Spectacular Shots in the Dark

By Frederic Golden

Some out-of-this-world surprises from an infrared satellite

For ten months, the 2,249-lb. satellite has been tirelessly circling the earth, speeding from pole to pole once every 103 minutes at an altitude of 563 miles. Unlike most satellites, it has kept its eyes not on the earth below but on the vast expanses of the universe. During each orbit it surveys a different slice of the sky, obtaining a nearly complete picture of the heavens. Last week, at a jubilant press conference in Washington, D.C., the multinational team of scientists and engineers responsible for the orbital telescope known as IRAS (for Infrared Astronomical Satellite) reported that they had succeeded beyond all expectations. As proof, they released some spectacular images, including a picture of the center of the Milky Way.

What makes the views from IRAS so unusual is that they provide the first look at a hitherto invisible world. Before IRAS, telescopes placed aboard spacecraft gathered either conventional "visible" light, in the range of the human eye, or higher-frequency ultraviolet radiation, X rays and gamma rays. IRAS, by contrast, operates at the other end of the electromagnetic spectrum: it "sees" in the dark by detecting the long waves of infrared radiation, or heat. Since water vapor in the earth's atmosphere soaks up most infrared radiation from space, such observations until now could only be made in a limited way from aircraft, balloons or extremely high-altitude observatories.

Launched from Vandenberg Air Force Base in California last January, the $250 million observatory, which was built jointly by the U.S. and The Netherlands, has completed four separate surveys of virtually the entire sky. During these sweeps, IRAS'S 22.4-in. mirror and electronic sensors, which are chilled by liquid helium to nearly 4DEG above absolute zero (-459.7DEG F) so that their own heat will not impede observations, picked up infrared emissions from more than 200,000 sources. Most of these celestial pinpoints are much too cool to have been recorded by conventional telescopes. Many are extremely dim young stars, just beginning to be stoked by their nuclear fires. Others are distant galaxies, perhaps millions or even billions of light-years away.

Nearer to earth, IRAS identified at least five new comets and spotted a "miniplanet" only 1.2 miles in diameter, possibly the cadaver of a comet, circling within the orbit of the innermost planet, Mercury. IRAS also uncovered some bands of fine dust spread over 100 million miles in the asteroid belt between the orbits of Mars and Jupiter. The dust may be the debris of collisions between asteroids.

As ground-based computers reconstructed artificially tinted images from the flood of data radioed by IRAS to a British receiving station, the discoveries that most astonished astronomers came from beyond our solar system. IRAS'S scientists had previously reported finding a shell of material around the bright star Vega. They thought it might be a sign of a solar system in the making, as well as the first tangible evidence that other stars may have planets. Last week the researchers reported that IRAS had identified as many as 50 stars with possible planetary systems. One especially curious husk of material was found in the constellation Orion around Betelgeuse, a red supergiant star that is 730 times as large as the sun. Normally such ancient stars, agitated by violent death spasms, throw off a cover of gases. But since this shell only half-circles the star, the debris may have been swept up by Betelgeuse as it traveled through a cloud of interstellar dust and gases.

Indeed, one of the most surprising conclusions from the IRAS scan is just how dirty the universe is. Long, wispy "cirrus" clouds of dust, as the astronomers called them, were found swirling throughout interstellar space. Since such debris is the breeding ground of new stars, the discovery suggests that the rate of star formation may be much greater than astronomers had supposed, perhaps as high as one a year in our own 10 billion-year-old Milky Way galaxy. This also suggests that the birth of stars like the sun, along with the life-supporting planets that may surround them, could well be a commonplace galactic event. --By Frederic Golden. Reported by Jerry Hannifin/Washington

With reporting by Jerry Hannifin/Washington This file is automatically generated by a robot program, so viewer discretion is required.