The main point was that it is possible to build nuclear reactors with a weight low enough to be feasible. The point was that it does not have to weight "hundreds of tons".
Quote from: RocketmanUS on 04/11/2016 07:14 pmThen heat transfer to the air inside the dome from water fountain in lake from the deep water . Water that is cooled by the air is now on the surface of the lake?Cooled water would be transferred first to the exterior of the dome. Eventually it would flow to the lake, completing the loop.
Then heat transfer to the air inside the dome from water fountain in lake from the deep water . Water that is cooled by the air is now on the surface of the lake?
Quote from: Elmar Moelzer on 04/12/2016 01:14 amThe main point was that it is possible to build nuclear reactors with a weight low enough to be feasible. The point was that it does not have to weight "hundreds of tons".No, it is not possible to build a gigawatt reactor which weighs "just a few tons".
Quote from: Robotbeat on 04/12/2016 12:52 amQuote from: Stan-1967 on 04/11/2016 10:36 pmQuote from: Elmar Moelzer on 04/11/2016 07:50 pmQuote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.A 1 gigawatt nuclear reactor core Weighs hundreds of tons and requires huge amounts of cooling.NERVA is a nuclear reactor core, output multiple GW and had a mass of just a few tons. Almost a gigawatt per ton for some designs. And we actually tested NERVA, so it's not like this overall idea is ridiculous. You could land a 10-20ton Gigawatt reactor on Mars on a typical human-rated lander design.NERVA at full power doesn't melt only because it rejects heat in the exhaust. ...
Quote from: Stan-1967 on 04/11/2016 10:36 pmQuote from: Elmar Moelzer on 04/11/2016 07:50 pmQuote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.A 1 gigawatt nuclear reactor core Weighs hundreds of tons and requires huge amounts of cooling.NERVA is a nuclear reactor core, output multiple GW and had a mass of just a few tons. Almost a gigawatt per ton for some designs. And we actually tested NERVA, so it's not like this overall idea is ridiculous. You could land a 10-20ton Gigawatt reactor on Mars on a typical human-rated lander design.
Quote from: Elmar Moelzer on 04/11/2016 07:50 pmQuote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.A 1 gigawatt nuclear reactor core Weighs hundreds of tons and requires huge amounts of cooling.
Quote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.
Building a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid.
Quote from: Stan-1967 on 04/11/2016 10:36 pmQuote from: Elmar Moelzer on 04/11/2016 07:50 pmQuote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.A 1 gigawatt nuclear reactor core Weighs hundreds of tons and requires huge amounts of cooling.NERVA is a nuclear reactor core, output multiple GW and had a mass of just a few tons. Almost a gigawatt per ton for some designs. And we actually tested NERVA, so it's not like this overall idea is ridiculous. You could land a 10-20ton Gigawatt reactor on Mars on a typical human-rated lander design. You would need ~12 tons of fuel if you had perfect burn-up. About 40 tons for a more realistic 40% burn-up. That's not a crazy number, but you'd likely need either an advanced breeder reactor design or highly enriched uranium. 20% burn-up (80 tons) has been demonstrated at this breeder reactor: https://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_IIThat's actually the neatest thing about nuclear thermal rockets is how ridiculously power dense. If you can find other uses for it other than wasting a bunch of precious liquid hydrogen with it, you're golden.You'd cool the reactor with Martian water, recirculating through the bedrock.
Quote from: gospacex on 04/11/2016 08:47 amBy the sound of it, this "startup" hired lawyers before engineers.We looked at the physics first, then the engineering, then legal matters. Might you do the same, in our shoes?Quote...anyone who struggled hard with a problem never forgets it...-Elon Musk
By the sound of it, this "startup" hired lawyers before engineers.
...anyone who struggled hard with a problem never forgets it...-Elon Musk
Quote from: LMT on 04/11/2016 09:08 pmQuote from: RocketmanUS on 04/11/2016 07:14 pmThen heat transfer to the air inside the dome from water fountain in lake from the deep water . Water that is cooled by the air is now on the surface of the lake?Cooled water would be transferred first to the exterior of the dome. Eventually it would flow to the lake, completing the loop.Are you saying once the air is heated by the water fountain the water is then used by the people and to water the plants? later the water is filtered and sent back to the lake?
