Link didn’t work for me but I was able to find it.
worked for me.
Once get market for lunar water, we then will get market for Space rock water.
Only quite recently thinking more about Venus. I thought Mars would a good spot to mine space rocks, and probably will be. But also Venus could a place to bring space rocks. In terms of delta-v, it seems Mars will more space rocks of lower delta-v available.
But it seems water in Venus orbit, should have highest price, and with higher price of water, it could have lower price of the rocket fuel. And Venus orbit could possibly be largest market for rocket fuel in space.
So, of course matters about time period, or when would Venus be a biggest. And what is big.
For our moon, it seems within a decade one has to doing 1000 tons of rocket fuel per year. And 10 years after reaching 1000 tons, you could have yearly of 10,000 tons.
So with Venus one looking 50,000 tons or more of rocket fuel per year. If imported 50,000 tons of water per year can you sell 50,000 tons of rocket fuel.
Say in world of doing New Horizon type of outer world exploration rather than years of doing inner planets gravity assist. You want get to Jupiter or further, faster. And that favors Venus. Fast New Horizon with +10 times payloads. Or nuclear reactor powerplants to Jupiter or further.
Other thing is people to Mars and from Mars.
So from Earth get to Venus in 2 months, and from Venus to Mars in 2 months, and other way from Mars, same 2 and 2 months. And at same time with different launch window, Earth to Mars in 3 months, and maybe Mars to Earth in 2 months time. And Venus has twice many launch windows to Mars as compared to with Earth.
It seems if when mining Main belt and/or Jupiter trojan space rocks.
Now if buying 50,000 tons of water for $200 per kg or $200,000 per ton: $200,000 times 50,000 is 10 billion dollar of water per year. Or rock with 1/2 million tons of water, in which is delivered and processed within 10 year of time. Or from Moon with some kind mass driver. No doesn’t work due to launch window. You mass drive to lunar orbit, and every 1.5 years ship the 50,000 tons of water to Venus orbit. Mars to Venus, every year. mass drive to Mars high orbit, and every year 50,000 tons for $200 per kg when delivered to Venus.
That make more sense from Mars
There may come a time in the easily foreseeable future when it will be cheaper to ship terrestrial seawater off earth than to mine and transport ET water in situ, much less ship it. If you’ve got a starship tanker that can put a few hundred tons of methalox in LEO for $2mln, then you can lift that same amount of seawater to LEO for the same. If you’re putting a kg of seawater in leo for $5, you’re not going to mine it elsewhere for less.
I’ve already talked about relying on the pipeline effect for inert cargoes, using solar sails to get ethane and whatnot from Titan, or tidally processed CHON from the Jovian Trojans (for your off-earth petrochemicals industry, if nothing else). Once you’ve unloaded the sail, you can send it back with a bladder of seawater. Maybe the workers out at Saturn would like it if you sent them some frozen fish in the seawater?
“If you’ve got a starship tanker that can put a few hundred tons of methalox in LEO for $2mln, then you can lift that same amount of seawater to LEO for the same.”
Starship does 100 ton to LEO, $2,000,000 / 100,000 kg is $20 per kg.
LOX is closer to price of seawater.
The lunar water to rocket fuel, would not start out selling to LEO. Instead it sells lunar surface and low lunar orbit. You could do either have rocket fuel at low orbit lunar or lunar surface or both to have a reusable lunar lander. For asteroid mining of water, your first market would be high orbits of Earth {or Mars or Venus]. High orbits not only are higher price if shipping from Planet, but the rocket fuel can give you more delta-v per kg of rocket fuel.
If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.
Though added anti-matter to chemical rocket fuel could a better way to do this.
I think a simple nuclear salt-water rocket would probably do the job.
That contradicts what Musk has been saying about the tankers (he says there will be a 2000 ton to LEO tanker). In fact, the 100 ton to LEO is the figure used by the “staship is nonsense” crowd who calculate 25 tanker launchers for each lunar landing.
