Author Topic: Power Supply for VASIMR  (Read 30426 times)

Offline wingod

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Re: Power Supply for VASIMR
« Reply #20 on: 12/01/2007 07:32 PM »
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neviden - 30/11/2007  5:53 PM

I agree with meiza. But the whole NEP concept doesn't even need 200 MWe to be useful. Even 10 MWe with present technology would work almost as good as chemical/NTP and allow reusable spaceship capable of reaching Mars orbit and returning back.

Anything with more power and better kW/kg ratio would only shorten transit times, increase payloads and increase capabilities.

yes but what it does is open the entire solar system to human exploration and development.  If this turns out to work it is civilization changing!!

The problem with low power VASIMR is that it has very low efficiency.  It needs the power to get into the best operating regime.

I am really stoked about this development!!





Offline neviden

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Re: Power Supply for VASIMR
« Reply #21 on: 12/02/2007 09:43 AM »
I agree that VASIMR could use lots and lots of power and that more power at lower weight will improve capabilities. Better reactors and more efficient power conversions will do both of those things.

But the thing that is holding VASIMR back is that it is used in the wrong way. It is almost like NASA always asks themselves: “OK, how will this technology help us in going to Mars. You know, something like Apollo.. “.

So that means that is not absolutely needed is “impossible”..

Reuse? “impossible”..
Existing launchers? “impossible”
Space refueling? “impossible”
Long term space flight? “impossible”
Growing food? “impossible”
Artificial gravity? “impossible”

So all plans for VASIMIR start at LEO, they must race to Mars at full speed (you know, because it is “impossible” to create 1 g environment in space or carry enough shielding to protect the crew) and return back. That means 200 MW space propulsion with minimum mass.. Reuse? Oh, that will come after that.. when they throw everything in the trash and start on completely new design in 50 years or so..

Offline TyMoore

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Re: Power Supply for VASIMR
« Reply #22 on: 12/02/2007 05:54 PM »
Just a few points:

1) The nuclear 'battery' concept is a possibly good choice for a stationary power supply, but as a flight weight reactor--it is unnecessarily heavy. A better choice of reactor power system would be a compact tungsten core with U-Zirconium alloy fuel rods (U-235 enriched to 90% or better) cooled with Helium gas run through a Brayton Cycle gas-turbine conversion system. Using two units counter rotating will eliminate undesirable gyroscopic effects. It's still heavy--but the conversion efficiency will approach 50%. The Uranium-Zirconium alloy fuel system is currently mature technology used aboard any US nuclear submarine (although they use pressurized water cooling and not helium gas!)

2) Thermodynamic efficiency isn't everything--because more efficient systems tend to expell heat at lower temperatures the size of the radiator increases inversely with the fourth power of the temperature of heat rejection. Because of this fact, a slightly less thermodynamically efficient power conversion system may actually end up being more mass-efficient (lighter weight) than it otherwise would have to be. In otherwords, it is sometimes O.K. to take a heat-efficiency hit if it means saving a lot of mass--you have to look at the system as a whole and identify and eliminate as many penalties as you can...

3) Electrostatic radiation shielding--works o.k., but it works better in conjunction with a strong magnetic field. And it won't work at all for shielding the eminations from a nuclear reactor. Why? Because the majority of the most dangerous radiation components are neutrons and gamma-rays--both of which are neutral and extremely penetrating. Only two things will help here: mass and distance. You put mass between yourself and the reactor--and you get the reactor as far away from you as you can. Unfortunately these operational requirements are at odds with the usual smaller, lighter design philosophy of spacecraft design. So the designer must then see if there is a way to use the reactor for another purpose--like as counter weight for a spinning artificial gravity system. The spacecraft designer will put much effort into attempting to solve more than one problem with the same solution!