Quote from: Robotbeat on 04/12/2016 12:52 amQuote from: Stan-1967 on 04/11/2016 10:36 pmQuote from: Elmar Moelzer on 04/11/2016 07:50 pmQuote from: Stan-1967 on 04/11/2016 07:30 pmBuilding a 1 GWe nuke plant on Mars is arguably further out of our technical grasp than diverting a very small asteroid. What makes you think that? Nuclear reactors can be very compact and small. They can even be their own way to get there (NERVA), The bigger issue with nuclear plants in space is the political resistance to them.A 1 gigawatt nuclear reactor core Weighs hundreds of tons and requires huge amounts of cooling.NERVA is a nuclear reactor core, output multiple GW and had a mass of just a few tons. Almost a gigawatt per ton for some designs. And we actually tested NERVA, so it's not like this overall idea is ridiculous. You could land a 10-20ton Gigawatt reactor on Mars on a typical human-rated lander design. You would need ~12 tons of fuel if you had perfect burn-up. About 40 tons for a more realistic 40% burn-up. That's not a crazy number, but you'd likely need either an advanced breeder reactor design or highly enriched uranium. 20% burn-up (80 tons) has been demonstrated at this breeder reactor: https://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_IIThat's actually the neatest thing about nuclear thermal rockets is how ridiculously power dense. If you can find other uses for it other than wasting a bunch of precious liquid hydrogen with it, you're golden.You'd cool the reactor with Martian water, recirculating through the bedrock.You are putting the cart ( cooling water) before the horse ( reactor ). A NERVA design is very poor for generation of electricity, and very good at making a lot of thermal energy, which needs very significant flow rates for cooling. Where are you going to get the initial water for cooling?
Can a NERVA reactor sustain criticality at those power levels for more than a few hours?
Doesn't the high velocity hydrogen erode the reactor interior and limit it's life?
Do you think a liquid will make this even worse? or better? At the temps of NERVA, the cooling fluid can only be in the channels for a very very short time. A liquid might undergo cavitation or boiling at the sidewall, and BANG!, your reactor fuel melts.
Besides, the WSTEWART said they are not thinking of using nuclear.
... If you were to volatilize it, the incident insolation's UV will crack much of it into hydrogen which will escape to space in about 10 years, and the oxygen will recombine with salts/chlorates to form peroxides/hyperoxides/hypochlorates/hyperchlorates/etc....
Mars surface averages a pressure of 600 pascals, and an average temperature of 200 K.
Quote from: Space Ghost 1962 on 04/12/2016 02:54 am... If you were to volatilize it, the incident insolation's UV will crack much of it into hydrogen which will escape to space in about 10 years, and the oxygen will recombine with salts/chlorates to form peroxides/hyperoxides/hypochlorates/hyperchlorates/etc...."much of it"......this is not a very well-thought-out critique of terraforming. A wet climate lasted on Mars for a quite long time. It's going to take more than just some hand-waving to say it's impossible.
Quote from: Space Ghost 1962Mars surface averages a pressure of 600 pascals, and an average temperature of 200 K. Stopping at your first assertive statement. It doesn't apply to the Lake Matthew scheme because this scheme takes advantage of a low-elevation site, one having significantly higher atmospheric pressure and, per the methods, persistent heat.
If you still want to make some point about pressure and temperature, first consider and describe the effect which persistent heat would have on the triple-point findings presented in Fig. 5 of Haberle et al., "On the possibility of liquid water on present-day Mars".
Snip...Hundreds of thousands of years of UV penetrate and dissociate molecules creating halogen speciation of highly oxidative volatiles and reductive salts of varying metals.So to undo that, you have to reverse the process. Once you have an aqueous environment on the surface, then you need to "unload" the accumulated energy that is collected in the chemical potentials that have been accumulated in highly concentrated ways.Snip...
That point has limited use as you know. A better way to use it would be in subterranean caverns or lava tubes. But then there are easy ways to exploit them without your scheme, which would have more efficacy because it could be employed many sites on Mars, and ones more "popular" for exploration.
Quote from: MikeAtkinson on 04/11/2016 02:39 pmIt would be easier to redirect a near Mars asteroid of the equivalent size.I'm going to agree with this and abondon my previous thoughts of pulling it off the surface of Phobos. This will mean the impactor can be much smaller, as its velocity wil be much higher. All the orbit needs is to be adjusted to intercept Mars. Any list of asteroids with close passes to Mars in the 2-4 years prior to the 2036 target date?
It would be easier to redirect a near Mars asteroid of the equivalent size.
Any idea on the velocity at perigee?