NASA ISS Expedition 13 Science Operations Status Report for the Week Ending May 19, 2006

Expedition 13 NASA Science Officer Jeffrey Williams ran the final sample for the Pore Formation and Mobility Investigation, or PFMI experiment. The experiment, operated inside the Microgravity Science Glovebox, investigates how bubbles form and migrate during solidification using a transparent modeling material. The model system is important for understanding the formation of flaws in molten metals as they are solidified.

Williams also performed a series of test flights with the first of three small free-flying satellites for the Synchronized Position Hold, Engage, Re-orient Experimental Satellites, or SPHERES experiment.

SPHERES will demonstrate the basics of formation flight and autonomous docking. For the first tests, only one satellite and two beacons — one mounted and one hand-held — were used. The satellite is eight inches in diameter and weighs about seven pounds. It also contains internal avionics, software and communications systems and is maneuvered using compressed carbon dioxide gas thrusters.

Performed autonomously in the U.S. Lab, the first test flight consisted of a series of 10 to15 pre-planned maneuvers lasting up to 10 minutes each. After Williams selected and loaded the appropriate software on the laptop, the satellite began its pre-programmed autonomous maneuvers.

Testing included attitude control, station keeping, re-targeting, collision avoidance and fuel balancing algorithms. This technology is of interest in designing constellation and array spacecraft configurations and also could be used for free-flying robotic assistants, capable of helping astronauts on future spacewalks.

NASA’s payload operations team at the Marshall Center coordinates U.S. science activities on space station.