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Successful Test of Superconducting Plasma Rocket Engine
xp65 writes to mention that Ad Astra has successfully tested their VX-200 plasma engine at full power in superconducting conditions, the first time such an engine has been tested at those power levels. "The VX-200 engine is the first flight-like prototype of the VASIMR® propulsion system, a new high-power plasma-based rocket, initially studied by NASA and now being developed privately by Ad Astra. VASIMR® engines could enable space operations far more efficiently than today's chemical rockets and ultimately they could also greatly speed up robotic and human transit times for missions to Mars and beyond."
Damn, this is terrible timing. On the weekend my lady and I were thinking that a new pet name for my penis was due. The current "Superfluidic Particle Accelerating Colossus" was getting a bit stale.
The better half suggested "Superconducting Plasma Rocket Engine". But now that that name is taken we'll have to use our second favourite choice: "Hank".
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Trolling is a art,
For those of you who are unclear on why the VASMIR system is so cool, allow me to give you a brief bit of background. Practically every propulsion method developed to date falls into one of two categories:
1. High thrust, low efficiency
2. Low thrust, high efficiency
Generally how it works is that the more power you get out of engines, the less energy you extract from the fuel. This is the case of chemical fuels like Liquid Hydrogen/Oxygen or Kerosine. These fuels provide the massive amounts of thrust necessary to get off the ground, but they burn through their fuel very quickly. Interestingly, LHOx is more efficient than Kerosine, but it's also harder to get as much raw thrust out of it. That's one of the reasons why Kerosine was the heavy lifter during the space race with the LHOx engines reserved for in-space stages.
On the other side of the coin, you have engines like Ion propulsion. These engines are able to inject incredible amounts of energy into tiny amounts of fuel, thus making them extremely fuel efficient. The only problem is that the amount of thrust is very low. Most of the ion engines that have operated to date produce thrust that matches the weight of a sheet of paper. Definitely not enough for liftoff, but perfect for extended missions in space where constant low thrust provides more velocity over time than the chemical engines which fire once, then coast the rest of the way.
The problem with both types of engines is that neither one gets spacecraft to their destination all that fast. Chemical rockets have the thrust to do it, but you couldn't feasibly build a chemical rocket with enough fuel to get you to another planet in a reasonable amount of time. A nuclear pulse propulsion craft could feasibly get fairly close, but it would just have more power in the intial thrust rather than providing a constant, high power thrust. (Obviously these have been discounted over the difficulties of building a large enough craft without using a nuclear ground launch. Nuclear ground launches are a no-no under current test-ban treaties.)
This is where VASMIR comes in. These engines are incredibly efficient. The specific impulse (measurement of efficiency) is between 3,000-30,000 seconds depending on the configuration and current thrust levels of the engine. This compares favorably with the ~450 seconds of shuttle engines and 3,000-10,000 seconds of Ion thrusters. Meanwhile, the thrust of Ion engines ranges from 90-3,000 mN while the thrust of VASMIR is expected to be ~5000 mN of thrust when tested at 200 kW of power.
What this means is that we may be able to build spacecraft where a trip from LEO to the moon is a daily affair and a trip from LEO to Mars takes only a few months (or less!) vs. the current flight time of nearly a year. The better these engines get (and the more we can put on a craft), the faster those flight times will get!
Javascript + Nintendo DSi = DSiCade
Superconducting Plasma Rocket Engine?
Sounds like it oughta be able to make at least Warp 3.
"People who think they know everything are very annoying to those of us who do."-Mark Twain
For comparison, your car needs about 20 kW of power to maintain cruising speed on the interstate. 200 kW of power would be akin to running a 300 horsepower engine at its peak power output. With the way cars are designed, that doesn't happen much with the possible exception of expensive sports cars and pickups hauling a heavy load.
If we take the case of the sports car, we find that it's enough energy to slam you against your seat and hold you there while you do 0-60 in 3 seconds. (Hey look, ma! Artificial gravity!) In the case of a pickup pulling a heavy load, it's enough to accelerate reasonably while dragging a trailer full of spools of heavy steel cabling.
The difference between your car and the spaceship is that the spaceship will be powered by some sort of long-term fuel supply. e.g. A nuclear reactor. Which means that the spaceship will be able to continue accelerating for millions of miles while your car would have run out of gas after the first few hundred miles.
Since acceleration is cumulative, being able to continuously accelerate like that means that distances between planets become a lot smaller on one "tank of gas" as it were. Add more engines for greater thrust and redundancy, and you have a souped-up hot-rod of a ship that can take you interplanetary distances in record time.
Hmm... I'm sure someone is about to chide me for some horribly sloppy analogies, but look on the bright side. It's got cars in it! And hopefully it will make the energy budget a bit more understandable. ;-)
Javascript + Nintendo DSi = DSiCade
For 200 kW per engine, we're thinking nukes.
Javascript + Nintendo DSi = DSiCade
Correct. While it's theoretically possible to use engines like this as part of a liftoff stack (assuming enough engines, low enough weight per engine, and a high enough power budget), it's not really practical to consider such a concept at this time. For the short term at least, LEO access will remain the purview of chemical rockets.
