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What Fits on One Shelf
Priya wants one shelf in the town museum to show what it takes for a person to leave Earth and come back alive. Visitors will not stay for a lecture. A shelf that holds every machine ever launched will teach nothing.
The first object is a rocket, because nothing else matters if you cannot get up. A launch rocket burns liquid or solid fuel and throws hot exhaust downward until the push beats Earth's pull. For a long time most of those rockets flew once. Some now return and land upright, so the same vehicle can fly again. Priya chooses a model of that kind. Landing again only means the ride up is not thrown away.
Beside it she puts a small satellite, the part of space people already use. Some relay phone calls, television, and internet.