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Q & A: Head East, Young Satellite...

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Most recent answer: 10/22/2007
Q:
Why is it easier (takes less fuel) to put an Earth satellite into orbit by launching it in an eastward direction than by launching it towards the west.
- Brian (age 16)
Fremont High School, Fremont, CA
A:
The Earth spins on an axis going through the North and South poles, and the direction of the spin is eastward. Someone standing on the surface of the Earth at the equator is traveling eastward at about 74 meters per second. The speed of a satellite in orbit depends on the height of the orbit, but if you send your satellite up to go around the Earth from West to East, you take advantage of the fact that the launch pad is already traveling in that direction and the speed of the rocket adds to that of the launch pad. Going the other way, it subtracts.

Tom

(published on 10/22/2007)

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