Javascript + Nintendo DSi = DSiCade
Superconducting: check
Plasma: check
Rocket: check
Linux:
Three for four isn't bad.
Write your representatives! Repeal the 2nd Law of Thermodynamics!
Just a comment before people get out of hand talking about how quickly we can go to Mars with better thrusters... anyone who's taken a class on Orbital mechanics should know that you can't just decide to go to Mars whenever you like. Part of the problem with trips to Mars is the distance, but also the timing. It would be extremely difficult to do an orbital transfer from Earth to Mars while they are on opposite sides of the sun. It would add months, if not years, to your trip, and the fuel requirements certainly wouldn't be aided by it. Unfortunately, because the an Earth-year and Mars-year are so close (like 1 mars-year is 1.8 earth years...?) it takes a while for the orbits to sync up again once they get out of sync (isn't this known as beat frequency in the audio world?).
Now don't quote me on this b/c it's been a while since I took orbital mechanics... but I seem to remember the "optimal" window for an Earth-to-Mars transfer opening up once every 2.5 years, it would take 8 months to travel there, 90-98% of your ship's mass would have to be fuel, and then you'd have to wait 1.5 more years for the "optimal" Mars-to-Earth orbital transfer window. In other words, doing a round-trip flight to Mars is no trivial matter.
Even with a more efficient fuel, perhaps you can stretch those windows, but you're not going to find an astronaut who is willing to leave now for a 1.5-year-commute to Mars, instead of waiting a year and doing an 8-month-commute. Even if those times are shrunk by a factor of 2 with a more efficient fuel, it's always going to be a huge operation.
Yes, but it should scale nicely to 100's of MW.
This was a full power test of the superconducting magnet and first stage only. The first stage is a 30kW ionization stage. The 170kW RF second stage has not yet been tested. Testing of the combined first and second stage will commence July 14th. From the manufacturer's site: http://www.adastrarocket.com/Release%20020709.pdf
In Yiddish (the Jewish-German creole of Eastern Europe), VASIMR means "woe is me".
I know, probably o/t.
In the land of the blind, the one-eyed man is king.
Biking for an hour at 25MPH costs 1181 kcal, according to this calendar (others suggest it costs even more calories), which translates to 1373 watt-hours. (Your body isn't that efficient at converting fuel to energy.) So let's assume your 250W figure is correct, and your body is about 18% efficient in converting calories to power.
Biking for an hour at 65MPH (if you could) would burn 18669 calories -- remember, wind resistance goes up as the cube of speed. That works out to -- let's see -- 21712 watt-hours. Assuming the same 18% efficiency (and some active cooling for your legs, not to mention the rest of your body), you'd be putting out 3.95KW to sustain that speed.
When you look at it that way, spending five times the energy to move a car, with probably five or ten times the frontal surface area and more than ten times the passenger and cargo capacity, starts to sound like not such a bad deal.
It doesn't matter too much how efficient a power source is, as long as the fuel is plentiful. For instance, if you have a REAL LOT of petrochemicals it doesn't really matter how much you have to use to get to mars, etc. BUT more important is how DENSE the energy source is...i.e, how much more of the fuel does it take to move the fuel that is going to be used later on. This gets to be a BIG PROBLEM with chemical fuels, as even at their best they are not very DENSE. Of course, efficiency helps. But say, for a moment, that you have a nice large nuclear power plant on earth...you could probably use all that heat to either directly or indirectly (though electricity) create some high-density chemical fuels...but there's a limit to how much power a chemical fuel can provide. We need NUCLEAR FUEL, be it fission or fusion, or even better ANTIMATTER fuel. While some people claim that nuclear fuel is too dangerous to use on earth, I disagree. But I do think that antimatter is too dangerous to be used anywhere in the vicinity of important and/or massive objects (can't have the earth or space station pummeled by shrapnel in the case of an antimatter explosion, can we? And remember, there's no air friction to slow this shrapnel down). So, the best advice is to use fission, or hopefully fusion once technology gives up on the silly Tokamak idea, to leave earth's gravity well and move far enough out of the plane to be safe, and then use antimatter to the long haul. What, you say antimatter is too expensive? That's only because you've picked the wrong places to manufacture it. Production using solar power in CLOSE SOLAR ORBIT, in a thousand factories, should make antimatter cheap enough. You just have to go fetch it from close-solar orbits, which can be robotically done using the antimatter as fuel itself! The factories themselves can be replicaed using easily available materials from the moon or asteroids, and then replicated in close solar orbit using the vast energy resouces of the sun.
So to sum up, the problem isn't the amount of energy required, but the location of that energy. Move our energy conversion devices closer to the source, and we'll have plnety of consumable energy, even if it has to go through several intermediate storage mechanisms to become safe and easily accessible.
And yes, I've said this in other places, over time. I just hope that I get through to someone who is charged with long-term planning for space exploration.