It is easy, in theory, to shoot something into orbit. The objection is purely practical.
Escape velocity is about 25K mph/40K kph. Anything short of that remains in the gravity well. However, if the trajectory of descent misses the planet you get an orbit. It's that simple. Many orbits are not stable, so the projectile will quickly return to ground. Indeed, no orbit is truly stable. However, putting something up for several orbital revolutions is simply a matter of careful calculation.
The problem is not air pressure, but acceleration. To reach 40K kph in a short acceleration time--hence shot into space--requires heavy acceleration. For example, 10 seconds requires well over 100 g of acceleration. Ten seconds is already unreasonably long. Two seconds requires almost 600 g. Doing this from the moon would be difficult, but possibly practical. There is a famous book about the possibilities.
That book, The Moon is a Harsh Mistress, outlines why this is generally frowned upon. Basically, a launch catapult is also a large piece of artillery. Simply throwing rocks at 40K kph will produce nuclear scale damage at impact.
J
Is it though?
Let's say we shoot a cannonball from the Earth. No atmosphere and no engines. If it stays in the gravity well, its trajectory must be an ellipse which includes the point where it was shot from.
You cannot put something directly into Earth orbit with a cannon, despite Newton's famous thought experiment. You could shoot something into solar orbit or go directly to the moon (but will need a kick stage to avoid crashing) but you cannot get into Earth orbit without some means for providing a second impulse to circularize the orbit. Launch straight up will either give you an escape trajectory (if it's fast enough) or come straight back down. And has been noted several times, the g load of going directly to an escape trajectory is insane. The g load to go to LEO (with a kick stage at apogee) is similarly insane but slightly less so. In any case this system will have limited utility for launching satellites and no utility for launching people but will be phenomenal for launching raw inputs for factories or colonies.
Didn't read the article, but I saw a headline that stated Trump wants to create a new branch of the military dedicated to assuring American orbital and space dominance. Now I know the idea of militarizing space worries a lot of people, but I don't really have a problem with it. The Russians have their own space branch for their military called the
Aerospace Forces. It was created in 2015 and replaced the Russian Air Force (which is now subordinate to the Aerospace Forces). I'm sure the Chinese have plans to do the same as well, so we might as well get on it too before we get completely left behind.
Yeah I'm ok (though not thrilled) with this and it's not nearly as dramatic as it sounds. The USAF already has a space command with about twice as many employees as NASA. They are in charge of a very wide range of responsibilities from controlling launch ranges, to monitoring space junk, to providing TLE's (navigational data) to satellite operators, to operating GPS and weather satellites.
The problem this new Space Force is meant to address (in addition to boosting Trump's ego and polling numbers) is that the space and launch vehicle markets are undergoing a sea change. The pace of innovation has begun to climb an exponential curve* and the current organization of the space command has been very slow to react and adapt to changing circumstances. The hope is that by making it an independent command it can be more responsive to market forces to better serve the public while maintaining vigilance on the defense side by allowing more innovative approaches in military acquisitions of space and launch vehicle hardware. The counter argument is that this will potentially add more bureaucracy to the processes already in place and make the military less responsive.
So far, this won't actually increase the military's presence in space, just reorganize the assets that already exist. If the effort is successful, we will see the launch ranges able to support a higher launch cadence than is currently possible and we will see more military payloads going up as rideshares on commercial satellites as well as a lot of military small satellites. SpaceX alone is already challenging the launch ranges as far as their operational cadence, when Blue Origin and other providers like Rocket Lab hit their stride they will break the military's ability to coordinate and support these launches. Moreover, the USAF spends a god-awful sum** on their military satellites and having them begin to ride the CubeSat revolution will bring down costs even as they increase capabilities.
I think a better proposal would be to turn over a lot of the functions of space command to a civilian agency.
*Remember that until about 5 years ago, basically the entire planet was using rockets with very little changes from the 60's and large, hyper-expensive satellites with similarly slow upgrade cycles. Now they are sending
shoe box sized satellites to Mars and landing rockets on their tails like something out of a Heinlein novel. The space age is really just beginning.
**For reference, if NASA had access to the budgets that the USAF and espionage agencies have for their own space efforts, we could launch a Hubble equivalent every 5 years or so.
