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Hyperdrive and Space Propulsion
Interested reader writes "MSNBC has an article covering the recent Space Technology and Applications Forum in New Mexico, which included a frontier physics session on hyperdrive, wormholes, and other blue sky ideas. The idea is a revival of NASA's long-dead (and heavily criticized) Advanced Propulsion Project."
Given that it was held in New Mexico, Blue Sky is appropriate.
*(For those who don't know, the sky in Santa Fe & Los Alamos -- due to the extreme altitude -- is a very deep shade of blue, brighter and darker than the typical light-blue you see at normal altitudes.)
Blue Sky refers to any endeavor where the future gain is all based on hope. In my business, the car business, you often see used car lots that say "we finance". What they are doing in acutality is selling you a car for $3,995 or some similar number for which they paid $995. They then require a $995 down payment. So they are whole from day 1. Any payments that you make to the seller are profit on that car. The profit is all "Blue Sky". They hope that you will make perhaps half or slightly more of the payments you promised and then default on the balance so they can repo your car and sell it again.
You can see how a proposal to use a Worm Hole as a means of moving through space could/should be referred to as a Blue Sky project.
http://www.nctimes.com/articles/2006/03/12/busines s/news/20_27_233_10_06.txt
Charging customers to send them into space is a lofty goal for any business owner, and perhaps particularly in an area whose economy draws much of its strength from the availability of cheap land.
But that's the goal that Bill Sprague has set, and he even said that he chose Temecula largely because of its low cost of living relative to the coastal cities where his aerospace suppliers are based.
Sprague is building a 52-foot rocket. By October 2007, he hopes, passengers with $250,000 to spend will be able to ride it to the edge of outer space, where the curve of the Earth is visible and where the planet's gravity is slightly weaker than at the surface.
"If they look in any direction except at the Earth, they'll see black," Sprague said. "It'll be just the sun sitting in a sea of blackness. The stars will be visible."
Cool article, although the fact the rocket parts are only valued at $3mil right now would make me concerned about riding in it.
Happily, this system produces 1/3 to 1/4 the acceleration of an average car.
:D
What he can't kill, he has sex on. Trent.
I haven't read your links yet, but I'm skeptical about this being "readily achievable with today's technology." To put an 11 km pylon in perspective, Tapei 101 is 508 meters (0.508 km, if you need the math done) tall. Burj Dubai will be 705 meters tall. The Mars oil platform is 990 meters tall, but 900 meters of that is underwater and mostly consists of cables running under tension to the sea floor, and it's definitely not evacuated. A similar design would have to be parked in the Marianas Trench (11 kilometers ~ 36000 feet) or have stick above the water a significant distance, and also have to maintain straightness in any currents or else deal with lateral accelerations on the launch vehicle due to curvature of the launch tube.
Evacuation is also a challenge. If you want to park it in an ocean trench, you'll need to deal with the pressure at the bottom (approximately 15000 psi at the bottom...there's a reason Trieste is the only manned vessel ever to go there). Even if you find a way to build an 11 km tall tower standing above the water, you've got to pump air out faster than it flows in the open top, or add the mass of a cover to the top... which means stuff moving at the end of an 11 km long moment arm.
I also went ahead and did some quick math. 1 m/s/s acceleration over 11 km is not enough:
s = s(0) + v(0)*t + 0.5*a*t^2, where s(0)=0 and v(0) = 0 so:
t = ((2*s)/a)^0.5 = 148 seconds to traverse the 11 km
v = v(0) + a*t = 0 + 1 m/s/s * 148 s = 148 m/s = 331 mph
Woefully short of escape velocity.
So then I tried 1 G and got 1040 mph, which still doesn't cut it. Next I went for 5 G's, which is on the order of what astronauts experience during a launch, and that gave me 2,326 mph. It's still not escape velocity, but surprisingly enough, it is sufficient kinetic energy to loft an object to a height of 22,000 miles, or the altitude of a geosynchronous orbit. Unfortunately, when it gets there it doesn't have sufficient tangetial velocity to stay there, so it follows a funny elliptical path 22,000 miles to the hard ground. I ran out of scratch paper before I could quantify that, however. I did have one line left to note that a 1000 kg payload accellerating at 5 G's requires 2.4 MW of power, not accounting for losses, which is one capability we do easily have.
It's a pity, because all of these ideas show some measure of original thought and are theoretically feasible in some fashion, but the technical challenges are rather mind-numbing. So far the only problems I see with the space elevator are a sufficiently strong ribbon, a reliable method for weaving the ribbon in place, absolute reliability of a car during the 22,000 mile trip, and power to the car. Naturally, none of these are very trivial.
Here's another way to view the math - if you start at standstill (i.e. v(0)=0) and expect to be moving at 11km/s at the exit of the tube, your average velocity is Vaverage = (v(exit) - v(0))/2 = 5.5km/s. Using this number you can calculate the time to traverse the launch tube: t = distance/Vaverage = 11km / 5.5 km/s = 2 seconds. You can also calculate the acceleration: a = v(exit)/t = 11km/s / 2 = 5.5km/s^2. So relative to 1 g = 9.8m/s^2, your launch system will require occupants and payload to sustain about 561 g's for the 2 second launch.
For electrical and mechanical payloads, that's achievable. Many small atmospheric-study payloads have been gun-launched to orbital altitudes, but on ballistic trajectories. Cited accelerations are on the order of 12000-14000 g's for very short durations.
For people and critters: pink goo.
Lets do the math.
...
;-(
Imagine a drag strip X kilometers long.
What acceleration would it take to reach escape
velocity (~11,200 meters per second)?
Newton say's a = (v*v)/(2*x), so:
if X = 1000m, A = 62,700 m/s^2
Hmmm. If you (or the cargo) can handle ~6.3 G's, it
would only take a rail (tube, whatever) 1000 km long
to put you in orbit. At 630 G's, a mere 10 Km long
launcher would do.
I had a similar idea some years ago, about using
rotary methods (aka high-speed catapults) to put
stuff in orbit. My head still hurts thinking
about it