NASA assessing procedures to leave space station vacant
BY STEPHEN CLARK
Posted: August 29, 2011
Engineers are evaluating what steps are necessary to safeguard the International Space Station should the orbiting lab be temporarily evacuated in the wake of last week's Soyuz rocket failure.
Engineers are analyzing what's needed to keep the station alive in case astronauts have to pull out of the international laboratory, according to Michael Suffredini, NASA's space station program manager.
"There is a greater risk of losing ISS if it were unmanned than if it were manned," Suffredini said Monday. "The risk increase is not insignificant."
Russia's Soyuz rocket -- the only vehicle able to carry astronauts to the space station after the space shuttle's retirement -- has been grounded since the Aug. 24 failure of a launch with a Progress resupply freighter heading for the outpost.
Russia has tentative plans to return the Soyuz to flight in October with a pair of unmanned missions, eventually leading to the launch of the next space station crew by November. But Russia still must complete its investigation into last week's loss and implement corrective actions.
Just in case the Soyuz rocket is still grounded in November, the space station's international partners assigned engineers to review procedures for abandoning the complex in orbit for up to several months.
The actions would ensure control teams on Earth would be able to monitor space station systems and respond to as many potential problems as possible.
Suffredini described some of the measures a departing crew would perform before leaving the space station unmanned. Astronauts would connect jumper cables to ensure the station has backup cooling, configure the spacecraft's heating system, and close hatches between the station's modules before boarding their Soyuz return capsules.
The crew would isolate the modules in case one of them lost pressure integrity, ensuring other portions of the complex were still habitable, according to Suffredini.
Locks on the station's docking ports would also be disabled to allow robotic Progress cargo craft to automatically come and go with supplies.
"As long as the systems keep operating, we can command the vehicle from the ground and keep it operating and remain in orbit indefinitely," Suffredini said.
But there are cases where multiple failures could limit the ability of ground teams to save the space station. The million-pound complex is at less risk with residents on-board, according to NASA.
The evacuation would cut short promising life sciences and medical research projects that require astronaut support inside the space station. Experimental payloads attached to the lab's exterior, such as the $2 billion Alpha Magnetic Spectrometer searching for dark matter, would continue to operate, officials said.
Space station officials expect to set a new landing date this week for commander Andrey Borisenko, Russian cosmonaut Alexander Samokutyaev and NASA flight engineer Ronald Garan. The trio was supposed to return to Earth on Sept. 8, but the landing will probably be moved about one week later, according to Suffredini.
A landing after approximately Sept. 19 would occur at night in the Soyuz touchdown zone in Kazakhstan, a situation officials would like to avoid. A daylight landing opportunity would not be available again until late October, when the Soyuz craft would be nearing the end of its design life.
Russia does not want to push the limits of the Soyuz capsule that far, so the most likely scenario would see Borisenko, Samokutyaev and Garan returning to Earth in mid-September, Suffredini said.
NASA flight engineer Michael Fossum, Russian cosmonaut Sergei Volkov and Japanese astronaut Satoshi Furukawa are scheduled to land Nov. 16, just before the Kazakhstan landing zone goes dark again until late December.
In order to avoid landing the crew in harsh winter conditions on the Kazakhtan steppe, Suffredini said Fossum, Volkov and Furukawa should land in daytime in November. If the Soyuz rocket isn't able to launch another crew by then, the station will be left vacant.
"In that configuration, assuming no significant anomalies, we can operate indefinitely," Suffredini said.
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