Offline wingod

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Re: Power Supply for VASIMR
« Reply #23 on: 12/02/2007 06:26 PM »
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neviden - 2/12/2007  4:43 AM

I agree that VASIMR could use lots and lots of power and that more power at lower weight will improve capabilities. Better reactors and more efficient power conversions will do both of those things.

But the thing that is holding VASIMR back is that it is used in the wrong way. It is almost like NASA always asks themselves: “OK, how will this technology help us in going to Mars. You know, something like Apollo.. “.

So that means that is not absolutely needed is “impossible”..

Reuse? “impossible”..
Existing launchers? “impossible”
Space refueling? “impossible”
Long term space flight? “impossible”
Growing food? “impossible”
Artificial gravity? “impossible”

So all plans for VASIMIR start at LEO, they must race to Mars at full speed (you know, because it is “impossible” to create 1 g environment in space or carry enough shielding to protect the crew) and return back. That means 200 MW space propulsion with minimum mass.. Reuse? Oh, that will come after that.. when they throw everything in the trash and start on completely new design in 50 years or so..

Oh I agree that trying to use VASIMR deep in a gravity well is not the best idea out there.  

Remember Babylon V and the Earth starships?  A VASIMR would be the first step down that road.



Offline neviden

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Re: Power Supply for VASIMR
« Reply #24 on: 12/02/2007 08:21 PM »
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wingod - 2/12/2007  8:26 PM
Remember Babylon V and the Earth starships?  
Babylon V style space station would actually be quite a good idea to have in LEO or even better in HEO. And it would not require anything high tech that we would not be able to do right now. All we would have to do is create a thick (crude) metal cylinder and rotate it. After that you can fill it with air and you have a safe place just like Earth.

Earth starships that would look like Omega class destroyers or Leonov from 2010 are also quite possible and something that would actually work (without hyperspace stuff of course).

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wingod - 2/12/2007  8:26 PM
A VASIMR would be the first step down that road.
VASIMR is not the only propulsion technology. There are many plasma drives possible. I think it would be better to start with smaller, cheaper spaceships that would not cost that much (200 MW seems like an overkill) and upgrade them later.

What is important is to actually start using those new things. NASA will get $15 billion to spend no matter what it does. While it may seem like a good idea to throw money at Ares I and V, I think that this is complete waste of money. Even Ares V that might even make sense is a waste of money, since it will promote “hey, why bother with refueling and all that stuff! Let’s just build it, launch it and dump it.. “. There are plenty of perfectly good launchers already operating and completely underused.

20 MW electric spaceship would be more then able to do basic things and would be (more then 200 MW) price competitive with chemical option. That is the thing that is important, not what kind of reactor you have or how much time you spend in ship.. or at least.. it should be..

Offline advancednano

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Re: Power Supply for VASIMR
« Reply #25 on: 12/02/2007 10:48 PM »
Neviden

The topic of how NASA or the other space or government programs should spend there money is a separate topic.

Part of my recommendation on that is related to my suggested plan for winning the google Xprize for lunar robot landing.

http://advancednano.blogspot.com/2007/09/outline-of-how-to-win-google-lunar.html

We should not spend a bunch of money on another big chemical rocket.

Nasa should use existing rockets like the russian Dnepr or SpaceX rockets ($10 million per rocket) and send a constant stream of rockets to the moon using low energy orbital transfers. Get 3000-4000lbs to earth orbit and then spend 10% of the weight to get to lunar orbit in 5 months. Help armidillo finish new lunar landers. They should land robots there like the Carnegie Mellon mining robot. Robotics should be used to build up facilities and resources for people to exploit later. We could start landing $30-50 million missions every week. About 2000 lbs on each trip to the lunar surface. Once all the facilities are built up we can look at when it makes sense to  send people.

For new vehicle development, we should only be paying for radical improvement.

