Fusion Rocket Could Take Us To Mars

New submitter imikem writes "University of Washington researchers and scientists at a Redmond-based space-propulsion company are building components of a fusion-powered rocket aimed to clear many of the hurdles that block deep space travel, including long times in transit, exorbitant costs and health risks. 'Using existing rocket fuels, it's nearly impossible for humans to explore much beyond Earth,' said lead researcher John Slough, a UW research associate professor of aeronautics and astronautics. 'We are hoping to give us a much more powerful source of energy in space that could eventually lead to making interplanetary travel commonplace.' 'The research team has developed a type of plasma that is encased in its own magnetic field. Nuclear fusion occurs when this plasma is compressed to high pressure with a magnetic field. The team has successfully tested this technique in the lab. Only a small amount of fusion is needed to power a rocket – a small grain of sand of this material has the same energy content as 1 gallon of rocket fuel.'"

Comments

Yuh huh

[Anonymous Coward]

A magical space unicorn could take us to Mars.

There are a few small details to deal with regarding both potential technologies.

Re:Yuh huh

[i kan reed]

I don't think practical fusion technologies are as far away as you're acting like they are. If you've been following fusion news, there are several projects that are getting pretty close to scientific net+(my favorite is the Focus Fusion experiment).

Re:Yuh huh

[0123456]

There are a few small details to deal with regarding both potential technologies.

Except we know how to create uncontrolled fusion, and a fusion rocket is closer to a hydrogen bomb than a fusion reactor. You're just trying to make fusion happen and throw the resulting plasma out the back, not keep the plasma in one place and generate power from it.

Re:Yuh huh

[Anonymous Coward]

So basically what you're saying is, "What could possibly go wrong?"

Re:Yuh huh

[ebno-10db]

What about radiation shielding?

Re:Yuh huh

[X0563511]

Lets not forget that the objective of the rocket is to move you, not generate usable energy. You don't necessarily have to have a net+ for this to be useful.

Think of it as a super high density fuel that just takes a lot of energy on the ground to process.

Re:Yuh huh

[ByOhTek]

boom.

Re:Yuh huh

[chill]

The Ford Focus Fusion is designed to move you.

Whoosh!

Re:Yuh huh

[Anonyme Connard]

In space no one can hear you boom.

Re:Yuh huh

[mozkill]

That's no problem. They use platics for that.

Re:Yuh huh

[binarylarry]

Pff radiation shielding is overrated.

And think of all the tasty settlers we could eat after a nice radiation bath.

Re:Yuh huh

[Anonymous Coward]

You're thinking of fission. You don't need all that much shielding for fusion, that's the beauty of it!

Re:Yuh huh

[0123456]

What about radiation shielding?

If you're using a nuclear rocket, you have plenty enough payload to add any required shielding. Besides, you want as many fusion products as possible to go out the back of the rocket, not the front.

Re:Yuh huh

[flyingfsck]

You can also make a really long space ship, with the engine at the far end. Most radiation will then miss the front end.

Re:Yuh huh

[khallow]

You're going to need radiation shielding anyway due to the uncontrolled nuclear reactor that sits at the center of the Solar System.

Re:Yuh huh

[Hoi Polloi]

Might as well use fission based energy then.

Re:Yuh huh

[Andy Dodd]

Actually that is fairly well controlled. Its excursions (flares, CMEs) are tiny compared to its steady-state output.

Problem is we don't know how to make a controlled reactor that isn't significantly bigger than the entire planet and uses gravity for confinment yet.

Re:Yuh huh

[Anonymous Coward]

You need plenty of neutron shielding for fusion. But the advantage of having a spacecraft over a power plant is that you can use distance, by putting it on the end of a long structure, and that you won't care what the neutrons will do to the shielding and equipment on timescales longer than the mission.

Re:Yuh huh

[Libertarian001]

I hear we're about 40 years away from viable fusion technology.

