STS-90 Mission Control Center Status Report # 18
Saturday, April 25, 1998, 6:30 p.m. CDT
A one-inch piece of aluminum tape and a measure of ingenuity by engineers on the ground today breathed new life into the STS-90 Neurolab mission.
Commander Rick Searfoss opened up a balky Regenerative Carbon Dioxide Removal System (RCRS) aboard Columbia about 3 p.m., removed a hose clamp and used the tape to bypass a suspected check valve that had threatened to cut the flight short by several days. The valve, part of the air-scrubbing systems plumbing that recirculates nitrogen back into the cabin atmosphere, apparently was allowing cabin pressure to leak into the system and throw off its electronics control unit.
Half an hour later, Mission Control told Searfoss the repair had succeeded after watching the system go through one of its 26-minute operational cycles. The RCRS system uses two beds of the chemical amine to alternately adsorb and release excess carbon dioxide given off by the crew and the research animals on board as part of their normal respiration. With the bypass in place, the system will vent about four extra pounds of nitrogen overboard each day. But nitrogen supplies on board are sufficient to support a full 17 days of research if mission managers decide later this week to grant an extension day.
Crew members also restored air circulation to one of the Research Animal Holding Facilty (RAHF) pens being carried in the Spacelab. The fan associated with RAHF unit #7 stopped working and they set up a bypass system that is allowing the fan in RAHF unit #3 to support the #7 unit.
Science operations for Flight Day 9 included continued work with the ball catch experiment which is part of the Sensory Motor and Performance, and the Effects of Gravity on Postnatal Motor Development Experiment that is one of the Mammalian Development Team’s projects. Columbia’s astronauts also spoke with Astronaut Andy Thomas, nearing his 100th day on the Russian Space Station, and answered questions posed by visitors to the New Hampshire McAuliffe Planetarium, and from students at York University and Dartmouth College.
Columbia remains in a 153 x 133 nautical mile orbit, circling the Earth every 90 minutes. The crew will begin its sleep shift at 9:19 p.m. A planned half day off on Sunday will be moved to the first half of the crew’s day so that they may sleep in after losing about an hour of sleep because of the RCRS shutdown on Friday night. The next STS-90 status report will be issued about 6 a.m. Saturday or as events warrant.
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