A ram accelerator launch system looks like it could be put together for $500 million and that it could send hardened payload into orbit for $500/kg.
http://advancednano.blogspot.com/2007/08/cheaper-space-launch-500kg-or-less-ram.html

Skylon or the plasma hypersonic vehicle might work and could make sense if the military wanted to help foot the bill. For Nasa, I would stick with nuclear and laser arrays. If the once a week 2000 lbs to the lunar surface worked out starting next year. Then I would look at using the lunar facilities to build simple nuclear rockets and power systems (plus solar). We need hundred of MW and GW for a real space infrastructure.

Offline Lampyridae

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Re: Power Supply for VASIMR
« Reply #26 on: 12/02/2007 11:37 PM »
What is really needed is a change in directive, as well as management in NASA. Bush said "go back to the moon, and then go on to Mars." That's exactly what they're doing, although flawed thinking and a lack of plain old common sense has landed them with the Ares problem. What would have been the easiest thing? Build a SDLV with oodles of power by banging on engines to the external tank. But no, NASA's doing the complicated thing because it looked easy at the time - and to carry out their directive given to them by the boss (George 2.0).

If George 2.0 had said "develop a sustainable lunar architecture," then NASA would have done it in a sub-optimal way, because they're about science and tech, not space economics. What NASA is doing right now with COTS and what's going on with the various X- and Google-prizes is in my opinion the best thing.

Sending cargo to the moon with low-cost, existing rockets would be far more expensive than doing it the NASA way. This has been discussed many times over:
1. Massive infrastructure upgrades needed to support required launch volume
2. Minimum mass requirements of systems which do not scale down well mean smaller payload fraction (e.g. avionics - you can't have 1/10 of an avionics box; also minimum thickness for fuel lines, nozzles etc)
3. Minimal economies of scaling
4. Fixed per-launch support costs (e.g. mission control requires almost the same staff for big rocket as a small one)

With all this a Dnepr could land maybe a 10kg payload on the moon for $10 million. A Falcon 9, OTOH, maybe 1 tonne for $100 million? That's an order of magnitude $/kg costs. Rather go with big commercial rockets, build up the robotic infrastructure as you suggested, and then land crew using dirt-cheap rocket chairs from orbit, much like the private lunar base plan. But leave NASA out of it, except to provide competition money. Further down the road, if someone invests $10 billion and 10 years into Skylon, then maybe after another 10 years we'll have a system which can do $1000/kg. Note that Skylon is only slightly more cost-effective as Falcon 9 Heavy, but has a lower payload mass. Hypersonic SSTO will only be an outgrowth of suborbital / hypersonic travel, nobody's going straight from A to Z.
SKYLON... The League of Extraordinary Gentlemen's preferred surface-to-orbit conveyance.

Offline wingod

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Re: Power Supply for VASIMR
« Reply #27 on: 12/02/2007 11:54 PM »
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Lampyridae - 2/12/2007  6:37 PM

What is really needed is a change in directive, as well as management in NASA. Bush said "go back to the moon, and then go on to Mars." That's exactly what they're doing, although flawed thinking and a lack of plain old common sense has landed them with the Ares problem. What would have been the easiest thing? Build a SDLV with oodles of power by banging on engines to the external tank. But no, NASA's doing the complicated thing because it looked easy at the time - and to carry out their directive given to them by the boss (George 2.0).

If George 2.0 had said "develop a sustainable lunar architecture," then NASA would have done it in a sub-optimal way, because they're about science and tech, not space economics. What NASA is doing right now with COTS and what's going on with the various X- and Google-prizes is in my opinion the best thing.

