The Year of the Planets

The U.S. begins a dazzling new era in space exploration

More than three years have passed without an American astronaut in space, and the once vigorous U.S. program of unmanned planetary exploration has been at low ebb since the Viking landings on Mars in 1976. Compared with the ambitious Soviets, whose cosmonauts have just spent almost 140 days orbiting the earth, U.S. space officials have had little to crow about. All that is about to change. Last week the U.S. made a dramatic start on what should be a spectacular twelve months in the annals of space exploration.

In a flawless launch, NASA lofted into earth orbit an $87 million remote-controlled astronomical observatory that should help answer some of the most fundamental questions about the universe. Two days later, some 29 million kilometers (18 million miles) further out in space and closing in on Venus, a U.S. spacecraft ejected the first of four probes that will thoroughly analyze the atmosphere of the cloud-shrouded planet before hitting its scalding surface.

The key instrument on board the cylindrical observatory is a 1,440-kg (3,200-Ib.) X-ray telescope, which is larger and has higher resolving power than any other ever built. From its perch high above the earth's obscuring blanket of air, it will provide new and sharper images of the myriad and puzzling sources of X rays found across the skies--and new insights into such bizarre phenomena as quasars, pulsars and black holes. As Harvard Astrophysicist Jonathan Grindlay put it: "We are at the dawn of a new era in our understanding of the universe." In honor of the man whose relativity theory has already contributed so much toward that understanding, the satellite, called HEAO 2 (for High Energy Astronomy Observatory 2), was last week unofficially renamed the Einstein Observatory.

Following the release of its first probe, the Pioneer Venus 2 spacecraft this week was scheduled to toss off three additional instrument-crammed packages. The four probes, as well as the mother ship, will arrive at Venus on Dec. 9. All five are aimed to descend over different areas of the planet, so that they will gather the widest possible range of data, including temperatures, composition, density and distribution of the atmosphere. They will be passing through hostile territory. At higher altitudes the probes will be whipped by winds with velocities that may be as high as 360 km (220 miles) an hour. They will drop through clouds thought to consist of sulfuric acid droplets. But their real test will come near the planet's surface, where temperatures reach 480DEG C (900DEG F) and the atmospheric pressure is nearly 100 times that of earth's at sea level.

To remain operative under these harsh conditions, the probes are outfitted with, among other things, tough heat-resistant diamond and sapphire windows through which their instruments should be able to peer with impunity. What they detect will provide a trove of important new information about Venus' atmosphere. By learning more about the meteorology of this kindred yet vastly different planet, scientists may gain new insights into terrestrial climate and weather.

Preceding Pioneer 2 will be another Venus-bound vehicle: the unmanned Pioneer Venus 1 spacecraft. Though launched almost three months before Pioneer 2, it has followed a more sweeping trajectory around the sun and will just barely nose out its sister ship, arriving at Venus on Dec. 4. Its assignment is different too; it will ease into orbit around Venus, and in addition to scanning the atmosphere below with an array of instruments, it will beam powerful radar signals through the Venusian clouds and bounce them off the surface. Pioneer 1 will then radio the radar data back to earth, where scientists hope to produce a topographic map of 35% of the hidden Venusian surface showing details 100 meters (330 ft.) high and 16 km (10 miles) across. Earlier radar scans of the surface by the giant radio telescope at Arecibo, Puerto Rico, indicate that Venus is pockmarked with craters, possibly active volcanos and great lava flows.

Still more revelations about other members of the solar system will follow. Between January and July 1979, first Voyager 1 and then Voyager 2, each after traveling more than half a billion miles, will begin closeup photographic surveys of the giant planet Jupiter and its larger moons. The surveys will be made with television cameras that have as much as 40 times better resolution than the devices carried by Pioneers 10 and 11, which flew by Jupiter in 1973 and 1974, and returned color photographs to earth. After approaching as close as 280,000 km (174,000 miles) of Jupiter's upper atmosphere, Voyager 1 will be catapulted by the powerful Jovian gravity toward Saturn, which it will not reach until 1981. Following closely behind, Voyager 2 may be sent even farther afield, to fly by Uranus in 1986 and Neptune in 1989.

The year's planetary grand finale will occur in September, when Pioneer 11 reaches Saturn almost five years after its visit to Jupiter. It will pass just outside Saturn's rings, sending back the first closeup pictures of those flat bands of icy debris. During that close encounter, Pioneer will also train its electronic gaze on the huge Saturnine moon, Titan, which has a diameter of some 5,800 km (3,600 miles) and a significant atmosphere, probably consisting of methane, other gases, and organic molecules like those that may have been the precursors of life on earth.

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