In any case, the point is, even at $20/kg, what to you have to do to produce competitive lunar water (how much is there?); how much do you have to do to get the perchlorates out of Mars water, etc. etc. What is the infrastructure necessary to produce lunar water in the first place? How much will that affect what you charge for it where? Versus pumping it out of the sea surrounding your ocean launch pad.
“If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.” is largely false. You want to go fast to Mars, in the near future, you build a bigger rocket.
@ElonMusk: Fully Fueled StarShip in orbit carrying 100 tons of cargo will have 6.9km/s of Delta-V.
Lunar surface from LEO is about 6 km/sec
From LEO to Mars can take less delta-v than Lunar surface if you use Mars atmosphere to reduce the delta-v cost of rocket power. So parachuting Mars robot, can use less delta-v from rocket power as compared landing lunar robot. And Starship designed is to use Mars atmosphere to lower the delta-v needed from rocket power. But despite being designed for Mars, it’s so cheap one can use for lunar landings. Well it can used, if refueled in orbit {which needed for both Mars and Moon}. Anything which can be refueled in LEO, has huge capability. And refueling in High orbit likewise gives a huge capability- you don’t need nuclear rockets.
“In any case, the point is, even at $20/kg, what to you have to do to produce competitive lunar water (how much is there?); how much do you have to do to get the perchlorates out of Mars water, etc. etc. ”
What makes lunar rocket fuel expensive is largely related to lack of market for rocket fuel on lunar surface.
My solution unrelated to anything about Mars, is to ship Lunar LOX to low lunar orbit- giving one lunar surface market and low lunar orbit market [get them coming and going}. Problem with water from space rocket is an even worse problem with lack of market for the water or rocket fuel. You bring 1 million tonnes of water to LEO and not being to sell it. Or Moon has inherent market, though small.
And Moon best place to sell the least amount of water.
But if making towns on Mars- market demand is not the problem. Both Moon and Mars help each other, and same with space rocks. Or strong competition is great. Maybe dangerous one person, but someone going to do it right, and that helps everyone.
And “purpose” of mining lunar water is to lower launch cost, lower launch cost more demand. But if Musk going to lower launch, the purpose of mining lunar is just to use this increased demand which Musk created- just make a lot money. Other lower launch costs, other “purpose” is lower cost electrical power in space. And the lowered launch cost- helps a lot to lower the cost of electrical power in space.
Or rather than go slower, one goes faster. Instead of idea of needed at least 1000 tons of lunar rocket fuel per year, it shifts to 5000 tons of rocket rocket fuel per year, and lowers the price of lunar rocket fuel. But without getting the help, you might have run in the red for few years, and might need a year less of running in the red. And not “giving away” cheap lunar rocket to create more demand. So just make rocket fuel a bit cheaper than what Musk rocket ship could deliver it at. Musk doing all your work.
How much lunar depends of cost lunar electrical power, cheap lunar electrical power, billions of tons of water??
Mar is + tens of trillion of ton of water, Moon is couple billion and rest of lunar water, not really minable, but maybe gotten from mining something else- like H2.
Why dirty seawater rather than clean water?
Well, I did provide two thoughts, one being simplicity (you just pump the water aboard, no treatment needed) and the other humorous (“thanks for all the fish”). The point being, you have to make sterile, chemically pure water. If this ever became a reality, you’d probably want to filter out the wildlife. And seawater might turn out to be a more valuable resource than rocket fuel. I can imagine a scenario where the solar sail tanker comes by from Titan, you unhook the bladder of ethane, replace it with a bladder of seawater, and send it back to Titan (or wherever). That way, the sail isn’t going back empty (and the Saturn system has plenty of indigenous water, which may not be as valuable as vintage terrestrial seawater).
–“If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.” is largely false. You want to go fast to Mars, in the near future, you build a bigger rocket.”–
There limits with chemical rockets, one way to extend the limit is use rocket stages. But with stages, it’s around 20 km/sec, but in terms of what has been done, it’s closer to 18 km/sec. Roughly speaking Apollo was around 18 km/sec delta-v . And it started with biggest rocket will has yet to be built {Musk will take the record- if successful}.
