The Hubble Telescope Is Back Online a Month After Going Dark


According to the mission team, science operations will resume in a matter of days.

The world’s space lovers collectively breathed a sigh of relief Friday after NASA announced the Hubble Space Telescope was restored to online operation more than a month after it was shut down due to a failure with its primary computer. This caused speculation and concern about the future of the famous observatory.


Hubble’s mission chief Tom Brown said, “Hubble is back!” in an email to his colleagues early in the morning, Science reports. “I’m excited to see Hubble return to exploring the universe.”

Hubble was shut down June 13, when the primary computer that controls the science instruments aboard the spacecraft lost the “keep-alive” signal, which coordinates communications between all telescope computers, and stopped receiving it. Hubble has been offline since then to allow the mission team perform diagnostics that may help to isolate the problem. NASA maintains an updated log of all ongoing procedures at this link.

Operators initially hoped to fix this problem with the primary computer. However, they changed their minds after several weeks of unsuccessful attempts. The primary Power Control Unit (PCU) is the problem. It supplies steady voltage levels to telescope’s hardware. The primary computer has signals that it should stop operating because the voltage has dropped below its normal levels. This is something that the team is still investigating.

NASA has many redundancies built into its spacecraft. Hubble is equipped both with a backup computer system as well as a PCU. On Thursday, the observatory was switched to the secondary system. Mission leaders are running tests to make sure all backups work as expected. Although it may take some time for the instruments of the telescope to be removed from safe mode and calibrated properly, NASA expects that the mission’s science goals will resume soon.

Hubble’s harrowing experience over the last month serves as a reminder of the telescope’s advanced age and its extraordinary resilience. Hubble’s computers were built in 1980s. The observatory was launched into orbit in 1990. Hubble has been through many technical difficulties and near misses over the years, but has survived them all and is still one of the most important science instruments of history.

NASA is currently preparing to launch Hubble’s successor, James Webb Space Telescope within the next year. This telescope will offer a more stunning and high-resolution view into the universe. As space enthusiasts around the globe celebrate Hubble’s supposed return to observations, it is clear that no telescope can ever replace this workhorse mission.

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