STS-75 Mission Control Center 
Status Report # 15 

Thursday, February 29, 1996, 9 a.m. CST 

Columbia's crew continues its work with the United States Microgravity
Payload experiments supporting a variety of investigations including
crystal growth, materials solidification and fluid
dynamics. Meanwhile, payload controllers continue to obtain snapshots
of data from the tethered satellite as it passes within range of
available groundstations around the world.

As TSS battery power diminishes, plans are in work to turn on science
instruments, Earth sensors and stabilizing gyros in anticipation of
the closest approach of TSS to Columbia at about 11 p.m.  central time
today (approximately 07/08:50 mission elapsed time). At that point,
the orbiter should pass within about 50 miles of the satellite
possibly allowing payload bay instruments a chance to gather data on
the satellite as well.

Because of the instability of the satellite and its varying
gravitational drag, the distance between the two spacecraft and the
time of closest approach likely will change. In any case, there is no
concern about Columbia passing too close to the satellite. Whether or
not the crew can visually observe the satellite during the fly-by will
depend on lighting conditions at that time.

The Tethered Satellite is currently about 3,000 nautical miles ahead
of Columbia with the distance between the two spacecraft closing at
the rate of 340 nm with every revolution of the Earth.

Later today, several of the crewmembers will participate in two
in-flight interviews. The first at 4:20 p.m. is with two Philadelphia
television stations and the second at 6:08 p.m. is with the United
States Information Agency's Worldnet program.

Columbia is functioning normally, with no problems being tracked by
the flight control team as the Shuttle orbits the Earth every 90
minutes at an altitude of 180 statute miles.

The JSC newsroom will close at 5 p.m. today and will reopen at 6
a.m. Friday.