Scientists went looking for solid results with an unusual fluid experiment on board the International Space Station during the past week.

Commanded by scientists on the ground, the Experiment on Physics of Colloids in Space completed a total of 108 hours of operations last week. A colloid is a system of solid particles suspended in a fluid. On the Station, beyond the influence of Earth's gravity on colloids, scientists hope to learn more about their behavior and perhaps engineer new materials useful on Earth.

The space station as viewed by a departing space shuttle. Photo: NASA

The colloids experiment, managed by NASA's Glenn Research Center in Cleveland and developed by Harvard University, continued on a series of detailed diagnostic measurements on the crystallization of AB6 and AB13 samples. Those designations indicate a larger "A" particle surrounded by either 6 or 13 smaller "B" particles, both made of poly methyl methacrylate. The samples are mixed and then allowed to crystallize. Scientists photograph them and shine light through them to reveal the placement of particles suspended in the fluid.

"If you could use different materials for A and B, you could perhaps invent new colloidal alloys," said Mike Doherty, project manager with the Glenn field center. Potential new materials might have applications in optical computing and other fields of manufacturing, he said.

The colloids science team continued operating over the weekend with 12-hour runs on Saturday and Sunday, September 29-30, and 24-hour runs on Monday and Tuesday, October 1-2. Additional tests were scheduled for Thursday, October 4 and the following Saturday and Sunday. This week's experiments investigate the behavior of the glass and colloid-polymer gel samples. The gel sample is nearly a liquid, since only 3 percent of the sample is occupied by colloids. Yet the colloids form structures that prevent the sample from flowing. In microgravity, the colloidal glass crystallizes over a period of several days, a behavior not seen on Earth. Scientists want to learn about the structures and how they are formed.

Photography targets uplinked to the Station for the Crew Earth Observations research program included ice and snow in the South Sandwich Islands, ice flow and snow cover in Chilean glaciers, biomass burning in southern Africa, fault lines and volcanoes in the Rukwa Transform of Tanzania, coral reefs in Malaysia and the Philippines and human development in the Ganges River Delta and the Red Basin in the Sichuan province in Western China. Crew photography of the Earth has been a part of every space mission since 1961. As part of the Crew Earth Observations experiment, crew members spend about 10 minutes a day taking photographs with 35 and 70 mm cameras, as well as a digital camera. The most frequent subjects include human expansion and its environmental impacts, seasonal changes and fleeting events like fires, floods, storms and volcanic eruptions.

On Monday, October 1, Commander Frank Culbertson radioed that he had finished re-packing samples in the Biotechnology Refrigerator, allowing cold air to circulate more freely among the samples. The science team was concerned the samples might be getting too warm. Culbertson also complimented the payload team for their efforts to simplify experiment procedures sent to the crew. The refrigerator is a thermo-electric, temperature-controlled unit which provides 0.53 cubic feet of on-orbit cold storage at 39.2 degrees Fahrenheit (4 degrees Celsius). Processed earlier in Expedition 3, the samples, contained in 64 syringes, are being preserved in the refrigerator until they are returned to Earth for analysis later this year. The objective of NASA's biotechnology cell science research aboard the International Space Station is to provide a controlled environment for the cultivation of cells into healthy, three-dimensional tissues that retain the form and function of natural, living tissue. Cell growth in microgravity permits cultivation of tissue cultures of sizes and quantities not possible on Earth, allowing research in areas pertinent to human diseases, including cancer, diabetes, heart disease and AIDS. The refrigerator is part of the Cellular Biotechnology Operations Support System, managed by NASA's Johnson Space Center in Houston, and is part of the Microgravity Research Program at Marshall ‹ NASA's Lead Center for low-gravity research.

The Space Acceleration Measurement System and the Microgravity Acceleration Measurement System, managed by Glenn field center, are currently operating and ready to record during a test of a Station control moment gyro, used to keep the outpost oriented properly in orbit. That 40-hour test, including thruster firings, is scheduled to begin on Saturday, October 6.

The Active Rack Isolation System (ARIS) underwent a "hammer test" on Tuesday, October 2. A crew member used a small mallet to tap on various locations around the lab module while the experimental vibration dampening device attempts to counteract them. The ARIS team has conducted more than 1,000 tests to date, and the team is busy analyzing the results, preparing for future missions when the device will go operational to protect new microgravity experiments from vibrations. ARIS was developed by The Boeing Company and managed by NASA's Johnson field center.

About 15.3 hours of payload activities were scheduled for Culbertson and Flight Engineer Mikhail Tyurin and Pilot Vladimir Dezhurov this week as the crew prepares for a Russian spacewalk on Monday, October 8. They continued checks and maintenance on Station experiments this week, including a 90-day health check today on the Gas Analyzer System for Metabolic Analysis Physiology in the Human Research Facility rack. Crew Earth Observations photography and Dreamtime videography are on a list of optional items for the crew to conduct as their other duties allow.

The Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala., manages all science research experiment operations aboard the International Space Station. The center is also home for coordination of the mission-planning work of a variety of international sources, all science payload deliveries and retrieval, and payload training and payload safety programs for the Station crew and all ground personnel.