How Humans Could Get to Mars in Weeks, Rather than Months

[Rascal Nag]

http://io9.com/5921673/nuclear-slapshots-could-propel-a-spacecraft-to-mars-in-just-weeks

Reminds me of Orion, but without the whole 'full-fledged nuclear bombs in space' problem.

[Randox]

I thought we hadn\'t yet figured out how to create a self sutaining fusion reaction yet. So either they think they can solve that, or they are neglecting to mention the power source needed to keep the engine running (also, a self sustaining fusion reaction attached to your rocket sounds like a very bad idea anyway).

I mean, its very cool, but I can\'t see it actually working any time soon.

[RedDwarfIV]

Who says its self sustaining? The description was that a \'DM2\' would be used to initiate fusion between a very small number of atoms. This would nevertheless break even, apparently. But the fusion of those atoms does not provide energy for more atoms to fuse.

Fine for a rocket engine, but it\'s not on a large enough scale to be used in powerplants.

[Phoenix Aerospace]

So, essentially a hybrid of the Dadaelus and Project Orion. I\'m all in.

I thought we hadn\'t yet figured out how to create a self sutaining fusion reaction yet.

Right, though like RedDwarf said, it\'s not capable of being turned into a power source, we have been able to fuse stuff since the \'50s. Also, it works more like a type of controlled thermonuclear detonation than a 'conventional' tritium/deutrium reactor, using magnetic fields instead of a fission bomb. At least, that\'s what I can gather from the article.

[shhhilent1]

Meh, you dont need that! you just need this:

http://www.buildtheenterprise.org/

[Phoenix Aerospace]

If that thing uses a 'warp drive', forget it. We\'re unto that kind of technology as our hunter-gatherer ancestors were to a hypersonic bomber. Call me a skeptic, but it just seems like another pipe dream to me.

[shhhilent1]

If that thing uses a 'warp drive', forget it. We\'re unto that kind of technology as our hunter-gatherer ancestors were to a hypersonic bomber. Call me a skeptic, but it just seems like another pipe dream to me.

No. its not gonna have a warp drive, but it will have the most powerfull engines available.

[BamBam]

No. its not gonna have a warp drive, but it will have the most powerfull engines available.

one or two generations further down the VASMIR engine will do the trick.

That guy seems to have done his homework, and the idea seems viable to me.

problem is, there is no way that politics and funding in the current world scene will ever line up.

no politician would commit to that for the length of time it takes to get it done.

[LaydeeDem]

The only problem with going so quick is, first of all, we are going to need a way to protect against micro meteoroids and other debris traveling that fast. Also, better save some fuel to slow down. =P

If we can over come the micro meteoroid issue, which I\'m sure would be as easy as putting a thicker shield on the craft. Maybe having a large shield like this:

>shamelessly stolen from Nova Silisko\'s Orbiter mod thread.

[Dobrodav]

Talking about micro meteorites protection.

Going to a Mars in a weeks, means prolonged thrust burn time of engines. Lets cut max Gs to a 1, for a safety reason. Not sure, but t looks, like about 2 weeks of accelerating, and then, again, 2 weeks of braking. (i will check numbers later, maybe ).

Point is, that we will need micro-meteorites defense, on braking stage too. Well, we can use engines as shield. But how? Our engines are essential part of a craft, - we must be sure, that our engines must be protected enough to withstand and continue to operate after impacts.

So, conception of few weeks Mars travel, seemed little to overoptimistic in some overseen future. Concept of, for example, 6 month`s traveling, looks more reliable in the next 50 years.

[Ascensiam]

Not to sound too negative, but this is overkill, gotta brake too, you know.

I will happily wait the required months until arrival.

[Menelmacar]

http://io9.com/5921673/nuclear-slapshots-could-propel-a-spacecraft-to-mars-in-just-weeks

Reminds me of Orion, but without the whole 'full-fledged nuclear bombs in space' problem.

We already have full-fledged nuclear bombs in space - I forget how many but here are satellites with reactors in them revolving our planet as we speak - one day bound to decay.