But one make reusable rocket for the space environment which don’t have built to handle gee load of Earth launch [non vacuum environment, drag- atmospheric and gravity loss- so why I say 20 km/sec is around upper limit.
So can use stages from high orbit, you drop nearest to the gravity well, use “first stage” and then reuse that spent first stage, and then the second stage gets you to Mars [or where ever}.
But it might done with just one stage.
Nuclear rockets are solution to not needing to refuel. Nuclear rockets don’t need to use depots or having any rocket fuel sold in space. Though nuclear rockets are “theory” rather than proven usefulness. Making nuclear rockets that work could make the SLS look cheap in comparison.
“Nuclear rockets are solution to not needing to refuel. Nuclear rockets don’t need to use depots or having any rocket fuel sold in space. Though nuclear rockets are “theory” rather than proven usefulness. Making nuclear rockets that work could make the SLS look cheap in comparison.”
A NERVA type nuclear thermal rocket would still need propellant; H2 or some other gas, possibly water. Likewise with a nuclear electric rocket. The question for a nuclear thermal rocket is how reusable would it turn out to be compared to a chemical rocket? How many times can you fire up the NTR fuel elements to near melting point to do a direct heat exchange with the H2 propellant then cool it down afterward and then repeat? Never heard figures on that as to how many cycles you can go through.
Yeah, but reusability of rocket is a new thing {something thought impossible by governments]. There is a lot problems with nuclear rockets {and why a second rocket could cost more than SLS}. But Hydrogen only used by rocket has a low mass to lift to orbit. Though have problem of tankage weight vs fuel mass, and bigger plumbing and pumps of Hydrogen only.
With making rocket fuel in space- oxygen fairly quickly get cheaper faster than Hydrogen or Methane or whatever. Space can get to cheaper LOX than Earth with it’s “free” 20% of atmosphere being oxygen. Or if believe that SPS can happen, you saying electrical cost in space can be cheaper than on Earth [because there the added cost of delivering that electrical power to Earth surface.
So if electrical cost is as cheap and Earth surface electrical cost- LOX will be cheaper in space than Earth. And iron will cheaper in space than Earth. But that will take decades to do. I say at least 50 years, once lunar water mining starts, or Mars settlements starts, but least 50 years, assume both are happening. If assume sky cities on Venus, or something “better”, then maybe less than 50 years.
I’ll just point out that I did mention nuclear salt water rockets, which are superior to nuclear thermal and nuclear electric propulsion in most ways that matter. If you rigged a Starship with NSWR propulsion, with say a .66 mass fraction, a 25% radionuclide salt density (plutonium or uranium, and I assume thorium would work as well), with a probable 10,000+sec Isp, you’re pretty much talking about single-stage to Mars. Obviously, you’re not talking about liftoff from Boca Chica (which would pretty much depopulate Brownsville and Matamoros), but its easy to imagine how you’d get it close to LEO before lighting the NSWRs. The political climate for that to happen is harder to imagine. In any case, NSWRs involve no magic technology; it’s just a big, tough engineering challenge.
I think Musk’s mentioning {not sure, particularly serious] of adding anti-matter to chemical rockets would be easier. And could blast off from Boca Chica with the anti-matter “rocket fuel additive”. Saltwater is just scary and need serious madmen in order to do it. {NASA or US military probably, won’t}
Hmm. So my question is, how small can you make a salt water reactor?
I assumed it had to be a large scale. But couldn’t find any mention of how big it needed to be. The idea is to use it for star travel, so there is a tendency to think big. But why can’t engine fit in shoe box?
A thing that made think it was big was the drawing of rocket nozzle.
As someone said it could be likened to Nuclear Orion {and that has no nozzle}, and as another said like nuclear orion but constant fuel add and would like very intense nuclear meltdown.
Of course hard to make, but if make small, it’s not much safer, but it’s easier.
Actually my first question where could you test it {and I was thinking it would be a massive thing}
What testing is, basically, a “controlled meltdown” when controlling it, you have huge thrust velocity {with very radioactive material- nuclear bomb like stuff at 1/10th the speed of light- and just trying to contain that exhaust seems even more dangerous then anything else.
