National Geographic : 1959 Feb
The National Geographic Magazine and hurls waves of sound upon us. Steam from thousands of gallons of protective water gushing over the pad's metal flame deflector envelops Pioneer's base. Slowly at first, then rapidly, eagerly, the white shaft rises (page 158). It rides atop a streamer of magnificent fire, almost as long as the rocket. The flame is furious, maddened, raging. A light as from the sun streams over our upturned faces. And the sound! Not booming, muttering thunder, but something more vital. It cycles, pulses, very rapidly. It whiplashes, stabs. With others I find myself shouting, "Go! Go! Go! All the way! All the way!" Now the rocket flees earth with tremendous velocity. Searchlights can no longer track it. We watch the flame, dwindling, curving to the northeast on Pioneer'sprogrammed course. A brief flare-up, a winking of light, and the sec ond stage fires. Then the rocket is gone, indistinguishable among the witnessing stars. Lunar Orbit Requires Critical Speed Various authorities have estimated that the gallant Pioneer I had no better than a one in twenty-five chance, or perhaps one in twenty, of orbiting the moon. The laws of celestial mechanics, as well as the complexity of the rockets, dictated long-shot odds. Complicated movements of moon, earth, and sun in relation to one another all had to be taken into consideration. Astrophysicists computed that the rocket might be fired suc cessfully only during three 18-minute periods falling on successive days each month. Nearly a year ago they set 3:42 a. m., eastern standard time, October 11, as the earliest pos sible moment for launching Pioneer I. It lifted off only nine seconds late, no small feat in itself. Ideally, a moon rocket should be launched to the east from a point at or near the Equator. Such a site imparts to the rocket the maximum benefit of earth's 1.000-mile an-hour rotational speed. Also, a shot from the Equator offers the best parabolic trajec tory to the moon. The favorable factors diminish slightly with each degree of latitude - and Cape Canaveral lies at 280 north. Missilemen also faced a spiny problem in boosting the probe to a certain critical veloc ity. Escape velocity, the speed necessary to send an object forever from earth's gravita tional clutch, is approximately 25,000 miles an hour. Contrary to published reports, the Air Force did not seek, or want, such speed. Earth and moon share a common center of gravity, deep beneath our planet's crust. Escape velocity would shoot a payload past the moon, as well as away from earth, or possibly into the lunar surface like a meteorite. So the Air Force sought a velocity just above 24,000 miles an hour. Given this initial speed, the probe would coast to a point about 175,000 miles from earth, where lunar gravity gradually gains ascendancy over our own. Its pace now reduced to a relative crawl, the instrumented package would be captured by this secondary gravitational field, and would fall toward the moon, again accelerating. Atop its payload the Air Force placed a small retro-, or braking, rocket (opposite). A radio command signal from earth, it was hoped, would fire the rocket and tilt the pack age into orbit around the moon. Earth-to moon distance, about 223,000 miles for Pio neer I's interception attempt, would require a journey lasting 2'2 days (chart, page 166). I stood near the moon rocket gantry one morning, reviewing with an engineer the in exorable laws nature imposes upon lunar probes. A workman, lounging near by while nibbling a doughnut, grinned broadly and broke into the conversation. Pioneer I Not Quite Brainy Enough "That's not the worst of it. What happens if you don't have a brainy bird?" In Cape Canaveral parlance, a "brainy bird" is a rocket that performs well. Pioneer I was brainy, but its I. Q. was not quite high enough. It started the journey at slightly too high an angle, and later stages com pounded the error. Thor's normal guidance system would have sensed and corrected the minor deviation, but it had been removed because of weight con siderations. In its place rode a less sophisti cated system. Since Thor, an intermediate range ballistic missile, is a military weapon, much detail about it remains behind the curtain of secu rity. But I saw demonstrated some unclassi fied principles of its guidance on my first visit to Pioneer I, two days before lift-off. J. E. Harrison, night manager of the proj ect for Douglas Aircraft Company, led me atop a metal collar encircling the 100,000 pound first stage just above its stabilizing fins. Below me, extending from the missile's tail, I could see a ponderous rocket nozzle.