We closed the thermal vacuum chamber door Thursday evening and started the pump-down. We started the transition cold about 10:00 am and powered up early Friday afternoon to begin the first of six balance points. Currently, the temperatures are starting to stabilize and the pressure in the chamber is 0.0000010 torrs, (atmospheric pressure is 760 torrs). During thermal balance we fix the external thermal environment and measure the temperatures of the spacecraft components after they stabilize. We then compare those temperatures to what was predicted by the thermal model, and we adjust the thermal model to make the predictions agree. Then we use the thermal model with the on-orbit environmental conditions to predict the temperatures of components on the spacecraft during the mission. If those predictions exceed the operational limits of the components, we must resize the thermal radiators.
Here are scenes from our move to the thermal vacuum chamber. The left
photo shows the spacecraft being moved to the "saw horses" so that we can work
underneath safely. The next two pictures show Bruce and Gary closing out the
blankets and harness on the bottom of the spacecraft. The last two pictures
show the spacecraft being lifted up so that it can be lowered in through the
top of thermal vacuum chamber 238. The wiring hanging from the spacecraft
goes to the thermocouples and test heaters which are needed for the test. The
wires will be removed after this test.
Here are two views in the thermal vacuum chamber. The left photo shows
Kelvin Garcia setting up the cryo panels which will control spacecraft
component temperatures. The right photo shows the spacecraft in the thermal
vacuum chamber just before we closed the door. The -y side is facing the
camera, and the instrument simulator is visible toward the top. Most of the
spacecraft is hidden by the blanketed cryo panels and plumbing.
Previous updates:
August 18, 1997
October 20, 1997
October 31, 1997
November 7, 1997
November 14, 1997
November 21, 1997
December 5, 1997
December 23, 1997
January 9, 1998
January 16, 1998
January 23, 1998
January 30, 1998
February 6, 1998
February 20, 1998
March 12, 1998
March 23, 1998
April 3, 1998
April 20, 1998