Mission managers decided today not to redeploy the solar-observing Spartan satellite, which has been in Columbia’s payload bay since being captured by astronauts Winston Scott and Takao Doi during a space walk earlier in the mission. The Spartan’s attitude control system failed to activate following its release from Columbia’s robot arm on Flight Day 2.
Lee Briscoe of Mission Operations reported in a 3 p.m. Sunday status briefing that flight controllers had looked at as many as five different options for a second deployment of Spartan, but had narrowed them to two—one involving a Monday deploy and Tuesday retrieval by Scott and Doi, and the other a Tuesday deploy and Wednesday retrieval. Because the Monday option would have required immediate action by the flight control team, mission managers decided to meet Sunday to make a final decision.
After a thorough review, mission managers decided that the risk of not being able to retrieve Spartan again was too great, that the adverse effects of such a deployment on the United States Microgravity Payload-4 science work were too extensive, and that steering jet propellant was insufficient to protect all possible contingencies and landing scenarios.
"It just wasn’t enough," Briscoe said, adding that Spartan program managers believe the free-flying spacecraft is healthy and should be able to support a reflight on a future shuttle mission as quickly as a flight opportunity can be identified.
Columbia’s crew will be notified of the decision shortly after they are awakened by Mission Control at 6:46 p.m. today. The astronauts will again turn their attention to investigations on plant growth, combustion and materials processing as they continue to support the U.S. Microgravity Payload.
Late Saturday morning, an investigation that could improve metals used in automobiles and jet engines produced a measurement that has never been witnessed by scientists on the ground. Science team members studying dendrites -- tiny tree-like crystal structures that form in materials as they solidify -- witnessed the fastest dendritic growth rate ever measured for pivalic acid. The transparent acid has similar properties to nonferrous metals such as aluminum, but unlike molten metals alows the science team to see into the solution and observe the dendrites.
This evening and tomorrow morning, the crew will work with the glovebox facility on Columbia’s middeck to process samples for the Particle Engulfment and Pushing by a Solid/Liquid Interface experiment. PEP is studying the formation of composite materials, attempting to accurately map the roles of gravity-induced convection and sedimentation in the process by removing the gravity from the equation. The Enclosed Laminar Flames investigation will study the effects of different air flow velocities on the stability of an enclosed jet diffusion flame--the kind used in industrial combustion processes and jet afterburners.
Scientists working with the Advanced Automated Directional Solidification Furnace in the payload bay processed two different lead-tin-telluride crystals today, but stopped processing before a third experiment run when several temperature sensors used to control the solidification of the sample showed unusual readings. A successful lead-tin-telluride sample already has been processed on STS-87.
Status checks also will continue on the Collaborative Ukrainian Experiment investigating plant growth in space. Monday morning, Ukrainian Payload Specialist Leonid Kadenyuk will compare the results of the on-orbit plant growth, with similar plants being grown by students in both the Ukraine and the United States.
The next mission status report will be issued about 6 a.m. Monday.
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