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The VASIMR plasma rocket faces its biggest test yet: operating at a 100 kW power level for a continuous 100 hours:
As part of a program to develop the next generation of in-space propulsion systems, NASA awarded Franklin Chang-Díaz's company, Ad Astra, a three-year, $9 million contract in 2015. This unlocked an opportunity long awaited—a chance to prove the doubters wrong. Naturally, it won't be easy. Ad Astra must fire its plasma rocket for 100 hours, at a power level of 100 kilowatts, next year. [...] During a visit this month, the VASIMR engine fired at 100kW for 10 seconds and 50kW for one minute.
[...] Proven, powerful electric propulsion would lower the cost of human landings on Mars. NASA already has plenty of experience with chemical rocket engines and in-space propulsion, but such missions would require multiple launches of the Space Launch System rocket to provide all of the fuel needed for a Mars journey. A gas-sipping, electric engine for in-space propulsion would require far less fuel—and fewer launches from Earth to pre-position rocket fuel. To determine whether any of the electric approaches is feasible, the agency has set a rigid requirement of firing a 100kW engine for 100 continuous hours by mid-2018. "At that point in time you either do it or you don't," Crusan said. "This gets rid of a lot of ambiguity, because you can't really game a 100-hour test."
[...] For now, the skepticism toward Ad Astra is understandable. Virtually every news headline about the company's efforts to develop a plasma engine have focused on a single, fantastical number—39 days to Mars. While such a low transit time between Earth and Mars is theoretically possible with a much larger and more powerful VASIMR engine, there is one big catch: it would require a nuclear reactor in space to provide enough power to reach Mars that quickly.
NASA has had some abortive attempts, such as the Prometheus project, to develop nuclear energy for in-space propulsion. But due to the politics and sensitivity surrounding nuclear energy, the agency has never gotten very far down the path toward deploying some kind of in-space propulsion system driven by nuclear power. Based upon current technology, Chang-Díaz figures that large but manageable solar arrays could eventually provide up to 1 megawatt of energy for electric propulsion. But that is the value at Earth's distance from the Sun, and solar energy really falls off beyond Mars. So solar power seems to be good for transport in the inner Solar System. For areas beyond Mars, solar really won't work.
Advances in Duration Testing of the VASIMR VX-200SS System (PPT PDF).
(Score: 3, Insightful) by jmorris on Saturday February 25 2017, @05:29AM
If they can make it run at half power for a minute it is just a matter of engineering to find and improve the parts that fail.
I was more interested by the numbers in the article that say normal rockets are 5km/s thrust and this one gets ten times more at 50km/s. So it looks like there is quite a bit more upside for the future before worrying about relativistic weirdness. But it also means that for all the talk about being an electric drive it only gets ten times the efficiency from the propellant and I suspect this engine + power supply is somewhat larger than a chemical engine. So we will still be lugging around honking big fuel tanks and argon is a lot more expensive than any other propellant I can think of.
(Score: 4, Informative) by takyon on Saturday February 25 2017, @05:47AM
VASIMR looks promising for sending stuff around in the inner solar system. But if we were to scale it up to the Megawatt class using nuclear power, we could just do a fission or fusion rocket instead.
https://en.wikipedia.org/wiki/Nuclear_thermal_rocket [wikipedia.org]
http://www.space.com/23084-mars-exploration-nuclear-fusion-rocket.html [space.com]
It's more efficient to use the energy from nuclear reactions to directly expel a propellant than it would be to use electricity to power the VASIMR. Even if EmDrive Level 1 (no flying cars and free energy, that's Level 2) was a proven technology, it might not be as favorable as a fusion rocket in many scenarios.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1) by khallow on Saturday February 25 2017, @02:38PM
But it also means that for all the talk about being an electric drive it only gets ten times the efficiency from the propellant and I suspect this engine + power supply is somewhat larger than a chemical engine.
It depends on the application as to whether thrust/weight or ISP is more important. Chemical propulsion is used for Earth to orbit (and any scenario where a lot of acceleration in a short period of time is desired), because it currently is the only thing that can manage the thrust/weight needed to escape Earth's gravity to space. But once you're in space, ISP tends to be more useful with these far more efficient propulsion systems able to accelerate for years, making up for their disadvantages. That means a much smaller mass fraction needs to be devoted to propellant in order to achieve a particular final velocity.