However I have been thinking about this - why not use Thorium reactors in space? We won\'t use them down here because they\'re too close to 'free energy', there are still some dangers with this tech but compared to your standard nuclear reactor they are completely safe and self regulating.

[Johno]

I have to break in here. Radioisotope Thermal Generators, or RTGs, are NOT \'nuclear bombs in space\'. They are simply a small pellet of radioactive stuff used to generate a hot point in space, nothing more and nothing less; you can generate electricity from the heat gradient.

They\'re not even truly a nuclear REACTOR in space. Reactors rarely hurt people, but they CAN in bad situations. By contrast, the only way a falling RTG could hurt you would be impact damage if it fell on your head.

Incidentally, for the reasons I have just outlined, the idea of using thorium reactors in space isn\'t actually relevant - they don\'t use Uranium in RTGs, but an isotope which will produce heat for the required time (often, but not always, plutonium).

Finally: Thorium reactors are safe because they\'re new technology reactors. We can make Uranium reactors as safe, with the advantage that we don\'t have to develop a whole new fuel cycle for them.

[Kryten]

There were some genuine nuclear reactors in space, the soviets used them for a few high-power radar satellites. However, three of them have already re-entered (two had a failure in the system that boosted the core to a higher orbit, and one didn\'t reach orbit at all); two landed in the ocean, and were barely noticed. The other one burnt up over canada, dispersing a few highly radioactive fragments, but still clearly not something you could compare to a \'full-fledged nuclear bomb\'.

[Rascal Nag]

Not to sound too negative, but this is overkill, gotta brake too, you know.

I will happily wait the required months until arrival.

Well, that\'s why you just turn around part way through the journey and burn the other way to slow down...

Finally: Thorium reactors are safe because they\'re new technology reactors. We can make Uranium reactors as safe, with the advantage that we don\'t have to develop a whole new fuel cycle for them.

While Thorium has a lot of safety advantages, like being unable to melt down, less radioactive fuel (you could hold some thorium in your pocket with no ill effects), cannot be used in reactors to make nuclear fuel, consumes other nuclear waste, no high pressure explosions due to different containment, among others, safety is not the main advantage. The main advantage is that thorium will give us much more energy for what we put in - a golf ball of thorium could provide anyone with enough power for their entire life. It\'s as common as tin as well, so it\'s far less expensive to obtain, and because it gives more bang for your buck, you don\'t need as much anyway, making it even cheaper. Then once you\'re done, much of the waste is actually quite useful in other fields, so it can go right back into the market rather than be sitting in containment.

Sure, you can make Uranium reactors far safer with enough work. But you can\'t magically make Uranium more energy-dense and common on Earth.

[Endeavour]

So how would a nuclear reactor work in space? On Earth, they heat up huge quantities of water and use the steam created to generate electricity. I don\'t think that would work in space as well, as water is heavy and everything else needs it too.

[Johno]

Endeavour: Well, if RTGs are available to you, a full scale nuclear reactor would seem to be unnecessary complexity for most applications. You could easily[1] build one using molten lead or sodium as the coolant, and keeping steam water under pressure; but the question would be simply why one would bother.

Rascal Nag: Most of the advantages to Thorium you list will also be part of the next generation of Uranium reactors by default. The trick is that Thorium is fertile, not fissile; this means that rather than having large atoms that can easily be split to release energy, such atoms can be generated in a breeder reactor. But the next generation of Uranium reactors will ALSO be breeders, so instead of the highly radioactive, rare and expensive enriched uranium in current reactors, they will be able to use depleted uranium or natural uranium, which are both abundant and cheap (and as safe as thorium in most respects, though their oxides are slow poisons [similar to lead]).

To be clear, I\'m massively in favour of Thorium reactors, but it needs to be said that the Uranium reactors are (at this stage) a much more practical concern. I firmly believe that Thorium will get there, especially if we pump in the money and time it deserves, but for now we can do much of what you say with Uranium.

[1] For a given value of easily!