September 14, 1999

Chandra X-ray Observatory Status Update

Dave Drachlis, Media Relations Office, NASA Marshall Space Flight Center, Huntsville, AL (Phone: 256/544-0034)

NASA's Chandra X-ray Observatory continues to produce the highest resolution x-ray images ever as the observatory enters its eighth week of on-orbit checkout. With the successful deployment of the Low Energy Transmission Grating on Sept. 5, all Chandra instruments have now been activated. Overall, the telescope is in excellent health and performing as expected.

Normally every complex space facility encounters a few problems during its checkout period; even though Chandra's has gone very smoothly, the science and engineering team is working a concern with a portion of one science instrument.

The team is investigating a reduction in the energy resolution of one of two sets of X-ray detectors in the Advanced Charge-coupled Device Imaging Spectrometer (ACIS) science instrument.

A series of diagnostic activities to characterize the degradation, identify possible causes, and test potential remedial procedures is underway.

The degradation appeared in the front-side illuminated Charge-Coupled Device (CCD) chips of the ACIS. The instrument's back-side illuminated chips have shown no reduction in capability and continue to perform flawlessly.

The front-side chips are currently in use for science observations. Even if these chips degrade to a point where they are no longer usable for spectroscopy, the vast majority of the experiments planned with the ACIS instrument can still be performed using the back-side illuminated chips or the other focal plane instrument, the High Resolution Camera (HRC).

"The bottom line is that we are looking forward to performing a full complement of scientific research with Chandra, the world's most powerful X-ray telescope," according to Drs. Martin Weisskopf, Chandra Project Scientist at the Marshall Space Flight Center in Huntsville, Ala., and Harvey Tananbaum, Director of the Smithsonian Astrophysical Observatory Chandra X-ray Center in Cambridge, Mass.

Over the past several days, Chandra has performed a number of celestial observations including a coordinated multi-wavelength observation of the Capella star system that involved the NASA's Hubble Space Telescope and Extreme Ultraviolate Explorer satellites, The National Science Foundation's Very Large Array radio telescope and the Italian-Dutch Beppo-Sax satellite.

Editor's Note: Chandra images and more information on the observatory are available at and

Dave Drachlis, MSFC Media Relations Office