Re:Yuh huh

[Anonymous Coward]

I dunno, the Z machine at Sandia looks pretty nice.

Re:Yuh huh

[Redmancometh]

Classical fusion (not he-3/deuterium) emits extremely high energy neutrinos that tear up shielding. This I'd one of the major hurdles in *reactors.*

Re:Yuh huh

[Anonymous Coward]

This is just a process for converting electrical power into propulsion with a decent specific impulse. If you wanted, you could generate the electricity with fission, or any other convenient way. However, this method should have better specific impulse than a more direct fission based drive (e.g. using the fission to heat the fuel), while being more efficient than other electricity based methods of a similar specific impulse.

Re:Yuh huh

[Anonymous Coward]

Well, sure you do! If you don't have a net+, you're just wasting energy. You take energy X and convert it to YX, which is then used for propulsion. That makes no sense. For that grain of salt to be used, you'd have to carry around 2 gallons of fuel.

Re:Yuh huh

[RoccamOccam]

Neutrinos? That doesn't sound right. Did you mean "neutrons" (and I honestly don't know)?

Re:Yuh huh

[roc97007]

Ok, apologies if this is a joke that's wooshing over my head, but nuclear fusion produces very little radiation. A small fraction of the reaction energy is released in neutrons and some x-rays. Most of the energy is released as heat. I'm not a nuclear physicist, but hydrogen fusion is causing hydrogen atoms to smack into each other with enough energy that they fuse producing helium and a very large amount of energy. You're thinking perhaps of fission, which is when radioactive isotopes give off energy as they change into different radioactive isotopes. It's a completely different thing.

Re:Yuh huh

[Anonymous Coward]

Unless your form of energy X is not useful for propulsion or every other method of using it for propulsion is less efficient for a desired specific impulse.

Re:Yuh huh

[Anonymous Coward]

The devices we call 'hydrogen bombs' are not pure fusion explosives. They are more correctly known as 'hydrogen-boosted fission' devices. The hydrogen fusion is used to provide more neutrons to sustain the fission reaction, but in most cases the majority of the energy still comes from fission.

(At least, that's my understanding.)

Re:Yuh huh

[artfulshrapnel]

The obvious solution is to go so fast the radiation never catches up. I hear that electromagnetic energy has some sort of hard speed limit, perhaps they could just go a little faster than that?

Re:Yuh huh

[Bengie]

Pretty sure you're right in that he meant neutrons. Neutrinos will pass through almost anything, so no worry about them "tearing up" anything.

Re:Yuh huh

[WheezyJoe]

The devices we call 'hydrogen bombs' are not pure fusion explosives. They are more correctly known as 'hydrogen-boosted fission' devices. The hydrogen fusion is used to provide more neutrons to sustain the fission reaction, but in most cases the majority of the energy still comes from fission.

(At least, that's my understanding.)

Correct. Fission --> Fusion --> Lots More Fission --> Very Big Kaboom
Although the energy density of hydrogen fusion is greater than that of Uranium/Plutonium fission, the energy of individual fusion reactions are generally much less energetic than individual fission ones. H-bombs are crazy because fusion produces high-energy neutrons (and lots of 'em), which are sufficient to cause fission in normally non-fissile U238. So, they jacket the fusion part with cheap U238, which is useful as a tamper for slow neutrons until the fusion fuel ignites (by way of energy from a separate, fission primary), after which the cheap U238 is fuel for boosting the yield off the charts.

Re:Yuh huh

[Golddess]

Question, does your car require you to carry around raw, unprocessed oil, complete with an oil refinery to convert it into gasoline, or can you just fill it straight with gasoline?

Re:Yuh huh

[HiThere]

All of the fusion projects that I'm aware of are not only heavy, they're also delicate, and require lots of skilled technical attention.

I'd say we're *at least* two decades from a fusion engine that's practical in a spaceship. Three or four wouldn't surprise me. And I also wouldn't be totally surprised if it is one of those things that can just never be made practical (though I'd be very disappoiinted).

