No Satellite in Sight

When the artificial satellite takes to the sky some time next year, it will probably meet no opposition from natural satellites. This is the tentative conclusion of Astronomer Clyde W. Tombaugh, discoverer of Pluto, who has searched nearby space for three years for the Army Office of Ordnance Research. In some ways the news is good news for spacemen. Even a very small satellite would be unpleasant to meet. In other ways, Tombaugh's report is disappointing. A small, nearby satellite of the earth might be handy as a space base. It would certainly be useful as a point of reference for mapping the earth.

Wide & Fast. Most laymen assume that the moon is the earth's only satellite, but astronomers make no such easy assumption. One of the planets, Saturn, is surrounded by millions of small objects that form its decorative rings, and the earth may have at least a few such followers. The solar system is littered with such homeless rubbish as asteroids, meteors and comets, and some of these may have settled into permanent orbits around the steady earth.

No small satellites have been seen, of course, even with the biggest telescope, but this is not surprising. To stay in an orbit near the earth, a satellite must move so fast that it will flash across the narrow field of an ordinary telescope without making any impression on the photographic plate. To have a good chance of catching a satellite, a telescope would have to have a wide field of view, and it would have to sweep across the sky at about the same speed as the satellite that it is hunting.

Working at Lowell Observatory, Flagstaff, Ariz., Dr. Tombaugh used some fancy apparatus: a Schmidt telescopic camera so sensitive that it could photograph a tennis ball, half-lit by the sun, 1,000 miles away, or a V-2 rocket at the distance of the moon. It covered a 13DEG field, 26 times the apparent diameter of the full moon, and a complicated driving mechanism swung it across the sky, fast for nearby satellites, slower for satellites farther away. On its plates the stars showed as streaks. A satellite, if one had been found, would have shown as a dot or a short track.

Flaws & Asteroids. In three years of patient searching, covering most of the space near the earth up to 22,000 miles from the surface, only a few suspicious dots appeared on the star-streaked plates. Most of these proved to be flaws in the plates or small asteroids cruising past the earth. There is still a chance that the remainder may have been satellites too small to take a good picture, but Dr. Tombaugh thinks not.

Last summer the apparatus was dismantled and shipped to Quito, Ecuador, where space above the equator can be searched between the altitudes of 300 and 1,600 miles. This region, which cannot be photographed from Flagstaff, is considered especially favorable. If the earth has small satellites, they will probably be found cruising low over Quito.

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