( Space )- As astronauts prepare to open the International Space Station's (ISS) new Japanese room Friday, mission controllers continue to tackle a power supply glitch afflicting a giant robot outside the orbiting laboratory.
Specialists in NASA's Mission Control center here at the Johnson Space Center sent power-supplying commands to a pallet holding pieces of Dextre, a two-armed Canadian-built robot, but the Thursday morning operation failed. Following a successful spacewalk by two astronauts early Friday, an upload of new power-regulating software also failed to deliver power to the platform.
"We weren't going to fool ourselves by thinking that there weren't going to be any issues," said Pierre Jean, acting program manager for the Canadian space station program, of the robot. "But nonetheless we have to deal with them."
Smoking gun
Despite the two foiled attempts to supply Dextre with power crucial for protecting the robot from circuit-snapping cold, Jean said his team has likely pinpointed the problem's origin.
"It's basically a design error in the cable," Jean said of a power line that routes electricity through the pallet to Dextre. He explained that the improperly designed cable allows power to flow, but doesn't relay data to and from a computer.
To confirm that the cable is to blame - and not Dextre - Jean said astronauts will see if the robot can be powered directly by grappling its head with the space station's power-supplying robotic arm around 9:53 p.m. EDT (0153 GMT March 15) Friday night.
"That will validate our assumptions," he said.
LeRoy Cain, chair of NASA's mission management team, said during a Friday evening breifing that the operation's success or failure should be known within minutes of grappling the robot.
"I think it will be pretty clear pretty quickly whether or not we actually have power," Cain said. If the fix doesn't work, he said it will be back to the drawing board for mission managers, and that four remaining spacewalks could be shuffled or removed from the flight plan.
Leak check
Cain also noted that technicians formally approved Endeavour's heat shield, also known as its thermal protection system (TPS), to make a searing reentry through Earth's atmosphere.
"Today in our mission management team [meeting], we went ahead and cleared the TPS for deorbit and entry," Cain said. "So the vehicle is safe to come home whenever we are ready to do so."
During the briefing, Cain said that an auxiliary power unit - which has compartments of hydrogen and hydrazine - has a small leak, adding that specialists will continue to monitor the problem.
"We've seen this kind of flights before," Cain said of shuttle Discovery's STS-121 flight. He said a hydrogen leak would be of little concern, but hydrazine would pose somewhat of a threat and can be detected by it temperature-dropping properties.
"We're looking for thermal indications, or any kind of ice or frost, or snow flakey looking stuff developing on the vents," he said.
Grand opening
Dextre's power supply test is slated to kick off as Endeavour mission specialist Takao Doi, a veteran Japanese spaceflyer, and other astronauts finish outfitting the space station's latest addition: the Japanese Logistics Pressurized module, or JLP.
The module is the first segment of the Japan Aerospace Exploration Agency's (JAXA) massive Kibo, or "Hope," laboratory to be delivered to the station.
"It is a very big day," said ISS flight director Dana Weigel. "In total, they'll spend about five and a half hours preparing the JLP."
The astronauts have begun bolting down Japan's first orbital room and hooking up power cables, and Doi will take the honors of opening the module for the first time early Saturday morning.
"It's just amazing that now the day will soon come when we can open the Kibo hatch, realizing the dream that many people have had for a long time," Doi said before his spaceflight of the moment of ingress.
"We can't wait to see his smiling face going into the JLP," said Endeavour shuttle commander Dominic Gorie.
At 16 planned days in duration, Endeavour's STS-123 mission is the longest ISS-bound flight to date. Four more spacewalks remain to build Dextre, deliver on-orbit experiments and test a new system to repair heat-resistant tiles crucial to the shuttle's safe atmospheric reentry.
Endeavour launched from Kennedy Space Center early Tuesday morning and docked at the space station Wednesday night and is scheduled to return to Earth on March 26.