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Space Transportation Science

The Science Behind Building a Space Gun 131

Posted by samzenpus
from the acme-approved dept.
An anonymous reader writes "Astronomer and gamer Scott Manley (more famous for his Kerbal Space program coverage) has created a fantastic video explaining the science behind building guns that could one day be used to launch payloads into space. It's not as easy as simply making a bigger gun, there's a whole host of unorthodox 'gun' designs which work around the limitations of garden variety propellants."

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The Science Behind Building a Space Gun

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  • by Anonymous Coward on Thursday January 10, 2013 @10:10PM (#42554287)
    before the Mossad kills this guy...
  • by Anonymous Coward on Thursday January 10, 2013 @10:44PM (#42554469)
    We know even vacuum tubes can withstand the 100000G acceleration and 20000RPM rotation from being fired out of a WWII cannon.

    http://en.wikipedia.org/wiki/Proximity_fuze [wikipedia.org]

    But for what else can you use this gun? We already have plenty of electronic junk up there and it's made its way there just fine without a gun.

    This is probably a case of "it's time to revive a decades-old idea to make a name for myself"...

  • by crtlaptop (1923984) on Thursday January 10, 2013 @11:17PM (#42554635)
    Orbital speeds in atmosphere means bleeding off speed and part of the payload being vaporized. Its the same forces acting on re-entry. As far as I know (not very far) this makes it harder to send smaller objects.
  • by F34nor (321515) on Thursday January 10, 2013 @11:38PM (#42554725)

    Everything is expensive. As to what to do with a gun, just launch water into space. It provides fuel, air, food, and of course water.

  • by steveha (103154) on Thursday January 10, 2013 @11:42PM (#42554751) Homepage

    This would be ideal for sending inert things like oxygen, water, rocket fuel, or some kinds of food. It would even work for structural parts or electronics if they could take the accelerations without damage.

    For that matter, one of the problems of a Mars flight is having adequate shielding against the radiation the craft would encounter between Earth and Mars. With a system like this, the cost of getting the shielding up would be as cheap as possible. (I guess the mass of the shielding would affect the accelerations the craft could make and thus affect the length of the trip.)

    One problem, as I understand it: a projectile launched from a big space gun would need to have its orbit adjusted or it will return to Earth. Either you need to catch it while in orbit (you get one chance) and add additional acceleration to put it in a stable orbit, or else the projectile needs to have rockets or something to adjust its speed. The video mentioned this issue briefly (the part about Newton figuring out that the projectile would return to the point of launch if no other forces acted upon it).

    P.S. I saw proposals for an Apollo-style mission from Earth to Mars: a single giant rocket launches everything in one launch. Why is anyone even looking at doing it that way? Send the craft to space without fuel or consumables; send it up in parts even and assemble it in space. Then, as it is in orbit, fuel it up, load it with consumables, and then when it is ready send it on its way.

    We don't really need giant space guns to make space access more affordable; we just need practical, reusable craft that can carry a small load to orbit, return, and do it again soon. It must not need man-decades of work to completely overhaul it, as the Space Shuttle needed. Single stage to orbit, two stage to orbit, whatever... but not single-use rockets. Rockets that fall into pieces as they ascend, where you never get a test flight because each flight uses up one rocket, will never give us cheap access to space.

    According to Jerry Pournelle, the fuel cost of putting something into orbit is similar to the cost of flying it most of the way around the world on an aircraft. Because the aircraft isn't consumed by the flight, we can do this for much less than the cost of sending something into orbit. Practical, reusable transportation would be a total game-changer.

  • by Grayhand (2610049) on Friday January 11, 2013 @12:23AM (#42554947)

    I think it's called a mass driver

    By any other name the gee force issues are the same. The problem with mass drivers would be the expense. Imagine building a 500 kilometer CERN collider. Mass drivers are practical on the Moon because of the low gravity and no atmosphere.

  • by Thud457 (234763) on Friday January 11, 2013 @09:06AM (#42556957) Homepage Journal
    Really?!
    The Israelis are bad for killing the guy that was going to give Saddam a GIANT GODDAMNED GUN to lob poison gas shells at Tel Aviv ?!!

    Bull was pulling a Von Braun and just didn't have the luck of getting a buyout offer at the end.

As in certain cults it is possible to kill a process if you know its true name. -- Ken Thompson and Dennis M. Ritchie

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