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Magnetic Space Launches
DiZNoG writes "This CNN article discusses NASA experimenting with the idea of using Mag-Lev technology to launch payloads into space. Mentioned in the article is that the U.S. Navy is working on the technology for it's aircraft carriers to launch fighters. Unfortunately the NASA project is horribly underfunded ($30,000) for research. Cool technology, let's hope that the Navy research gets us a step closer to not burning all that Oxygen and Hydrogen to get to space...
Lots of reasons. First problem is to keep the ISS from being flung in the opposite direction of the direction of the launch. You could possibly solve that one by making each launch fire the actual launch vehicle and a waste mass in the opposite direction to conserve momentum, but then you double the power requirements and the mass you have to get into orbit.
The next problem is that because of tidal forces any long linear object in orbit will be pulled into an orientation where the long axis of the station is pointed directly at the earth. The center of mass of any object in orbit at orbital speed, but anything closer to the earth is moving slower than orbital speed (because speed to maintain orbit gets faster the closer you get to the center of the earth, but the whole object can only go at a fixed speed) and anything further away from the center of mass of the station is moving faster than orbital velocity.
At any rate, if you've got a long structure in orbit, one end will point at the earth, the other directly away. The amount of energy required to point the launcher anywhere remotely useful would probably be better spent attached to the object you want to launch in the first place.
Jherico
What can the average user can do to ensure his security? "Nothing, you're screwed"
I'm not positive, but I'm pretty sure that no material has the tensile strength to hold its own weight all the way to the moon. If you held a 5 foot string, it weighs practically nothing. If you dug a 100 mile hold and held a 100 mile string that was dangling down it it would rip your arm off. If you suspended it from something stronger than you, the string would just break under its own weight.
Plus you can't anchor a string to the earth and the moon. The earth rotates much faster than the moon orbits. If you attached it to just the earth it would only line up with the moon once a day, and it would be going so fast as it passed it you would be smashed into the moon. By the same token if you attached it to the moon, it would fly around the earth every 24 hours, meaning it would be blazingly fast, about 350 mph. Bad rope burn if you try to grab it.
However, it might be possible to build a 'string' that is strong enough to simply lead into orbit. Anchor one end to the earth, and the other to a large mass slightly outside geosync orbit, which is still way way closer than the moon. Then you can climb the string all the way to the mass and be flung away from the earth. At any rate we still don't have strong enough string. Yet.
Jherico
What can the average user can do to ensure his security? "Nothing, you're screwed"
I think you're missing a very important detail -- I was making a joke. But let's go ahead and apply this to the shuttle. Here's how far you have to make your acceleration track in order to reach 7,814 m/sec (minimum orbital velocity) at various G-forces:
............ 1.0 km ............ 31.1 km ............ 207.5 km .... 389.0 km
3112 gees
100 gees
15 gees
8 gees (comfy?)
Think about how long you watch a shuttle launch, and that it's accelerating for that entire time. It takes a long, long track to pull this off. Better to build short, fast ones and use them for launching construction materials into orbit.
The advantage here would be that you dont need to burn fuel to make the fuel move. You dont need to add extra weight to get started. Im not an expert, but i assume that the basic idea would be gather speed (not even necessarily vertically to begin with), and then launch it vertically. It needs to be vertical to escape the drag of the atmosphere as quickly as possible.
dominionrd.blogspot.com - Restaurants on
> I'm either 5'11" (say, roughly 6') tall or 180.34cm. Now, which of those gives you a better mental picture of how tall I am?
The one you are more used to of course. That doesn't make it better in any objective sense.
I'm about 190cm (say, a handswidth under 2m), or 0.009 furlongs, or 0.3 rods, or 0.09 chains. Which of those gives a better mental picture?
Incidentally are you really 5'11" to within 1/200th of an inch? If not, the apparent accuracy of the ".34" you quote is completely bogus.
> Does metric even have "dry volume" measurements?
Yes of course. Cubic metres. Same as wet volume, since a volume doesn't actually change depending whether its contents are wet or dry. The dimensions of volume are length^3, so the SI unit for volume is (unit for length)^3.
rant
You'd be launching the probe on a tangent to the orbit, not on a perpendicular to the orbit. This would cause the ISS to accelerate along the tangent to the orbit, giving it a higher velocity. You achieve higher orbit by going faster, not by going away from the orbited mass.
Lots of counterintuitive things happen in orbit. For example, if you are chasing a probe and accelerate toward it, it will move farther away - you accelerate, you go into a higher orbit, and your orbital period decreases, so you aren't going around as fast. The probe's orbital period stays the same, so it's now going around faster than you.
Definitely doesn't need to be vertical - you're out of half the atmosphere in 7 miles, out of over 99% of the atmosphere by 50 miles high, and by that point the velocity you need to get to orbit needs to be horizontal, not vertical; you still need some vertical thrust to counteract gravity of course, the main point is there's an optimal thrust/weight ratio beyond the atmosphere that is also associated with a specific curved trajectory, far from vertical...
Energy: time to change the picture.