After decades of peering into the cosmos, the Hubble Space Telescope is experiencing a major computer issue and is running in safe mode.

On June 13, NASA detected a problem when Hubble’s computer halted. Attempts to restart it failed, with a degrading memory module identified as the problem. Further attempts to bring the memory module online also failed.

NASA says the computer running Hubble’s instruments is a 1980s computer, with a full backup system as well. There are four memory modules that either computer can access, but attempts to have the primary computer switch to the backup modules failed.

When the operations team attempted to switch to a back-up memory module, however, the command to initiate the backup module failed to complete. Another attempt was conducted on both modules Thursday evening to obtain more diagnostic information while again trying to bring those memory modules online. However, those attempts were not successful.

It remains to be seen if NASA engineers will need to switch to the backup computer, but the longer the issue persists the more likely the switch will happen.

It is fully redundant in that a second computer, along with its associated hardware, exists on orbit that can be switched over to in the event of a problem. Both computers can access and use any of four independent memory modules, which each contain 64K of Complementary Metal-Oxide Semiconductor (CMOS) memory. The payload computer uses only one memory module operationally at a time, with the other three serving as backups.

If engineers are not able to fix the problem remotely, NASA may need to send astronauts to the telescope to fix it.