Less noticed outside the institute are the unexpected contributions Hubble has made in characterizing other worlds and developing solar systems, places where researchers are eager to look for signs of life.

Hubble has unexpectedly become an astrobiology machine.

Last week, biologists, geologists, chemists, astrophysicists and planet hunters gathered here to swap ideas about where and how to look for extraterrestrial life. Steven Beckwith, director of the STScI, said Hubble is pushing the "astro" of astrobiology. In one example, the telescope recently revealed the first known atmosphere around a planet outside our solar system.

"Hubble was not designed to do this," Beckwith said. "The Hubble Space Telescope was built to do cosmology, not astrobiology."

But the telescope has also emerged as a premier device for exploring nascent solar systems, dusty disks around stars where planets like our own might be in the process of forming. It has found several of these disks, showing them to be ubiquitous, said Mario Livio, head of the Institute Science Division at STScI.

The Keck and Gemini observatories in Hawaii, as well as others, have also begun discovering and examining these dust disks, which have opened a new window into what our own solar system might have looked like at birth.

Despite Hubble's prowess, several astronomers said it will be late in this decade before Earth-sized planets are found, likely by a next-generation telescope called Kepler. The French COROT mission, which would also look for Earth-sized planets, could launch in late 2004.

Yet it will be at least 2010 before a another space observatory, called NGST, explores the atmospheres of extrasolar planets, possibly revealing whether any of them have the right conditions to support life.

But astronomers know that breakthrough discoveries have a history of coming out of the blue.

As one NASA researcher pointed out, few people expected the ground-based Lick Observatory to discover extrasolar planets. It has accomplished this feat since 1995 with a creative method that involves noting how a planet's gravity causes its host star to wobble. Some 85 of these extrasolar planets have since been detected. All, however, are too large to be considered habitable. None have been photographed.

Researchers are eager to come up with creative ways to spot smaller planets and to probe known planets more fully. Hubble, outfitted with a more powerful camera in March, is a tool they were already tinkering with.

As an example, astrobiologists were surprised and elated recently when researchers used Hubble to find sodium in the atmosphere of an extrasolar planet. One researcher not involved in this first detection of an extrasolar planet's atmosphere called it an "important milestone in exoplanetary science."

The chemical was detected as the planet's orbit took it in front of its host star, as seen from Hubble's point of view.

Another planned trick could allow Hubble to leapfrog several long-range plans to accomplish a much sought-after Kodak moment. Johns Hopkins researcher David Golimowski and some colleagues will use Hubble's newly installed Advanced Camera for Survey's in a long-shot attempt to make the first photograph of a planet outside our solar system.

The approach will involve blocking out starlight so the camera can record reflected light from an orbiting Jupiter-sized planet, which would be a billion times fainter.

Researchers will have to come up with something even more creative if Hubble is to directly answer astrobiology's most pressing questions -- whether there are other Earths and whether they have atmospheres that seem conducive to life. Otherwise, those answers will be credited to other telescopes and won't likely come for many years.

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