With nearly all of their science studies complete, Columbia’s astronauts were awakened at 3:29 a.m. CDT today to begin a busy day preparing for their return to the Kennedy Space Center late Sunday morning.

Commander Rick Searfoss is scheduled to route a line from Columbia’s waste tank to a Contingency Waste Container (CWC) to offload about 80 pounds of waste water throughout the course of the day. This will ensure that the tank's capacity will be adequate to support as much as two additional days in orbit in the event Columbia cannot land as planned due to weather conditions.

Columbia’s science crew -- Mission Specialists Rick Linnehan and Dave Williams and Payload Specialists Jim Pawelczyk and Jay Buckey -- will wrap up science activities this morning when they complete some vestibular experiments. Crew members also will begin cabin stowage activities.

Commander Rick Searfoss, Pilot Scott Altman and Mission Specialist Kay Hire will conduct a hot-fire test of the shuttle’s reaction control system to ensure Columbia’s readiness for tomorrow’s entry and landing. About an hour later, they will activate one auxiliary power unit and check out the flight control system to make sure Columbia has full use of its flight control surfaces in anticipation of Sunday’s landing. They also will conduct landing simulations with the Portable In-flight Landing Operations Trainer (PILOT). The astronauts will conduct a deorbit briefing among themselves early in the afternoon.

Payload commander Rick Linnehan will replenish water supplies and carry out other routine husbandry tasks for the rodents on board and the science crew will put away experiment hardware and partially deactivate the Spacelab module. Columbia’s KU-band communications antenna also will be stowed just before 11 a.m. today.

Meteorologists are forecasting favorable conditions at the Kennedy Space Center on Sunday for a landing at 11:09 a.m. CDT.

Columbia remains in a 150 x 131 nautical mile orbit, circling the Earth every 90 minutes.

The next STS-90 status report will be issued about 6 p.m. Saturday or as events warrant.

UPCOMING EVENTS ON NASA TV, MAY 2, 1998

MET CDT EDT

MISSION STATUS BRIEFING/ 14/22:41 1200 PM 01:00 PM

FLIGHT DAY HIGHLIGHTS 15/02:41 04:00 PM 05:00 PM

CREW ACTIVITY REPORT / 15/03:41 05:00 PM 06:00 PM FLIGHT DAY HIGHLIGHTS REPLAY / VIDEO FILE REPLAY (replayed every hour on the hour through crew wake up)

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