Space Agency’s Glovebox Facility is an enclosed transparent container that permits the crew to handle and manipulate materials through glove ports and allows the safe handling of hazardous materials. Seven Glovebox investigations, from a fluid flow to a particle dispersion experiment, will be conducted on this flight.

The Advanced Protein Crystallization Facility (ACPF) will use three methods of protein crystal growth and will house 15 investigations that will study crystal development. Several experiments will measure and record orbiter accelerations and vibrations in the microgravity environment, including the Space Acceleration Measurement System (SAMS), the Three Dimensional Microgravity Accelerometer (3DMA) and the Orbital Acceleration Research Experiment (OARE).

Middeck USML-2 Payloads
The Zeolite Crystal Growth (ZCG) furnace will process 38 zeolite sample containers during the mission to examine techniques to create large near-perfect crystals. Zeolite is used for the purification of fluids in life support systems, the petroleum refining process and in the waste management and biomedical fields.

The Single Locker Protein Crystal Growth experiment will process more than 800 protein samples stored in two types of crystal growth containers. The new container, the Diffusion-controlled Crystallization Appa-ratus for Microgravity (DCAM), uses a methodology that could lead to long- duration controlled crystal growth aboard the international space station.

The Commercial Protein Crystal Growth (CPCG) experiment will be housed in three middeck lockers. It is designed to grow large quantities of crystals of various proteins using the batch process method.

The Commercial Generic Bioprocessing Apparatus (CGBA) will house a variety of investigations in the areas of biomedical testing and drug development, ecological test systems and biomaterials products and processes. Many of the experiments could lead to advances in human medicine.

The Astroculture Facility will be used to conduct research on plant growth in microgravity. One goal will be to verify the effectiveness of the unit as an on-orbit plant growth system, while another will be to investigate the nature of starch accumulation in microgravity.

KSC Payload Processing
Payload integration of the USML-2 module began in January 1995 in the Operations and Checkout (O&C) Building. Final testing for the integrated module was completed on June 13. The payload was then transported to Orbiter Processing Facility (OPF) 3 to be installed in Columbia’s payload bay July 10.

Because of the perishable nature of some of the USML-2 experiment materials, KSC payload engineers and technicians will be installing the samples into the module beginning at L-40 hours before liftoff. All middeck experiment materials will be installed starting at 22 hours before launch. This operation will be completed at L-19 hours.

Columbia’s last mission was the STS-65/International Microgravity Laboratory-2 (IML-2), which lifted off July 8, 1994 and ended with a KSC landing on July 23. The orbiter was rolled out to Pad 39B on Aug. 28, 1995.