CAPE CANAVERAL, Fla. - Astronauts aboard NASA's space shuttle Atlantis once more scanned their spacecraft's heat shield Monday, this time in search of any signs of strikes by micrometeorites or orbital debris (MMOD).
STS-115 shuttle pilot Chris Ferguson wielded Atlantis' 100-foot (30-meter) assembly of a robotic arm and sensor-laden inspection boom to hunt for potential damage along the shuttle's wing leading edges and nose cap, areas that see the highest temperatures during reentry.
"If you look at the cumulative risks we take in flight, MMOD risks is not insignificant," Phil Engelhauf, NASA's chief of the flight directors office, said Sunday of the micrometeorite and orbital debris hazard to space shuttles in flight. "[But] it is not at the highest end of the scale."
Atlantis' heat shield has already been cleared for reentry based on studies of imagery taken during its Sept. 9 launch, a similar Flight Day 2 inspection, and a photographic survey taken by astronauts aboard the International Space Station (ISS) prior to the shuttle's Sept. 11 docking.
Paul Dye, NASA's lead shuttle flight director for Atlantis' STS-115 mission, said Saturday that anytime a spacecraft flies in orbit, there is a risk it could be struck by natural or man-made orbital debris.
"It is a small risk," Dye said. "We've taken very few hits. We take the occasional hit, and it's something we think that, since we have the time, it's prudent to go take a look at."
Atlantis mission specialists Daniel Burbank and Steven MacLean are aiding Ferguson's heat shield scan - known as a late inspection - which was first performed on NASA's STS-121 shuttle flight aboard Discovery in July.
During that flight, astronauts actually began the late inspection while still docked at the ISS, but the crew - and mission controllers - found that the task ran long because of additional procedures and clearance issues associated with using a 100-foot (30-foot) robotic arm combination in close proximity with the ISS.
"It wound up taking quite a bit longer to run the procedure because they had to take a lot more care and kind of depart from the rehearsed procedures," Engelhauf said of the STS-121 late inspection, adding that shifting the scan to post-undocking for STS-115 was an easy trade on crew time and energy. "We think it'll go faster, it'll be less stressful for the crew and just makes it easier all around."
Atlantis' STS-115 mission has delivered a $372 million, 17.5-ton pair of trusses and new solar arrays to the ISS in NASA's first dedicated space station construction flight since the 2003 Columbia accident. The shuttle undocked from the orbital laboratory early Sunday after jump starting what NASA expects to be four more years of ISS construction.
NASA roused Atlantis' crew today with John Denver's "Rocky Mountain High," a song chosen for STS-115 mission specialist Joseph Tanner by his wife Martha.
"So good morning, Houston," Tanner said. "And we just flew over Colorado yesterday. It was beautiful [and] looked like a great place to live. And thank you, Martha. The next few years are gonna be pretty exciting."
Water dump interruption
Atlantis' heat shield inspection was paused intermittently as the STS-115 crew eyed a glitch with the orbiter's waste water dump system.
Earlier today, shuttle commander Brent Jett reported seeing a sort of burping action from an exterior nozzle that vents waste and extra water overboard, NASA commentator Kelly Humphries said.
The glitch was not expected to pose a great concern for Atlantis, though mission controllers want to ensure the extra water did not freeze into ice along the nozzle area and pose a debris hazard later in the shuttle's flight, he added.
After more troubleshooting work by flight controllers on Earth and the STS-115 crew - which included clearing out the pump nozzle of any water using air - the matter was resolved.
"We're going to continue to monitor the [temperatures] to make sure that no ice forms," NASA astronaut Megan McArthur, serving as spacecraft communicator, told Jett.
Meanwhile, STS-115 mission specialists Heidemarie Stefanyshyn-Piper worked with Jett and others to ready Atlantis for its Sept. 20 landing.
12 people on orbit
While Atlantis headed for a waypoint about 70 nautical (129 kilometers) behind the ISS - where its crew will await analysis of today's heat shield inspection - the shuttle's orbital neighborhood got a bit more crowded.
At 12:09 a.m. EDT (0409 GMT) today, two professional astronauts and one private spaceflyer rocketed spaceward atop a Russian Soyuz rocket on a two-day trek towards the ISS. Aboard are Expedition 14 commander Michael Lopez-Alegria, flight engineer - and Soyuz commander - Mikhail Tyurin and U.S. entrepreneur Anousheh Ansari, who became the first female space tourist with the successful launch.
The Soyuz is currently about 720 miles (1,158 kilometers) ahead of the ISS but chasing the station from behind, leaving about 18,000 miles (28,968 kilometers) of forward flight before it catches up with the orbital laboratory, NASA said.
The space shot brings the number of humans currently in Earth orbit to an even dozen: three on Soyuz, six aboard Atlantis, and the three-astronaut crew of Expedition 13 aboard the ISS.
"It really shows you how well we've really come together as a team," said NASA associate administrator for space operations William Gerstenmaier of the international partnership that allowed such a feat during a NASA TV interview at the Soyuz's Baikonur Cosmodrome launch site in Kazakhstan. "This is truly amazing."
The Soyuz TMA-9 spacecraft with Ansari and the Expedition 14 crew will dock at the ISS on Sept. 20, just a few short hours before Atlantis is expected to land at NASA's Kennedy Space Center, now slated for 5:57 a.m. EDT (0957 GMT). The space station's current Expedition 13 crew must also jettison an unmanned Russian cargo ship Monday night before the Soyuz docks.
"It's like some sort of intricate ballet," NASA associate administrator Rex Geveden said in the taped NASA TV interview. "It's a daunting thing to do."
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