Cutting Edge Space Propulsion

My buddy Mark, he who wrote the insightful article on Tardigrades, forwarded me this article about VASMIR propulsion and I thought it was worth taking a look at here despite being published almost three years ago, if for no other reason than to show how others are thinking beyond the chemical rocket.

An artists rendition of a VASMIR powered ship.

In this case the VASMIR (Variable Specific Impulse Magnetoplasma Rocket) engine is a three stage engine that uses magnets and radio waves to superheat a neutral gas into a plasma state which can then be focused into propulsion. From the article:

The first stage works a bit like a kettle, heating the atoms of a neutral gas like argon with a radio frequency (RF) generator until electrons “boil” off, creating plasma.

The plasma is now very hot – about 50,000 degrees Celsius – but not hot enough to produce efficient thrust. The second stage of VASIMR acts as an amplifier, further energizing the plasma using electromagnetic waves. By now, the plasma reaches about a million degrees, comparable to the center of the sun.

The third and final stage is a “magnetic nozzle” that converts the energy of this superheated plasma into directed motion and, ultimately, high velocity thrust. And, in case you’re wondering how anything so hot could be possibly contained, that’s one of the reasons the cells are all magnetic. A magnetic field not only helps heat plasma but also contains it, so it won’t ever actually touch anything.

VASIMR could, theoretically, reach power levels a hundred times that of other ion engines.

The downside?

The first [problem] is that the 200kW VASIMR only produces a pound of thrust. That’s more than enough in the vacuum of space, where the ion engine can fire continuously for months on end and a pound of thrust can push two tonnes of cargo from the sun to Jupiter in 19 months. But it means VASIMR will never get off the earth on its own – it would need to catch a lift with one of those old gas-guzzling rockets.

The second issue is that, while the current engine can run entirely on solar power – making it perfect for moon trips and other near-earth duties – for a deep space mission, it would need more like 200MW of power. And only an on-board nuclear reactor could provide that.

An onboard nuclear reactor… or an Ion-Plasma power plant?

A diagram showing the three stages of a VASMIR engine.

I will admit that I’d read about the VASMIR years ago when coming up with the “technology” of the Unified Republic of Stars storyworld and I knew that in order to make something like the VASMIR or an Alcubierre Field work, there was going to have to be some cheap but massively power generating tool to make it all work. Hence, the “Ion-Plasma Power Plant”.

How does it work? Beats me. It’s the “leap” necessary for the rest of the world to function. In this way, it’s a lot like Star Trek’s Matter/Anti-Matter drive. The main difference is that, with mine, I haven’t composed a whole bunch of bullshit techno-babble around it to try and justify how it works. In the URS it’s just a fact of life.

So I suppose my question to you is, when reading science-fiction, do you care about whether something like that is real? Does it matter if there’s not an explanation? Or do you prefer your sci-fi to be a little more “sci” and a little less “fi”?

Also, if anyone has heard of other neat experimental ship engines, please let me know. It’s always fascinating to see what engineers are coming up with.

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