Sophisticated Satellite

The Navy's test satellite, Vanguard I, may be small, but it is high and wondrously sophisticated, and it will probably stay in space many years longer than any of its earlier rivals. Its elliptical orbit varies between 404 miles and 2,466 miles above the earth. When it is ending its climb toward the high point (apogee), the satellite is moving slowest: only 12,000 m.p.h. Then it swoops down to the low point (perigee) and increases its speed to 18,400 m.p.h. It makes a full trip around the ellipse, 34,100 miles, in 134 minutes.

Stable Orbit. Since Vanguard I never dips low enough to tangle with serious air resistance, it should stay in space for a very long time, certainly years. Instead of spiraling down slowly, like the Sputniks and Explorer I, it will stay on an almost stable orbit that will be only slightly disturbed by irregularities of the earth's gravitation.

Vanguard I might seem too small (diameter: 6.4 in.; weight: 3.25 Ibs.) to carry much cargo, but an amazing amount of delicate apparatus was packed into it. Most novel items: its six solar batteries made of subtly treated silicon that look out through windows distributed over the sphere in such a way that at least one of them is always facing the sun. Each battery develops about 25 milliwatts of power when in sunlight, and feeds a miniature transmitter that broadcasts continuously on 108.03 megacycles. Another transmitter, powered by a mercury battery, broadcasts on 108 megacycles.

Besides being useful for tracking the tiny sphere by radio, the transmitters report the temperature inside it. The surface of the sphere is made of shiny aluminum covered with a thin coat of silicon monoxide. This material is transparent to visible light from the sun, which it permits the polished aluminum to reflect back into space. But it looks black to the long infra-red (heat) waves. Since black surfaces radiate well, it permits the satellite to get rid of its internal heat by radiation. The system seems to be working well. Both transmitters have reported that the temperature inside Vanguard I is staying at a reasonable level, certainly below the point where the germanium transistors in the electrical circuits will be damaged.

No Navy electronic experts want to predict officially how long the solar batteries will keep supplying power. One of them guesses unofficially that "our grandchildren may hear its signals." Eventually the windows in the skin of the sphere will be clouded by the sandblasting of micro-meteorites. No one knows how long this will take, or how much it will affect the action of the batteries.

Fellow Travelers. Following the satellite through space is the empty third-stage rocket, which was separated from it by a clockwork device that released a weak spring and pushed the two bodies apart. Dr. John P. Hagen, head of Project Vanguard, says that satellite and rocket are still moving apart slowly. The rocket, which has an irregular shape, will be more strongly affected by such little air resistance as there is even at orbit's perigee and will therefore be the first to drop back into the atmosphere and vaporize. But this will not happen for a long time.

The next Vanguard satellite to be launched, a full-sized 21 1/2-lb. sphere, will carry a much more elaborate cargo. Be sides temperature sensers, it will have an instrument to measure soft X rays from the sun. Other instruments will keep track of micrometeorites by measuring the erosion they cause, the slight noises they make when they hit the satellite, and the holes they make if they puncture parts of the skin. Another instrument, a solar cell, will stare into space, measuring as the satellite turns the amount of light that is falling upon it.

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