Three weeks after astronauts installed new optics and made other repairs, the Hubble Space Telescope has passed all its initial performance tests and is now ready to begin taking pictures to see if its vision has been corrected to match preflight expectations.
Results might be available in less than a month, project astronomers said.
They said yesterday in a briefing that the methodical testing so far had revealed no problems with the orbiting telescope's new components and no sign of any contamination introduced from the exhausts of the space shuttle Endeavour during the repairs.
They said the checkout was running ahead of schedule, and the first pictures that could demonstrate the telescope's improved vision might come in a few weeks.
"I am completely delighted with the way things have gone so far," said Dr. David S. Leckrone, senior project scientist at the Goddard Space Flight Center in Greenbelt, Md., where flight engineers are conducting the telescope tests.
"I will not declare victory until we have victory in hand. But I will say, people are very pleased with what they have seen."
Dr. Leckrone and other project officials described the test results in a teleconference from Goddard.
In their 11-day mission, the shuttle astronauts installed a replacement for the wide field-planetary camera, equipped with tiny mirrors ground to compensate for a focusing flaw in the telescope's primary mirror. The camera is used in at least half of all observations.
They also inserted a set of corrective mirrors to improve the focus on light reaching three other critical instruments: the faint object camera, the faint object spectrograph and the high-resolution spectrograph.
This mechanism, called the Corrective Optics Space Telescope Axial Replacement, or Costar, underwent its first critical test last weekend.
The mechanical arms holding the tiny mirrors were moved from their stowed positions and placed where the mirrors could intercept light from the primary mirror and properly focus it prior to entering the faint object camera and spectrograph. The arm holding corrective mirrors for the high-resolution spectrograph will be moved later.
"It was a fully successful deployment," Dr. Leckrone said.
Over the next two weeks, ground controllers plan to point the telescope to take test pictures with both the wide field and the faint object cameras.
The targets will include Orion Nebula, a region of dense clouds of gas; two distant but highly luminous objects known as quasars; M-100 spiral galaxyl; and a star that is surrounded by material it has ejected.
Dr. Edward J. Weiler, the chief Hubble scientist, said the corrective optics should increase the telescope's sensitivity, range and ability to detect single objects in a crowded field of stars and gases. The targets for the tests, he said, were chosen "to illustrate these science capabilities very clearly."
Dr. Weiler said that engineers were confident that the new, more stable solar-power wings attached by the astronauts had substantially reduced the jittery motions that used to beset the Hubble telescope.
Any remaining jitters, he said, could easily be steadied by computer-driven maneuvers to keep the Hubble virtually motionless during astronomical observations.