STS-103 Commander Curt Brown, along with Pilot Scott Kelly, first performed checks of the Flight Control System by activating one of the three Auxiliary Power Units aboard Discovery to allow them to test the various aerosurfaces that will be used to steer the Shuttle once it has re-entered the atmosphere. The crew then did a check of the Reaction Control System, the maneuvering jets that steer Discovery while the Shuttle is in space. Both the FCS and RCS checkouts were without issue, with all systems ready to support Discovery's return to Earth.
The weather forecast for the two available landing sites is very good for both a nominal end of mission as well as the two extension days that are planned into every Shuttle flight. The prediction for KSC on Monday is for only a few clouds at the upper levels and very good visibility. The only possible concern is crosswinds that are predicted to be near the peak of what is allowed at the three-mile-long Shuttle Landing Facility at KSC. Weather at the alternate landing site at NASA's Dryden Flight Research Center in Edwards, California also is predicted to be very good on Monday, with only a few high clouds and light winds. The extended forecast for both landing sites on Tuesday and Wednesday shows continued favorable weather.
At tonight's mission status briefing, Entry Flight Director Wayne Hale said that given the very good forecast at both landing sites for the next three days, the Shuttle team's current plan for Monday afternoon would be to try for the first two landing opportunities at KSC. If Discovery cannot land on one of those opportunities and the weather forecast for Tuesday and Wednesday remains the same, Discovery and her crew would be kept in orbit one additional day to try and allow a KSC landing on Tuesday. Shuttle managers would like to land at KSC if possible in order to avoid the work associated with transporting an orbiter from California back to Florida.
The first opportunity to land at KSC on Monday takes place on orbit 118 with a deorbit burn at 3:06 p.m. CST and a landing at KSC at 4:18 p.m. The second opportunity on orbit 119 would have a deorbit burn taking place at 4:49 p.m. and a landing at KSC at 6:00 p.m. CST. A third and final opportunity for a KSC landing is available on orbit 120 if needed. The third opportunity has a deorbit burn at 6:32 p.m. and landing at 7:43 p.m. CST.
Should the extended weather forecast change, there are landing opportunities at the Edwards site on the same three orbits, along with an additional opportunity on orbit 121.
The STS-103 crew will begin a planned eight-hour sleep period at 11:20 p.m. this evening. A wake-up call from Mission Control to begin what should be their final day in space for this flight will come at 7:20 a.m. on Monday.