With the Chandra X-Ray Observatory undergoing what so far has been a flawless checkout on orbit for future scientific investigations, Commander Eileen Collins and Pilot Jeff Ashby successfully exercised Columbia's aerosurfaces and fired all of its steering jets late Monday night, confirming that the Shuttle is ready to support its high speed return to Earth.
With all systems operating in good fashion, Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini stowed all of their hardware and deactivated secondary experiments in preparation for tonight's landing opportunities at the Florida spaceport.
The astronauts have two chances to land tonight, the first calling for a firing of the orbital maneuvering system engines in a braking maneuver at 9:19 p.m. Central time tonight. That will slow Columbia down by 250 feet per second, allowing it to drop out of orbit for its hour-long entry back to Earth. If all goes as planned, landing will occur on Runway 3-3 at the Kennedy Space Center at 10:20 p.m. Central Daylight time, after Collins executes an overhead right hand turn to align Columbia with the southeast to northwest approach to the 3-mile long landing strip. This will be the 12th night landing in Shuttle program history.
If weather somehow prevents a landing on the first opportunity, a backup opportunity exists 90 minutes later. The alternate landing site at California's Edwards Air Force Base will not be called up for landing support tonight.
Additional opportunities for landing will be available on Wednesday at both landing sites if weather prevents Columbia from coming home tonight. The forecast, however, looks very favorable, with only a few clouds predicted near the Shuttle Landing Facility and a slight chance of a thundershower offshore at the time of touchdown.
The astronauts began an eight-hour sleep period at 6:31 a.m. Central time this morning and will be awakened at 2:31 this afternoon to begin deorbit preparations.
The first major task will be the closing of Columbia's cargo bay doors at about 6:40 this evening, followed by the astronauts climbing into their launch and entry suits shortly before 8 p.m. Entry Flight Director John Shannon and his team of flight controllers will receive updated weather forecasts throughout the late afternoon and evening before a "go-no go" decision for the deorbit burn is issued around 9 p.m.
Assuming clear weather, the orbiter should be visible as it streaks across the night sky over Texas, Lousiana, and then Florida. In Houston, Columbia should appear in the northern sky at about 10:05 p.m. CDT before the 10:20 landing.
If Columbia lands this evening, the astronauts are due back at Ellington Field in Houston around mid-morning on Wednesday. An exact time for crew arrival will be firmed up after landing.
Columbia is orbiting the Earth every 90 minutes at an altitude of 179 statute miles with all systems operating normally.