The Hubble Space Telescope is flying partially blind across the heavens because of a short circuit in its most popular instrument, the advanced camera for surveys.

NASA engineers reported today that most of that camera’s capabilities — including the ability to take the sort of deep cosmic postcards that have inspired the public and to track the mysterious dark energy splitting the universe to the ends of time — have probably been lost for good.

In a telephone news conference from NASA headquarters, Hubble engineers and scientists said the telescope itself was in fine shape and would continue operating with its remaining instruments, which include another camera, the wide-field planetary camera 2, or wfpc2, and an infrared camera and spectrograph named Nicmos. The advanced camera for surveys stopped working Saturday morning.

He and his colleagues said that it was unlikely they would be able to repair the camera during the next Hubble servicing mission, which is scheduled for September 2008. On that mission, astronauts will replace the existing wide field camera with a powerful new version, wfpc3, which will extend Hubble’s vision to ultraviolet and infrared wavelengths and restore the lost capabilities. They will also install a new ultraviolet spectrograph, among many pressing repairs.

The Advanced Camera for Surveys was installed on the telescope in March 2002, and it has been Hubble’s workhorse ever since. Among its other feats, in 2003 camera took the deepest photograph of the cosmos ever taken, the Hubble Ultra Deep Field, showing young galaxy fragments only one billion to two billion years after the Big Bang. In the most recent round of proposals from astronomers to use the Hubble, about two-thirds of them required the advance camera.