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Getting to Space is Easy. Staying There is Hard.


Space is not like this:

Orbital Speed

It is like this:

Orbital Speed

Source: http://what-if.xkcd.com/58/

But getting to space is easy. The problem is staying there.

Gravity in low Earth orbit is almost as strong as gravity on the surface. The Space Station hasn't escaped Earth's gravity at all; it's experiencing about 90% the pull that we feel on the surface.

To avoid falling back into the atmosphere, you have to go sideways really, really fast.

The speed you need to stay in orbit is about 8 kilometers per second.[4] Only a fraction of a rocket's energy is used to lift up out of the atmosphere; the vast majority of it is used to gain orbital (sideways) speed.

Stashed in: Science!, xkcd!, Mars!, space, Space!, Space

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Thanks for the explanation, xkcd.

Seems like we need a combination of science, engineering, and luck.

It also seems like many who sign up to be first to go to Mars will never come back.

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