Doing this testing in LEO seems wildly hopeful.
So say, test the rocket engine on the far side to Moon?
So make a lot thin long pipe which is curvy and dump it straight but all thin pipes will intersect once going thru water.
And fluid flow of thin pipe is about 200 mph. And “nozzle” a V rather restriction of normal rocket engine. Doesn’t that work?
Since a nuclear salt water rocket isn’t a “reactor,” per se (cloer to a bomb than anything else), in principle it could be no bigger than a large rocket engine. Whatever size is necessary to get a critical mass of radionuclei. The moderator tubes full of a 20% solution of whatever can be any size, so long as no one tube contains a critical mass.
The problem seems to be the material of the reaction chamber. I always wondered if corundum would do. We can make pretty big artificial sapphires, which would look cool with the “bomb light” shining through (other than blinding anyone who looked at it).
Zubrin was of the opinion if you injected the reactant at the average speed of thermal neutrons, the fission wave front would form at the exhaust and not be a problem. Lots of people dispute that for various reasons. Since the propagation rate of thermal neutrons is 2.19 km/s (what is that, 4500 mph or more?) the reactant would have to be pumped. After the fission wave front, the exhaust would be around 66 km/s.
A couple of interesting issues. You could stick a NSWR Starship on top of a stretched SuperHeavy and loft it 400km down range (so top of the arc would be 200km, if I remember right). You light the engines up there, and fly away. Of course, if your engine RUDs and shatters the moderator tubes, such that 300 tons of radionuclides go critical all at once, that might add up to a civilization destroying catastrophe.
If you lit one off at Jackass Flats, it’d be exoatmopheric in about 90 seconds, leaving a radioactive hole behind that would match the ones left by bomb tests when I was a kid. There’d be fallout down wind, but not a huge amount. If it went RUD at liftoff, I think the result would be akin to Tsar Bomba. The troposphere would contain the pressure wave, and blow the exhaust out the top of the atmophere. Of course, anything directly overhead would be toast, but what the heck…
Link didn’t work for me but I was able to find it.
worked for me.
Once get market for lunar water, we then will get market for Space rock water.
Only quite recently thinking more about Venus. I thought Mars would a good spot to mine space rocks, and probably will be. But also Venus could a place to bring space rocks. In terms of delta-v, it seems Mars will more space rocks of lower delta-v available.
But it seems water in Venus orbit, should have highest price, and with higher price of water, it could have lower price of the rocket fuel. And Venus orbit could possibly be largest market for rocket fuel in space.
So, of course matters about time period, or when would Venus be a biggest. And what is big.
For our moon, it seems within a decade one has to doing 1000 tons of rocket fuel per year. And 10 years after reaching 1000 tons, you could have yearly of 10,000 tons.
So with Venus one looking 50,000 tons or more of rocket fuel per year. If imported 50,000 tons of water per year can you sell 50,000 tons of rocket fuel.
Say in world of doing New Horizon type of outer world exploration rather than years of doing inner planets gravity assist. You want get to Jupiter or further, faster. And that favors Venus. Fast New Horizon with +10 times payloads. Or nuclear reactor powerplants to Jupiter or further.
Other thing is people to Mars and from Mars.
So from Earth get to Venus in 2 months, and from Venus to Mars in 2 months, and other way from Mars, same 2 and 2 months. And at same time with different launch window, Earth to Mars in 3 months, and maybe Mars to Earth in 2 months time. And Venus has twice many launch windows to Mars as compared to with Earth.
It seems if when mining Main belt and/or Jupiter trojan space rocks.
Now if buying 50,000 tons of water for $200 per kg or $200,000 per ton: $200,000 times 50,000 is 10 billion dollar of water per year. Or rock with 1/2 million tons of water, in which is delivered and processed within 10 year of time. Or from Moon with some kind mass driver. No doesn’t work due to launch window. You mass drive to lunar orbit, and every 1.5 years ship the 50,000 tons of water to Venus orbit. Mars to Venus, every year. mass drive to Mars high orbit, and every year 50,000 tons for $200 per kg when delivered to Venus.
That make more sense from Mars
There may come a time in the easily foreseeable future when it will be cheaper to ship terrestrial seawater off earth than to mine and transport ET water in situ, much less ship it. If you’ve got a starship tanker that can put a few hundred tons of methalox in LEO for $2mln, then you can lift that same amount of seawater to LEO for the same. If you’re putting a kg of seawater in leo for $5, you’re not going to mine it elsewhere for less.
I’ve already talked about relying on the pipeline effect for inert cargoes, using solar sails to get ethane and whatnot from Titan, or tidally processed CHON from the Jovian Trojans (for your off-earth petrochemicals industry, if nothing else). Once you’ve unloaded the sail, you can send it back with a bladder of seawater. Maybe the workers out at Saturn would like it if you sent them some frozen fish in the seawater?
“If you’ve got a starship tanker that can put a few hundred tons of methalox in LEO for $2mln, then you can lift that same amount of seawater to LEO for the same.”
Starship does 100 ton to LEO, $2,000,000 / 100,000 kg is $20 per kg.
LOX is closer to price of seawater.
The lunar water to rocket fuel, would not start out selling to LEO. Instead it sells lunar surface and low lunar orbit. You could do either have rocket fuel at low orbit lunar or lunar surface or both to have a reusable lunar lander. For asteroid mining of water, your first market would be high orbits of Earth {or Mars or Venus]. High orbits not only are higher price if shipping from Planet, but the rocket fuel can give you more delta-v per kg of rocket fuel.
If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.
Though added anti-matter to chemical rocket fuel could a better way to do this.
I think a simple nuclear salt-water rocket would probably do the job.
That contradicts what Musk has been saying about the tankers (he says there will be a 2000 ton to LEO tanker). In fact, the 100 ton to LEO is the figure used by the “staship is nonsense” crowd who calculate 25 tanker launchers for each lunar landing.
In any case, the point is, even at $20/kg, what to you have to do to produce competitive lunar water (how much is there?); how much do you have to do to get the perchlorates out of Mars water, etc. etc. What is the infrastructure necessary to produce lunar water in the first place? How much will that affect what you charge for it where? Versus pumping it out of the sea surrounding your ocean launch pad.
“If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.” is largely false. You want to go fast to Mars, in the near future, you build a bigger rocket.
@ElonMusk: Fully Fueled StarShip in orbit carrying 100 tons of cargo will have 6.9km/s of Delta-V.
Lunar surface from LEO is about 6 km/sec
From LEO to Mars can take less delta-v than Lunar surface if you use Mars atmosphere to reduce the delta-v cost of rocket power. So parachuting Mars robot, can use less delta-v from rocket power as compared landing lunar robot. And Starship designed is to use Mars atmosphere to lower the delta-v needed from rocket power. But despite being designed for Mars, it’s so cheap one can use for lunar landings. Well it can used, if refueled in orbit {which needed for both Mars and Moon}. Anything which can be refueled in LEO, has huge capability. And refueling in High orbit likewise gives a huge capability- you don’t need nuclear rockets.
“In any case, the point is, even at $20/kg, what to you have to do to produce competitive lunar water (how much is there?); how much do you have to do to get the perchlorates out of Mars water, etc. etc. ”
What makes lunar rocket fuel expensive is largely related to lack of market for rocket fuel on lunar surface.
My solution unrelated to anything about Mars, is to ship Lunar LOX to low lunar orbit- giving one lunar surface market and low lunar orbit market [get them coming and going}. Problem with water from space rocket is an even worse problem with lack of market for the water or rocket fuel. You bring 1 million tonnes of water to LEO and not being to sell it. Or Moon has inherent market, though small.
And Moon best place to sell the least amount of water.
But if making towns on Mars- market demand is not the problem. Both Moon and Mars help each other, and same with space rocks. Or strong competition is great. Maybe dangerous one person, but someone going to do it right, and that helps everyone.
And “purpose” of mining lunar water is to lower launch cost, lower launch cost more demand. But if Musk going to lower launch, the purpose of mining lunar is just to use this increased demand which Musk created- just make a lot money. Other lower launch costs, other “purpose” is lower cost electrical power in space. And the lowered launch cost- helps a lot to lower the cost of electrical power in space.
