Steady Acceleration

The countdown was perfect. Up from the launch pad of Cape Canaveral at 10:23 one morning last week roared a 90-ft., 52 1/2-ton Thor-Able rocket, lifting cleanly into an overcast sky with steadily increasing acceleration. Two minutes and 40 seconds later the second stage fired smoothly, then the third. Out from the sides of the globular pay load unfolded four strange paddles. As the "paddlewheel satellite" tumbled through space at 171 revolutions per minute, 8,000 solar cells in the 20-inch-square vanes picked up the sun's energy to charge the chemical batteries, send messages back to the earthlings. Seventeen minutes after launching, its first radio signals beeped to the tracking station in Manchester. England. By 1 o'clock Cape Canaveral passed the message to the world: the U.S. had orbited the most advanced satellite in the young era of space.

Explorer VI windmilled into orbit just 18 months after the U.S. had orbited Explorer I, its first space satellite, in belated reply to the Soviets' Sputnik challenge. The difference between the two marked the steady acceleration of the U.S. space program. Explorer I, still riding in space, is a 30.8-lb. cylinder that reaches an apogee of 1,600 miles. Explorer VI, weighing 142 Ibs., is more complex and reaches higher than anything ever orbited around the earth--26,400 miles, with ellipses to a low perigee of 157 miles. Its aluminum skin encases scores of miniaturized scientific instruments that are already reporting facts on space (see SCIENCE) never before revealed to men.

Equally important is the data that Explorer VI will send back about its own solar-powered performance. If it continues to be successful, solar energy will be used to drive future U.S. satellite instruments and to operate orbiting TV scanners that will transmit unclouded images of the solar system. Last week, with a wink at Christopher Columbus and George Eastman, Explorer VI televised back a crude image of smudges and blurs--the first picture of the earth ever shot from so far out in space.

This week U.S. spacemen were, soberly predicting that, with winged Explorer VI opening the door to the second generation of satellites, a shoot at Mars and Venus cannot be too far away.

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