STS-87 mission managers Monday afternoon decided to add a second spacewalk to this mission, giving astronauts and EVA designers more confidence in techniques which will be important to assembly of the International Space Station.
Astronauts Winston Scott and Takao Doi will exit Columbia’s airlock at approximately 2:15 a.m. CST Wednesday for a five-hour spacewalk which will repeat part of the crane operations, handling the smaller of the boxes which represent objects it will have to move during Space Station assembly.
Greg Harbaugh, acting manager of the EVA Projects Office at Johnson Space Center, explained in a press conference Monday that planners want to get as much confidence as possible that the movement of ORUs (Orbit Replaceable Units) can be done successfully. He noted that handling of the boxes during the first spacewalk did not give EVA designers all the information they needed. The original spacewalk timeline was modified last week to accommodate the retrieval of the SPARTAN satellite.
Another component of the second EVA will be checkout of the AERCAM SPRINT flying video camera which will be used during Space Station assembly and operations as a second point of view to observe work outside the station.
With the juggling of the crew timeline to add the second EVA, other mission activities have been rescheduled. After the astronauts awaken tonight at about 7:45 p.m. CST, their flight day 13 will include three hours of PEP operations (Particle Engulfment and Pushing), the MEPHISTO furnace experiment and SOLSE (Shuttle Ozone Limb Sounding Experiment) observations. The in-flight crew press conference has been moved earlier, now scheduled to begin at 4:36 a.m. CST. Media at Johnson Space Center in Houston, Kennedy Space Center in Florida and in Kiev, the Ukraine, will participate.
Just before 9 a.m. CST Tuesday, Columbia’s crew will reduce the cabin atmospheric pressure to 10.2 psi, giving Scott and Doi 16 hours of advance pre-breathe time which reduces their in-suit pre-breathe to just one hour.
The next status report will be issued at approximately 6 a.m. CST Tuesday.
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