Sending cargo to the moon with low-cost, existing rockets would be far more expensive than doing it the NASA way. This has been discussed many times over:
1. Massive infrastructure upgrades needed to support required launch volume
2. Minimum mass requirements of systems which do not scale down well mean smaller payload fraction (e.g. avionics - you can't have 1/10 of an avionics box; also minimum thickness for fuel lines, nozzles etc)
3. Minimal economies of scaling
4. Fixed per-launch support costs (e.g. mission control requires almost the same staff for big rocket as a small one)

With all this a Dnepr could land maybe a 10kg payload on the moon for $10 million. A Falcon 9, OTOH, maybe 1 tonne for $100 million? That's an order of magnitude $/kg costs. Rather go with big commercial rockets, build up the robotic infrastructure as you suggested, and then land crew using dirt-cheap rocket chairs from orbit, much like the private lunar base plan. But leave NASA out of it, except to provide competition money. Further down the road, if someone invests $10 billion and 10 years into Skylon, then maybe after another 10 years we'll have a system which can do $1000/kg. Note that Skylon is only slightly more cost-effective as Falcon 9 Heavy, but has a lower payload mass. Hypersonic SSTO will only be an outgrowth of suborbital / hypersonic travel, nobody's going straight from A to Z.

You know I don't buy this at all.  Bush in his speech specifically said that the ships that go to Mars could do it with propellants made on the Moon.  This implies a robust ISRU capability that NASA has ignored so far as ISRU propellant production is not anywhere near the baselines for the Lunar DRM.

Also, EELV's will be critical for the RTM.  The Ares V is going to be a billion dollars a launch and there are few payloads that need that kind of system.  The Delta IV or Atlas V heavies can put 4500 kg on the lunar surface and the small ones can put 1500 kg.  This is plenty for resupply, for a lot of hardware, and a much higher delivery rate than just a single cargo mission per year.

Also, it is not true about the infrastructure.  Today in Decatur AL there is the ability to manufacture 23 booster cores per year with the existing tooling and facilities.  That is plenty to support lunar missions and this does not count the production capacity in Colorado which is probably another 15 more cores per year.  

A sustainable architecture will have more than just the Ares system, no matter how it is built out.



Offline wingod

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Re: Power Supply for VASIMR
« Reply #28 on: 12/02/2007 11:56 PM »
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neviden - 2/12/2007  3:21 PM

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wingod - 2/12/2007  8:26 PM
Remember Babylon V and the Earth starships?  
Babylon V style space station would actually be quite a good idea to have in LEO or even better in HEO. And it would not require anything high tech that we would not be able to do right now. All we would have to do is create a thick (crude) metal cylinder and rotate it. After that you can fill it with air and you have a safe place just like Earth.

Earth starships that would look like Omega class destroyers or Leonov from 2010 are also quite possible and something that would actually work (without hyperspace stuff of course).

Quote
wingod - 2/12/2007  8:26 PM
A VASIMR would be the first step down that road.
VASIMR is not the only propulsion technology. There are many plasma drives possible. I think it would be better to start with smaller, cheaper spaceships that would not cost that much (200 MW seems like an overkill) and upgrade them later.

What is important is to actually start using those new things. NASA will get $15 billion to spend no matter what it does. While it may seem like a good idea to throw money at Ares I and V, I think that this is complete waste of money. Even Ares V that might even make sense is a waste of money, since it will promote “hey, why bother with refueling and all that stuff! Let’s just build it, launch it and dump it.. “. There are plenty of perfectly good launchers already operating and completely underused.

20 MW electric spaceship would be more then able to do basic things and would be (more then 200 MW) price competitive with chemical option. That is the thing that is important, not what kind of reactor you have or how much time you spend in ship.. or at least.. it should be..

I am thinking about their large transportation vehicles that had the spinning section for the humans.  The B-V space station is a bit down the road.

Offline neviden

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Re: Power Supply for VASIMR
« Reply #29 on: 12/03/2007 08:56 AM »
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advancednano - 3/12/2007  12:48 AM
The topic of how NASA or the other space or government programs should spend there money is a separate topic.
It is, but VASIMR and things like that don’t get used because of the way money is spent. There is nothing wrong with technology or the concept.

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advancednano - 3/12/2007  12:48 AM
Nasa should use existing rockets like the russian Dnepr or SpaceX rockets ($10 million per rocket) and send a constant stream of rockets to the moon using low energy orbital transfers.
You can’t get things from LEO to Moon via low energy orbital transfers (ITN I presume). You need 3 km/s delta-v to come anywhere near the place where you could enter ITN and by then you are already at the Moon. You could use SEP/NEP to cut down the fuel requirements though.

