UPDATED 4:20 p.m. ET

The Hubble Space Telescope's showcase camera has been offline since Monday, June 19.

Managers are scrambling to use the observatory's other cameras as science operations continue.

Meanwhile, engineers have yet to figure out what caused the Advanced Camera for Surveys (ACS) to go into "safe mode," essentially a sleep state that prevents normal operations. But the outlook is bright.

"We're very optimistic" that the camera will be fixed, said Ed Ruitberg, associate program manager for Hubble at NASA's Goddard Space Flight Center.

Ruitberg told SPACE.com that some potential causes have been ruled out and that the problem is likely with a low-voltage power supply interface, something between the batteries and a camera component. If that's the case, then redundant electronics can be relied on to bypass the problem area.

"We're still investigating the problem and working on all sorts of contingencies," said Max Mutchler at the Space Telescope Science Institute (STScI) in Baltimore, where Hubble's science operations are run. "We're hoping for the best but preparing for other contingencies."

The ACS, installed on the orbiting observatory by astronauts in 2002, has gone into safe mode "more than once" recently, Mutchler said, but this time the problem is more serious.

"We've recovered from these before," Mutchler told SPACE.com. "But this is kind of a little bit longer and is more involved than previous ones that were simple software resets."

Various approaches to solve the problem are being tentatively planned, but they can't be implemented until the core problem is known. "Right now we don't know what the core problem is," Mutchler said.

Ruitberg said if the investigation reveals what he suspects, then a reconfiguration could take place Friday, June 30 and the camera would be started up again. Even if the root problem is something else, he said, other repair options are likely available. Ultimately, he "fully expects" the camera to work again.

If ACS can be fixed, then Hubble's overall science operations should not be compromised much, said Bruce Margon, STScI's Associate Director for Science.

"We just have to rush around a bit to change the schedule." Margon said in a telephone interview. "The targets scheduled [for ACS] appear to be available conveniently available throughout the year."

Hubble is in need of new batteries and gyroscopes if it is to run much past 2007. NASA has considered a shuttle mission to service Hubble, and possibly install a new camera, but the agency does not plan to discuss the possibility again until at least October.

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