Shuttle Astronauts Deploy Satellites Ahead of Landing
Endeavour shuttle astronauts deploy the Naval Research Laboratory's ANDE 2 satellite experiment as they fly over Texas and Arkansas on July 30, 2009 during the STS-127 mission.
Credit: NASA TV.090730-ande2-A-02.jpg

Astronauts aboard the space shuttle Endeavour successfully deployed two sets of tiny satellites Thursday as they received word they were cleared to come home.

The seven astronauts aboard Endeavour jettisoned the two satellite experiments to demonstrate new technology and study Earth?s atmosphere Thursday as they gear up for a planned mid-morning landing in Florida tomorrow. Engineers also gave the shuttle?s heat shield a clean bill of health today, setting the stage for the Friday landing, Mission Control said.

?Well thank you Houston, that?s good news,? Endeavour skipper Mark Polansky radioed back. ?We?re looking forward to trying to come back tomorrow.?

Polansky and his crew are returning to Earth to wrap up a grueling 16-day construction flight to the International Space Station. Endeavour astronauts replaced one member of the station?s crew and performed five complex spacewalks to deliver spare parts and install a new experiment porch on Japan?s Kibo giant lab during their 11 days docked at the orbital outpost.

?Frankly, I do think it?s time to come back,? Polansky told the Associated Press Thursday.

Endeavour is also ferrying Japanese astronaut Koichi Wakata back to Earth to end what, for him, will be a 4 1/2-month mission in orbit. Wakata arrived at the space station in March on a different space shuttle and is Japan?s first long-term resident at the orbiting lab. He watched over Japan?s $1 billion Kibo lab and performed some unconventional experiments during the flight before being replaced by NASA astronaut Tim Kopra, who arrived on Endeavour.

Landing day ahead

Polansky and his crew are slated to land at 10:48 a.m. EDT (1448 GMT) at NASA?s Kennedy Space Center in Florida to end their marathon mission to the station. NASA flight director Bryan Lunney said the weather looks promising for landing, though there is a chance of rain and thunderstorms within 30 miles of the shuttle runway.

?I?m really optimistic things are going to play out well,? Lunney said.

Polansky and shuttle pilot Doug Hurley tested Endeavour?s flight control surfaces and thrusters to prepare for tomorrow?s landing. One thruster failed to fire, but will not be needed during re-entry.

The first of the two satellite experiments deployed Thursday was DRAGONsat, a pair of small satellites that launched from Endeavour?s payload bay as part of a study to demonstrate autonomous rendezvous and docking technologies, as well as global positioning systems. The satellites were built by students at the University of Texas at Austin and Texas A&M University.

Later, the astronauts jettisoned two perfect spheres that make up the Naval Research Laboratory?s ANDE 2 mission. The two spheres are each 19 inches across, but have different masses. By watching differences in their orbits, researchers will study the density of Earth?s atmosphere.

Astronauts repair station air purifier

While Endeavour?s astronauts prepared for landing, the six-man crew of the International Space Station tackled another glitch with an air-scrubbing device in NASA?s Destiny laboratory.

Called the Carbon Dioxide Removal Assembly (CDRA), the air-scrubbing device broke down late Wednesday - just a few days after engineers revived it on Sunday following an earlier glitch.

A short circuit in one of the device's 12 heater pads appeared to be at fault, mission managers said. Station astronauts spent much of Thursday repairing the air scrubber, which is one of two used to clean carbon dioxide out of the station?s atmosphere.

?We?re confident that it will activate and we?ll be back up to full capacity in the carbon dioxide removal operations,? said Mike Suffredini, NASA?s space station program manager, in an afternoon briefing.

The space station relies on American and Russian air scrubbers to continually refresh the its internal atmosphere. Both are required to support the station?s full-six man crew. If the repairs to NASA?s air scrubber are unsuccessful, the station has a stockpile of lithium hydroxide canisters that can also be used to purify the station?s cabin.

That stockpile could support the station?s six-person crew for up to two months if required, Suffredini said. NASA?s space shuttle Discovery, meanwhile, is already expected to deliver a new American air-scrubbing device to the station in late August as part of a preplanned supply mission.

That mission is slated to launch on Aug. 25.

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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.