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advancednano - 3/12/2007  12:48 AM
Once all the facilities are built up we can look at when it makes sense to  send people.
I think you underestimate the size of the problem. Dnepr size chunks would be too small to make them into a base for humans (you can’t make humans smaller). You would probably need 20 mT size chunks.

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Lampyridae - 3/12/2007  1:37 AM
Sending cargo to the moon with low-cost, existing rockets would be far more expensive than doing it the NASA way. This has been discussed many times over:
And that thinking is the reason why it costs $100 billion to send 4 men to Moon/Mars..

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Lampyridae - 3/12/2007  1:37 AM
1. Massive infrastructure upgrades needed to support required launch volume
Seriously? You believe that?

There is no reason why you would need anything more massive then you have now. Sure, you would have to build few more factories that would mass produce those rockets, but that is about it. Ask the Russians if it is possible to launch one rocket every week and how hard would that be..

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Lampyridae - 3/12/2007  1:37 AM
2. Minimum mass requirements of systems which do not scale down well mean smaller payload fraction (e.g. avionics - you can't have 1/10 of an avionics box; also minimum thickness for fuel lines, nozzles etc)
So? Who cares.. all that it matters is that you can bring some reasonable payload into LEO for certain price.

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Lampyridae - 3/12/2007  1:37 AM
3. Minimal economies of scaling
Not surprising since you must support everything even if you build and launch few rockets.. try building hundreds of rockets then come back to me with economies of scale..

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Lampyridae - 3/12/2007  1:37 AM
4. Fixed per-launch support costs (e.g. mission control requires almost the same staff for big rocket as a small one)
And whose fault is it that you must have few thousand people for every launch instead of few dozens? How about if you automate some of that work, eh?

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Lampyridae - 3/12/2007  1:37 AM
With all this a Dnepr could land maybe a 10kg payload on the moon for $10 million. A Falcon 9, OTOH, maybe 1 tonne for $100 million?
Try looking at the problem in terms of containers. You make things in some factory in China, you put them into big box. After that you use trucks, rail, ship, rail again, ship and at the end you get your things delivered to your door in wherehouse in some city in US. Only there you open your box to get the things.

Dnepr and Falcon 9 would launch containers. “Trucks, rail, ship and stuff” would also launch on those rockets but on a separate occasions.

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wingod - 3/12/2007  1:56 AM
I am thinking about their large transportation vehicles that had the spinning section for the humans.
http://en.wikipedia.org/wiki/Leonov_%28fictional_spacecraft%29
http://en.wikipedia.org/wiki/EAS_Churchill (Omega)

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wingod - 3/12/2007  1:56 AM
The B-V space station is a bit down the road.
It shouldn’t be. All you would need to know is how to create big plates out of some metal (how do you get them and where is the hard part. Easiest would be to get materials from NEOs since that has the lowest delta-v to get to HEO, or even melted down upper stages from rockets in LEO), weld them together and spin them up. After that you can use any technology that you use on Earth since you have 1 g.

Radiation and temperature protection?
Put some of the material on the lowest floor (outer most floor). Concrete, dirt, water, propellants… whatever..

Food and air?
http://ag.arizona.edu/ceac/research/SouthPoleChamber/index.htm

Offline advancednano

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Re: Power Supply for VASIMR
« Reply #30 on: 12/03/2007 09:30 PM »
I had believed that low energy orbital transfers would work better considering how well the Hiten did. Checking it again I guess the Belbruno Transfer is only 18% better than Holmann.

I guess then some kind of electrical propulsion tug would be needed to move things from low earth orbit to ITN entry to achieve what I envision. Which is get most of what we stick in LEO over to the moon. Then the chunks would become bigger.

