Science: Journey into Space

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The trouble is, each stage must be enormously larger than the next stage. Rocket men argue endlessly about the details, but the more sensible ones believe that it would take a multi-stage rocket as big as an ocean liner to spit even a jeep-sized space ship free of the earth.

The space men believe that the leap from the earth must be made in two jumps, with a resting and refueling spot partway up the slope of the earth's gravitational whirlpool.

If a rocket is shot straight up at less than escape velocity and makes the proper turn as it clears the atmosphere, it will be sidetracked to an orbit above the earth and will circle around endlessly. The centrifugal force of the rocket's motion around the earth will exactly balance the pull of the earth's gravitation. This same balance of forces keeps the moon on its rails.

Since it takes less energy to reach an orbit than to escape from the earth, astronauts believe that a moderate-sized three-stage rocket, or even a two-stage one, could make the trip with a good payload. It would park its load (e.g., fuel) in the orbit, where it would circle as safely as if it were back at the filling station.

After enough fuel had been accumulated on the little, man-made satellite, a rocket could fill its tanks and blast itself off into space. Since it would already be moving in its earth-circling orbit at a good clip (16,000 m.p.h.), it would need only a moderate additional push to give it escape velocity. Then it could cruise freely in space, like a ship that has risen out of a whirlpool and reached the smooth surface of a lake.

Approach with Caution. Astronauts who plot long journeys in space assume that such dull, preliminary steps have already been taken. Later steps are more fun. To reach the moon from an artificial orbit is elementary stuff; voyages to a planet take more figuring. One plan for a trip to Venus, for instance, uses space ships from an orbit around the earth to establish a base on the moon (see diagram). A special ship then takes off from the moon at a moment when Venus is considerably behind both earth and moon on its shorter and faster orbit around the sun.

Such larger bodies as Mars and Venus, both powerful gravitational whirlpools, should be approached with caution. But Mars and Venus both have atmospheres, which the space men plan to use as frictional buffers. Their ships would circle in the atmospheric fringes until they were moving slowly enough to land. An alternate plan: cruise warily around the planet and send small space-dinghies down to explore its surface.

The Long Voyage Home. How to get back home is the really tough problem. If the space men want to see the earth again, they must climb back out of the gravitational field of the target planet. This would be about as difficult as the painful escape from the earth, and every pound of fuel for the effort would have to be brought from the earth.

The moon would be a poor, dismal place to start a colony. It has no detectable atmosphere, certainly no water. Other planets are not much better. Mercury is fiercely hot on the side that it keeps toward the sun and fiercely cold on its sunless side. Outer planets (Jupiter, Saturn, Uranus, Neptune) are cold worlds with hostile atmospheres of methane and ammonia.