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."

Comments

Re:Total power

[AKAImBatman]

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. ;-)

Re:Let's not get out of hand about Mars

[vlm]

You're mixing about a zillion different orbits into one recollection.

If you've got enough fuel, just turn and burn man... simple. Of course that takes a heck of a lot of fuel, like your idea of 98% mass fraction of fuel.

A Hohmann TO is the simplest imaginable transfer to design and is pretty quick too. Draw an ellipse that touches both orbits...

http://en.wikipedia.org/wiki/Hohmann_transfer_orbit

A Bi-elliptic is way slow, but if you're making a major/huge change to your orbital parameters it takes less fuel. Enter a giant orbit way the heck out there, then on the return pass enter your new orbit. Handy for inclination changes too.

http://en.wikipedia.org/wiki/Bi-elliptic_transfer

And if you literally have decades of spare time there is the famous "ITN" which takes practically no fuel and takes practically forever, which works by wandering around the various eddies of the Lagrange points or something very vaguely like that.

http://en.wikipedia.org/wiki/Interplanetary_Transport_Network

As for your claim of 98% mass fraction, check out the math on

http://www.iki.rssi.ru/mirrors/stern/stargaze/Smars2.htm

"showing we need add just 2.966 km/s, a shade short of 3 km/s or 10% of the orbital velocity."

and then when you get there you need another 2.5 km/s to match mars orbit, although you can play various gravitational slingshot games to help that out...