People don't get smaller but if we are only sending people after we have stuff built out then the cost and number of trips would go way down.

Offline neviden

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Re: Power Supply for VASIMR
« Reply #31 on: 12/03/2007 10:13 PM »
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advancednano - 3/12/2007  11:30 PM
People don't get smaller but if we are only sending people after we have stuff built out then the cost and number of trips would go way down.
20 mT is the payload of the cargo Ares V to the Moon surface. It is also maximum payload for quite a few rockets that fly. It is probably the best number to plan things around. Number of landings until you get “ready for humans” would also be lower with higher weight.

VASIMR could probably be quite useful here, but it would need somewhere in the neighborhood of 1 - 10 MW of electricity to move things in some reasonable timeframe. Van Allen belt would mean that you need quite robust solar cells, but SEP would be quite feasible. Starting LEO orbit would have to be a little higher then NEP, but then again everybody would get very nervous if NEP got to close to Earth.

STP (solar thermal propulsion) would be an option also but its isp is quite low (around 800 s) and it would not be that much faster then high power SEP with far smaller propellant requirement. I wouldn’t even consider NTP. Chemical would probably be preferable for fast manned transfer to Moon orbit.

Offline clongton

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Re: Power Supply for VASIMR
« Reply #32 on: 12/03/2007 10:38 PM »
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neviden - 3/12/2007  6:13 PM

{snip} Starting in LEO orbit would have to be a little higher than NEP, but then again everybody would get very nervous if NEP got to close to Earth. {/snip}
Slightly off topic, but people seem to have this morbid fear of an EXTREMELY overblown danger of the NEP. People appear to think that the earth is MUCH smaller than it really is, and that the NEP power supply is MUCH bigger than it is. It is a completely irrational and thoroughly overblown and unfounded fear. If a spacecraft with a NEP power source actually "exploded", the NEP power source would drop most likely into the ocean, completely intact, with NO radiation leak. That's how they would be designed because they wouldn't be allowed to fly in any other condition.

I personally would have absolutely no fear of a NEP or even an NTP powered spacecraft going over my head. They are, or would be safe, completely safe.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline neviden

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Re: Power Supply for VASIMR
« Reply #33 on: 12/03/2007 11:06 PM »
I don't think that is off topic since the topic is "Power Supply for VASIMR"..

I do agree that nuclear fear is overblown, but that is politics. Solar is clean, nuclear isn’t and will get protests or worse. Deep space NEP missions could possibly get less attention, but LEO - Moon orbit - LEO tug would always stay near the Earth.

I would dismiss NTP even without that fear consideration based only on performance. It delivers small improvement over chemical, with bunch of extra problems and costs.

Offline superczar

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RE: Power Supply for VASIMR
« Reply #34 on: 01/26/2008 07:20 PM »
:cool:
Let's hear it for some of the Vasimr power supply posters but I think we'll have to admit that the Vasimr concept is not one of a propulsion system if it dosen't include what's been gone over in many of the posts, i.e power densities, launch costs, overall mission ISPs. Plus there isn't alot to recommend Vasimr. for instance what are the actual specs not the hype I've had to swallow. There's no reason that an ion propulsion engine couldn't be devised that was superior to Vasimr and didn't use what I consider its downfall - magnetic fields, or more specifically the gimmicky way they're touted for varying specific impulse. It certainly dosen't seem possible that its the best way to vary ISP. Frankly, I think we all got robbed on this one. Varying the ISP of an ion discharge is as easy as changing the accelerating voltage - not a major project in my estimation. There are some fairly efficient ways to ionize matter too, i.e hollow cathodes as in a few successful missions which have already flown. Or how about small radius-of-curvature ionization. It seems feasible that a powerful enough lightweight engine could easily be constructed using one of these concepts or even helicon waves which Vasimr uses and which I explored independently of Vasimr knowledge some years ago.

