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Ex-Astronaut Developing Plasma Rocket To Revitalize NASA
TechReviewAl writes "Former astronaut Franklin Chang Diaz believes that the private sector can revitalize NASA, and his company is developing a plasma rocket to back up that claim. Chang Diaz argues that private industry can be used to develop much of the basic technology needed for space exploration, allowing NASA to focus on more sophisticated and critical components. His company, Ad Astra, is developing a variable specific impulse magnetoplasma rocket (VASIMR) that will be used to reposition the International Space Station. Last week, the rocket passed an important milestone in testing — reaching 200 kilowatts (enough to move the ISS). A video of the rocket can be seen on Ad Astra's site."
VASIMR means the only expensive part is getting to LEO. Once there, a space tug using VASIMR can lift satellites to GEO for almost nothing (compared to today's prices). It's not really fast enough for human travel, but for moving equipment around Earth orbit (or elsewhere), it's very promising. Between this and SpaceX reducing the price to LEO, the next 10 years should be very exciting in commercial space travel.
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And maybe with the same level of risk (equipment failure / no hope of rescue, medical emergencies, solar storms, meteor strikes etc.). Although with our modern day aversion to risk, I can't see it getting a very enthusiastic welcome from todays "sailors". Not unless the rewards were very good indeed. Is there that much good stuff to be had to incentivise people to go?
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The classic example is if you spread a gallon of gasoline out evenly and ignite it perfectly it can raise the Empire State building one foot in the air. Translated a gallon of gasoline could potentially lift a human into orbit, less spaceship. Three things are keeping us Earth bound. Gravity, friction and efficient use of fuel. Remove any two of these factors and you can orbit a human for the price of a modest plane ticket.
The simplest way to remove the problem of risk is to pay each person X million dollars upon arival back to Earth so long as they give up the right to sue for anythimg that can be traced back to the trip.
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Without oversight by NASA, components won't have the compatibility required to integrate within the launch vehicle. Essentially it means that all of these companies will just be contractors to NASA (Company X builds the fuel injection, Company Y builds the stage seperators, etc). Is that really cheaper than paying NASA employees to develop the same technology?
Bank in 1999. electricity has been generated in space by dragging a copper tether though the earth's magnetic field (http://www.independent.co.uk/news/astronauts-seek-power-in-space-1319781.html).
Presumably this produced drag. Can't this "drag" be used for some near earth maneuvering using a mesh system to create an electromagnetic sail by which one might tack? Or is the amount of force to small to be useful?
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I'm not sure you understand the potential that any particular astronaut has to ruin hundreds of billions of dollars of government investment. If an astronaut meant to, or just screwed up at something that may have seemed inconsequential at the time, the deaths of the people onboard would be, while publicly tear-jerking, relatively inconsequential compared to the gross loss of capital for the agency. (Less now that they're intending to stop using the shuttles altogether, but to some degree still.)
The fact that he made it through training and became an astronaut means that he was worthy of being trusted with a hundred-billion-plus dollar space ship. That's what the training is for. That's why we pay their training, and why we pay them. Not only could they die in a spectacular fireball if they make the wrong mistake--or if someone else does--but it's possible they could completely ruin NASA's chances of ever being useful again by swaying public opinion. A single person could--or could have--singlehandedly set back mankind's exploration of space by decades or longer.
And you've really got the balls to say that spending the money that he got as part of that trust to keep advancing something he loves and believes in is less respectable than if he had taken his money, gambled with it on the stock market, and taken whatever gains he had and spent them on this as an outsider?
Disclosure: I am related to a former high-ranking NASA employee, and while that doesn't make me an expert, I do have at least SOME sense of scale about the damned thing.
Despite it's high specific impulse this engine isn't the whole answer to the exploration of the solar system. Blame the inverse square law.
It may be feasible to power an slow unmanned Earth-Moon VASIMR transfer vehicle with solar, but at Mars solar radiation is only 25% as strong and at Jupiter it's 4%. So you are talking about nuclear for probes to the outer planets and for manned missions to anywhere.
There's nothing technological that would stop space-based nuclear but you just know it'll take years to get that done.
New Scientist has an article that says VASIMR + nuclear = 39-day transit time to Mars.
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... a gallon of gasoline could potentially lift a human into orbit, less spaceship.
Actually it's quite a bit more than a gallon. (LEO is very high and very fast. Other orbits are moreso.) But the basic idea is sound.
Rockets are HORRIBLE energy-spenders. (Their big advantage is that they do work and are self-contained.) That's why there's all that work on various "space elevators", where you can use electric motors (or the equivalent), at efficiencies in the 75 to 98% range from electricity to kinetic energy, to move stuff from the ground to LEO, geosynch, or otherwise get it persistently off the ground and out of the atmosphere.
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Mass of ISS = 3x10^5 Kg .333x10-5 = 3.33x10-6 m/sec^2
Diameter of Pluto's major orbital axis = 14x10^9m
Thrust from a 200KW VASMIR engine = 5 newtons
f=ma=5N so a=f/m=1/(3x10^5)=
s=1/2 at^2 so t=sqrt(2s/a)
t=sqrt((28x10^9) / (3.33*10^-6)) = 1061 days
So as anyone who completed high school physics can see even one of these engines can cross the entire solar system along Pluto's major axis in just under 3 years or about the amount of time it took Magellan's crew to circumnavigate the globe.
This is a silly example of course. Orbits aren't straight lines. Why would anyone want to completely cross the solar system? (At most you would cross half) climbing out of the gravity well would be slower and falling in would be faster. I also assume you want to stop at your destination so half the trip would be spent in deceleration.
But it does show the power of even one of these engines if you can carry the fuel and a power source. It is the magic of constant low acceleration without opposing friction. It is why ion engines are attractive and VASMIR is a step up from them.
This is the kind of engine that will allow us to settle the solar system. Now if only we can find a good way to climb out of this stinking gravity well!
I think ion thrusters would be a better way to go for ISS boosting.
These calcs show the drag force on the ISS is about 0.25N.
These tables show that to get 250 mN thrust you are going to need ~10 kW of constant electrical power. That is 8-ish % of the ISS available electrical power. It seems very do-able.
Possibly ISS electrical power is so stretched that using it to boost is considered a waste. Certainly it is possible without VASIMR.
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