The Space Review: VASIMR and a new war of the currents Comments

Nelson Bridwell

Fri, 19 Aug 2011 00:06:17 +0000

A reply posted on the Ad Astra website: http://www.adastrarocket.com/VASIMR_development_A... "Ad Astra has explored the scaling of the VASIMR® technology to multi-megawatt engines driven by nuclear- electric power and conducted interplanetary mission studies of very high power architectures. These studies yield a wide range of fast interplanetary mission options with one-way trip times to Mars ranging from four to just over one month, depending on the performance of the nuclear power source (generally specified in kilograms/kilowatt). It is abundantly clear that the nuclear reactor technology required for such missions is not available today and major advances in reactor design and power conversion are needed. However, a number of serious research studies have been conducted that point to reactor and power conversion designs that meet the kg/kW required for such a mission. Again, much remains to be done, and closing the door on these possibilities on the basis of the relatively primitive state of our present nuclear space technology would be highly premature."

Nelson Bridwell

Thu, 18 Aug 2011 23:51:01 +0000

So, did Diaz take Zurbin up on the challenge? If Diaz has a real solution to the power/weight ratio roadblock identified by Zurbin, I am sure that we would all be interested. Zurbin wants to go to Mars, and if VASIMR could really get us there sooner, The Mars Society would be behind it, 200%. Unfortunately, Mr Black, the author of this essay, does not appear to have requested a formal reply from Ad Astra, and instead falsely characterize Zurbin as a Thomas Edison, using an irrelevant analogy... Ad Astra Rocket Company 141 W. Bay Area Blvd Webster, TX 77598 281.526.0500 281.526.0599 (fax) aarcinfo@adastrarocket.com Make the call, Chuck. Inquiring minds want to know!

ken anthony

Mon, 8 Aug 2011 10:49:35 +0000

Trent has a great post along these lines... http://quantumg.blogspot.com/2011/08/weve-already...

ken anthony

Sun, 7 Aug 2011 16:37:19 +0000

Actually we should send two ships tethered together to provide redundancy for safety and artificial gravity. So a dozen to mars for $1.6b. Sounds pretty cheap for a whole planet. That's how I define self financing.

ken anthony

Sun, 7 Aug 2011 16:34:31 +0000

If there were no showstoppers we would be there by now. And nothing is self-financing. Thank you for summarizing your own illogic. Short def of self-financing: Growth capital from its own income. Nothing is, is an ignorant statement. Absence of show stoppers does not mean a thing will happen. That [lack of] reasoning is insane. The ISP of below 350 seconds for storables puts even an unshielded spaceship into the multi-thousand ton range. This is governed by the rocket equation and just means you need a certain multiple of ship mass in fuel to achieve a required delta V. Somewhere between the BA330 (23k kg.) and a BA2100 (65k kg.) you have the core of a ship that could be launched by a Falcon Heavy. The upper stage of that FH provides a vacuum engine. Sending a BA330 to mars would require about five FH launches for fuel. So fueling this ship gives you five engines for a marginal cost close to zero. Radiation shielding is part of the design of those inflatables. Supplies and fuel add more protection. As far as not talking about it, they talk about the bogus radiation boogie man every chance they get. You want a solution for that, send non smokers and packing peanuts. Or just include the recent British shield design that required the power of a toaster. Include just one Dragon (w/LES) and we could send seven people safely to the surface of mars for about $800m (about what NASA spent to send Spirit and Opportunity.) We should of course oversupply them prior to their landing. You are right in one respect... because there are no showstoppers, I expect we will do something like this in less than ten years and certainly in less than twenty. Watch the skies!

