VASIMR Discussions

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pathfinder_01

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I love panels where people discuss the pros and cons of things but so far I am not impressed with this one. Reminds me of a religious program I used to watch years ago where they would try to present a discussion, but really the “panelist” were on the same side of the issues or the panelist who was on the opposite side was rarely given equal time or seemed equally prepared.

The panel assumed you would use vasmir as the main propulsion of a manned mission, when you might not use it in that fashion at all. The panel also assumed the 39 day trip was all one could do with it. Juzz, what is it. You would think the mars society would welcome anything that could be helpful for a mars trip.

The part where is discusses that spending on EDL(are capture ect.) helps reduce mass in other systems is a bit like taking a 500 pound man and a 100 pound man and putting them on a diet. They both loss ten pounds, but since the 500 pound man only loss 2% of his weight while the 100 pound man lost 10% you conclude the diet was ineffective on the 500 pound man. Of course reducing mass via areocapture helps reduce the mass of a chemical stage more than an electrical one. The chemical rocket needs more mass of propellant per mass of payload than the electric one. In short every pound you save on the payload of a chemical rocket reduces the in space mass of the chemical rocket more than the electric one but that is solely due to the inefficiency of the chemical rocket.

The part where he discusses the question of wither or not there is a net thrust and how much of one is a good one, but could have been presented better. This is a critical question about this technology. Also I though with rockets accelerating the mass out the rear was what caused it to go forward. I can understand that a charge on the ship will short the process (i.e. despite accelerating the plasma out the back there is no net mass loss because the plasma and rocket attract each other), but I don’t see this whole “plasma needs to push on metal parts for thrust” for this process to happen.

The part about the thrust to weight ratio adds nothing. Electric propulsion has a low thrust to weight ratio. That is known. However how long the trip time takes depends on more than just the thrust to weight ratio (i.e. The turtle vs. the hare) and even if the trip time is slower there are advantages to not taking a much lower amount of propellant(i.e. a 1-1.5 year trip time for mars cargo could be just fine if doing so means you need ten times less propellant in orbit).

The part on the mass of nuclear vasmir is a good part, but you might not need nuclear power for this to be useful.

The reason why we can’t go to mars today is because I as tax payer am not willing to pay for mars direct if every time we send a mission there we need to throw everything away. Mars direct was a move in the right direction over previous ones, but not enough. I really don’t want to pay for a new habitat complete with a nuclear reactor for each and every mission as well as two nuclear thermal escape stages. If we keep spending money on throw away stuff, how on earth can we afford to achieve anything expect wave a flag at mars?
 
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DarkenedOne

Guest
Gravity_Ray":2twwvyim said:
I don’t want to mess with Jakethesnake's VASIMR update tread, but I really want to talk about this technology.

1. I really want to see Bolden move NASA towards massive funding of this technology and also nuclear power to provide the power VASIMR needs to get to the 200-kilowatt engine, the VX-200.

2. NASA should be giving Ad Astra a contract with some money for additional testing to get this technology to level 7 ASAP.

3. I really want to see NASA make this a demonstration mission for the ISS after the Russian re-boost contract with the ISS is finished.

4. Talk about a natural fit for building a space ship in space (preferably in high Earth orbit) maybe in a LaGrange point. This is the ship that we should be building (and I want the first one to be named Enterprise). This ship is perfect for our NEO encounters and also the first trip to Mars in a decade or so.

5. Is Chang Diaz the best astronaut scientist out there or what?

Bring on the discussions.

Ultimately I think it comes down to what happens here in congress. VASIMR is a "game changing" technology. It is such because VASIMR's plasma propulsion has far greater impulse than chemical rockets, thus greatly reducing fuel requirements. Since most of the mass for a manned mission beyond LEO would be fuel than much less mass would have to be It also will greatly improve the economics of human spaceflight. It will also likely improve travel times.

However there seems to be a great resistance to investing in such technology. VASIMR used to be a NASA project. Unfortunately it had its budget cut and Mr. Diaz decided to form a company in order to raise money from the private sector to continue its development.

If the traditionalists who are opposing the new vision have it there way than new technologies like VASIMR will not be invested in favor of older more proven technology.

There seems to be a number of people who are simply unwilling to invest in such technology
 
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neutrino78x

Guest
EarthlingX":1ffpird1 said:
I guess something like Hyperion Power Module ?
No, hyperion is way too big. We need something compact and light, which could fit inside a hab module which can be launched by an Atlas V. Recall that the portable aspect of hyperion, which is buried underground, is the reactor vessel only; the user still has to provide cooling on the surface of the ground.

