Apollo 15: A Giant Step for Science

FOR several chilling minutes last week, millions of television viewers wondered if Astronauts Dave Scott, Jim Irwin and Al Worden were going to make it safety back to earth. As the command module Endeavour came into sight high above the fluffy clouds over the Pacific, it became apparent that one of its three big orange-and-white chutes was fouled and thus not supporting its share of the load. Dropping into the calm seas 300 miles north of Hawaii several feet per second faster than planned, the moonship created a mighty splash. But despite the jolting landing the astronauts were safely home. Man's fourth and most productive moon-landing mission had ended successfully.

Few fictional adventures could rival the real-life drama of Apollo 15--or match its superlatives. During their twelve-day mission, the Apollo crewmen roamed the moon for more than 17 hours, almost as long as did the Apollo 11, 12 and 14 astronauts combined. They traveled 17.5 miles in the first car man has ever driven on the moon, took the first walk in deep space, and returned with a record-breaking haul of more than 170 lbs. of lunar rocks. But the really significant accomplishment of Apollo 15 was its scientific payoff, which in the words of Paul Cast, chief of lunar and planetary science at the Manned Spacecraft Center, will enable man to take "a real giant step in the understanding of the solar system."

Perhaps the most important discovery was made early in the week during the second excursion by Astronauts Dave Scott and Jim Irwin. After driving past a group of craters called the South Cluster, they made their way up a 7DEG slope toward the mountainous Apennine Front, and approached an imposing 12,000-ft. peak called Hadley Delta. The astronauts stepped out of the rover and began to select rocks, describing each to the fascinated geologists back in the science support room in Houston. One rock looked like "green cheese"--until Scott raised his gold-tinted visor and saw that it was really gray.

Elusive Fragment. Suddenly, Scott exclaimed: "Guess what we just found!" His prize was a rock made up of large crystals; to scientists his description indicated that it had once been molten and had cooled slowly, probably far below the surface. "The Holy Grail," proclaimed NASA Geochemist Robin Brett, who, like Scott, immediately concluded that the specimen could well be an elusive fragment of the moon's original crust. The crystalline rock, the first large one of its kind found by astronauts, may well give scientists a new slant on the early history of the 4.6 billion-year-old moon. It may also expand man's knowledge of the primordial earth, where wind, water and crustal movements apparently obliterated all rocks older than about 3.4 billion years. The prized rock, Scott reported later in a televised press conference from space, was found on top of a larger brown rock--"sitting there like it was waiting for us."

Next day, the third foray from the lunar lander Falcon provided more scientific treasures. Returning to a core tube that they had driven deep into the lunar surface and had been unable to extract. Scott and Irwin tried again. "Ready," said Scott as they hauled at the tube, "one . . . two . . . three . . . uhhh." After six minutes of struggle, the tube came out. "Nothing like a little P.T. [physical training] to start out the day," said Scott. His exercises were only beginning. Both men struggled for 20 minutes--uttering at least one audible obscenity--before they could separate the sections of the 8-ft.-long core, which had apparently welded together in the vacuum and searing heat of the moon.

Rille's Origin. Besides revealing much about the moon, the core may provide an intriguing record of the activities of the sun. Has it suddenly flared up during the past few billion years? Have its fires ever diminished? By studying the microscopic tracks left by the bombardment of cosmic rays in each layer of the core, and by looking for traces of an element like argon--which is blown from the sun to the moon in the stream of particles known as the solar wind--scientists may eventually get their answers.

After returning to the rover, Astronauts Scott and Irwin drove to Hadley Rille, a long, winding, 1,200-ft.-deep canyon whose origin has long been the subject of scientific debate. While the rover's remote-controlled TV camera followed them with its big-brotherly eye, the astronauts walked slowly down the rille's gently sloping near side. On the almost vertical far wall, they spotted at least two major layers of material. Even more interesting to the scientists in Houston was the astronauts' report that the second major layer contained at least ten subordinate layers.

Lunar Tumble. To Egyptian-born Geologist Farouk El Baz, who helped train the astronauts, the layering meant that the rille was not created by the collapse of a single lava tube, as some lunar scientists have suggested, but by a number of separate lava flows. Not so, said Astronaut Harrison Schmitt, a professional geologist himself and a member of Apollo 15's back-up crew. He insisted that the rille could just as well have been the result of faulting, or cracking, of the moon's surface as it cooled off.

As Scott and Irwin edged farther down into the rille, Nobel Laureate Harold Urey, watching in Houston, nervously warned: "Don't get too close, fellows." Moments later, catching a foot on a rock, Scott took a headlong tumble and fell clumsily forward on his right arm and shoulder. Not until Scott was helped to his feet by Irwin and continued his jaunt did the world breathe easy. "This time," vowed the unhurt Scott, "I'll look and make sure I don't fall over some silly rock."

A little later, Scott was on his knees again, intentionally. Using a hammer, he chipped a large chunk off a big, lava-like boulder sitting on the rille's ledge. Then he tucked the piece under his arm like a football and galloped enthusiastically back to the rover. Scientists in Houston shared Scott's exuberance. He had apparently snared a valuable chunk of the moon's bedrock.

