Plumber's Satellite

The U.S. satellite will not be launched in its orbit for a considerable time to come (no one wants to say just when), but that is no reason why the teams that are training to track it should stare at an empty sky. An airplane flying at moderate speed at a moderate altitude can pretend, for research purposes, to be a satellite swinging around its orbit at 18,000 m.p.h. 300 miles up.

Minitrack. Last week at Blossom Point, Md., about 40 miles south of Washington, the Naval Research Laboratory showed how the satellite's feeble radio signals will be picked up. Nine enormous antennas scattered over a 25-acre field waited for whispers of energy from the sky. The satellite's role was played by a Navy airplane flying at 15,000 ft. and carrying the 13-oz. Minitrack radio transmitter that the real satellite will carry, its power suitably reduced to make up for the difference in altitude.

The signal came in strong, was amplified by a trailerful of electronic apparatus (made for the purpose by Bendix Aviation Corp.), and recorded on a chart. When the first real satellite takes to space, ten Minitrack receiving stations will be ready in the U.S., Cuba, Antigua, Ecuador, Peru, Chile and Australia. Their information about the satellite's motion will be flashed electronically to Washington, where past orbits will be charted and future orbits predicted by computer.

The satellite will not be tracked by radio alone. Optical observations are needed to chart the orbit accurately, and the satellite moves so fast that the big, slow-moving telescopes of professional astronomers have little chance of holding it for long. So teams of amateur astronomers, organized into "Operation Moonwatch," will spot the satellite with widefield, low-power, low-cost telescopes.

Dim Star. Two Moonwatch teams near Washington have already had live practice. At Springfield, Va. 20 observers arranged themselves after dark under an odd-looking "T" of iron pipe with dim lights glowing at the ends of its horizontal member. The T showed the meridian, and the observers trained their telescopes so that their overlapping fields covered a north-and-south slice of sky through which the satellite should pass.

In this case the satellite was a Civil Air Patrol airplane, towing at the end of 100 ft. of clothesline a rubber plumber's helper fitted with two flashlight batteries and a one-tenth candlepower bulb. The airplane flew 110 m.p.h. at 7,000 ft, which simulated the motion of the satellite in its orbit. The dim bulb gave enough light to look like the satellite at dawn or dusk, when it is in sunlight and the earth below is in darkness.

When the airplane passed over for the first time, dark clouds above it made the light faintly visible to the naked eye. When the clouds cleared away, the light could not be seen against the starry sky except with the low-powered telescopes. They picked it up easily, like a sixth-magnitude star.

The plumber's-helper satellite (cost: $2.50) was so successful that 100 of them are being assembled by the Air Force and Navy for use by Moonwatch teams across the country. Like the elaborate Minitrack stations, the teams will prepare for the day when the satellite is wheeling through space and any shred of news about it will be important.

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