For that matter, while several of the fusion projects appear to be near the technical "break even" point, I can't think of one of them that's even approaching the economic break even point. Even fission is a bit dubious about that, when you count in all if the expenses. (E.g., government providing "insurance" against massive problems [in the form of saying "you won't be held liable"], and what to do with spent reactors and fuel.) That said, one mussn't forget that coal also gets massive subsidies, if only in the form of permission to engage in environmental degradation and pollution.

Note that all mining is environmentally destructive, and it is rare for the costs of that destructuion to be included in the cost of the products of the mining. So it's quite difficult to come to a rational balance of which technology is more expensive. Fusion has the problem that it's less dependant on mining, so it doesn't get the benefit of free pollution of the environment. This makes it more difficult for it to compete with established technologies. But it's not even nearly ready yet anyway. None of the existing projects have passed the technological break even point, which is a lot easier than the economic break even point.

Re:Yuh huh

[Anonymous Coward]

Yes, but with ford sync in it, you will more likely have blue screams of death.

Re:Yuh huh

[HiThere]

FWIW, perhaps a version of the original "Project Orion" which propelled the ship by exploding nuclear explosives behind it could be built, but that would be a lot easier to design with fusion explosives than with fusion explosives. Gramted that fusion explosives would probably be less polluting, and thus could be used closer to an inhabited planet (or space station?).

Even if ground based fusion reactors turn out to be cheap and simple in the near term, I have severe doubts about thier suitablitity for powering a spaceship until a LOT more development is done. Before the end of the century wouldn't surprise me. Before 2030 would.

That said, I disagree with the basic premise, that such capabilities are necessary (though they would certainly be advantageous). From my viewpoiint we need to be doing work on long-term closed cycle ecologies. With that capability we wouldn't need fast transport. So ion-rockets would be perfectly suitable for orbit-to-orbit movement, and some kind of skyhook (probably not a space-elevator, but something much simpler, like a pinwheel) for orbit to near planet movement, with the final step made by either a high-flying airplane or a electro-magnetic catapult, depending on the thickness of the atmosphere. This requires some fancy timing for the transfers, but it's something that we could actually build now if we had the commitment...except for the long-term sustainable closed cycle ecology.

Re:Yuh huh

[Existential Wombat]

You can use astronaut poo for shielding.

And on a nuclear ship I'm sure there'd be plenty.

Re:Yuh huh

[Anonymous Coward]

First off, you probably mean neutron instead of neutrino, as the other poster already pointed out. Second, the He3+D reaction produces MeV energy protons which are nothing to sneeze at in an environment intended to confine 10s of keV plasma. Second, assuming you are doing using thermal plasma as in a scheme discussed about here for the engine, you would have significant D+D reactions too which would produce a bunch of neutrons. And it doesn't take much unless you have some distance between the reaction and you, as there are plasma experiments now that can produce dangerous amounts of D+D neutrons even without being anywhere near useful amounts of fusion power being produced.

Re:Yuh huh

[Anonymous Coward]

Per unit of energy produced in raw reactions, fusion produces 3-5 times as many neutrons as fission of uranium. And depending on how you are using the energy, the amount of energy you get from the process may require much more fusion than fission. In fission, some 90+% of the energy goes into the kinetic energy of the nuclei which then becomes heat in the very immediate area of the reaction. In fusion, for example D+T reaction, some 80% of the energy goes into the neutron, which will carry the energy some distance away from the reaction. For a reactor, this is fine, as that 80% is the energy scooped away to make electricity via heating the area around the reactor, but for a rocket engine, much of that may represent lost energy (other reactions have their own significant portion converted to high energy neutrons or protons that may only partially give energy back to the reaction). Additionally, there is secondary radiation from all of those neutrons being absorbed into structure and equipment near the reaction.