Or rather than go slower, one goes faster. Instead of idea of needed at least 1000 tons of lunar rocket fuel per year, it shifts to 5000 tons of rocket rocket fuel per year, and lowers the price of lunar rocket fuel. But without getting the help, you might have run in the red for few years, and might need a year less of running in the red. And not “giving away” cheap lunar rocket to create more demand. So just make rocket fuel a bit cheaper than what Musk rocket ship could deliver it at. Musk doing all your work.
How much lunar depends of cost lunar electrical power, cheap lunar electrical power, billions of tons of water??
Mar is + tens of trillion of ton of water, Moon is couple billion and rest of lunar water, not really minable, but maybe gotten from mining something else- like H2.
Why dirty seawater rather than clean water?
Well, I did provide two thoughts, one being simplicity (you just pump the water aboard, no treatment needed) and the other humorous (“thanks for all the fish”). The point being, you have to make sterile, chemically pure water. If this ever became a reality, you’d probably want to filter out the wildlife. And seawater might turn out to be a more valuable resource than rocket fuel. I can imagine a scenario where the solar sail tanker comes by from Titan, you unhook the bladder of ethane, replace it with a bladder of seawater, and send it back to Titan (or wherever). That way, the sail isn’t going back empty (and the Saturn system has plenty of indigenous water, which may not be as valuable as vintage terrestrial seawater).
–“If want to use chemical rockets to travel fast to Mars, you need this high orbit rocket fuel with it’s higher delta-v.” is largely false. You want to go fast to Mars, in the near future, you build a bigger rocket.”–
There limits with chemical rockets, one way to extend the limit is use rocket stages. But with stages, it’s around 20 km/sec, but in terms of what has been done, it’s closer to 18 km/sec. Roughly speaking Apollo was around 18 km/sec delta-v . And it started with biggest rocket will has yet to be built {Musk will take the record- if successful}.
But one make reusable rocket for the space environment which don’t have built to handle gee load of Earth launch [non vacuum environment, drag- atmospheric and gravity loss- so why I say 20 km/sec is around upper limit.
So can use stages from high orbit, you drop nearest to the gravity well, use “first stage” and then reuse that spent first stage, and then the second stage gets you to Mars [or where ever}.
But it might done with just one stage.
Nuclear rockets are solution to not needing to refuel. Nuclear rockets don’t need to use depots or having any rocket fuel sold in space. Though nuclear rockets are “theory” rather than proven usefulness. Making nuclear rockets that work could make the SLS look cheap in comparison.
“Nuclear rockets are solution to not needing to refuel. Nuclear rockets don’t need to use depots or having any rocket fuel sold in space. Though nuclear rockets are “theory” rather than proven usefulness. Making nuclear rockets that work could make the SLS look cheap in comparison.”
A NERVA type nuclear thermal rocket would still need propellant; H2 or some other gas, possibly water. Likewise with a nuclear electric rocket. The question for a nuclear thermal rocket is how reusable would it turn out to be compared to a chemical rocket? How many times can you fire up the NTR fuel elements to near melting point to do a direct heat exchange with the H2 propellant then cool it down afterward and then repeat? Never heard figures on that as to how many cycles you can go through.
Yeah, but reusability of rocket is a new thing {something thought impossible by governments]. There is a lot problems with nuclear rockets {and why a second rocket could cost more than SLS}. But Hydrogen only used by rocket has a low mass to lift to orbit. Though have problem of tankage weight vs fuel mass, and bigger plumbing and pumps of Hydrogen only.
With making rocket fuel in space- oxygen fairly quickly get cheaper faster than Hydrogen or Methane or whatever. Space can get to cheaper LOX than Earth with it’s “free” 20% of atmosphere being oxygen. Or if believe that SPS can happen, you saying electrical cost in space can be cheaper than on Earth [because there the added cost of delivering that electrical power to Earth surface.
