The second United States Microgravity Laboratory (USML-2) Spacelab mission will be the centerpiece of the STS-73 space shuttle flight, as it combines the efforts of the U.S. government, universities and industry "to push back the frontiers of science and technology in microgravity." Some of the experiments being carried on the USML-2 payload were suggested by the results of the first USML mission that flew aboard Columbia in 1992 during mission STS-50. The USML-1 mission provided new insights into theoretical models of fluid physics, the role of gravity in combustion and flame spreading, and how gravity affects the formation of semiconductor crystals. It is also considered to have been one of the most successful NASA science missions.
The experiments being carried as part of the USML-2 payload cover a variety of scientific disciplines including fluid physics, materials science, biotechnology and combustion science. Also during the mission, students at four sites will interact with Columbia's astronauts to discuss and compare onboard microgravity experiments with similar ground-based experiments. The goal is to involve students as participants in Shuttle investigations in an effort to generate excitement in physical science and chemistry. Students at South High School in Worcester were selected to participate in the second live downlink, which is scheduled for the 13th day of the flight and they will discuss fluid experiments.
The flight will be the 18th flight of space shuttle Columbia and the 72nd flight of the space shuttle system. The USML-2 experiment racks are housed in a 23-foot Spacelab module inside the shuttle's cargo bay. The laboratory is pressurized, which will allow "researchers to work in their shirtsleeves. . .and it is furnished with much of the same kind of equipment that they would use in their labs back home."
Materials science research in the crystal growth furnace and zeolite crystal growth experiment will increase insight into the relationships between the structure, processing and properties of materials. Mixtures that separate on Earth because of different component densities can be evenly mixed and processed in microgravity.
Dr. Sacco will continue a series of experiments investigating the formation of zeolite crystals, which are widely used in the chemical process industry as filters, catalysts for reactions and purifiers. Zeolites can act as "molecular sieves" to separate out specific molecules from solutions. They also are used in life support systems, petroleum refining, waste management and in the biomedical field for purification of fluids. By using the Zeolite Crystal Growth (ZCG) furnace, it is hoped that a better understanding can be gained of the structure of the crystals, through growing large, near perfect crystals in microgravity.
Forty-four zeolite sample containers (autoclaves) will be processed during the mission. Each container will be loaded with two solutions - one aluminum-based and one silicone-based. A crew member will mix the solutions in orbit by turning a screw inside each separate sample container. The containers will then be placed in the ZCG furnace where they will be heated, allowing crystallization to begin.
ZCG flew for the first time on USML-1 and results from that flight indicate that crystals whose nucleation and growth were controlled from the onset of the experiment achieved a higher degree of crystal perfection than any crystals produced on Earth.
A team from WPI has been at the Kennedy Space Center since September 19th, completing the necessary ground procedures, including: flight hardware assembly, solution preparation and loading for the 44 zeolite crystal growth autoclaves to be used on the flight and 44 identical ones to be tested on the ground. Team members include: Research Professor of chemical engineering Nurcan Bac, chief chemist Juliusz Warzywoda, EAS-Delft representative Eric Coker, principal lab machinist Jack Ferraro, graduate student Ipek Guray, and Michelle Marceau and Teran Sacco, both of whom are juniors majoring in chemical engineering.
The ground control experiment will begin at WPI four days after the launch and will continue during the same period as the experiment on the shuttle. "The ground control experiment will be done with duplicate hardware" says professor Bac. "The lag enables us to implement the same temperature profile as the control solutions. As soon as Columbia is launched, Bac and Warzywoda will fly to Huntsville to man the control console during the mission. The rest of the team will drive or fly back with the equipment and solutions for the ground control experiment.
Professor Sacco, 46 received his bachelor's degree with honors from Northeastern University in 1973 and a doctorate from the Massachusetts Institute of Technology in 1977, both in chemical engineering. He has been on the faculty here since 1977 and he was appointed department head in 1989. He also has consulted for numerous companies in the field of catalysis, solid/gas contacting and equipment design for space applications. Also, with his father and brother, he ran a family restaurant in Boston for more than 20 years. Sacco has over 70 publications in the areas of carbon filament initiation and growth, catalyst deactivation, and zeolite synthesis. He is the principal investigator for the Zeolite Crystal Growth Experiment and he served as an alternate payload specialist on USML-1.
"My wife, Terri, the rest of the crew and I are very excited," says Sacco. "I hope all your prayers for a safe and successful mission are with us."
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