the moon, ending either in a “hard” landing or a circling of the moon. Next in difficulty would be a “soft” landing. And most difficult of all would be a “soft” landing followed by a safe return to earth.
The payload for a simple moon shot might be a small instrument carrier similar to a satellite. For the more difficult “soft” landing, the carrier would have to include, as part of its payload, a “retro-rocket” (a decelerating rocket) to provide braking action, since the moon has no atmosphere that could serve as a cushion.
To carry out tho most difficult feat, a round trip to the moon, will require that the initial payload include not only “retro-rockets” but rockets to take off again from the moon. Equipment will also be required aboard to get the payload through the atmosphere and safely back to earth, To land a man on the moon and get him home safely again will require a very big rocket engine indeed—one with a thrust in the neighborhood of one or two million pounds, While nuclear power may prove superior to chemical fuels in engines of multi-million-pound thrust, even the atom will provide no short cut to space exploration.
Sending a small instrument carrier to Mars, although not requiring much more initial propulsion than a simple moon shot, would take a much longer travel time (8 months or more), and the problems of navigation and final guidance are formidable.
A MESSAGE FROM MARS
Fortunately, the exploration of the moon and nearby planets need not be held up for lack of rocket engines big enough to send men and instrument carriers out into space and home again. Much that scientists wish to learn from satellites and space voyages into the solar system can be gathered by instruments and transmitted back to earth. This transmission, it turns out, is relatively easy with today’s rugged and tiny electronic equipment.
For example, a transmitter with a power of just one or two watts can easily radio information from
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