Engineering Question #2936

David Howard, a male from UK asks on September 15, 2005,

Can you tell me whether it would be possible to launch a spacecraft into orbit using a giant catapult? I can see no reason why not. Obviously any life form would instantly turn to mush under the immense g force, but for satellites I'm sure it would be possible, - the picture in my head is a 1 mile deep catapult with computer controlled tension, maybe it would be possible to use a natural hole like the grand canyon. Anyway... in theory would it work?

viewed 13641 times

The answer

John Jones answered on September 15, 2005

The problem with this scheme is atmospheric friction. When you launch with a catapult, the spacecraft is going fastest where the atmosphere is thickest. (This is just the opposite of what happens with a rocket launch.) To maintain a low earth orbit at an altitude of 185 km, a spacecraft would need to be travelling at 7.79 km/s; to have this velocity at 185 km, it would need to start off with a velocity of at least 9.69 km/s at sea level -- that's about 35,000 km/h, or about 35 times the speed of sound. It would therefore experience intense frictional heating -- much worse than the space shuttle experiences on re-entry. The outer surface of the spacecraft would become incandescent, like a meteor.

To get round this problem, you might consider launching the spacecraft inside a tube from which all the air has been removed, with the tube going up the side of a high mountain. Designing the top end of the tube so that the spacecraft could get out, but air couldn't get in, would be a challenge.

Add to or comment on this answer using the form below.

Note: All submissions are moderated prior to posting.

If you found this answer useful, please consider making a small donation to