As planned, NASA engineers successfully re-activated the Hubble Space Telescope's main camera Friday morning.

Officials had said Friday they had initiated the switchover to backup power for the camera. Now they've said switchover was successful, the camera has been restarted, and science observations are schedule to resume Sunday.

The Advanced Camera for Surveys (ACS) had been offline since June 19.

"This is the best possible news," said Ed Ruitberg, deputy associate director for the Astrophysics Division at NASA's Goddard Space Flight Center. "We were confident we could work through the camera issue, and now we can get back to doing more incredible science with the camera."

The problem involved a power supply interface that functions similarly to the power adaptor on a laptop computer.

"You have an adaptor that you plug into your wall that provides the correct voltage to your power charger on your laptop," Ruitberg explained. "It's something like that power adaptor."

Engineers began uploading commands to the observatory Thursday to switch to a physically separate, redundant power supply route. The switch was completed at 10:20 a.m. ET Friday.

Since June 19, observing time has been shifted to other cameras on Hubble that remained online. Hubble officials said earlier that targets missed during the ACS's downtime should be available for imaging later in the year, so overall no observing plans will be dropped.

The ACS is made up of three electronic cameras that detect light from the ultraviolet to the near infrared. The instrument was installed during a March 2002 servicing mission and doubled Hubble's existing field of view.

NASA officials said today they are optimistic that the ACS will continue functioning until Hubble's next servicing mission, which is tentatively scheduled for 2007.

"The ACS was designed with a 5-year lifetime; we're well into year four and only just now are we having to begin to use the redundant capabilities. So I'm hoping it has a good long lifetime to go," Ruitberg said Friday.