ChuckBlack

Sat, 6 Aug 2011 18:51:29 +0000

Thanks for all the comments. But I'm hoping we keep in mind that the article tried to point out some of the economic and business constraints influencing current space focused activities and provide a little background using historical analogues. The examples discussed are noteworthy and fun to talk about but they're certainly not the only two current space industry personalities using a little hyperbole to help generate interest and drive funding.

ken anthony

Fri, 5 Aug 2011 11:53:37 +0000

Nobody, including Zubrin, is saying research is a bad thing. What Zubrin is saying, and he is completely correct is, if you're going to take the hill, take the hill. Don't look for magic bullets. Look at what we have and pursue the goal without distractions. Vasimir will prove itself one way or the other. But putting it on the critical path and stalling progress requires that somebody point out the problems. Zubrin did. To say we can't go to mars with chemical rockets when we clearly can makes one suspect the argument being made against it are motivated by something other than the merits. That's dishonest. We can get to mars with storable methane or kerosene engines. Storable fuel being a good thing for a ship we intend to use for years. We can add reliable ion thrusters using solar power to that as well. We don't have to make it more complicated than that and we can do it now with components already tested in orbit. Zero-g rated high power nuclear energy would be a good thing. It's not something we have to delay for. Dragon, taking scientific packages, will give NASA and others a low cost alternative to the martian surface while providing lots of experience before using them to put humans on the martian surface. There are no showstoppers. It's time to get humans on mars to research ISRU settlement. For the price of about five shuttle launches we could settle our first new planet. Oh, and it's self financing.

Travis

Thu, 4 Aug 2011 21:40:56 +0000

Hm, Zubrin's paper studies, vs Astra's in-testing prototype. Astra has a working relationship with NASA, Zubrin has....? If the man had any sense, he'd be willing to upgrade his Mars plans to include new technologies.

Dwayne Day

Wed, 3 Aug 2011 18:56:23 +0000

I think Zubrin's figure for the Topaz reactor is high--it was reported as being 10 kilowatts, but in actuality was around 6. He's apparently referring to what was commonly called the "Topaz 2" reactor, but was in reality designated the "Enisy" reactor. If the lower figure is correct, it actually adds more support to his claim.

Luca

Wed, 3 Aug 2011 15:58:35 +0000

Zubrin is considering a Vasimir+nuclear reactor configuration. It is more ferasible a config Vasimir+solarPV. There is no need for a mandatory 39 days trip to Mars. A trip of 4-6 month will reduce a lot the the needs of a high density energy power.

Roderick Reilly

Wed, 3 Aug 2011 15:15:27 +0000

The notion that Mars could be settled by pioneers using conventional propulsion is a delusion. The best we can do with conventional is one or two plant-the-flag missions. Zubrin is wrong on that notion. "Mars Direct" might as well be as big a "hoax" as VASIMR is purported to be. I'm sorry that advanced propulsion concepts haven't been developed sufficiently to date, but they are necessary for any serious, long-term human exploration intiative to Mars.

Sidney Clouston

Wed, 3 Aug 2011 13:09:03 +0000

Hello Mr. Black I wrote to the ESA in Europe months ago that went through their review process. It was about use of the ISS in the future. They have funded another time period. I suggested that the ISS could be used as an assembly point for a spacecraft for Mars missions. It could also be sent to orbit Mars as a cargo ship. I like the success of Deap Space 1 that had solar PV and Ion engines.

Pat Flannery

Tue, 2 Aug 2011 22:11:04 +0000

What this shows is a really fundamental problem that's happening in regards to developing any new space technology; instead of just talking up their favorite approach, they feel it's also necessary to tear down any other approach as well. End result is that anyone reading their criticisms thinks all the alternatives are bad in one way or another and decides the whole concept should be ignored. This was really noticeable in the battle inside NASA between the supporters of DIRECT and Ares I-V, and was one of the main reasons Constellation got scrapped.

Paul March

Tue, 2 Aug 2011 20:13:13 +0000

The VASIMR VF200 is supposed to be tested in the NASA GRC Plumb Brook Facility's 100 ft OD by 122 ft tall vacuum chamber that is located near Sandusky, Ohio. See: http://www.grc.nasa.gov/WWW/Facilities/ext/spf/in... http://www.nasa.gov/mission_pages/constellation/o... Even then this chamber's vacuum pumping capabilities will only allow a few minutes of operation before the internal pressure builds up above the VF-200's maximum operating pressure of ~1x10^-4 Torr. These "high" thrust (~5 Newton), high Isp (5,000 to 30,000 sec) plasma thrusters require a lot of space to work properly.

