"Initial indications are that the burn went exactly as planned," reported NASA's Program Manager, Fred Wojtalik of the Marshall Space Flight Center in Huntsville, Ala. "All systems aboard the world's most powerful X-ray telescope continue to function well as the team here in Cambridge steps through the planned two-month activation and checkout," he said.

Controllers at the observatory's operations control center in Cambridge, Mass., commanded Chandra's liquid apogee engines to ignite at approximately 6:33 p.m. EDT, over the South Pacific near Australia, to boost the observatory's apogee to 86,992 miles (140,000 kilometers. Chandra's perigee, or low point, remains at an estimated 2,150 miles (3,460 kilometers).

This was the third of five planned burns of the TRW-built Integral Propulsion System, and the only one done to raise apogee. The next firing is scheduled for 12:35 a.m. EDT Monday, Aug. 2. It will further raise the observatory's perigee. A final burn to trim Chandra's orbit is planned for Wednesday, Aug. 4.

The firing was performed by a redundant set of two 105-pound-thrust liquid apogee engines, the highest performing space-qualified engines of this type in the industry. The engines are fueled by hydrazine and nitrogen tetroxide.

Since July 27, the Chandra control team has continued with step-by-step activation and checkout of two of the observatory's instruments, the Advanced Charge-coupled device Imaging Spectrometer and the High Resolution Camera. Controllers also initiated the several-day process of replacing the pre-launch software in the observatory's interface units and computers with software designed for use on-orbit.

The control team successfully performed a test of Chandra's Electrical Interface Assembly Sequencer. The sequencer controls the initial safemode hardware reconfiguration should a problem be detected with the observatory. And the team continued to perform Earth sensor scans twice each orbit to update the spacecraft's attitude reference for Integral Propulsion System engine firings.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra X-ray Observatory for NASA's Office of Space Science, NASA Headquarters, Washington, D.C. The Smithsonian Astrophysical Observatory in Cambridge, Mass., manages the Chandra science program and controls the observatory for NASA. TRW Space and Electronics Group of Redondo Beach, Calif., leads the contractor team that built Chandra.