Space Station (ISS) Status 5/19/06
In space this week, a satellite flew within a satellite. International
Space Station Flight Engineer Jeff Williams "piloted" a unique
spacecraft in three dimensions for the first time around the
pressurized Destiny module. The demonstration tested the basics of
formation flight and autonomous docking that could be useful in
future multiple spacecraft formation flying.
That test flight wrapped up a week of experiments, maintenance,
spacewalk preparations and packing of equipment set to return to
Earth aboard Space Shuttle Discovery following its next mission to
the station, targeted for July.
Along with Expedition 13 Commander Pavel Vinogradov, Williams oversaw
activities through the 50th day of their planned 180-day mission,
focusing on laboratory science experiments in the microgravity
science glovebox. That facility hosted the final sample for the Pore
Formation and Mobility Investigation experiment, which uses a
transparent modeling material to study how bubbles form and migrate
during liquid solidification. This is important to understanding the
formation of flaws in molten metals as they solidify.
Much of the attention, however, focused on a new experiment flying for
the first time on the station ? the Synchronized Position Hold,
Engage, Re-orient Experimental Satellites, also known as SPHERES.
Williams, also NASA's station science officer, performed a series of
test flights with the first of what eventually will be a
constellation of three small free-flying satellites designed to
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 has a mass of about seven pounds. It also contains
internal avionics, software and communications systems and is
maneuvered using compressed carbon dioxide gas thrusters.
During the first test flight, performed autonomously in Destiny, the
satellite made a series of 10-15 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
maneuvers to test attitude control, station keeping, re-targeting,
collision avoidance and fuel balancing.
This technology could be used to design spacecraft constellations or
arrays or to develop free-flying robotic assistants to help
astronauts on future spacewalks.
NASA's payload operations team at the agency's Marshall Space Flight
Center, Huntsville, Ala., coordinates U.S. science activities on the
On the maintenance front, Vinogradov prepped for a June 1 space walk
by reconfiguring ventilation lines associated with the Elektron
oxygen generating system in the Zvezda module. One of the spacewalk
tasks will be to install a new external hydrogen vent line for the
Elektron. Oxygen is being provided now by storage tanks in the
Progress supply vehicle. The Elektron will remain deactivated until
after the spacewalk.
Early in the week, the carbon dioxide removal system, known as
Vozdukh, in the Russian segment malfunctioned. Flight controllers
activated the carbon dioxide removal system in Destiny until
troubleshooting restored Vozdukh's operation. Both units will run in
tandem until next week when a new gas analyzer is installed in