Astronauts on the International Space Station are taking a break from spacewalking to perform some complex robotic maneuvers Sunday.
The seven astronauts of the space shuttle Endeavour's STS-127 crew are on the third day of their docked mission at the station.
One major objective for the day is to use the shuttle robotic arm to grab a container of spare parts for the station out of the space shuttle's cargo bay and temporarily stow it on the space station's robotic arm. The carrier is set to be unpacked Monday during the mission's second spacewalk.
"It?s basically a platform and attached to the platform are three very large pieces of equipment," commander Mark Polansky said in a preflight interview. "If required at some point in the future, it?s basically a hot spare ready to go on orbit."
Inside the container are a set of new batteries to power the station when it is not exposed to solar light, as well as a spare antenna and pump for systems onboard the station.
"We will be changing the batteries on the P-6 solar array, six large batteries that each weigh around 300, 350 pounds, the size of small refrigerators," said mission specialist Dave Wolf in a preflight interview. "That?s the oldest solar array system on the space station so we?ll rejuvenate that solar array system."
That robotic work will be carried out by Polansky and pilot Doug Hurley. Mission specialists Tim Kopra and Koichi Wakata will spend their time in the Japanese Kibo laboratory, calibrating the Japanese robotic arm there. Wakata also plans to replace some broken parts on a resistance exercise machine on the station.
The rest of the crew plans to make preparations for the next day's spacewalk, including configuring the spacesuits and tools that will be needed.
The day will be slightly less hectic than it might have been since mission managers determined a focused inspection of Endeavour's heat shield is not necessary. This precaution is an option if NASA needs more data to decide if a shuttle is safe to return home through Earth's atmosphere.
"Flight day five was where we had planned a focused inspection if required preflight," said lead station flight director Holly Ridings. "That is not required and so are going to move some of the robotic activities that were planned for flight day six a little bit forward."
Though mission managers have not officially cleared Endeavour for re-entry, they think they have enough information to make the decision from the first detailed inspection the astronauts conducted, as well as a series of photographs taken by station astronauts as Endeavour approached on Friday.
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SPACE.com is providing continuous coverage of STS-127 with reporter Clara Moskowitz and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed.