39 days to Mars possible now with nuclear-powered VASIMR.

[peadar1987]

I'm curious. What does the NIST REFPROP 9.0 program say is the efficiency of the SSME when you take into account the mixture ratio is only 6 to 1? This would leave 1/4th the hydrogen uncombusted so would reduce the initial thermal energy.

Hydrogen combines with oxygen at 8:1 mass ratio, so if the mass ratio is 6:1, then for every 3 H2O you make, you're left with 1 H2 left over, giving you 96.4% H2O in your exhaust, with the remaining 3.6% being H2 (by mass).

Turns out a mass fraction of 0.036 hydrogen doesn't make much of a difference in the calculation, it still comes out as roughly 12500kJ/kg, so the thermal efficiency isn't affected. The ISp will go up though, because the propellant you're throwing out the back is lighter.

About the efficiency of turbopumps in general, the source I read that said some pumps were able to reach 90% efficiency was on general centrifugal pumps, which no doubt included water pumps:

Centrifugal Pump Efficiencyâ€â€What Is Efficiency?

2012-02-01 ISSUE

by Joe Evans, Ph.D

The only case I saw of a pump with higher than 90% efficiency was of hydroelectric turbines driven by water flow that convert this to mechanical power at 95% efficiency.

The SSME hydrogen pumps from a different source, were quoted as at 80% efficiency. Probably good enough, but I'd like to see if they could be pushed to 90% by sacrificing some weight efficiency.

Bob Clark

Yep, these won't be thermal efficiencies, they'll be isentropic efficiencies.

Things like centrifugal pumps aren't heat engines, so they work slightly differently. As your link says, it's a relation between the amount of mechanical work you put in at the shaft, compared to the amount of energy that actually ends up being added to the fluid. You're not converting heat to mechanical energy in this case, you're converting mechanical energy to mechanical energy, which is a much easier conversion.

Edited September 1, 2015 by peadar1987

[tater]

VASIMIR is pixie dust right now for the OP statement of 39 days to Mars. It requires higher specific power than is available. For both solar and nuclear, electric conversion is lossy compared to thermal, so it might be better to just go that route. There are loads of propulsion options open if you allow yourself to imagine arbitrarily good nuclear reactors to power them.

Guestimating nukes based on a Sterling engine calculator is not terribly helpful, as higher power reactors are likely not going to use Sterling cycle, instead, a different cycle (Brayton, etc) as Sterling becomes complicated in the real world (which is why you don't see many being used).

[AngelLestat]

>_<!

still with the pumps?

Electrical engines = 90% to 95% efficiency, of course the penalty comes with the batteries.

Turbo Pumps = 50% efficiency.

Here´s a paper that compare turbo pumps, electrical pumps or just with pressurized gas.

Only the first 34 pages.

http://www.aacademica.com/hernan.emilio.tacca/9.pdf

[PB666]

>_<!

still with the pumps?

Electrical engines = 90% to 95% efficiency, of course the penalty comes with the batteries.

Turbo Pumps = 50% efficiency.

Here´s a paper that compare turbo pumps, electrical pumps or just with pressurized gas.

Only the first 34 pages.

http://www.aacademica.com/hernan.emilio.tacca/9.pdf

I have been resisting commenting on this until now. The problem with this analysis is two fold.

First the SSME in its most efficient varient is around 460 sec, which is only 10 ISP units lower than the most efficient B-X. Both are very close to the theoretical maximum ISP for LFOx engines. The difference between the B-X and the SSME is that the shuttle engine is designed to run both at lift-off and in space, the second is a second/third stage engine designed to carry payload to its final destination. THe SSME does not have the advantage of moderate burns, at lift off it might be pushed to 109%, and at the thrust, temperatures, and heat transfers it has to keep vapor locks from developing in either of the too pumps. So its not going to be as perfect if you have two perfectly pressurized tanks feeding an engine that ca operating at its optimum thrust.

The second issue is this. The SSME bleeds a little H and O to run the burner that the turns the Turbopump, its not very efficient, but the energy is largely not lost, because the outlet gas is fed into the reaction chamber and the further expands and is ejected with the other gases. The calculation does not consider the alternative, how efficient would an electric turbine be in the same position.

Another issue I want to pick on, 39 days is not a magic number. If you had infinite acceleration you could reach Mars in a day. The VASIMR does not need to achieve Mars in 39 days, the engine itself could be used at a much lower power setting than its maximum, while using battery and solar to kick obeth effects around the earth for several days prior to pushing itself into space. For most of the trip niether drive will be used, the oroblem is stopping before reaching Mars, howver there is alot of time to decelerate. If you create an artificial goal of 39 days then many strategies will fail

The fact of the matter is, you don't need to use nukes or ion to leave earth, you can stage LFOx until the craft is on an escape trajectory and use a little ion drive to reach Mars Orbit. The trip back is going to be a wait, and here again an Ion drive parked at Mars L1 will have sufficient enough power to return to earth.

Lets not create artficial targets. The real problem here is landing on mars and keeping folks alive for 2 years.

[problemecium]

Neat!

That is all. xD

[Exoscientist]

Hydrogen combines with oxygen at 8:1 mass ratio, so if the mass ratio is 6:1, then for every 3 H2O you make, you're left with 1 H2 left over, giving you 96.4% H2O in your exhaust, with the remaining 3.6% being H2 (by mass).

Turns out a mass fraction of 0.036 hydrogen doesn't make much of a difference in the calculation, it still comes out as roughly 12500kJ/kg, so the thermal efficiency isn't affected. The ISp will go up though, because the propellant you're throwing out the back is lighter.

So what is the percentage of the energy that gets converted to kinetic energy when you take into account the higher Isp?

Bob Clark

[peadar1987]

So what is the percentage of the energy that gets converted to kinetic energy when you take into account the higher Isp?

Bob Clark

It'll be the same as before.

My previous calculation didn't assume anything about the velocity of the exhaust, it just took the figure from wikipedia. Apparently, to get that figure, you need a small proportion of hydrogen in the exhaust. If the hydrogen wasn't there, the exhaust velocity would be slightly lower, so I'd need to redo the calculation with that new exhaust velocity.

[shynung]

I have been resisting commenting on this until now. The problem with this analysis is two fold.

First the SSME in its most efficient varient is around 460 sec, which is only 10 ISP units lower than the most efficient B-X. Both are very close to the theoretical maximum ISP for LFOx engines. The difference between the B-X and the SSME is that the shuttle engine is designed to run both at lift-off and in space, the second is a second/third stage engine designed to carry payload to its final destination. THe SSME does not have the advantage of moderate burns, at lift off it might be pushed to 109%, and at the thrust, temperatures, and heat transfers it has to keep vapor locks from developing in either of the too pumps. So its not going to be as perfect if you have two perfectly pressurized tanks feeding an engine that ca operating at its optimum thrust.

The second issue is this. The SSME bleeds a little H and O to run the burner that the turns the Turbopump, its not very efficient, but the energy is largely not lost, because the outlet gas is fed into the reaction chamber and the further expands and is ejected with the other gases. The calculation does not consider the alternative, how efficient would an electric turbine be in the same position.

Another issue I want to pick on, 39 days is not a magic number. If you had infinite acceleration you could reach Mars in a day. The VASIMR does not need to achieve Mars in 39 days, the engine itself could be used at a much lower power setting than its maximum, while using battery and solar to kick obeth effects around the earth for several days prior to pushing itself into space. For most of the trip niether drive will be used, the oroblem is stopping before reaching Mars, howver there is alot of time to decelerate. If you create an artificial goal of 39 days then many strategies will fail

The fact of the matter is, you don't need to use nukes or ion to leave earth, you can stage LFOx until the craft is on an escape trajectory and use a little ion drive to reach Mars Orbit. The trip back is going to be a wait, and here again an Ion drive parked at Mars L1 will have sufficient enough power to return to earth.

Lets not create artficial targets. The real problem here is landing on mars and keeping folks alive for 2 years.

May I suggest a large inflatable heatshield?

[PB666]

May I suggest a large inflatable heatshield?

NASA is testing a devise right now, not a heat sheild but a hig velocity parachute, its failed twice so ......

[shynung]

NASA is testing a devise right now, not a heat sheild but a hig velocity parachute, its failed twice so ......

For aerobraking, not final descent. Something like NASA's Low Density Supersonic Decelerator.

Basically, stick this thing on the nose of the ship going to Mars. Aerobrake into Martian orbit.

[AngelLestat]

Ok, now I understand why the mass ratio of the atomic rockets site is so big, they assumed for a fix wasteheat of 250 mw.

And I guess they showed that way, because that site serve as source for space role games.

But that is not the best way to represent radiators values.. The best way is kw/kg, in this way, not matter how much heat you need to radiate, you can calculate depending the tech of choice, how much mass you are adding.

This site support my view to maximize the core temperature:

"There is a conflicting requirement to both maximise thermal efficiency and maximise the temperature at which heat is rejected. Need to maximise the reactor outlet temperature."

http://www.nnl.co.uk/media/1921/nnl-tech-conference-15-fcs-zara-hodgson.pdf

Here there is a good site that explain how to make all calculations needed for a radiator.

http://www.icarusinterstellar.org/starship-radiators/

For a Nuclear-radiator-vasimr setup, we might be talking about 2 kw/kg.

For solar-vasimr setup, we might be talking about 4kw/kg at distances equal or lower than 1au, the benefic that is a lot cheaper and easy to make, it also seems more usefull for low payloads and travels to venus.

Advances in Graphene, cnt and optics can improve both setups Nuclear-Solar by a considerable margin.

It will be nice if they can build a reusable nuclear-vasimr ship to realize all missions beyond earth, but it will take time.. We should focus on Venus first.

[PB666]

Ok, now I understand why the mass ratio of the atomic rockets site is so big, they assumed for a fix wasteheat of 250 mw.

And I guess they showed that way, because that site serve as source for space role games.

But that is not the best way to represent radiators values.. The best way is kw/kg, in this way, not matter how much heat you need to radiate, you can calculate depending the tech of choice, how much mass you are adding.

This site support my view to maximize the core temperature:

"There is a conflicting requirement to both maximise thermal efficiency and maximise the temperature at which heat is rejected. Need to maximise the reactor outlet temperature."

http://www.nnl.co.uk/media/1921/nnl-tech-conference-15-fcs-zara-hodgson.pdf

Here there is a good site that explain how to make all calculations needed for a radiator.

http://www.icarusinterstellar.org/starship-radiators/

For a Nuclear-radiator-vasimr setup, we might be talking about 2 kw/kg.

For solar-vasimr setup, we might be talking about 4kw/kg at distances equal or lower than 1au, the benefic that is a lot cheaper and easy to make, it also seems more usefull for low payloads and travels to venus.

Advances in Graphene, cnt and optics can improve both setups Nuclear-Solar by a considerable margin.

It will be nice if they can build a reusable nuclear-vasimr ship to realize all missions beyond earth, but it will take time.. We should focus on Venus first.

The problem with VASIMR, IIRC, is the RF generators (2) and containment of RF heat. Sure you can get the RF generators 'into' high conductivity metals and the like, sort of like an RF laser, but the problem is that RF is heat once it is absorbed by something afterall that is how it moves the ions in the drive. If they can provide perfect containment of RF and ions inside of the acceleration chamber, then they can get rid of the heat as it is ejected completely out the back as EM drive would with ion velocity increases. I read something the other day and posted it in questions that don't deserve that one cannot precisely control the frequency polarity and direction of light because of the Heisenberg uncertainty principle. The manage to make very green light by quantum scattering it off of atoms.

Venus is not a smart choice if you are having a problem keeping things cool, you have to add mass to protect from the sunlight. Of they can cut down the waste heat problem, they need less power, if they need less power then they may be able to avoid the nuclear stuff.

[tater]

First you'd need to actually make power, and 2 or 4 kW/kg power production is science fiction, so rejecting waste heat is not even an issue at this point. The OP claim requires power production that doesn't exist. It might as well say, "electrical generation via antimatter or fusion makes VASIMR now possible."

Nuclear power is effective, and safe, and should be in space (yesterday), but 39 days to Mars with VASIMR is not anywhere on the horizon.

[AngelLestat]

The problem with VASIMR, IIRC, is the RF generators (2) and containment of RF heat. Sure you can get the RF generators 'into' high conductivity metals and the like, sort of like an RF laser, but the problem is that RF is heat once it is absorbed by something afterall that is how it moves the ions in the drive. If they can provide perfect containment of RF and ions inside of the acceleration chamber, then they can get rid of the heat as it is ejected completely out the back as EM drive would with ion velocity increases. I read something the other day and posted it in questions that don't deserve that one cannot precisely control the frequency polarity and direction of light because of the Heisenberg uncertainty principle. The manage to make very green light by quantum scattering it off of atoms.

I think that I am not qualify to discuss in deep the vasimr mechanism and physsics involve, not sure how you relate this with EM drive..

One has totally sense, the other not.

If it needs superconductors to improve its efficiency, then I dont see any problem with that, you will need an extra radiator for that, it may worth it or not.

Venus is not a smart choice if you are having a problem keeping things cool, you have to add mass to protect from the sunlight. Of they can cut down the waste heat problem, they need less power, if they need less power then they may be able to avoid the nuclear stuff.

Missions to venus (manned or not) are cheaper and easier. You get all your power from sunlight, why that would be bad?

The same solar panels can be your radiators.. the amount of power you need to radiate by unit of area is low. In any case you can use a stirling engine with extra radiators to increase your efficiency.

Or you can make a full thermal collector instead PV if you manage to concentrate solar light using very thin reflective layers.

But PV already reach 45% efficiency so not sure if it worth it. Also as I said, a solar system is a lot cheaper than nuclear, but to go mars or beyond, a nuclear ship has a lot of sense.. but you need to talk about 300 to 400 tons with many safety measures, it might cost more than the ISS.

First you'd need to actually make power, and 2 or 4 kW/kg power production is science fiction, so rejecting waste heat is not even an issue at this point. The OP claim requires power production that doesn't exist. It might as well say, "electrical generation via antimatter or fusion makes VASIMR now possible."

but 39 days to Mars with VASIMR is not anywhere on the horizon.

100 days might be a logical goal, you dont need huge radiators with powerful reactors and big thermal engines.

PD: I send you the answer by PM explaning why the source of nuclear vs wind "safest energy source" was trash.

[tater]

Even 100 days is not a thing with VASIMR.

There is no reactor, and any plausible reactors of the right output will have a total mass (including radiators) substantially higher than VASIMR needs for the hype numbers quoted.

PS, it's not trash at all, and I never said "safest," I think I said that nuclear is "incredibly safe," and it certainly is. Solar is not inherently dangerous (past mounting stuff on roofs), and no one is actually saying this, it just makes a small amount of power. The point isn't that nuclear is grossly safer, the point is that it is not grossly more dangerous (it's clearly safer than coal, miners die yearly, and there has only been one nuke accident that has caused deaths past normal workplace injuries, ever, with a bad, old design). For the US, each death even tangentially related to the solar power industry requires 61 deaths in the nuclear industry to be equal in safety per TWh. There are likely a few deaths in each industry per year, just as there are a few deaths in Walmart due to fork lift crashes, etc. Unless nuclear has 61 times more, it's safer.

[AngelLestat]

If we manage to do reactors of more than 1 gigawatt in earth, why we can not do a reactor from 10 to 100 megawatts in space?

About radiators, just 1 week ago they found a way to manage and control a fluid dopplet radiator:

https://mipt.ru/en/news/cooling_201508

By the way, not sure why they choose "X" setup for radiators instead line "l", the X setup absorb radiation from other radiatiors, and sun.

You have also this project that is trying to find the best way to solve all problems related to:

Megawatt Highly Efficient Technologies for Space Power and Propulsion Systems for Long-duration Exploration Missions

http://cordis.europa.eu/result/rcn/161150_en.html

---------------------------

I told you that you can not compare house rooftop with nuclear plants, if you want to compare do it with solar farms vs nuclear plant "global", not just picking locations, I dont know the real numbers for solar, I just knew that the data for wind was total false, and if they was so unprofessional to manage wind data and nuclear data, then is not hard to imagine is the same for the rest of the study.

Remember that this original publication was removed due hard and proven criticism.

Edited September 3, 2015 by AngelLestat

[tater]

What is the mass of a terrestrial 1 GW reactor? Include all heat sinks (say seawater passed through a heat exchanger, plus the entire mass of air that the seawater might also interact with. And the earth, for conductive heat loss).

The issue is power per unit mass, not the ability to make X power on earth with no mass limitations. Spaceflight is about payload fraction.

- - - Updated - - -

I told you that you can not compare house rooftop with nuclear plants, if you want to compare do it with solar farms vs nuclear plant "global", not just picking locations, I dont know the real numbers for solar, I just knew that the data for wind was total false, and if they was so unprofessional to manage wind data and nuclear data, then is not hard to imagine is the same for the rest of the study.

Remember that this original publication was removed due hard and proven criticism.

I'm not quoting any study whatsoever. Do the math. It is not solar farms vs nuke plants, it's ALL solar. You cannot cherry pick, as solar is a distributed system*. You are welcome to use occupational safety stats, and compare to power produced. When you get to a certain level of safety, ranking things is sort of silly. Nuclear, solar, and wind are all very safe. If you make a claim nuclear is more dangerous, prove it. I only argue that nuclear is safe, and in fact substantially safer than fossil fuels.

*BTW, you'd still lose, assume the safety of nuclear plants for both "plant only" sources (US nuke plants have 1/2 the national average of fatalities per 100,000 workers). Now weight by power produced. Nukes win. We're down in the small decimal places, because BOTH ARE VERY SAFE. Seriously, all three forms of production are at the point where their death stats are from workers slipping in the bathroom.

Edited September 3, 2015 by tater

[Kibble]

Why not power it with gasoline? A 300 kg 60s era Chevy big block could run three Space Stations! x3

[tater]

BTW, the SAFE-400 concept was about 5kg/kW, but I am unsure if that included radiators (it's a 400 kWt, 100 kWe system). It is my understanding that the VASIMR claims require more like 1kg/kWe. It's important to note that OP says "possible now." That would mean an off the shelf solution we could launch basically right away.

[shynung]

Why not power it with gasoline? A 300 kg 60s era Chevy big block could run three Space Stations! x3

Mass of gasoline and oxygen needed to feed those Chevy big blocks.

Jokes aside, if chemical generator is what's needed, an array of fuel cells could do the job much more efficiently.

[Exoscientist]

Sandia nuclear lab is working on a Brayton-cycle nuclear plant. This is the thermodynamic cycle used for jet engines and gas turbine power plants:

Sandia’s heat-producing turbine boosts small nuclear reactor efficiency.

Industry is ‘buzzing’ over DOE’s release of $452M for a cost-share program to develop SMRs.

May 4, 2012, 4:00am MDT

http://www.bizjournals.com/albuquerque/print-edition/2012/05/04/sandias-heat-producing-turbine-boosts.html

The researchers expect to boost efficiency to 50%, where it's commonly at 30%. Could this efficiency be made even higher? With a jet or rocket engine you get higher efficiency by expanding the exhaust out to a lower pressure, at most out to vacuum. Could this work for these plants or gas turbine plants in general?

For Earth bound plants you would need large nozzles but more importantly this large nozzle would have to exhaust out into a vacuum chamber. Getting a large vacuum chamber would be difficult and expensive on Earth, because of the thick heavy walls that would be needed to hold out the air pressure.

However, in the vacuum of space it should be much easier to do.

