Science: The Moon’s Far Side

Just before midnight, Soviet TV viewers sat up and paid rapt attention. On the screen flashed the first pictures men had ever seen of the moon’s hidden face. The Soviet’s Lunik III had performed just as Russian space scientists predicted, in a display of engineering virtuosity that was the greatest achievement yet in man’s exploration of space.

Next day the Russians released a picture of Lunik III and a fairly detailed explanation of how it took its epoch-making pictures. Lunik III, a notably sophisticated mechanism, proved to be a top-shaped 614-lb. object incrusted with antennas and solar cells, and packed with instruments. As Lunik passed 4,000 miles below the moon’s south side, the moon’s gravitation tugged at it, pulling it upward (south to north) and behind the moon. This was as planned, the Russians said, so that when Lunik III returned to earth it would come closest to the Northern Hemisphere, where radio stations on Soviet territory could communicate with it to best advantage.

Lunik’s course and timing were chosen, the Russians said, so that on the far side it would come close to a line drawn between the moon and the sun. As it approached the line, an electronic signal from the earth started its automatic machinery—and all sorts of things began to happen. Lunik was spinning (for directional stability) with one of its ends pointing roughly toward the sun; the first thing the orienting mechanism did was to stop the spinning, probably by ejecting small spurts of gas through nozzles. Then optical viewing devices looking through ports in the sunward end told the mechanism to point that end directly at the sun. This oriented Lunik’s other end to point roughly toward the moon. Then the first optical device shut off, and a second device took over, centered Lunik’s axis exactly on the moon’s disk and kept it there. A cover opened, exposing the lenses of two cameras, one of them magnifying the moon 2½ times as much as the other.

Automatic Developer. On signal from the earth, both cameras began taking pictures on 35-mm. film that had been carefully protected from the fogging effect of cosmic rays. Exposures were automatically varied from frame to frame to make sure of some negatives with good contrast. As soon as the film was shot, it passed into a developing and fixing device that was specially designed to function properly under conditions of weightlessness. After being dried, the film went into a case to wait for transmission to earth. Some of this operation was automatic, but marks on the moving film, the Russians said, caused radio signals to be sent to the earth and enabled Soviet scientists more than a quarter of a million miles away to control the picture-snapping and photo-finishing process on the far side of the moon.

After all its film was exposed, an automatic mechanism set Lunik to spinning again, so that sunlight during its journey would not scorch one side while the other side froze and upset the delicate mechanism inside. Then, having gone around the moon, Lunik swung back toward the earth, began to transmit the pictures. A slow system was used when Lunik was still at a great distance from the earth, a faster system when it came nearer and its signals were easier to receive. The transmission was done by a sort of TV camera that scanned the pictures electronically, line by line, and translated their varying shades of brightness into varying radio signals. The number of lines could be changed to give different degrees of definition. The maximum was 1,000 lines a picture, which yields a definition about twice as fine as the normal TV picture.

Sea of Dreams. The moon pictures released so far look fuzzy, but experts consider them extraordinarily good, considering the fantastic difficulty of getting them at all. To laymen, the moon’s far side, long populated by storytellers with strange beasts and weird civilizations, looks disappointingly like its visible side. But astronomers find it surprisingly different. They point to the comparative lack of the big, roundish, dark “seas” that are so common on its known face. The area newly pictured shows only one really big sea, which the Russians named the Sea of Dreams. A smaller sea they named the Sea of Moscow, and to several craters they gave the names of Communist or Russian scientist heroes. (Discoverers of lunar features have long been privileged to name them as they please, and it seems likely that nearly every major feature on the moon’s far side will have a Russian name.)

Most of the moon’s hidden face is covered with what appears to be mountains, which always look brighter than seas. The Russians named one conspicuous series the Soviet Range; the rest of the area is probably, a Jacqwork of circular meteor craters. The published pictures were taken at almost “full moon” from Lunik’s point of view, i.e., with the sun directly “overhead.” At such a time, even steep slopes near the center of the moon’s disk cast no shadows and are therefore hard to photograph. Other pictures may show many more craters, cracks, valleys and other features.

Holes & Meteors. The apparent scarcity of seas on the far side of the moon will keep moon experts theorizing for many years. The seas are really flat, low plains filled with dust or lava. They must have been formed rather late in the moon’s history, because few meteor craters pit their surfaces. Astronomer Gerard Kuiper of the University of Chicago thinks that the seas were made by the impact of asteroids up to 90 miles in diameter, which blasted great holes in the crust at a time when the moon’s interior was hot and plastic. Dark lava welled up in the holes, and is visible there today. Kuiper thinks that the shock of the last big asteroid, which dug the sea called Mare Imbrium (Sea of Rains), may have caused pressures inside the moon that made lava flow out in other places, forming other seas. The lack of seas on the far side of the moon, says Kuiper, favors this theory, since the meteor impact that dug Mare Imbrium would affect the far side less strongly.

Soviet Astronomer Mikhailov, interviewed at Pulkovo Observatory, Leningrad, warned against rushing to conclusions. Several circumstances, he said, might explain the differences between the near and far sides of the moon. The near side, for instance, gets more gravitational pull from the earth. This presumably might make it bulge (and wrinkle) more than the more distant side. Or perhaps the moon is asymmetrical for the same unknown reason that the earth is, whose high land areas are mostly bunched in one hemisphere.

More to Come. Lunik III took and transmitted “dozens” of photographs, Mikhailov revealed. The streaks on the published pictures were caused by electronic troubles during transmission, and perhaps they can be eliminated by superimposing many photographs. This job will take about six months, he estimated. Lunik III will take no more pictures on its future swings around the moon; its film has all been exposed. But perhaps, he said, it can be retriggered to transmit the same pictures again under more favorable electronic conditions. The next step in lunar exploration, said Mikhailov, would be to land a station on the moon without damaging the instruments.

Riding the crest of Russian success, Alexander Nesmeyanov (TIME cover, June 2. 1958), president of the Soviet Academy of Sciences, allowed himself a boastful projection into the future. Said he: “The penetration of outer space will not stop. Flights of men through space, flights of rockets to Mars and Venus lie ahead. Next will come the study of these planets, their conquest and population.” .