Anyway the general high ISP-NEP concept is sound and would seem the way to go in pushing forward exploration (including interstellar), asteroid deflection,and other apps. Also any push to develop a decent power supply would have spinoff benefits. I think this is most easily achieved with a particle bed design (fission) although there has been some bad press and a debacle in relation to it. Certainly all of the claims dealing with technology that tries to cut the edge where there's no edge to cut shouldn't be funded. There is reason to hope that a non-Carnot heat engine principle could be developed to eliminate bulky heat rejectors. An MHD or similar conversion system seems the best hope. Powerchips (whatever they are) are most likely not designed to function efficiently or at all in this app (basically they're looking like a puddle of goo). By the way the efficiency was listed as 70-80% of the Ideal Carnot efficiency which does not imply anywhere near 70-80% efficiency.

Since there already have been high ISP missions flown  and the only place to go is to augment with a superior power supply the death-knell for the cutting-edgedness of Vasimr was sounded long ago. Cheers.

Offline advancednano

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many small cheap rockets
« Reply #35 on: 02/05/2008 04:37 PM »
Using fuel depots in low earth orbit would increase the payload that could be delivered to the moon by 3-15 times. This would make the many smaller cheaper approach more feasible and effective

Offline clongton

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RE: many small cheap rockets
« Reply #36 on: 02/05/2008 04:44 PM »
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advancednano - 5/2/2008  12:37 PM

Using fuel depots in low earth orbit would increase the payload that could be delivered to the moon by 3-15 times. This would make the many smaller cheaper approach more feasible and effective
And this relates to Vasimr power supply how?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline advancednano

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RE: many small cheap rockets
« Reply #37 on: 02/05/2008 10:49 PM »
As part of the thread (this thread) about Vasimr there was a discussion about how money is currently spent on space (whether Vasimr should be funded or other things). I mentioned that a lot of cheap rockets would be better than spending many billions developing just another chemical rocket like Nasa is doing now. Then it was pointed out that cheap rockets would not be able to deliver much payload to the moon. The space fuel depot would be an affordable system and architecture which would help enable the use a bunch of cheap rockets to do more in space approach. Relating to Vasimr in that any advanced system is within the context of doing more in space cheaper and sooner.

Offline clongton

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RE: many small cheap rockets
« Reply #38 on: 02/06/2008 03:23 AM »
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advancednano - 5/2/2008  6:49 PM

As part of the thread (this thread) about Vasimr there was a discussion about how money is currently spent on space (whether Vasimr should be funded or other things). I mentioned that a lot of cheap rockets would be better than spending many billions developing just another chemical rocket like Nasa is doing now. Then it was pointed out that cheap rockets would not be able to deliver much payload to the moon. The space fuel depot would be an affordable system and architecture which would help enable the use a bunch of cheap rockets to do more in space approach. Relating to Vasimr in that any advanced system is within the context of doing more in space cheaper and sooner.
I follow your thinking but the thread is about the VASIMR Power Supply, not about other ways to do things with other kinds of rockets.
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I started my career on the Saturn-V F-1A engine

Offline Patchouli

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RE: Power Supply for VASIMR
« Reply #39 on: 02/13/2008 05:34 PM »
The nuclear battery sounds like what we have been waiting for as it solves the issues with the size of the radiators you'll still need them but they can be much smaller now also maybe see if you can get a few more tens of KW out of said nuclear battery by making it's cooling system a Rankine organic cycle turbine which do work well with small temperature gradients.
Heck maybe also include some thermoelectric devices on the batts just to squeeze that last bit of power out of the system but only after it's found they will not add more mass then what the extra delta V you'll get from the extra power can move.

the ORC turbine http://en.wikipedia.org/wiki/Organic_Rankine_Cycle

I believe producing lots of electric power in space is likely the most important engineering breakthrough needed for crewed deep space missions even HLLVs like ares V are optional as most things can be launched in pieces if needed but energy dense power sources are not optional as there is no way around it.

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