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Hubble memory errors persist despite NASA booting long-idle backup payload computer

Different hardware, same problem

NASA has fired up the Hubble Space Telescope's backup payload computer to find that the spacecraft still has problems.

The primary payload computer halted on 13 June, ceasing collection of science data and tripping the veteran observatory into Safe Mode. Troubleshooting has continued ever since.

Last week NASA engineers decided to fire up the backup payload computer, which has not booted since its installation by the last Space Shuttle servicing mission, STS-125, in 2009.

Despite trying multiple combinations of hardware from both the primary and backup computers, engineers found the same error – commands to write to or read from memory failed.

Noting that "it is highly unlikely that all individual hardware elements have a problem," the team has spread the fault-finding net a little wider.

Having looked at the Central Processing Module (CPM), the interface bridge between the CPM and other components, a communications bus, and the memory modules, the team is now looking at the Command Unit/Science Data Formatter (CU/SDF) as well as the power regulator.

The former is responsible for formatting and sending commands and data around the spacecraft as well formatting science data for transmission to the ground while the latter is supposed to ensure a steady constant voltage supply. "If the voltage is out of limits," said NASA, "it could cause the problems observed."

The CU/SDF module and the power regulator both have backups should either (or both) turn out to be at fault. The team will also continue remotely prodding the Science Instrument and Command and Data Handling (SI C&DH) unit (where the payload computers and CU/SDF modules are located) in the hope of tracking down other causes for the outage.

It appears that scientists have at least another week without the services of the space telescope as hardware assessments continue. On the plus side, "the telescope itself and its science instruments remain in good health and are currently in a safe configuration," even if the elderly hardware behind the scenes does not appear quite so happy. ®

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