VASIMR plasma drive

[Dr Mordrid]

For a long time its been said that VASIMR (Variable Specific Impulse Magnetoplasma Rocket) could turn a years voyage to Mars into weeks.

Now it looks to be ready, and it's a private company doing it.

Note the test versions are to be 100-200 kw. VASIMR can use MEGAWATTS, meaning nuclear or even fusion reactors to give chemical rocket thrust for months or years at a time. What gas is used for fuel doesn't matter much either. With some adjustments most will do.

Estimates are that a large VASIMR could accelerate at .5 to 1G continuously, allowing the ship to have acceleration induced artificial gravity. Downside: you can only accelerate half way there; the rest of the trip you have to decelerate.

Aviation Week & Space Technology, 02/19/2007, page 17

(subscription required, so no link)

Ad Astra Rocket Co. expects to begin operating a 200-kw. "flight-like" engine prototype in ground test by the end of the year. Ad Astra is a Houston-based company that grew out of research into Variable Specific Impulse Magnetoplasma Rocket (VASIMR) technology conducted at Johnson Space Center by seven-time shuttle astronaut Franklin Chang-Diaz. The company has opened a facility in Costa Rica, where Chang-Diaz was born, for life-cycle testing that started at lower power levels in December 2006.

Next up is a test series with a 100-kw. unit already in early checkout. Assembly of two flight variants of the engine is set for early next year, with in-space testing targeted for 2011. The company, which has an exclusive license to the original VASIMR patents under a privatization agreement with NASA (AW&ST Jan. 30, 2006, p. 12), has added new intellectual property in the past year. The VASIMR engine uses radio waves to heat propellant gas to extremely high temperatures, producing exhaust velocities in the 40-50-km./sec. range.

[rylan]

Finally impulse drive... now we need warp reactors!
Set up a collector for interstellar gas and you're all set without needing to carry around crazy amounts of propellant.

[Dr Mordrid]

One more notch on Gene Roddenberry's belt.

Dr. Bussard's collectors should work for short dips through planetary atmospheres etc. Good enough for the Enterprise's nacelles

Now imagine if they could achieve fusion temperatures in VASIMR's chamber using a D-D fuel. A 100M °F chamber temp should provide one helluva kick in the pants.

[VJ]

Interesting!

Estimates are that a large VASIMR could accelerate at .5 to 1G continuously, allowing the ship to have acceleration induced artificial gravity. Downside: you can only accelerate half way there; the rest of the trip you have to decelerate.

But wouldn't one also get an acceleration induced artificial gravity if one decelerates at e.g. -1 G ?


Jörg

[Brian Ellis]

Excuse me if I sound naive but I have a little problem. Let's assume the pinch coils are superconducting so you would get bags of gauss for relatively little watts, but where is the energy coming from in a spaceship for the pulses? Even with a duty ratio of 20:1, this would require an average output power of 5 kW for a 100 kW module and an input power to the electronics of at least twice this. If you're going up to the MW region, I foresee practical problems for stowing solar panels of sufficient size for the engine AND all the rest of the gear, including the life support systems.

[Wulfman]

I guess that's why people want to establish nuclear powered spacecraft. still, I don't feel overly confident about nuclear material getting shot into orbit...

mfg
wulfman

[Dr Mordrid]

The powerplants most talked about for VASIMR powered spacecraft include nuclear with MHD electric conversion, nuclear isotope generators with thermophotovoltaic cells instead of thermocouples or reactors with superconductive turbines.

The US military & NASA are working on the latter since a 20MW SC turbine unit of this type can now be fit in a dumpster sized space. Smaller and larger units are also in the works including one that would fit in an F-35 Lightning II fighter.

Look for 'em on the new DDX stealth destroyers powering rail guns and in aircraft armed with directed energy weapons.

[Technoid]

I guess that's why people want to establish nuclear powered spacecraft. still, I don't feel overly confident about nuclear material getting shot into orbit...

mfg
wulfman

There are tons of the stuff already in orbit, what do you think powers the spysats?

[Dr Mordrid]

Yup, and about every deep space mission uses RTG's (radioisotope thermoelectric generators) that are powered by Plutonium, Strontium or any number of other radioisotopes. Voyager, Cassini, New Horizons....whatever is too far from the sun to use photocell arrays.

[Gurm]

How about a crew module that rotates? For the first half of the trip it's locked in artificial-gravity-inducing mode where the acceleration thrust generates the gravity. Then, halfway through, they FLIP it over and DECELERATE. Of course you could always just turn the whole vehicle around for the deceleration thrust... either way, it would be good. Artificial gravity is one of the real kickers for prolonged spaceflight.