Chandra X-ray Observatory

Tuesday, April 6, 1999

Dave Drachlis
Media Relations Office
NASA Marshall Space Flight Center
(256) 544-6538

George Diller
Kennedy Space Center Media Relations
(407) 867-2468
george.diller-l@ksc.nasa.gov

NASA's Chandra X-ray Observatory has been moved onto its fueling stand.

Pressure testing of the fuel system began Tuesday, April 6. Loading of nitrogen tetroxide oxidizer into the spacecraft is planned to begin on April 9. The bi-hydrazine, used by the telescope's propulsion system to achieve final orbit, will be loaded on April 13. Hydrazine, used by one of the subsystems that points the telescope in space, will be loaded April 15. Work continues on schedule toward a July 9 launch aboard the Space Shuttle Columbia on mission STS-93.

The spacecraft's batteries are scheduled to be installed April 19. Chandra will then be ready for the arrival and mating to the Inertial Upper Stage.

The solar arrays were installed on March 26 and testing of the mechanical and electrical interfaces was successfully completed on April 1. Their high performance could be noticed when, during the deployment test of one of the arrays, a small amount of power was already being generated with only the available lighting in the Vertical Processing Facility at Kennedy Space Center, Fla.

The Payload Operations Procedure - to verify the network command telemetry path from the observatory through NASA's Deep Space Network to the Operations Control Center ground station in Cambridge, Mass. - was successfully completed March 26. Test engineers are expected to re-run selected procedures from the test sequence this week to verify results of the payload test effort.

An overall state-of-health test of the observatory was completed March 18 in the Vertical Processing Facility at NASA's Kennedy Space Center, Fla. The test, a 24-hour activation of all observatory electrical systems, was followed by a helium flow test of the observatory's attitude control thrusters on March 18.

Chandra's reworked Command and Telemetry Unit arrived at Kennedy March 2 and was reinstalled on the observatory the following day. The Interface Unit was received and reinstalled March 8. A three-day retest of both elements was completed March 11. Both these elements are responsible for handling commands and telemetry to and from the ground.

Chandra arrived at Kennedy Space Center aboard an Air Force C-5 transport aircraft Feb. 4.