One of the main differences for use in a reactor on Earth comes down to the difference between waste produced by fusion and fission. With fusion you have more flexibility and choice what kind of radioactivity is produced by careful control what material is used to make the reactor. You can choose materials that will become short lived radioactive waste that is easier to manage than the radioactive byproducts of fission. For a rocket though, this may not matter as the engine would not be running for decades and could be dumped some place as a whole where it couldn't contaminate Earth. What would matter instead would be the energy efficiency, the specific impulse, and the practical concerns of radiation produced while running (as opposed to longer term waste).

Re:Yuh huh

[Anonymous Coward]

All of the fusion projects that I'm aware of are not only heavy, they're also delicate, and require lots of skilled technical attention.

All of the ones I've worked on were quite robust and solid for the basic structure, as they basic plasma is created and managed with not much more than just a large vacuum vessel, magnets and some power supplies or capacitor banks. This is to the point no one would bother with ladders half the time, because the large bolts and plates on the vacuum vessel turned it into essentially a giant jungle gym that let you get to wherever you needed to on the machine. What tended to be really fragile on the other hand were a lot of the diagnostics, especially stuff like precision optics for spectroscopy or laser based diagnostics, imaging diagnostics, x-ray diagnostics, probes that were stuck into the plasma and shielded with ceramics. But an operating machine would not need 90+% of the diagnostics, and can probably get by on things like magnetic diagnostics that can be made rock solid. I think you could probably go at some of the machines with a sledgehammer, and as long as you avoided the windows on the vacuum vessel and the diagnostics, it would take you a while to do any actual damage.

About the only exception might be some of the heating techniques being used, although those are mostly only relevant to getting steady state reactors going. And those consist of things like high power RF, which the military has some experience with making resilient, and things like neutral beams which would be on par with ion engines that we've already tested in space.

And from your other comment:

Even if ground based fusion reactors turn out to be cheap and simple in the near term, I have severe doubts about thier suitablitity for powering a spaceship until a LOT more development is done.

Assuming there is a demand and hence money for development, I would expect fusion engines to be developed long before ground based fusion reactors are made practical. There are much fewer constraints or much looser constraints for using fusion as propulsion than as a primary source of energy. If you view it as a process for converting electricity into propulsion, you can get by with a lot less efficiency than something that is trying to produce electricity through inefficiency conversion and additionally kept itself going. Because you don't have to worry about contaminating your environment, you have a lot more flexibility and choice in construction materials, and don't need designs that are meant to last decades. The only additional constrain would be worry about mass, but then you at least don't need a whole vacuum vessel and all of the vacuum equipment.

Re:Yuh huh

[khallow]

Actually that is fairly well controlled.

A stable system is not inherently a controlled system. There's a big different in control of the Sun between "I put my sunglasses on" (which just controls the little bit of solar power that falls on you) and "I use the Hand of Omega to increase solar output by 0.1%" (which is controlling the entire Sun).

Re:Yuh huh

[roc97007]

Thanks for providing some clarity. What if we're not depending on the actual fusion reactor for motive force? Heinlein's torchships, as I recall, use the fusion energy to heat reaction mass (usually water) to something approaching plasma. The fusion reactor in this concept exists to provide heat, not motive force, which is provided instead by the reaction mass. This allows the reactor to have something closer to the configuration of a power plant rather than a rocket engine.

Re:Yuh huh

[Anonymous Coward]

In the long run, that might provide more efficiency on a smaller scale, but on the short run, it might be much more difficult. Using fusion as described in the article seems to combine the best parts of working in space, e.g. no neighbors and minimal neighboring equipment, and the best parts of fusion, a lot of energy, in a way that doesn't need a complicated stead state confinement method. Using fusion instead to produce electricity may end up focusing more on the negatives of both being in space, mass & size constraints, and fusion, e.g. getting it to work and efficiently produce power. The collection of power and/or heat in the latter case might be difficult too, depending on how much volume that heat is spread out over.

