WASHINGTON -- NASA will host a media teleconference at 6 p.m. EDT today to discuss a significant Hubble Space Telescope anomaly that occurred this weekend affecting the storage and transmittal of science data to Earth. Fixing the problem will delay next month's space shuttle Atlantis' Hubble servicing mission.

The briefing participants are:

- Ed Weiler, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington

- John Shannon, Shuttle Program manager at NASA's Johnson Space Center in Houston

- Preston Burch, Hubble manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

To participate in the teleconference, reporters in the U.S. should call 1-800-369-6087 and use the pass code Hubble. International reporters should call 1-773-756-0843.

As a result of the launch delay, NASA has postponed the planned Oct. 3 Flight Readiness Review and subsequent news conference. The review will occur at a later date.

The malfunctioning system is Hubble's Control Unit/Science Data Formatter - Side A. Shortly after 8 p.m. on Saturday, Sept. 27, the telescope's spacecraft computer issued commands to safe the payload computer and science instruments when errors were detected within the Science Data Formatter. An attempt to reset the formatter and obtain a dump of the payload computer's memory was unsuccessful.

Additional testing demonstrates Side A no longer supports the transfer of science data to the ground. A transition to the redundant Side B should restore full functionality to the science instruments and operations.

The transition to Side B operations is complex. It requires that five other modules used in managing data also be switched to their B-side systems. The B-sides of these modules last were activated during ground tests in the late 1980's and/or early 1990, prior to launch.

The Hubble operations team has begun work on the Side B transition and believes it will be ready to reconfigure Hubble later this week. The transition will happen after the team completes a readiness review.

Hubble could return to science operations in the immediate future if the reconfiguration is successful. Even so, the agency is investigating the possibility of flying a back-up replacement system, which could be installed during the servicing mission.

Audio of the teleconference will be streamed live at:

http://www.nasa.gov/newsaudio

Related images for the briefing will be available at:

http://www.nasa.gov/hubble

For more information about the Space Shuttle Program, visit:

http://www.nasa.gov/shuttle