NASA Plans Emergency Spacewalks to Fix Space Station
2010 08 02

By Tariq Malik | Space.com


NASA is planning a pair of emergency spacewalks to repair the International Space Station after half of its cooling system shut down unexpectedly Saturday, forcing astronauts to power down several systems.

The two repair spacewalks will be performed by American astronauts Doug Wheelock and Tracy Caldwell Dyson and could begin Thursday to replace a pump module in one of the space station’s two cooling system loops. Engineers are assessing the spacewalk plans before making a final decision.

"The crew is being informed that replanning for alternate spacewalk activity is underway," NASA officials said in a statement. A spacewalk had already been planned for Thursday for the Wheelock and Caldwell Dyson to upgrade some station systems.

NASA has stressed that Wheelock, Caldwell Dyson and the rest of the six astronauts living aboard the International Space Station are in no danger from the cooling system problem. But it is something Mission Control would like to address quickly since initial troubleshooting efforts have failed.

"An attempt overnight Sunday to close the circuit breaker and restart the Pump Module was not successful," NASA officials said. The space agency will give an update on the space station’s status and spacewalk planning at 4 p.m. EDT (2000 GMT).

Cooling system problems

The space station’s cooling system troubles began late Saturday when a circuit breaker tripped and shut down the Loop A cooling system pump module, which is used to move super-cold liquid ammonia through the station to remove excess heat from its systems and laboratories.

The shutdown triggered alarms in the space station, awakening the outpost’s six astronauts so they could begin turning off systems to reduce the heat load on the space station’s only remaining working cooling system string Loop B. The space station’s cooling system is critical to the outpost’s operation since it prevents the station from overheating.

Station astronauts shut down two control moment gyroscopes (used to maintain the station’s orientation in space without thrusters), some station power converters and command-routing equipment, and backup systems for the station’s S-band communications antenna and Global Positioning System. So some station systems were running without backups in place if they fail.

Mission Control reactivated one of the two offline gyroscopes on Sunday and astronauts installed jumper cables between some station systems and the power system on the outpost’s U.S. Destiny laboratory to preserve redundancy.

The space station is currently in stable shape with "most systems receiving cooling and many systems operating with redundancy following the installation of jumper cables from the Destiny Lab’s power system overnight," NASA officials said. "Temperatures on the Main Bus Switching Units, which route power to various systems, are a little higher than normal, but well within normal parameters and are stable."

Repair spacewalks ahead

The next step is a spacewalk repair. To prepare for the first spacewalk, Mission Control vented any remaining liquid ammonia from the Loop A system.

The space repair would likely call for two spacewalks by Wheelock and Caldwell Dyson, who would physically replace the afflicted pump module in the first excursion and hook up ammonia fluid and electrical connections in the second one.

There are two spare ammonia pump modules stored outside the space station on spare parts platforms attached to the orbiting laboratory’s backbone-like main truss.

The space station is currently home to three Americans (NASA astronaut Shannon Walker is the third) and three Russian cosmonauts representing Russia’s Federal Space Agency.

Wheelock and Caldwell Dyson had originally planned to perform a spacewalk Thursday to hook up a power extension cord for a future Russian laboratory and install equipment on part of the station’s Russian segment. That work will be rescheduled to a later date, NASA officials said.

Astronauts have been living aboard the $100 billion International Space Station, which is being built by five international space agencies representing 16 different countries, for nearly 10 years. Construction began on the orbiting laboratory in 1998.

NASA plans to fly two space shuttle missions (in November and February, respectively) to complete construction of the space station before retiring the shuttle fleet next year. Congress is discussing the possible addition of a third and final shuttle mission, which if approved would likely carry spare parts and other supplies to the space station in next summer.

Article from: space.com




Related Articles
International Space Station sex ban
Russian supply spacecraft misses Space Station for first time ever - spins out of reach (Video)
Aurora Australis Observed from the International Space Station
International Space Station Growth During 12 Years
Canadian circus billionaire heads to space station
US Astronauts May Have to Leave Space Station in 2012
NASA, USDA Sign Space Station Research Agreement
Space station deploys its new set of solar wings
International Space Station holed by meteorite


Latest News from our Front Page

Gene That Once Aided Survival in the Arctic Found to Have Negative Impact on Health Today
2014 10 23
In individuals living in the Arctic, researchers have discovered a gene variant that arose thousands of years ago and most likely provided an evolutionary advantage for processing high-fat diets or for surviving in a cold environment; however, the variant also seems to increase the risk of hypoglycemia, or low blood sugar, and infant mortality in today’s northern populations. {snip} “Our work ...
The Ebola hoax: questions, answers, and the false belief in the “One It”
2014 10 23
“The Reality Manufacturing Company doesn’t just sell ‘fake paintings’ that are easy to spot. No. They also sell images that are geared to mesh with people’s deeply held instincts and thereby produce rigid false beliefs. People are sure that if they gave up such beliefs, their world would fall apart and blow away in the wind.” ...
New Controversial Theory Suggests "Hobbits" Were Not Human - Who Were These Mysterious Beings?
2014 10 23
The origin of the Hobbit species remains a challenging subject to scientists. The Hobbit’s discovery confirmed the view that the Earth was once populated by many species of human, but new research the Hobbit’s were not human at all! So, who were these mysterious beings? Where did they come from? The idea that our species, Homo sapiens, was the only species of human on ...
Right into enemy hands? ISIS shows off new weapons allegedly airdropped by US (VIDEO)
2014 10 23
Islamic State has published a new video in which a jihadist shows off brand-new American hardware, which was purportedly intended for the Kurds they are fighting in the Syrian border town of Kobani. The undated video, posted by the unofficial IS mouthpiece “a3maq news”, sees a jihadist showing several boxes of munitions with English-language markings, with a parachute spread out on ...
STAGED INFECTION: Has The Ebola ‘Outbreak’ Narrative Fallen Apart?
2014 10 22
Over the past month, the ‘pandemic’ propaganda surrounding the deadly Ebola virus seemed to reach vitriolic levels – raising serious questions about the validity of this current viral outbreak… On Monday of this week, it was reported that 48 people were released and cleared after a 21-day quarantine due to their contact with the now deceased Ebola-stricken patient Thomas Eric ...
More News »