There are also reactors used on submarines and carriers ?
Yes, but again, far too large. Also, like hyperion, the reactor vessel itself is not the whole plant. There are other devices which attach to the plant, such as pumps. Like I said, I am limited in what I am allowed to say about machines in the engine room, but the essential point is that Naval reactors are far too large. Even the one on NR-1, the nuclear powered deep diving submersible, is bigger than what we would need.

--Brian
 
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neutrino78x

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pathfinder_01":31h2s9il said:
You would think the mars society would welcome anything that could be helpful for a mars trip.
Mars Society wants to use today's technology only. Not something that might be available in 20 years. We can go to Mars today with chemical rockets.

The reason why we can’t go to mars today is because I as tax payer am not willing to pay for mars direct if every time we send a mission there we need to throw everything away.
Mars Direct doesn't throw anything away, man. Each landing adds to the base. With each landing, you get more hab space and more electric power. I do not agree with Robert Zubrin on using nuclear power on the surface of a planet where people are going to live, and I would use an electric rover, but other than that, I agree with his plan.

Actually, the other thing I don't like about the original Mars Direct is the requirement for heavy lift boosters. I would say, send up a hab module, then an Earth Departure Stage, mate them in LEO, then send the crew to get inside the hab, and blast away. All using existing commercial rockets. So, five launches for every trip: Earth Return Vehicle, EDS for ERV, Hab, EDS for Hab, Crew. But there is a plan like that, called Mars for Less.

Mars direct was a move in the right direction over previous ones, but not enough. I really don’t want to pay for a new habitat complete with a nuclear reactor for each and every mission as well as two nuclear thermal escape stages.
Mars Direct ONLY uses chemical rockets. No nuclear thermal escape stage. The fuel to return to Earth is generated via chemical reactions with the Martian atmosphere.

--Brian
 
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kk434

Guest
I have heard about VARIMR for years now, isn't VARIMR like fusion power, always 20 years in the future?

Ups!! a typo.
 
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Gravity_Ray

Guest
Thanks for the videos Nimbus...

I must admit they did deflate me a bit. I do however understand that Mars society wants to get to Mars now, so obviously they will be less inclined for a future tech that does seems still to be many years in the future.

Dr. Zubrin has been stating (and for a while now), that you can get people to Mars now with chemical rockets, and I have never disagreed with him. But if VASIMR is still in the future and needs time, getting people to Mars now with chemicals is enormously expensive. How much has never been fully realized but some knowledgeable estimates range upwards of half a Trillion dollars. That’s huge. I know Mars Society says 30 Billion, but based on what GAO said it was going to cost 30 to 50 Billion dollars just to build the Constellation program. So I am not too optimistic about the Mars society costs for chemical rockets program to put humans on Mars permanently.

New technology that will cut transportation cost is too important to just be axed due to some unknowns. One reason why I wanted to start a discussion on VASIMR is to find good points for continuing the development of this technology.

I am even willing to accept any type of Ion engine discussions here. It’s just that chemical rockets to Mars are just not in the cards in the foreseeable future due to extreme costs.
 
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MeteorWayne

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Gravity_Ray":1n1elo5m said:
I am even willing to accept any type of Ion engine discussions here. It’s just that chemical rockets to Mars are just not in the cards in the foreseeable future due to extreme costs.
You may be, but this thread is for the exclusive discussion of VASIMR
 
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csmyth3025

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As I understand it, ion thrusters are divided into two broad categories: electrostatic (such as used on the Deep Space 1 probe) and electromagnetic (types like VASIMR). Is more attention given to VASIMR because it can produce higher thusts than electrostatic thrusters, or are there other reasons?

Chris
 
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pathfinder_01

Guest
csmyth3025":oaasliig said:
As I understand it, ion thrusters are divided into two broad categories: electrostatic (such as used on the Deep Space 1 probe) and electromagnetic (types like VASIMR). Is more attention given to VASIMR because it can produce higher thusts than electrostatic thrusters, or are there other reasons?

Chris
VASIMR has some advantages over other electric rocket engines. It produces enough thrust to be useful for a manned mission or for cargo. It has greater ability to trade isp and thrust so you can for instance spiral out at high trust then switch to a fuel efficient cruise mode. Thrusters like the ones on deep space 1 produce too little trust to be useful for most manned missions. Although I did see a scaled up 50kw one that could be handy. VASIMR also doesn’t have a problem with slowly wearing out the nuertalizing element(which limits engine life). However, it might have some engine life limiting problems of its own.
 
