Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, March 5, 1995 TAG: 9503080046
SECTION: NATIONAL/INTERNATIONAL PAGE: A12 EDITION: METRO
SOURCE: KNIGHT-RIDDER NEWSPAPERS
DATELINE: WASHINGTON LENGTH: Long
A government-financed search for distant planets that could support life outside the solar system is making remarkable progress, astronomers report.
If such an Earthlike body is found, it could help to answer a question that scientists, philosophers and religious leaders have wrestled with since the dawn of civilization: Are we alone in the universe?
Since 1991, four new planets - three certain and one not yet officially announced - have been detected, bringing the total known in the universe to 13. The new planets are orbiting in the constellation Virgo, about 8,000 trillion miles from Earth, a short hop by astronomical standards.
Unfortunately for those hoping to find inhabited worlds, the object at the center of this planetary system is a neutron star, the burned-out hulk of a violent stellar explosion a billion years ago.
Only 12 miles across but heavier than the Sun, the dead star is so intensely radioactive that life would be impossible on the planets in its orbit.
``You'd need a lead umbrella to go the beach,'' said Alexander Wolczszan, the Pennsylvania State University astronomer who reported the first two planets in January 1992 and has since discovered the other two.
But the National Aeronautics and Space Administration is also looking for planets in more hospitable neighborhoods. The search is part of an accelerating effort - made possible by new astronomical tools - to explore the remotest corners of the universe.
``It's a very exciting time,'' Robert A. Brown of the Space Telescope Science Institute in Baltimore, a NASA contractor, said last week. ``We're finally on the verge of being able to detect planets around normal stars.''
NASA is holding a series of planning conferences this spring to lay out a ``road map'' for the planet hunt, deciding which of the hundreds of nearby stars to search first and what tools to use.
The searchers' home base, starting in 1996, will be the twin 33-foot-wide Keck telescopes - the world's largest - on top of the 13,600-foot Mauna Kea volcano in Hawaii. One of every six minutes of observing time will be dedicated to the planetary project, according to Ed Barker, the project director in Washington.
Astronomical skills are growing so rapidly that NASA Administrator Dan Goldin predicts that, 10 to 20 years from now, observers will be able to detect objects as small as 100 miles across - such as clouds, oceans or continents - at a distance of 200 trillion miles. There are 310 stars within that range.
Already, disk-shaped clouds of dust and gas have been observed around a number of young stars. Anneila Sargent, an astronomer at the California Institute of Technology who discovered one of these disks, said they probably are the breeding ground for future planets.
Within five years, astronomers hope to pass a milestone by spotting ``brown dwarfs'' - mysterious objects halfway between a small star and a big planet.
``The race is on to find the first brown dwarf,'' said Todd Henry, another planet hunter at the Space Telescope Science Institute. ``We haven't found any yet, but we're getting close.''
The next target would be to find a planet the size of Jupiter, the largest in this solar system. Such a body would be too big and heavy to permit life, astronomers say, but would be a signpost pointing to a planetary system that could be explored by more precise observations.
Finally, if an Earth-sized planet is located, the ultimate goal would be in sight - discovering life outside the solar system.
``It would really change the way we think about ourselves if we find another planet like Earth,'' Goldin said.
Chris McKay, an astronomer at NASA's Ames Research Center, said, ``I'm confident we will find other planets. But will we find life? And what will it look like?''
Even with the best instruments, humans won't be able to pick out individual life forms on distant planets. Instead, scientists will look for signs of water, which they have come to believe is the key to life as we know it. The water must be in liquid form - not a vapor as on torrid Venus, not frozen solid as on frigid Mars.
``Searching for life on other planets means searching for liquid water,'' said McKay. ``Venus is too hot; Mars is too cold; Earth is just right,'' he said.
The set of planets Wolczszan discovered in Virgo bear an intriguing similarity to our solar system. If they were rotating around the Sun, the first three planets would lie in the orbits of Mercury, Venus and Earth, he said. The fourth one, if confirmed, would fall in Jupiter's slot.
Now Wolczszan and colleagues are surveying 700 other neutron stars in hopes of finding additional planetary systems. He said he expects new sightings to be reported soon.
Barker estimated that NASA's search for planets around ordinary stars will cost about $10 million a year for at least 15 years. That's petty cash for the space agency, with its $14 billion budget, but Barker worries whether Congress in its present mood is willing to undertake a long-term commitment: ``I'm afraid Congress is looking for short-term successes,'' he said.
Goldin believes the search for life on other planets is a grand enough goal to stir the public imagination and win support for the space program the way the Apollo mission to the Moon did a generation ago.
``If we can say we have another Earth sitting out there, it would have a most significant impact on mankind,'' said Wolczszan. ``A search for our place in the universe seems to be encoded in our genes.''
by CNB