A Man and His Planets

More than half a billion miles from earth this week, a small (570 Ibs.), unmanned spacecraft is completing the first lap of an incredible journey. As it hurtles past Jupiter at a speed of 107,000 m.p.h., some 50 times faster than a rifle bullet, Pioneer 11 is slated to use its cameras and instruments to reconnoiter the solar system's largest planet. That will be only part of its task. As it passes 26,000 miles above Jupiter's turbulent cloudtops, the spacecraft will be pulled by the planet's gravitational field into a corkscrew-shaped turn and whipped out on a new trajectory. Its next target, after a five-year trip across a vast expanse of space: the ringed planet Saturn, never before explored by a ship from earth.

By skirting Jupiter so closely, Pioneer 11 will plunge deeper into the planet's intense radiation belts than did Pioneer 10, which passed 81,000 miles from the cloudtops last December. As a result, Pioneer 11 will be subjected to radiation perhaps ten times as powerful as that encountered by its predecessor, which escaped with only minor damage to its instruments. If Pioneer 11's electronic gear survives, it should produce a bonanza of data: 22 closeup color pictures of Jupiter, including the first of its polar regions; new studies of the planet's temperature, radiation levels and magnetic field; and the first measurements of Amalthea, smallest and innermost of Jupiter's 13 known moons.* Space Pioneer. No one is watching Pioneer 11's travels with more interest than another pioneer, Physicist James Van Allen, who scored the first triumph of American space science by discovering the radiation belts around the earth that now bear his name (TIME cover, May 4, 1959). Even before Pioneer 11 was launched nearly two years ago, Van Allen was urging that the planned flyby of Jupiter should be changed into a two-for-one mission that would include Saturn. NASA had just scuttled its even more ambitious "grand tours," which would have taken advantage of the alignment of the outer planets in the late 1970s to send, for example, a single spacecraft past Jupiter, Uranus and Neptune, using the gravity of one planet to fling the ship toward the next. But Van Allen stubbornly refused to give up. At his suggestion, imaginative "back-room" trajectory experts at Pasadena's Jet Propulsion Laboratory showed that a corkscrew turn could get Pioneer to Saturn at no extra cost.

For the genial, contemplative Van Allen, ingenuity in planning space missions is nothing new. It was the University of Iowa scientist who had the foresight to prepare the tiny, 5 1/2-in.-wide Geiger counter and transmitter that rode the first successful U.S. satellite, Explorer 1, into space in 1958 and provided the initial clues that the earth is surrounded by belts of charged particles trapped in its magnetic field.

Jigsaw Puzzle. Since that momentous discovery, Van Allen, now 60, has quietly continued his contributions to the exploration of space, designing instruments for 20 spacecraft, including a particle counter for the current Pioneer.

Now he is trying to win approval of a two-planet flight that would be launched in 1979 to send a single spacecraft past Jupiter and Uranus. He is also trying to whip up enthusiasm for a ship that would go into orbit around Jupiter, monitoring the planet up to three years.

Van Allen does not dismiss the value of less expensive, earth-based observations. But he feels that terrestrial telescopes are not enough. Says he: "If you really want to bore in, find out what a planet is like, if it has a magnetic field and radiation belts, what its makeup is, its shape and mass--all these things, you've got to get near." Consequently, his most driving ambition has been to look at each planet close up--"whether I'm part of the mission or not."

Behind it all, says Van Allen, is his desire to gain a "fundamental understanding about how nature operates, to assemble the great jigsaw puzzle in the sky." He laughs at his metaphor, then adds more seriously: "I want to find out how the solar system originated, how it works, what its future is. I'm not claiming it will do anybody any good. It's a matter of intellectual endeavor."

The 13th moon was recently discovered by Caltech Astronomer Charles Kowal.

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