oldeng

Tue, 2 Aug 2011 19:37:19 +0000

When I started in aerospace (1965), we were testing Kaufmann type (low thrust) ion thrusters in relatively small high vacuum chambers (8 ft dia and 18 ft dia) without the problems of "edge effects" mentioned in this article. There are ways to do this testing that mitigate these issues. And we were running 20 MW arc jet test facilities with internal plasma pressures up to 200 atmospheres in the 1960s in 6-ft diameter vacuum chambers. We could hold vacuum levels equivalent to 300,000 ft altitude while swallowing huge gas flows from the arc jet in our pumping system. One of my final jobs before retiring in 1997 was testing advanced shuttle TPS components (carbon-silicon carbide panels to replace the carbon-carbon used on the orbiter) in the 50 MW arc jet test facility at NASA Ames. My guess is that this facility (if it's still operational) could be used to test VASIMR.

Robert

Tue, 2 Aug 2011 12:19:52 +0000

I suppose VASIMR will work well in deep space; however, in the atmospheric environment, the phase-shift plasma turbine can work better lifting off the spaceship. A proposal could be: Phase-shift Turbine to take off; Chemical rocket aligned with Turbine to get into space; and VASIMR to travel long distances into space; all that powered by He3 or p-B11 aneutronic fusion. http://www.youtube.com/watch?v=GSkxPghXTCg

Andres Villavicencio

Tue, 2 Aug 2011 05:01:03 +0000

I always understood that the advantage of VASIMR was its flexibility, it could do high thrust, low thrust use a variety of fuels. Not sure if that is feasible with other propulsion types, because if the space equivalent of the diesel engine will run only in xenon, i don't think we are going to get a lot of trucks. Also lets be honest if we are not going to produce to be able to produce that kind of energy eventually, then your case for mars is useless, as we'll never be able to go there reliably or in a economically viable way and we'll be limited to flag waving and other useless stuff. So why bother.

Doug Weathers

Tue, 2 Aug 2011 04:57:40 +0000

When you say "huge vacuum chamber", how big is "huge"? NASA's White Sands Test Facility in New Mexico has what I would call "huge" vacuum chambers. They were built to test full-size Apollo Lunar Modules in space conditions, and are able to maintain a vacuum even while the LEM's descent engine is running at full throttle. They should be able to keep up with an electric thruster. They are still in use today. More info: http://www.nasa.gov/centers/wstf/propulsion/altit... And if for some reason these chambers are not suitable, then why not a relatively cheap sounding rocket flight? I flew a payload into space on this rocket: http://www.upaerospace.us.com/#!vstc0=sl4 and got it back in perfect condition afterwards, too. Or what about one of the new breed of reusable suborbital vehicles (SS2, Masten, XCOR, Blue Origin, Armadillo, etc) when they begin operations? We don't need to haul a VASIMR motor into orbit just to test it in the space environment - including the effect of zero gravity, which is not available in Earth-bound vacuum chambers. (Unless there's one on a zero-gee airplane of which I am unaware.) IMO, Zubrin has a problem with any idea, technology, or mission that shifts attention away from Mars Direct. He has similar unkind things to say about missions to the Moon, for example. He should calm down. VASIMR probably won't be ready any time soon, so it won't distract people from Mars Direct. And if it *is* ready soon, then he can use it!

JJ Barr

Mon, 1 Aug 2011 23:32:03 +0000

The U.S. space program is in big enough trouble right now -- and any prospect of a Mars mission with it -- that it really doesn't need a nasty intramural fist-fight over VASIMR. Robert Zubrin has done great work educating the public about the "case for Mars" but I hope he will settle down a little and take the nasty edge off his criticisms of VASIMR. Its scientific and technical merits should be analyzed a little more thoughtfully, and ideally independently from both Zubrin and Chang-Diaz.

Sidney Clouston

Mon, 1 Aug 2011 23:17:52 +0000

Hi Chuck: You wrote up a problem, "This means you need a huge vacuum chamber to perform any sort of accurate test of an electrical propulsion engine and the chamber needs to be capable of a very high vacuum during the test since even small amounts of residual gas can mess up electric-thruster measurements." I think that the ISS is in a rather large vacuum location. Assembly there would be feasible.