Bob Clark

[Streetwind]

Why not power it with gasoline? A 300 kg 60s era Chevy big block could run three Space Stations! x3

Joke's on you - internal combustion engines have been proposed (by Robert Zubrin among others) for use on manned Mars rovers. They adjust better to the the low temperatures than batteries do, can heat the crew compartment from waste heat instead of using precious battery charge for it, and can run through the night. They would run a closed bipropellant cycle - likely liquid methane and liquid oxygen in tanks, though gaseous at the moment of combustion. You could achieve large ranges in large, rugged vehicles in those, and on Mars, nobody complains about more greenhouse gases

[Rune]

Sandia nuclear lab is working on a Brayton-cycle nuclear plant. This is the thermodynamic cycle used for jet engines and gas turbine power plants:

Sandia’s heat-producing turbine boosts small nuclear reactor efficiency.

Industry is ‘buzzing’ over DOE’s release of $452M for a cost-share program to develop SMRs.

May 4, 2012, 4:00am MDT

http://www.bizjournals.com/albuquerque/print-edition/2012/05/04/sandias-heat-producing-turbine-boosts.html

The researchers expect to boost efficiency to 50%, where it's commonly at 30%. Could this efficiency be made even higher? With a jet or rocket engine you get higher efficiency by expanding the exhaust out to a lower pressure, at most out to vacuum. Could this work for these plants or gas turbine plants in general?

For Earth bound plants you would need large nozzles but more importantly this large nozzle would have to exhaust out into a vacuum chamber. Getting a large vacuum chamber would be difficult and expensive on Earth, because of the thick heavy walls that would be needed to hold out the air pressure.

However, in the vacuum of space it should be much easier to do.

Bob Clark

You probably could, but you would be really fighting hard for the last 5%. And consider that the vacuum of space is irrelevant: you limit is what pressure differential your pumps-run-in-reverse (AKA turbines) can achieve, and at some point you are adding another whole blade stage for a 1% increase. Also consider these are humongous land-based turbines where having a lot of big low-pressure stages taking space doesn't cost you much. These things all go exponential when they taper to their theoretical maximums, and as you have often commented, gas turbines are already at the high 90's of their theoretical upper performance.

>_<!

still with the pumps?

Electrical engines = 90% to 95% efficiency, of course the penalty comes with the batteries.

Turbo Pumps = 50% efficiency.

Here´s a paper that compare turbo pumps, electrical pumps or just with pressurized gas.

Only the first 34 pages.

http://www.aacademica.com/hernan.emilio.tacca/9.pdf

Actually, the pumps are the achiles heel of any such system. See, "The Problem" is we are discussing electrical systems, and electrical systems need electricity. And the only ways we know how to generate electricity (thermocouples, photovoltaics, heat engines and alternators, whatever you want to consider) all produce more waste heat than electricity. So what dominates electric drives, all of them, is the radiator mass, since radiating is the only way to get rid of heat in space. It is the crucial weak point in ALL electric drives. Because here you can't really invent anything, you are limited by very basic equations we have known for ages, and those say the weight of the drive system is dominated by the weight of the cooling system. Which uses lots of pumps and fluid engineering. And let me tell you, those haven't changed much since the last century.

Now there is another problem related to heat people often forget. How cold is your cold side? Because you can cheat a bit with the ideal gas law by compressing and expanding gasses to change their temperature (at a cost in energy), but you really can't go too far without seriously staging your system, which adds complexity and mass really quick, and produces additional sources of low-level heat (which is basically stuff heating below the temperature your radiator works at but still over their working temperature). Also, this is where all spacecraft start to resemble a plumber's worst nightmare. So how do you keep your fancy superconductors and control electronics cool when you run your fancy droplet radiator at 1600ºK with liquid lithium? Yeah, a sad fact: all those exotic radiator concepts that give orders of magnitude less mass than what spacecraft use today? They are only really capable of taking heat out of high-temperature machinery like, say, a bulky fission reactor. Which is why spacecraft use today what they use, and why VASIMIR is even deader than the analysis we have done here imply.