So if electrical cost is as cheap and Earth surface electrical cost- LOX will be cheaper in space than Earth. And iron will cheaper in space than Earth. But that will take decades to do. I say at least 50 years, once lunar water mining starts, or Mars settlements starts, but least 50 years, assume both are happening. If assume sky cities on Venus, or something “better”, then maybe less than 50 years.
I’ll just point out that I did mention nuclear salt water rockets, which are superior to nuclear thermal and nuclear electric propulsion in most ways that matter. If you rigged a Starship with NSWR propulsion, with say a .66 mass fraction, a 25% radionuclide salt density (plutonium or uranium, and I assume thorium would work as well), with a probable 10,000+sec Isp, you’re pretty much talking about single-stage to Mars. Obviously, you’re not talking about liftoff from Boca Chica (which would pretty much depopulate Brownsville and Matamoros), but its easy to imagine how you’d get it close to LEO before lighting the NSWRs. The political climate for that to happen is harder to imagine. In any case, NSWRs involve no magic technology; it’s just a big, tough engineering challenge.
I think Musk’s mentioning {not sure, particularly serious] of adding anti-matter to chemical rockets would be easier. And could blast off from Boca Chica with the anti-matter “rocket fuel additive”. Saltwater is just scary and need serious madmen in order to do it. {NASA or US military probably, won’t}
Hmm. So my question is, how small can you make a salt water reactor?
I assumed it had to be a large scale. But couldn’t find any mention of how big it needed to be. The idea is to use it for star travel, so there is a tendency to think big. But why can’t engine fit in shoe box?
A thing that made think it was big was the drawing of rocket nozzle.
As someone said it could be likened to Nuclear Orion {and that has no nozzle}, and as another said like nuclear orion but constant fuel add and would like very intense nuclear meltdown.
Of course hard to make, but if make small, it’s not much safer, but it’s easier.
Actually my first question where could you test it {and I was thinking it would be a massive thing}
What testing is, basically, a “controlled meltdown” when controlling it, you have huge thrust velocity {with very radioactive material- nuclear bomb like stuff at 1/10th the speed of light- and just trying to contain that exhaust seems even more dangerous then anything else.
Doing this testing in LEO seems wildly hopeful.
So say, test the rocket engine on the far side to Moon?
So make a lot thin long pipe which is curvy and dump it straight but all thin pipes will intersect once going thru water.
And fluid flow of thin pipe is about 200 mph. And “nozzle” a V rather restriction of normal rocket engine. Doesn’t that work?
Since a nuclear salt water rocket isn’t a “reactor,” per se (cloer to a bomb than anything else), in principle it could be no bigger than a large rocket engine. Whatever size is necessary to get a critical mass of radionuclei. The moderator tubes full of a 20% solution of whatever can be any size, so long as no one tube contains a critical mass.
The problem seems to be the material of the reaction chamber. I always wondered if corundum would do. We can make pretty big artificial sapphires, which would look cool with the “bomb light” shining through (other than blinding anyone who looked at it).
Zubrin was of the opinion if you injected the reactant at the average speed of thermal neutrons, the fission wave front would form at the exhaust and not be a problem. Lots of people dispute that for various reasons. Since the propagation rate of thermal neutrons is 2.19 km/s (what is that, 4500 mph or more?) the reactant would have to be pumped. After the fission wave front, the exhaust would be around 66 km/s.
A couple of interesting issues. You could stick a NSWR Starship on top of a stretched SuperHeavy and loft it 400km down range (so top of the arc would be 200km, if I remember right). You light the engines up there, and fly away. Of course, if your engine RUDs and shatters the moderator tubes, such that 300 tons of radionuclides go critical all at once, that might add up to a civilization destroying catastrophe.
If you lit one off at Jackass Flats, it’d be exoatmopheric in about 90 seconds, leaving a radioactive hole behind that would match the ones left by bomb tests when I was a kid. There’d be fallout down wind, but not a huge amount. If it went RUD at liftoff, I think the result would be akin to Tsar Bomba. The troposphere would contain the pressure wave, and blow the exhaust out the top of the atmophere. Of course, anything directly overhead would be toast, but what the heck…