The launch of STS-83, the first Microgravity Science Laboratory (MSL-1) mission, was postponed for a day to replace some insulation around a water coolant line in Columbia's payload bay. Liftoff was further delayed 20 minutes due to anomalous oxygen readings in the orbiter's payload bay. STS-83 was cut short due to a problem with one of the three fuel cells that provide electricity and water to Columbia (flight rules required that all three must be operating). At 14:30 GMT on April 6 the crew were ordered to begin a Minimum Duration Flight (MDF). On April 8 the OMS engines ignited at 17:30 GMT for the deorbit burn, and Columbia landed on Runway 33 at Kennedy Space Center at 18:33 GMT.

With delays in International Space Station construction leaving ample room in the shuttle schedule, NASA made the unique decision to leave the equipment installed in Columbia and refly this mission with the same crew later in 1997 as STS-94.

The launch came at 1920:36 GMT on Apr 4. Solid rocket motors RSRM-59 separated two minutes after launch and the external tank ET-84 was jettisoned at 19:29 GMT, leaving Columbia in an elliptical transfer orbit with an apogee near 300 km. The OMS 2 orbit circularization burn came at 20:00 GMT. Columbia opened its payload bay doors by 21:09 GMT, beginning what was intended as a marathon Spacelab research mission.

Cargo Bay Payloads:

MSL-1: The Microgravity Science Laboratory included the first test of the International Space Station�s EXPRESS Rack, designed for quick and easy installation of experiment and facility hardware on orbit. The EXPRESS Rack replaced a Spacelab double rack, and special hardware provided the same structural and resource connections the rack will have on Space Station. Two payloads -- the Physics of Hard Spheres experiment and the Astro/Plant Generic Bioprocessing Apparatus experiment -- were flown to check the design, development and adaptation of the EXPRESS Rack hardware. MSL-1 also contained numerous other experiment payloads to test materials and combustion processes in zero gravity.

CRYOFD: The Cryogenic Flexible Diode (CRYOFD) heat pipe was a Hitchhiker payload jointly developed and sponsored by NASA�s Goddard Space Flight Center in Greenbelt, Md. and the U.S. Air Force Phillips Laboratory in Albuquerque. The payload consisted of the Cryogenic Flexible Diode Heat Pipe (CFDHP) and the American Loop Heat Pipe with Ammonia (ALPHA).

OARE: The Orbital Acceleration Research Experiment was a self-calibrating instrument that monitored extremely small accelerations and vibrations experienced during orbit of the Shuttle. OARE could detect accelerations down to one-billionth the acceleration of Earth's gravity -- at a frequency of less than 1 Hertz. The instrument's principal purpose was to determine the orientation of the least acceleration disturbance for the Shuttle orbiter during flight. The Shuttle's flight attitude can then be adjusted to satisfy the needs of any particular experiment.

In-Cabin Payloads: SAREX, MSX

The mission this time went for its full two week duration as the crew conducted the full list of experiments. The deorbit burn was at 0944 GMT following payload bay door closing at around 0700 GMT. Columbia landed on KSC's Runway 33 at 1046:34 GMT on Jul 17.

Development Test Objectives / Detailed Supplementary Objectives / Risk Mitigation Experiments

DTO 255: Wraparound DAP Flight Test Verification

DTO 312: External Tank TPS Performance

DTO 416: Water Spray Boiler Quick Restart Capability

DTO 667: Portable In-Flight Landing Operations Trainer

DTO 677: Evaluation of Microbial Capture Device in Microgravity

DTO 684: Radiation Measurement in Crew Compartment

DTO 805: Crosswind Landing Performance

DSO 331: Integration of the Space Shuttle Launch and Entry Suit

DSO 487: Immunological Assessment of Crewmembers

DSO 493: Monitoring Latent Virus Reactivation and Shedding in Astronauts

RME 1330: Wireless Data Acquisition System