NASA is struggling to fix a computer glitch that has left the Hubble Space Telescope offline for about two weeks — and its backup computer appears to have the same issue, too.
The Hubble Space Telescope, which launched in 1990, halted operations on June 13 just after 4 p.m. EDT (2000 GMT), following a problem with one of the telescope's computers. While the spacecraft has stopped collecting science data, its other hardware and science instruments remain in good health, according to a statement from NASA.
"Hubble has been observing the universe for over 31 years," NASA officials said in the statement. "It has contributed to some of the most significant discoveries of our cosmos, including the accelerating expansion of the universe, the evolution of galaxies over time, and the first atmospheric studies of planets beyond our solar system."
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Hubble is equipped with two payload computers, both of which are located on the Science Instrument and Command and Data Handling (SI C&DH) unit. The computers were installed in 2009, but were built in the 1980s. One of the computers serves as a backup; that unit was turned on for the first time in space during tests performed on June 23 and 24. This latest attempt to revive the telescope revealed that both the primary and backup computers are experiencing the same error, which suggests the issue lies somewhere else, NASA said.
The primary and backup computers are comprised of various pieces of hardware, which perform functions such as processing and storing operational commands, coordinating and controlling the telescope's science instruments, and supporting communications between different components of the spacecraft. The tests conducted on June 23 and 24 showed that numerous combinations of these hardware pieces all experienced the same error in which commands to write into or read from memory were not successful, according to the statement from NASA.
As a result, engineers are now investigating other hardware that may be causing the issue. This includes the Command Unit/Science Data Formatter (CU/SDF) — another module on the SI C&DH that is responsible for formatting and transmitting data — and the power regulator, which provides a constant voltage supply to the computer's hardware. "If the voltage is out of limits, it could cause the problems observed," NASA officials wrote.
NASA is continuing tests to further isolate the problem and identify a potential solution. If needed, the telescope can switch over to using its backup CU/SDF module or backup power regulator, according to the statement.
Hubble went into a protective "safe mode," or electronic hibernation, when its primary payload computer suddenly stopped working on June 13. Since then, NASA has been working to troubleshoot the issue and get the telescope back up and running.
After a failed attempt to restart the computer on June 14, the space agency made multiple attempts to switch over to one of the telescope's backup memory modules on June 16 and June 17. However, both those attempts to bring the backup memory module online were not successful. On June 22, the space agency shifted its focus to test the spacecraft's Standard Interface (STINT) hardware and the computer's Central Processing Module (CPM).
This is not the first time that Hubble has experienced issues in orbit. NASA launched a total of five servicing missions to work on the telescope between 1993 and 2009. The aging telescope periodically experiences issues; most recently, the telescope suffered a temporary software glitch in March, following a code modification to address gyroscope issues.
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