The International Space Station's robotic Canadarm2 grapples the Leonardo Multi-purpose Logistics Module (MPLM) from the payload bay of the docked shuttle Discovery on April 8, 2010 during NASA's STS-131 mission. Earth's horizon and the blackness of space provide the backdrop for the scene. The Canadian-built Dextre maintenance robot is visible at bottom center.
This story was updated at 11:45 a.m. ET.
Astronauts on International Space Station and shuttle Discovery tackled a mountain of cargo delivery work early Saturday after getting an extra day added to their mission due to an antenna failure.
?Most of our day, a lot of us were involved in doing transfer, which is a lot like moving,? teacher-turned-astronaut Dorothy ?Dottie? Metcalf-Lindenburger told Mission Control as the day wound down.
The shuttle astronauts are hauling 17,000 pounds (7,711 kg) of vital supplies, experiments and spare parts to the station.
Mission Control decided Friday to extend their flight by one day, making it a now 14-day flight, to give them more time to move the cargo and use the space station?s main antenna later to send home the results of a standard heat shield inspection since their own shuttle antenna is broken. Discovery is now slated to land in Florida on April 19 after a two-week flight.
Space station flight director Ed Van Cise said the decision allows Discovery?s crew time to inspect their heat shield without sacrificing any of their remaining mission goals. Those goals include two more spacewalks and moving nearly 8 tons of cargo into the station while packing tons of trash and unneeded items up for the trip back to Earth.
And there?s another upside, Van Cise said.
?It means that other crewmembers are available to do other things, and we?ve got a laundry list of activities that were normally planned to be done on the space station after Discovery left us,? he added. ?We can carry some of those forward, and having 13 people on board means we can get a few things done in a faster manner just by having more bodies available.?
All hands on deck
The space station is normally home to six astronauts, but its population leaped to 13 people when Discovery arrived.
Four of the spaceflyers aboard are women. It?s the first time so many women are in space together in spaceflight history. Two of the joint station-shuttle crewmembers are Japanese ? another first, with Japan celebrating its most astronauts in space.
One of those Japanese astronauts, first-time flyer Naoko Yamazaki, is in charge of the deliveries being made by Discovery and its crew. The space shuttle launched on Monday with an Italian module the size of a small bus packed inside its payload bay.
The cargo module, called Leonardo, was filled with spare parts, supplies and large, refrigerator-sized racks of science experiments. Five of those hulking racks, including a spare astronaut bedroom (to be converted into a bathing room), science sample freezer and other gear, were moved into to station earlier this morning.
?We have to be very careful that we don?t hit any structure,? Yamazaki said of the big moves. ?So we have to be slow and steady.?
One of the big ticket items today is a science photography rack designed to cover a high-quality window in the space station?s U.S. Destiny laboratory.
Called the Window Observational Research Facility (WORF), the rack serves as a sort of dark room for astronauts and science instruments to observe the Earth without light contamination from within the station itself. The result: Supposedly ultra-clear photos and precise observations of Earth.
Each of the racks weighs up to 2,000 pounds (907 kg), Van Cise said.
?If you were doing it on Earth, it would be a pretty heavy, big deal. You?d need some special equipment,? he added. ?They were doing it with fingertips and their toes.?
Hauling heavy cargo is much easier when there?s no gravity to slow you down, he added.
Bon Jovi in Space
NASA roused Discovery?s crew Friday night with the song ?We Weren?t Born to Follow? by Bon Jovi, a tune selected for mission specialist Rick Mastracchio ? the flight?s chief spacewalker ? by his wife Candace and their three grown children. The shuttle astronauts are working an overnight shift while they fly in space.
?We?re having a great mission up here and I can?t wait to get back and see them,? Mastracchio said.
Mastracchio and crewmate Clayton Anderson took a spacewalk together on Friday to begin a lengthy ammonia tank replacement outside the space station. The two astronauts will spend much of Saturday preparing for their mission?s second spacewalk ? a Sunday excursion ? to continue that tank swap chore.
In all, the liquid ammonia tank ? which feeds the $100 billion space station?s cooling system ? will take three spacewalks to replace. The mission?s third spacewalk is scheduled for Tuesday.
The astronauts got some good news in their morning mail from Mission Control. NASA has cleared Discovery?s heat shield of any damage concerns related to its launch. The late inspection will seek out any new damage from space junk or micrometeorites while the shuttle has been in space.
Discovery?s STS-131 mission is one of NASA?s last few shuttle flights before the space agency retires the aging, three-orbiter fleet in September. Three more shuttle missions are planned after this one.
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SPACE.com is providing complete coverage of Discovery's STS-131 mission to the International Space Station with Managing Editor Tariq Malik and Staff Writer Clara Moskowitz based in New York. Click here for shuttle mission updates and a link to NASA TV