WHAT might well be called the most expensive prescription lenses in history appear to be working just fine, thanks.
Following December's space shuttle repair mission, the Hubble Telescope has been restored to the orbital equivalent of 20/20 vision, jubilant National Aeronautics and Space Administration (NASA) officials said last week.
A $50 million package of corrective optics, plus a new wide-field planetary camera, are now allowing Hubble to take sharp pictures of distant stellar light despite flaws ground into its main mirror.
``We believe the Hubble is fixed,'' said NASA administrator Daniel Goldin at a briefing last Thursday on the new pictures.
The five-spacewalk optometry upgrade will increase the telescope's range and ability to pick out individual objects from masses of space matter.
NASA scientists said they can now plan to proceed with important 21st-century science projects, such as the search for black holes and continued study of the universe's rate of expansion.
Black-hole research will entail study of single stars near the center of whirling galaxies. By tracking the behavior of these stars, scientists hope to be able to see whether they are near areas of collapsed matter with strong gravitational pull - dubbed ``black holes'' since not even light can escape their grasp.
A fully functioning Hubble would be a boost for NASA after a string of embarrassing problems.
Last August, for example, NASA lost track of the $980 million Mars Observer just three days before it was due to swing into its Mars orbit. A team of investigators determined this month that the most likely explanation for Observer's silence is a rupture in its pressurization system that has caused the spacecraft to spin helplessly out of control.
The Hubble itself has suffered a series of mishaps. Besides optics, the space-repair mission fixed Hubble solar panels and installed new computer backup capabilities.