Testing Gravity. Before re-entering Falcon for the final time, Scott unexpectedly demonstrated his scientific --and theatrical--expertise. Holding a hammer in his right hand and a feather from the Air Force Academy's pet falcon Hungry in his left, Scott said, "I guess one of the reasons we got here today was because of a gentleman named Galileo, who a long time ago made a rather significant discovery about falling objects in gravity fields."

Scott was referring to Galileo's assertion that objects in the same field fall at the same rate of acceleration regardless of their weight. Only air resistance, Galileo told the skeptics of his day, caused a lighter object like a feather to descend more slowly. Because there is no lunar atmosphere, Scott had decided the moon would be a perfect stage for a Galilean gravity demonstration. It was. Feather and hammer hit the surface simultaneously, and Scott jubilantly said, "How about that? This proves that Mr. Galileo was correct."

After Scott and Irwin climbed back aboard Falcon, TV watchers on earth were treated to their first view of a lunar launch. Unlike the huge Saturn rocket, which lifts ponderously and, at first, almost imperceptibly from the pad, Falcon suddenly shot up like a jack-in-the-box. Left behind was the lander's lower stage, its gold insulation foil shredding and scattering in the engine's blast. Almost simultaneously, the tape-recorded strains of the Air Force song, Off

We Go into the Wild Blue Yonder, came from Falcon's radio. "Hey," said Scott, "a good smooth ride."

Busy Pilot. High overhead in Endeavour, Al Worden was making good use of his time. During his three lonely days of solo orbiting, he was busier than any previous command module pilot, working through a taxing schedule of scientific experiments. Worden's first important finding was his observation of relatively young volcanically formed cones at the edge of the Sea of Serenity. According to NASA scientists, this is the best evidence yet that the moon may have been volcanically active as recently as a billion years ago. Until now, many scientists thought that the moon's eruptions had ceased much earlier in its history.

The $10 million package of instruments crammed into an equipment bay of Endeavour's service module provided equally spectacular findings. A mass spectrometer detected an eruption of carbon dioxide gas and traces of hydrocarbons on the moon's far side. Such emissions could be a sign of continued volcanism (although scientists cautioned that they might have come from Endeavour itself). Working in conjunction with a laser altimeter, X-ray and gamma-ray spectrometers radioed evidence of the moon's chemical composition. Readings showed greater concentrations of aluminum in the lunar highlands than in the moon's maria. In addition, sensors detected a curious radioactive "hot spot" in the Sea of Storms.

Later, on the homeward voyage, Worden conducted a more esoteric experiment. Pointing his instruments at X-ray sources far out in the galaxy, he recorded the emissions for clues that might be used to confirm the existence of "black holes"--weird, theorized remnants of huge, collapsed stars. He also awed earthlings--including his two daughters--by taking a televised 18-min. walk in deep space some 200,000 miles from earth to retrieve the exposed film cassettes from the service module's cameras.

Brief Concern. Two hours after their liftoff, Scott and Irwin were reunited with their hardworking buddy. After passing the precious cargo of moon rocks into Endeavour and closing the hatch, Scott said wistfully: "The Falcon is back on its roost and going to sleep." In fact, it came to a thunderous end. After a brief flurry of concern because of a possible hatch leak, the astronauts cut loose the lunar module's ascent stage and sent it crashing back to the moon's surface 59 miles west of Hadley Base. Its impact jiggled all three of the nuclear-powered seismometers on the moon, including the new Apollo 15 instrument. Geophysicist Gary Latham of Columbia University was delighted.

The shock waves, he reported, indicated that the moon has a crustlike surface layer at least 15 miles thick.

For the next two days, the reunited crew continued circling the moon--performing more experiments, photographing parts of the lunar surface never before seen by man, and in the case of Scott and Irwin, catching up on some badly needed sleep. On the last day in orbit, activities perked up. The astronauts were awakened by the theme from the film 2001: A Space Odyssey and later launched a 78.5-lb. scientific sub-satellite into orbit around the moon. Almost immediately, earthbound controllers detected radio signals from the $1.7 million instrument package. The satellite's sensors will provide new information about the plasmas and magnetic field in the vicinity of the moon. Ground trackers, recording irregularities in the satellite's orbit, will also be able to map the variations in the moon's gravitational field believed to be caused by "mascons" (for mass concentrations) under some lunar seas. As he caught a glimpse of the gleaming, spinning little moon outside his window, Scott exclaimed: "Tally ho! That's a very pretty satellite out there."

Good Burn. Just before Endeavour disappeared behind the moon on its 74th revolution, ground controllers gave it a "go" for one more important maneuver: firing the command ship's big 20,500-lb.-thrust engine to kick it out of lunar orbit. "Set your sails for home," said Mission Control. "We're predicting good weather, a strong tailwind, and we'll be waiting on the docks." Thirty-five minutes later, as Endeavour re-emerged and regained radio contact, Scott gave the happy word. The 2 min. 21 sec. burn had been flawless. Said Scott: "Endeavour is on the way home."

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