NASA has now tried and failed to fix the Hubble Space Telescope 3 times. It's been offline for a week.

• The computer that controls the Hubble Space Telescope's science instruments suddenly halted June 13.
• NASA has tried and failed to fix Hubble's computer issue three times.
• NASA engineers have yet to pinpoint the cause of the problem, but Hubble has a backup computer.

NASA is working to save its prized space telescope, Hubble, after a mysterious computer issue took it offline last week.

Hubble launched into space in 1990 and immediately began capturing the universe in revolutionary detail. The Earth-orbiting observatory has imaged the births and deaths of stars, discovered new moons around Pluto, and tracked two interstellar objects as they zipped through our solar system. It has allowed astronomers to calculate the age and expansion of the universe. It has spotted galaxies more than 13.4 billion light-years away, thereby capturing light from the universe's early years.

But the telescope's payload computer suddenly stopped working on June 13. That computer, built in the 1980s, is like Hubble's brain - it controls and monitors all the science instruments on the spacecraft. So NASA engineers rushed to analyze data from the telescope to pinpoint the problem.

They still haven't figured out why the computer halted. NASA tried, and failed, to restart it on June 14. Initial data indicated the issue could stem from a computer-memory module that was degrading, so the Hubble team tried switching to one of three backup modules aboard the telescope. But the command to start the new module didn't work.

On Thursday, the Hubble team tried again to bring both the current module and the backup online. Both attempts failed.

So now the Hubble operations team "will be running tests and collecting more information on the system to further isolate the problem," NASA said in an update Friday.

In the meantime, Hubble's science instruments are in a hibernation-like "safe mode." They're all in good health, NASA said Friday, as is the telescope itself.

Hubble has a second payload computer it should be able to switch to if NASA can't restore the current one.

Hubble has seen many fixes and upgrades in its 30 years

This isn't the first time Hubble has glitched or needed an upgrade - not even the first time this year. In March, a software error sent the observatory into safe mode. But within a week, NASA had fixed the problem and gotten the telescope back online.

Hubble is the first telescope designed for in-orbit servicing. Astronauts have visited the observatory to fix problems or replace old parts on five occasions.

The most recent Hubble-servicing mission, in 2009, repaired two failing instruments and gave the telescope a new computer, new batteries, new insulation, a new camera, and a spectrograph.

By replacing or upgrading aging parts in this way, astronauts have given Hubble new capabilities. That's why the telescope is still conducting groundbreaking science 30 years after its launch. It's unlikely, however, that NASA would send astronauts to address the latest problem because the backup computer should be able to fix it.

NASA also plans to launch a more sophisticated space telescope into orbit in November. The new observatory, called the James Webb Space Telescope, will have a field of view about 15 times that of Hubble.

Even though JWST is not intended to be a Hubble replacement, the legacy space telescope can't go on forever. During the 2009 mission, astronauts also installed a device that could push Hubble into Earth's atmosphere when it comes time to decommission the telescope. As the observatory falls toward Earth, friction will heat it until it burns up. It's unclear when that might be necessary.