By Chip Skambis
Two astronauts will go on their second spacewalk today after they unsuccessfully tried to fix an issue that caused the International Space Station to lose one-fourth of its power.
Suni Williams, an American astronaut, and Aki Hoshide, a Japanese astronaut, tried to replace a bolt in the main bus switching unit on space station for more than 8 hours Thursday, which is the third longest spacewalk in history.
The main bus switching unit directs electricity around to different areas of the international space station and supports of all the operations of the space station and the research that's going on, said Kelly Humphries, NASA spokesman.
"The main bus switching unit is important on the space station because it controls the distribution of about a quarter of the space station's power," he said. "And so we are down to three-quarters power right now."
Humphries said the space station can run on three-fourths of its power as long as mission control and astronauts use the electricity wisely.
"It does mean you have to do some extra-special planning on the use of your electricity just like if you were getting a brownout at your house," he said.
NASA has multiple backup plans in case the astronauts can't install the bolt again.
"We're confident that they are going to be able to do the tasks that are planned and we're hopeful that they'll succeed," Humphries said.
Benjamin S. Brasch edited this story online.