Peering into the night skies, astronomers find their view obscured by the ever-present veil of the earth's atmosphere. Swirling air currents blur the images of stars and planets. Scattered light and auroras in the atmosphere blot out faint stars. The thick blanket of air soaks up ultraviolet light and other radiation given off by distant stars, thus depriving scientists of valuable clues about the nature of the universe around them. Last week U.S. astronomers dramatically thrust their telescopes through the atmospheric veil and began to see the sky in a new light.
On Target. The fresh view of the universe was made possible by the successful launching of the Orbiting Astronomical Observatory, which began probing the heavens with eleven telescopes while circling the earth in a 480-mile-high orbit—well above the confining atmosphere. Unfolding its solar panels, the OAO obediently performed operations that assured ground controllers that it was in good working order. Then the 4,400-lb. spacecraft turned to its first assignment. Rolling slowly in space, it sought out two reference stars and unerringly swung its telescopes toward a bright Southern Hemisphere star named Miaplacidus.
Locked onto its target by a combination of control jets and spinning inertia wheels, OAO for several hours examined the ultraviolet emissions, telemetering its findings back to earth.
By the time that it turned to its next target, a super giant star named Iota Carina, the orbiting observatory had already transmitted a record amount of ul traviolet data. In the previous 15 years, scientists had accumulated only three hours of ultraviolet stargazing during the flights of 40 telescope-equipped sounding rockets, which briefly poke their noses above the atmosphere before falling back to earth.
In the next six months, OAO is scheduled to study more than 50,000 stars, most of them of the hot, young variety that emit 95% of their energy in heretofore unobservable ultraviolet light. From the ultraviolet TV pictures and data that the satellite transmits, scientists hope to learn more about the chemical composition of the stars, their temperatures, their rate of burning and their total energy emission. These characteristics in turn should help them understand how stars are born out of cosmic dust and gas, how heavy elements are formed in stars and how the universe itself evolved.
OAO's stellar performance should ensure continuation of the $321 million OAO program, which in the next three years is scheduled to launch three more observatories. Since April 1966, when a $69 million OAO went dead in orbit be fore it could return any useful information, NASA scientists have been aware that another failure might well spur Congress into cutting off the program's remaining funds.
NASA will apparently get its money's worth from the current $75 million observatory, which was planned to operate for at least six months. The craft is performing so perfectly, says OAO Project Scientist James Kupperian Jr., that "it now appears that all we have to worry about is the observatory's simply wearing out. It could last for two, three, four or even five years."