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oldAtlas_Eguy

Guest
For an Earth-Luna system tug using a microwave rectenna of 1 kg/kw is obtainable with current technology. The power source could actually be land based beaming power into space to the tug. 1 mega watt tug would have a power supply system of 1 to 2 MT for a VASMIR 25N thrust for ~6 hours out of every 24.

http://adsabs.harvard.edu/abs/1993STIN...9411357B
 
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SteveCNC

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oldAtlas_Eguy":36lu76du said:
For an Earth-Luna system tug using a microwave rectenna of 1 kg/kw is obtainable with current technology. The power source could actually be land based beaming power into space to the tug. 1 mega watt tug would have a power supply system of 1 to 2 MT for a VASMIR 25N thrust for ~6 hours out of every 24.

http://adsabs.harvard.edu/abs/1993STIN...9411357B
I looked at the link but after reading it I can't help but wonder what kind of efficiency it has and more importantly wouldn't this be sort of like running your microwave with the door open only higher power ? Stay back if you have a pacemaker :roll:
 
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oldAtlas_Eguy

Guest
SteveCNC":1t4gjoid said:
oldAtlas_Eguy":1t4gjoid said:
For an Earth-Luna system tug using a microwave rectenna of 1 kg/kw is obtainable with current technology. The power source could actually be land based beaming power into space to the tug. 1 mega watt tug would have a power supply system of 1 to 2 MT for a VASMIR 25N thrust for ~6 hours out of every 24.

http://adsabs.harvard.edu/abs/1993STIN...9411357B
I looked at the link but after reading it I can't help but wonder what kind of efficiency it has and more importantly wouldn't this be sort of like running your microwave with the door open only higher power ? Stay back if you have a pacemaker :roll:
Yes. If you have a composite preasure vessel it would definitly be a warming experience. A tug with such a low thrust would be for cargo. A total vehicle and payload weight of 20MT would over 1 hour increase in velocity of 4.5 meter per second. It will take a long time to get any significant delta V.
 
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EarthlingX

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http://www.ticotimes.net : Rocket Company Launches Stock Offering
Posted: Friday, October 01, 2010

By Adam Williams


Ronald Reyes / Tico Times

The Ad Astra Rocket Company, founded in 2005 by Costa Rican astronaut and physicist Franklin Chang, announced Wednesday that it will become a limited public corporation, offering stock to investors willing to pay a minimum of $25,000 on Costa Rica’s National Stock Exchange.

Ad Astra Rocket Company, headquartered in Houston, Texas, also has a branch in Liberia, capital of Costa Rica’s northwestern Guanacaste province.

“We expect investors of Ad Astra Rocket to be more sophisticated, knowledgeable investors who understand the stock market and the undertaking of larger investments,” said Oscar Luis Chaves, director of the economic consulting firm Aldesa, which is helping orchestrate Ad Astra’s limited public offering. “It’s not your normal investment. There aren’t a lot of investors who have committed funds to a rocket company before.”

According to José Rafael Brenes, general manager of the National Stock Exchange, the possibility of investing in Ad Astra Rocket Company should be available within the next three weeks, with a tentative Oct. 12 release date set for the stock. In addition to Costa Ricans, investors from Panama and El Salvador will also have the opportunity to buy shares in the company. According to Chaves, Ad Astra seeks a boost of $85 million in private investments over the next four years. Currently, about 70 percent of the investment that fuels the Ad Astra Rocket Company comes from Costa Rican contributions (TT, Aug. 13).
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“The enthusiasm of Costa Rica behind this project gives me a lot of confidence that investors will continue to want to be a part of supporting this mission,” Chang said Wednesday. “I am so proud to receive such support from my home country in financing the VASIMR and our mission to help solve the increasing problem of space junk.”
...
 
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EarthlingX

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spacefellowship.com : Vasimr VX-200 meets full power efficiency milestone
Published by Matt

on Thu Nov 25, 2010 10:20 am via: Ad Astra

Ad Astra Rocket Company’s VASIMR® VX-200 rocket prototype demonstrated its highest power efficiency and performance so far in tests, which ended Friday November 19 at the company’s Houston laboratory. Last week’s results met the efficiency milestone set by the company as it specifies the requirements for the VF-200 flight engine for the International Space Station. The VX-200 is the full power laboratory prototype that provides the technical basis for the design of the flight hardware.

Last week’s results are a new performance record for VX-200 and confirm an experimental trend observed earlier this month, as the research team continued to explore the high power performance envelope of the engine. Refinements to the second stage RF coupler and impedance matching circuits introduced early this fall, as well as modifications to some of the start-up and propellant control setpoints, contributed to these results. These modifications reduced the coupler’s operating voltage and hence its susceptibility to electrical breakdown but preserved the intrinsic RF coupling efficiency of the system.

