And, when writing about anything, never forget to trot out someone willing to use The T Word:
Previous studies have investigated the use of magnets to accelerate satellites to the high speeds required for launch. But most have focused on straight tracks, which have to gather speed in one quick burst. Supplying the huge spike of energy needed for this method has proven difficult. The advantage of a circular track is that the satellite can be gradually accelerated over a period of several hours.
The tunnel would direct the cone to a ramp angled at 30° to the horizon, where the cone would launch towards space at about 8 kilometres per second, or more than 23 times the speed of sound. A rocket at the back end of the cone would be used to adjust its trajectory and place it in a proper orbit.
Anything launched in this way would have to be able to survive enormous accelerations -- more than 2000 times the acceleration due to gravity (2000g). This would seem to be an obstacle for launching things like communications satellites, but Fiske points out that the US military uses electronics in laser-guided artillery, which survive being fired out of guns at up to 20,000g. [...]
If the ring launched hundreds of satellites a year, it would be cheaper than conventional rocket launches. With 300 launches per year, the team estimates the ring could put payloads into orbit for $745 per kilogram. If the launch rate reached 3000 launches per year, they calculate that would drop to $189 per kilogram. Today, it costs more than 100 times that to send payloads into space.
Although Epstein is sceptical about the prospects for such a ring, he cautions that if built, the ring itself could become a target for attacks. This is because of its potential for use as a weapon, launching missiles that could reach anywhere in the world. "The ring then becomes one of the most important targets on the planet," he told New Scientist.
Well, there goes magnetic data storage...
They should build it underground, though, I suppose.
I suspect it depends on where you build it. AFAIK all particle accellerators of any real size are built underground, but those also tend to be built relatively close to major cities (since it's a bit hard to attract researchers to the middle of nowhere, plus it just costs a lot more to build when you have to ship every nail in).
I've visited Bessy in Berlin which is not underground.
Wow, awesome technology. I find myself disliking Epstein immediately.
Y'know, that's really quite clever. I remember thinking about magnetic launch mechanisms when I was a kid, but they were always some sort of "ski jump" like contraption.
The acceleration here comes not from going faster and faster around the circle, but rather the act of turning. Think of banking that fast while going Mach 23. Even in a vaccum it's tossed cookies time.
I wonder what the radius of a circle is that gives the same velocity, but only gives 5G's of acceleration...
centripetal acceleration... a = v^2/r ... r = v^2/a = (8000m/s)^2/(~50m/s^2) = 64000000/50 = 1280000m = 1280km or ~830 miles.. *radius*, so the thing would be about 2500km across or 1600 miles across. And about 2*pi*1280km ~= 8000km of track
To get up to that speed (accelerating at 1G) you'd need v=at .. t = v/a = (8000m/s)/(~10m/s^2) = 800s... about 13 minutes. The human body can sustain 5 or 6 G's for 13 mintes. And that might be a doable roller coaster ride.
It would be a massive project. I'm guestimating it would be more track than all the bullet trains in Japan. But it needs to be compared to the cost of various space programs.
I have the flu from hell, so my math could be totally pooched.
I'm totally reposting this to <lj comm=astronomy>, thanks!
Everybody keeps saying that oh - huge G forces make launches like that unusable. Everyone kind of forgets that fuel, water and various supplies weight a lot and are needed up there.
I don't see how a track like this would contain centrifugal forces. Gerald Bull solved the problem of the power burst - you want 2000 Gs, you use a gun, shoot up a rocket and ignite the rocket motor at the top of the trajectory. Sadly, the only person interested was Saddam, and even he did not care so much for the satellite-shooting gun as he was in help to design and test nuclear missile nosecones (for which help Mossad offed Bull).
I bet Bull's gun could be built for less money than a single space tourist launch.
Or... drop the rocket from underneath a plane... :)
Plane launches are more expensive than gun launches. Also, you still have to achieve an escape velocity which is easier with missile that's already going up (I guess the engine should fire not at the top of the trajectory).
Actually, it takes next to nothing to change the objects trajectory. What's far more important is the balance between kinetic and potential energy (ie: speed vs gravity), the weight of fuel, and wind resistance.
The reason why rockets are so horribly inefficient is because a rocket is inherently a horrible way to lift something into the air. An airfoil is much, much more efficient.
That inefficiency means a rocket needs to burn a massive amount of fuel. Fuel that it needs to carry, and lift. By using a far more efficient engine (ie: a jet), and a far more efficient means of generating lift (ie: a wing), you can lift a lot more weight with a lot less fuel.
What's also very important is that you can do this at a much lower speed. In the dense lower-atmosphere, that makes a tremendous difference in the amount of drag caused by friction, which means even less fuel.
BTW, in case you haven't heard about it, the Pegasus rocket does exactly this... it's launched from a plane and then uses a more conventional rocket to get into orbit.
The downside to this tactic is that current aircraft severely limit how much you can lift. The Shuttle can put 60,000 pounds into orbit by using ~5 million pounds of equipment and fuel. AFAIK that's beyond the capabilities of current air and spacecraft technology (obviously, the better the spacecraft the less weight the aircraft needs to lift; the better the aircraft, the more it can lift and the heavier the spacecraft can be).
Looking at that picture, I keep thinking they're going to construct it around Burning Man.
"You kids just do whatever it is you're doing. We'll just be launching stuff over here."
Very cool. Wonder if they're planning to use Inductrack for it.
Isn't this straight out of "The Moon is a Harsh Mistress"?
If the launch rate reached 3000 launches per year, they calculate that would drop to $189 per kilogram.
This sounds an awful lot like the lines we were fed with regards to the Space Shuttle.
Unlike the shuttle, there's a hell of a lot fewer parts involved here, and the technology has actually been around for decades (think FermiLab, for starters).
Of course, 3000 sattelites per year would make things pretty damn crowded up there...
I think the ultimate goal here is to surround the Earth with enough LCD screen, or 'louvre' based satellites to effectively control the sunlight on a raster level, and then charge by region for its continued availability. Sort of an inverse Dyson sphere, in a sense.
Impoverished nations can opt for a lower-cost sponsored sunlight.
"THIS AFTERNOON BROUGHT TO YOU BY COKE"
...man has dreamed of destroying the Sun."
The article said the muzzle velocity is 8000m/s. This means air molecules are going to be striking the projectile at this speed, and its nose is going to instantly be given a temperature of about 2500 degrees Celsius. Steel melts at 1400 or so. There are ceramics that can withstand higher temperatures, but only for brief times -- not long enough to travel this speed through the whole 100 miles of atmosphere. So their payloads are going to melt and/or vaporize.
There may be some tricky idea to get around this problem, but they didn't mention having any. Fun toy to play with though.
Hey, wait, 8000 m/s is barely enough to be in low earth orbit. They must be neglecting drag. Doh!
You think they haven't thought of the problems you raise.
Slashdot called, they want their comment back.
"they didn't mention having any"
except for the "citing previous research on nuclear warheads, which are designed to move through the atmosphere at hypersonic speeds" part, you mean?
Fiske points out that the US military uses electronics in laser-guided artillery, which survive being fired out of guns at up to 20,000g.
The military also used atomic weapons fired by artillery, which opens up that set of prospects.
Yeah, 'cause such a facility built presumably reasonably away from any boarders would be a real easy target to take (and retain) control of.
I wonder which is bigger, the savings on launch costs, or the additional expense of using electronics capable of surviving the source of G-forces this launch method would generate?
ive been waiting, they kept talking about building that in my desert(NM).. and then 5 years pass with no word..
pumpkins and cows.