The International Space Station鈥檚 spine-like truss will grow by 14 metres on Tuesday, if all goes as planned.
The crews of the space shuttle Atlantis and the ISS spent Monday preparing for this addition. Using the shuttle鈥檚 Canadian robotic arm, astronauts Dan Burbank and Chris Ferguson lifted the 16-tonne P3/P4 truss segment out of the space shuttle Atlantis鈥檚 payload bay.
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They handed it off to the station鈥檚 larger robotic arm, which will hold onto it overnight. Atlantis crew member Steve MacLean became the first Canadian to fly his nation鈥檚 robot arm on the ISS.
The girder-like truss supports the station鈥檚 power and cooling systems. After the new truss segment鈥檚 solar arrays are deployed later in this mission, they will double the station鈥檚 power supply.
鈥淚t is great to have [the shuttle crew] onboard,鈥� ISS science officer Jeff Williams said before he went to sleep on Monday. 鈥淎nd today, I think we got off to a great start.鈥�
Atlantis docked to the ISS at 0648 EDT (1048 GMT) on Monday. 鈥淭he rendezvous this morning was just about as perfect of a rendezvous as I鈥檝e ever been a part of,鈥� says Atlantis鈥檚 lead flight director Paul Dye.
Airlock campout
Tuesday should be equally busy, with Atlantis crew members Heide Stefanyshyn-Piper and Joe Tanner performing the first of three planned spacewalks to install the P3/P4 truss (see Shuttle astronauts to begin trio of intense spacewalks).
To prepare for the spacewalk, the pair began an overnight 鈥渃ampout鈥� in the reduced air pressure of the station鈥檚 airlock on Monday. The campout is a new procedure designed to prevent the astronauts from getting a condition called decompression sickness (see Astronauts to camp out on space station).
The campout will actually save the pair time on Tuesday morning before their spacewalk. If they did not camp out, they would have to do rigorous exercise on a stationary bicycle, while breathing pure oxygen, right before leaving the station. The exercise helps to get rid of nitrogen in their bloodstream, which can cause decompression sickness in the low air pressures inside a spacesuit.
Focused inspections
Meanwhile, NASA managers decided on Monday evening not to extend the shuttle crew鈥檚 time in space to conduct a focused inspection of areas of potential concern on the orbiter鈥檚 heat shield.
They had considered keeping the shuttle docked to the station an extra day to inspect three 鈥済ap fillers鈥� that have been seen sticking up between heat shield tiles on the underside of the orbiter. The fillers are made of a felt-like material and are used both to keep the tiles from rattling against one another during launch and to prevent hot air from reaching the skin of the orbiter during atmospheric re-entry.
On the past two shuttle flights, inspections have revealed that some of these gap fillers come loose during launch. That could present a danger to the mission because the protruding pieces of fabric might cause turbulence below the orbiter on atmospheric re-entry, potentially heating it up beyond its design parameters. In a worst-case scenario, that might cause a Columbia-like disaster.
But managers say the three gap fillers on Atlantis do not look like they would pose a threat to the orbiter during its atmospheric re-entry. The shuttle is currently scheduled to undock from the station on Sunday.
