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In orbit since Jan. 25, the satellite became operational last week when, on command from the British tracking station, the telescope's cover was successfully exploded away. Two quick test scans produced such a flood of data that cheering broke out in the Chilton control room. Said Caltech's Gerry Neugebauer, IRAS' co-chief scientist: "Everything is going even better than we thought it would."
This week IRAS begins the first formal infrared survey of the entire sky, which should become an important guide for future observations. Before it exhausts its helium supply, the telescope is expected to spot as many as a million heavenly objects. IRAS will observe young cool stars now hidden behind veils of tiny dust particles that block ordinary light. It will also study old stars near the end of their lives. Such observations could help clarify the mysteries of stellar birth and death. Closer to home, it may spot the long-sought Planet X, which some astronomers suspect is lurking beyond Pluto.
The orbiting eye should also help establish the true size of our Milky Way Galaxy and discover distant galaxies and quasars. By identifying unknown sources of energy and adding data on the universe's mass, IRAS may help settle the grandest question of all: whether the universe will expand indefinitely or collapse upon itself under the remorseless tug of its own gravity.
Even while it took pride in the performance of the infrared telescope, NASA last week was confronted by new difficulties with the troubled space shuttle Challenger. Standing forlornly on its Florida pad since Nov. 30, the gleaming $1 billion orbiter will probably not be launched before mid-March at the earliest, two months late. Reason: a hazardous hydrogen leak required the removal last week of one of Challenger's three main rocket engines, a task never before attempted while a shuttle was still on the pad.
Using special sensors that can "sniff" the chemical signature of a gas, technicians traced the leak to a ¾-in.-long crack in the hot-gas manifold, where hydrogen and oxygen are gathered under high pressure (4,400 Ibs. per sq. in.) before combustion. Undiscovered, the leak might have caused an explosion. This week technicians hope to install a new engine, trucked from the National Space Technology Laboratories in Bay St. Louis, Miss.
NASA last week decided to forgo a test firing of the new $30 million engine. Two other test firings, at $1.5 million each, have already taken place. But the space agency still must weigh new quality-control procedures. The crack that ultimately caused the leak was discovered during the engine's manufacture at Rockwell International's Rocketdyne plant in Canoga Park, Calif. The crack was welded, but it was not considered necessary to take the additional step of hardening the weld (cost: about $200,000). Now the space agency faces extra bills totaling about $4 million, to say nothing of irritated customers waiting impatiently on the sidelines for Challenger's liftoff.
—By Frederic Golden. Reported by Bob Buderi/San Francisco and Jerry Hannifin/Washington