One of NASA’s most experienced spacewalkers paired with its newest for the space shuttle programme’s last servicing call outside the International Space Station today.
Astronauts Mike Fincke and Greg Chamitoff floated outside the space station’s airlock at around 12:30 a.m. EDT (0430 GMT) today to begin the fourth and final spacewalk planned during shuttle Endeavour’s 16-day mission, the next to last in the 30-year-old U.S. space shuttle program.
The 6 1/2-hour spacewalk was the 159th in support of assembly and maintenance of the station, which began with the robotic attachment of the U.S. Unity node with the Russian Zarya base block in 1998. Since then, the US$100 billion outpost, a project of 16 nations, has grown to more than 1 million pounds (455,000 kg) of hardware orbiting 220 miles above Earth.
During the spacewalk, the ninth for Fincke and the second for Chamitoff, NASA will hit the 1,000-hour mark of spacewalk time by astronauts working outside the station.
“In the early shuttle program, a flight with one or two EVAs (extravehicular activities, or spacewalks) was considered a pretty challenging mission. With the station missions that we fly today, with three and four EVAs the norm, the difference and the upgrade in the capability is just tremendous,” said NASA station flight director Derek Hassman.
NASA plans one last shuttle mission in July to deliver a year’s worth of supplies to the station before turning over Endeavour and sister ships Discovery and Atlantis to museums.
“I am sad to see the three space shuttles be rolled into a museum here shortly,” Endeavour commander Mark Kelly said during an in-flight news conference. “I think it’s a necessary step so we can go on and do some more exciting things.”
NASA plans to save the shuttles’ US$4 billion annual operating budget and develop new vehicles that can travel beyond the station’s orbit where the shuttles cannot go.
Russia already has picked up station crew taxi flights, and NASA hopes U.S. commercial companies will be offering similar services within about four years.
During today’s spacewalk, Fincke and Chamitoff will transfer the shuttle’s 50-foot (15-meter) inspection boom to the station so it can be used to extend the reach of the station’s robotic crane. With the boom’s installation, 11 years of station assembly by NASA comes to an end.
On Wednesday two of Endeavour’s spacewalkers ventured outside of the International Space Station to extend the reach of the station’s robotic crane and bolster its power supply.
Drew Feustel and Mike Fincke, Endeavour’s most experienced spacewalkers, completed an excursion that spanned nearly seven hours. It was the third of the four spacewalks planned for Endeavour’s mission.
Over the three spacewalks, astronauts have contended with a series of challenges — a faulty spacesuit sensor that spurred ground controllers to cut the first spacewalk short and errant bolts that unexpectedly floated free during the second.
On Wednesday, Fincke got temporarily entangled in his safety tether, and Feustel struggled with an irritated eye.
“My right eye is stinging like crazy,” Feustel said. “The problem with tears in space is that they don’t fall off of your eye.”
Despite the setbacks, both astronauts were awestruck by the spectacular views of the Earth, 220 miles below.
“There’s probably no better place to watch a … sunrise than from up here,” Feustel said as the station emerged into the daylight portion of its orbit over the coast of Mexico.
Endeavour and its six-man crew are due to leave the station late on Sunday. They arrived at the station on May 18 for a 12-day servicing call.
The shuttle delivered the station’s premiere science experiment, the US$2 billion Alpha Magnetic Spectrometer particle detector, and spare parts.
Landing is scheduled for 2:32 a.m. EDT on Wednesday at the Kennedy Space Center in Florida. Shuttle Atlantis is targeted to launch on July 8 for NASA’s 135th and final flight.