Why cant we launch a satellite from a cannon?

Question

Why cant we launch a satellite directly into a circular orbit at a constant distance from the earth using a cannon assuming that the cannon would give the satellite a largely sufficient velocity showing calculation.

Answer 1

A satellite must pass through its launch point once during each orbit.

If the cannon was pointed above the horizon the satellite must pass through the earth prior to returning to the position of that cannon.



If the cannon was pointed below the horizon then the satellite would be being fired into the earth immediately after launch.



If the cannon was exactly horizontal the satellite would graze the earth just above the surface on both sides of the earth. To do this is passes through the atmosphere and loses energy and burns up as well.



So no matter what the cannon, nor how powerful it is, nor how low we could get the acceleration, a satellite cannot be launched into its trajectory from the surface of the earth.

Answer 2

Gerald Bull thought so!...until the Mossad blew him away.

Answer 3

No problem except that it has to be about 396 miles long for a 10g acceleration. Much more would kill the astronauts. Do the math! Ok, hardware that can take 100g could do it in a cannon only 40 miles long.

Answer 4

You are referring to a 'space gun' which has already been tried. See link for example: https://en.wikipedia.org/wiki/Space_gun



You may also find this interesting: https://en.wikipedia.org/wiki/Non-rocket_spacelaunch

Answer 5

Ignoring acceleration damage..



If the trajectory starts at the Earth's surface, any orbital trajectory will repeatedly intersect the earth.

It would be whatever height set by the launch velocity, but near zero width.



A satellite needs velocity around the circumference of its orbit, which a ground based launch on its own cannot give.



A satellite launch by rocket starts vertically but almost immediately starts to tilt, to gain speed around the Earth. Once clear of the atmosphere it will be almost horizontal relative to the ground.



A good part of the total fuel and energy goes in to that "horizontal" acceleration to give a near-circular orbit.



See the image below for a typical launch path:

http://files.abovetopsecret.com/images/member/8ad72fecfb04.gif





Something like a long, angled linear accelerator running up the slope of a mountain near the equator has been proposed in the past by SciFi authors.



That could theoretically replace a good part of the first stage fuel and just need engine power to do the final orbital shaping, rather than the full lift against gravity.



If it is many miles long, it also keeps the acceleration forces to something more acceptable.



Info:

https://en.wikipedia.org/wiki/Mass_driver

Answer 6

Because there is not enough power to propel a satellite from an earthed cannon to compensate for Gravity.

Answer 7

A cannon provides all of its energy in an instant. That's fine if the projectile is a cast iron ball and you want to fire it 200 yards. If you used enough explosives to project a satellite into orbit, it would destroy the satellite and probably the canon.



It may be possible to launch a satellite using a very long tube which imparts energy to the satellite gradually. Scientists have been working on that idea off and on for over 60 years.

Answer 8

The acceleration would be too great. A rocket accelerates at an amazing rate to be sure but, it doesn't have to generate all the velocity it needs in an instant like a cannon would.