Scientists working with the troubled Hubble Space Telescope say the $2 billion instrument has begun to make "bona fide discoveries," even as it awaits repairs to correct mirror flaws discovered soon after its launch 13 months ago.
Among the first discoveries to be announced, at a recent workshop in Baltimore, is the detection of fast-moving comet-like bodies falling into a star only 50 light-years from our own solar system.
This and other discoveries provide "a glimpse of what the telescope can do now, and that's quite a lot," said Riccardo Giacconi, director of the Space Telescope Science Institute in Baltimore.
"People don't realize how much unique science the Hubble Space Telescope is producing, even now," he said.
In the meantime, plans are being developed for a 1993 repair mission to the orbiting telescope.
If it wins final approval, the mission will send space-walking shuttle astronauts to install a corrective mirror to sharpen Hubble's view of the universe, new solar panels to stop their persistent vibration, and a replacement for the telescope's Wide Field/Planetary Camera.
Scientists working with Hubble's Goddard High Resolution Spectrograph have focused on Beta-Pictoris, a star 50 light-years from Earth that has been the subject of intense interest for several years.
In 1983, astronomers using an earlier orbiting telescope discovered that Beta-Pictoris was surrounded by a disk of relatively warm dust. That suggested the possible presence of an orbiting system of planets, or at least some mass of material representing an early stage of planetary evolution. If so, it would be the first ever detected outside our own solar system, and an encouragement in the search for extraterrestrial life.
Using Hubble's far more powerful GHRS instruments, scientists at the Space Telescope Science Institute last February zeroed in on the innermost regions of the dust disk. In the changing spectrographic tracings of its light, they detected indications of comet-like clumps of gas that appear to be spiraling in toward the star.
Albert Boggess, associate director for Hubble at the Goddard Space Flight Center, said the clumps are "streaming in toward the star at a steady, well-defined rate" of perhaps 120 miles per second.
"It's a very complex, dynamic system . . . in some state of very rapid evolution," Boggess said. It is also puzzling to astronomers.
Our own solar system is thought by some scientists to have gone through a stage when a vast disk of gas and dust was gradually cleared away as some fell in toward the sun and the rest was swept up by the gravitation of forming planets.
"But this [Beta-Pictoris] is not a young star," Boggess said. "It is difficult to imagine how [this phenomenon] could last as long as it has, or that it has just begun."
The steady rain of gas down into the star "must be replenished," but it's not clear how. "We have an extra set of mysteries on our hands," Boggess said.
Astronomers hope further observations of Beta-Pictoris will provide more clues to what is going on.