Virtuosity on the Moon

Faithfully obeying its distant masters at Pasadena's Jet Propulsion Laboratory, Surveyor 3 last week continued to show remarkable versatility on the surface of the moon. It shot and transmitted hundreds of pictures, took the moon's temperature, did some scientific stargazing, dug trenches, uncovered a buried rock, and even played around with a bit of lunar soil.

With its facile, steel-tipped aluminum claw, which can be extended to 5 ft., Surveyor dug and photographed more trenches, helping to confirm its earlier finding that the soil at the surface in this area of the Ocean of Storms is dry and granular but has the cohesiveness of wet sand. By measuring the current drawn by the electric motors that operated the claw, JPL scientists determined that the surrounding surface has a bearing strength of 6 lbs. per sq. in., more than enough to support the Apollo astronauts.

400DEG Drop. Looking skyward, Surveyor spotted Venus, photographed it and transmitted the pictures to scientists, who will use them to obtain a precise fix on the spacecraft. Knowing the position of Venus in the sky and the angle of the camera mirror at the time each picture was taken, scientists can determine Surveyor's exact location.

Still looking up, Surveyor later scored another space-age first, shooting 20 spectacular photographs of a solar eclipse that was unlike any ever before seen by man. Instead of being blotted out by the moon--as it is during solar eclipses seen on earth--the sun was temporarily hidden behind the earth. During the two hours that Surveyor was in the shadow cast by the eclipse, lunar midday temperatures plummeted from 250DEGF to -150DEGF.

One of the eclipse photographs showed the earth silhouetted against a crescent of sunlight stretching from the Indian Ocean to the Pacific. From this and other eclipse pictures, astronomers hope to learn more about the characteristics of backlighted terrestrial atmosphere as a guide for studies of the atmospheres of other planets.

Half-Inch Accuracy. Surveyor's virtuoso performance was still to come. Noticing a clod of soil dug out of one of its trenches, the craft closed its claw on the clump, biting off about two cubic inches of soil. Carefully clutching its prize, Surveyor maneuvered it into position and then dropped it on one of its footpads, much like a child dropping a handful of sand on its shoe.

Surveyor had serious reasons for its frisky behavior. Rotating a series of color filters in front of its TV camera, it shot pictures of the soil scattered on its white footpad--which made an ideal photographic background. Scientists will compare the shade of the soil in black and white pictures with a color-coded wheel that is attached to Surveyor's leg and is visible in each picture. From the comparison, they hope to determine the approximate color of the soil. "We placed the soil just where we wanted it," said Caltech Engineer Ronald Scott, who supervised the experiment. "The operation was accurate to within half an inch, working at a range of a quarter of a million miles."

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