The thrust data represents a new company record and already exceeds the requirement specified for the VF-200 flight engine core by a factor of two. These data appear to follow a linear upward trend with input DC power with no evidence of saturation. The new record performance numbers for VASIMR® operating with Argon propellant are listed below:


The new record performance numbers for VASIMR. Credit: Ad Astra
...
 
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SteveCNC

Guest
looking at the Thrust[N] / DC Power[kW] graph it looks almost linear after the initial curve , makes you wonder just how high it can go .
 
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docm

Guest
Indeed. If that linearity proves to scale then it's time to start work on an evolved reactor design.

Probably should have already been working on one anyhow just so we could take faster advantage of an unexpected electric propulsion advance, but that's water inder the bridge.
 
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Skyskimmer

Guest
This stuff is a game changer for sure. It baffles me because from my perspective, asteroid mining/mars, aren't even possible without it. It's not just a nice thing to have it has to happen. What I can't believe is how cheaply there doing the research, vasmir was the last thing that I though nasa should be involved with in terms of RND,(habitats/launch) are out of their hands now thankfully. However it appears again that private can do a much better job without funding.
 
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dryson

Guest
Promising technology;
Argon plasma jets, no node erosion, but still need to solve the heat problem associated with magnetic containment. Same problem with mag-lev launch technologies; the heat generated by the magnets. Navy seems to have found some way around it as their next generation projected aircraft carriers are said to have mag-lev launchers.
So by alleviating the problem of heat which causes less magentism to occur due to the atoms being in a more excited state and moving around more rapidly so that the interaction between the particles of attracting and repelling each other does not occur that the plasma stream will become more magnetically cohesive so that the stream will yield a faster thrust velocity?

One way to possibly counter the problem of heat is by changing the use of the microwaves rate of involment that are used.

If the process can get by without having to have the combination of microwaves and particle beams operating in a continious flow from point A to point B but in a on off function where each type of wave or beam is turned on and off every Planck second there would be gaps within the interaction's between the plasma and the waves and beams. Gaps that would allow those particles most effected by the interaction between the microwaves and beams that are generating the most heat to have a Planck second or even upto five a Planck second of time to cool down.

Another approach might be to create atom sized pin holes in the cowling of the engine itself to allow the coldness of space to "draw" the heated particles into space and away from the plasma stream itself.

The question on how drawing the heat away from the plasma stream would depend on whether the particles creating the heat through the interaction's are long wave lengths or short wavelengths.

If the particles generating the heat are long wavelengths then their ability to continue to create heat when in the presence of a colder environment will drastically diminish. If the particles generating the heat are short wavelengths then their ability maintain their heat against the effects of cold will last longer thus allowing the heat to continue to be present.
 
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MeteorWayne

Guest
There was not one single sentence in that post that made any sense. :shock:
 
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csmyth3025

Guest
MeteorWayne":ik36cmt7 said:
There was not one single sentence in that post that made any sense. :shock:
I, too, am baffled by Dryson's post. The test results for the VX-200 are very encouraging with respect to making routine point-to-point space travel more practical.

My suggestion to Dryson is that, if you want to make design suggestions for this type of propulsion system, you should first learn how it works. A good place to start would be the Wikipedia article here: http://en.wikipedia.org/wiki/VASIMR#Development_of_the_200_kW_engine

Another good basic description (with pictures) can be found here: http://www.nytimes.com/imagepages/2009/10/27/science/space/27scillo_graphic.html?ref=space

Also, Dryson, I hope you meant to say Planck Time rather than "Planck Second". As far as I know, there is no such thing as a "Planck Second". The Planck Time is defined as ~5.39*10[super]-44[/super] seconds. The Wikipedia article on this unit of time can be found here: http://en.wikipedia.org/wiki/Planck_time

Chris
 
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dryson

Guest
Typical remarks coming from religious centrist's who cannot even produce evidence of their education into saying that someone does not know what they are talking about.
 
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dryson

Guest
I was reading in another post that heat was an issue. If the radio waves involved with creating the plasma process were emitted at broken interval's instead of a continous emittance then the particles that are generating the heat would be able to cool down thus eleviating some of the heat.

Basically it's similar to firing 1000 rounds of 5.56 ball ammo through a 249 SAW of which I have done while serving in the military. Anway. Unless the firing sequence is not done in short bursts the barrel will heat up causing the barrel to warp.

Interminent firing keeps the barrel cool due to the rounds not creating friction build-up within the barrel.

The same would occur with a constant radio wave being used in the process. The continious process of emitting the radio waves causes more heat to occur instead of the actual process of generating plasma. If the radio waves were emitted in a timed burst sequence then the process of creating the plasma energy release would be possibly see less heat generated and more plasma release to be used as thrust.
 
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