Status Report

STS-104, Mission Control Center Status Report # 19 Saturday, July 21, 2001 – 6 a.m. CDT

By SpaceRef Editor
July 21, 2001
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The first space walk to originate from the International Space Station’s new airlock, Quest, lasted 4 hours, 2
minutes, and established a higher degree of station independence in its own construction and
maintenance.

The space walk also was the first to be supported primarily from the space station Flight Control Room in
Houston, and the first demonstration of a new pre-breathing protocol that uses vigorous exercise to help
purge nitrogen bubbles from the space walkers’ bloodstreams and prevent what is known as “the bends.”

Mission Specialists Mike Gernhardt and Jim Reilly exited the new airlock at 11:35 p.m. CDT Friday and were
back inside by 3:37 a.m. Saturday. Working in tandem with the station’s Canadarm2 operator and
Expedition Two Flight Engineer Jim Voss and shuttle arm operator and Atlantis Commander Steve Lindsey,
the space-age construction workers attached a nitrogen supply tank to the airlock’s shell. This completed
the installation of two nitrogen and two oxygen tanks that will be used to pressurize the airlock and resupply
space suits. Atlantis Pilot Charlie Hobaugh and Station Commander Yury Usachev coordinated the space
walk from inside, while Flight Engineer Susan Helms supported station arm operations.

Depressurizing the airlock took longer than expected – about 40 minutes instead of the anticipated 7
minutes. Flight controllers and engineers have not yet identified what caused the pressure equalization
valve on the Crew Lock’s hatch to react so slowly, but are continuing to evaluate data and reports from the
crew.

During the mission’s third spacewalk, Gernhardt and Reilly also moved hand-over-hand up the station’s solar
array truss to take a look at a gimbal assembly mechanism that allows the arrays to swivel with the Sun.
They reported no visible signs that could account for high-current readings being witnessed by flight
controllers on the ground.

The successful construction foray brings the total time for space station-based walks to 4 hours, 21 minutes.
There have been 24 space walks devoted to station assembly, a combined total of 155 hours, 39 minutes.

The crews will go to bed at 8:04 a.m., and awaken at 4:04 p.m. to begin preparations for an undocking at
11:54 p.m. CDT Saturday. The Atlantis and Expedition Two crews will say good-bye and close the hatches
at 8:59 a.m.

The JSC Newsroom will close at 7:30 a.m. CDT Saturday, and reopen at 3:30 p.m. The next mission status
report will be issued about 6 p.m. Saturday or as events warrant.

SpaceRef staff editor.