You might be wondering now how is it that commsats and probes and such can run ion engines without issues. The answer is simple: they are already designed to handle the kilowatts of waste heat their solar panels generate, whether they use the small fraction (~15-20%) of power that gets turned into electricity, or not. And kilowats is a long way from drive systems that have to be in the gigawatt range to fulfil that absurd "39 days to Mars" really-high-energy trajectory with a ship in the hundreds of tonnes. Hundreds of tonnes vs Gigawatts in heat... really, that can't go well in those proportions.

Rune. Why would you want to shorten the trip below a Hohmann anyhow? It's only six months! Do it single-stage with increased payload instead.

Edited September 3, 2015 by Rune

[PB666]

Hydrogen Oxygen Fuel cell, easier to recycle water back into either. Once Gasoline is burnt, its wasted carbon dioxide mass and the water is difficult but not impossible to recapture.

- - - Updated - - -

If we manage to do reactors of more than 1 gigawatt in earth, why we can not do a reactor from 10 to 100 megawatts in space?

About radiators, just 1 week ago they found a way to manage and control a fluid dopplet radiator:

https://mipt.ru/en/news/cooling_201508

http://noticiasdelaciencia.com/upload/img/periodico/img_30364.jpg

By the way, not sure why they choose "X" setup for radiators instead line "l", the X setup absorb radiation from other radiatiors, and sun.

You have also this project that is trying to find the best way to solve all problems related to:

Megawatt Highly Efficient Technologies for Space Power and Propulsion Systems for Long-duration Exploration Missions

http://cordis.europa.eu/result/rcn/161150_en.html

---------------------------

I told you that you can not compare house rooftop with nuclear plants, if you want to compare do it with solar farms vs nuclear plant "global", not just picking locations, I dont know the real numbers for solar, I just knew that the data for wind was total false, and if they was so unprofessional to manage wind data and nuclear data, then is not hard to imagine is the same for the rest of the study.

Remember that this original publication was removed due hard and proven criticism.

However, the new system gives rise to a different problem: droplets of the heat transfer liquid - due to the effects of solar radiation, particles in the ionosphere and other factors - become charged and begin to scatter in different directions, failing to make it into the receiver. Thus, the droplet cooling system was viewed as unsuitable for space technology. But the MIPT scientists have found a solution.

Who knew the russians were still working on such lofty ideas. But . . . . .this is an insane idea.

“We’ve devised a numerical description of the system’s outer part, where the fluid circulates in open space. It was critically important to assess the effect of scattering and work out how to make up for it. To this end, the staff in our lab created a special set of programs to simulate real flight conditions in outer space.â€ÂThe development of the new system was not confined to mathematical modeling – the scientists created a special setup to simulate real space flight conditions and carried out a series of tests in it. The results showed that the proposed solution works. The next step is testing in space.

This is in-silico analysis, and its a fail. Solar weather changes at 500,000 miles per hour, if the solar flux changes the computer would not have a chance to collect water vapor molecules already in motion and they would be lost.

[Exoscientist]

...

Rune. Why would you want to shorten the trip below a Hohmann anyhow? It's only six months! Do it single-stage with increased payload instead.

The problems of such space trips in BEO space for several months have been much discussed, from bone and muscle loss, to radiation damage, to the recently discovered eye damage. In fact William Gerstenmaier, head of NASA's human spaceflight division, has said the NASA Mars mission architectures, and also Bob Zubrin's, that might take 900 days total round trip are unworkable:

Yes, NASA really is reconsidering the moon, and here’s why that’s important.

Posted on April 6, 2015 | BY ERIC BERGER

http://blog.mysanantonio.com/newswatch/2015/04/yes-nasa-really-is-reconsidering-the-moon-and-heres-why-thats-important/

Gerstenmaier suggested, as have many others outside of NASA, that using lunar derived fuel in orbital propellant depots would make Mars missions easier and cheaper. It could also be done by using plasma propulsion such as VASIMR to shorten the flight time.

Bob Clark