With the major objective of their mission successfully completed, Columbia’s astronauts spent a busy night conducting a variety of secondary experiments on both the flight deck and the middeck of the Shuttle.

Commander Eileen Collins, Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini worked on experiments involving everything from astronomy to biomedicine to plant growth as the shuttle continued to orbit the Earth every 90 minutes in excellent shape.

Hawley, the resident astronomer on board, used the Southwest Ultraviolet Imaging System, or SWUIS instrument, to collect imagery of Mercury, Venus, Jupiter and the moon in this, its second flight into space. Hawley reported that he could not see a new comet called Lynn, but that the SWUIS may have captured imagery of the comet for investigators on the ground. The telescopic instrument is mounted on the side hatch window in the shuttle’s middeck.

Coleman monitored several plant growth experiments while Tognini collected data from a biological cell culture experiment. The two astronauts collaborated on the smooth deployment of the Chandra X-Ray Observatory yesterday.

Chandra is currently orbiting the Earth in a highly elliptical orbit of about 200 statute miles by 44,000 statute miles, thanks to the successful firing of its two-stage Inertial Upper Stage booster an hour after it was spring-ejected from Columbia’s cargo bay cradle. The first of five scheduled firings of Chandra’s thrusters to refine its orbit is planned for 8:16 p.m. Central time tonight, a five-minute firing of the telescope’s liquid-fuel propulsion system. That maneuver should leave Chandra in an orbit of about 774 statute miles by 44,600 miles. Four additional maneuvers are expected over the next two weeks.

Collins and Ashby fired Columbia’s large orbital maneuvering system engines and primary reaction control system jets on several occasions to provide data for researchers in a pair of experiments designed to characterize jet thruster plumes in the space environment.

They also conducted a successful test of a procedure called the “flycast” maneuver in a rehearsal for the STS-99 mission in September, in which a 200-foot mast will be deployed from the cargo bay of the shuttle Endeavour equipped with a sophisticated radar system to study Earth’s topographical features. The maneuver uses multiple thruster firings and the shuttle’s autopilot system to maintain stability. The procedure will be crucial for the September mission to minimize disturbances to the radar mast.

Coleman also conducted several tests of High Definition Television equipment carried on board Columbia. HDTV gear is being tested for future use on both the shuttle and the International Space Station to conform to evolving broadcasting industry standards for television products.

The astronauts are scheduled to begin an eight-hour sleep period at 9:31 a.m. Central time this morning and will be awakened at 5:31 this afternoon to begin their third day in space.

Columbia is currently orbiting at an altitude of 177 statute miles. The next STS-93 status report will be issued early this evening after crew wake up or as developments warrant.

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