I would expect fusion based rockets as outlined in the article could be achievable much sooner than more generic power or heat generation from fusion reactors, assuming there is interest in actually developing it.

Re:Yuh huh

[multi io]

Think of it as a super high density fuel that just takes a lot of energy on the ground to process.

It doesn't even have to be exothermic (net energy gain) on the spacecraft, without considering any ground processing. In other words, it's perfectly fine if, for each kWh of electric energy you supply into the engine, you only get e.g. 0.4 kWh of kinetic energy of exhaust gases (plasma) coming out of the engine's nozzle. What's much more important is that the engine puts that 0.4 kWh into a very tiny amount of plasma, so that the plasma's velocity is very high (for a given amount of kinetic energy, the velocity is proportional to the reciprocal of the square root of the mass). That velocity is the "specific impulse" of the engine, and it determines how much fuel mass you need to achieve a given delta-v of the vehicle.

Re:Yuh huh

[RsG]

Actually, thinking about it for a minute, a hydrogen bomb is a bad comparison. What this idea is closer to is a Farnsworth Fusor. For those of you who haven't heard of those, click the link. Short version: we can very easily make a device that causes fusion to happen, in a controlled non-explody way, provided we aren't too concerned about breaking even on energy. And fusors date from 1964, just to give you an idea of how long the tech has existed. There are even homemade ones in existence.

Achieving fusion is easy. Making fusion POWER PLANTS is hard.

Since the object of the exercise is propulsion, rather than power, the usual objection to fusion need not apply. Doesn't matter that it takes more energy than it could turn into electricity as a powerpant; an ion engine isn't a viable source for power, but we already use those on probes. What matters is how much reaction mass you have to carry to get where you're going. A fusion engine with a solar or fission power source could outperform conventional rockets on specific impulse and outperform ion engines on pure thrust.

Re:Yuh huh

[Orleron]

Oh yeah, and what do you use for powering the magnetic field to contain the plasma?

Re:Yuh huh

[Anonymous Coward]

Does space-rockets require to be operated in an ocean of fuel (oxygen)? There is a reason we don't use gasoline in space.

Re:Yuh huh

[multi io]

Oh yeah, and what do you use for powering the magnetic field to contain the plasma?

The design proposed here uses inertial confinement and pulsed (rather than continuous) operation.

Re:Yuh huh

[KingBenny]

i hardly dare comment here since it's way out of my comprehension but the advantage here would be the reduction in mass as a whole then so with the same amount of fuel (in volume) a rocket could go a lot further (or deeper) into space instead of achieving greater speeds to get further faster or is it a little bit of both ? I suppose its not quite jumpgate technology yet ?

Re:Yuh huh

[X0563511]

You'd get more energy out of a kilogram of this fuel than you would with a kilogram of, say, hydrazine and oxygen.

That means you can either:
1. Keep the total energy the same but launch with less mass (cheaper launch, better acceleration in orbit as you have less mass to move around)
2. Keep the same launch mass but bring along more energy (same or more expensive launch (increased volume?), more fuel to orbit so more endurance)

You'd need to do a much deeper analysis and have actual numbers to figure out what would get you farther, though. It could well be that the reduced mass means you have to expend less fuel to make the trip - OR it might not, and you'd need the extra fuel to make the trip instead.

Re:Yuh huh

[Golddess]

Yes, but how is that relevant? The point I was making is that you do your converting of X into YX on the ground, and then you do not need to carry around that extra 2 gallons of fuel.

Roads?

[Anonymous Coward]

Marty, where we're going, we don't need roads......

nuclear fusion?

[gbjbaanb]

erm... if they've got nuclear fusion working, couldn't they just forget about Mars and work on making it available as a power source to replace conventional powerplants to solve the world's energy needs?

Re:nuclear fusion?

[i kan reed]

And if the fuels take more energy to prepare than they yield when reacted(tritium is one such fuel), then they're not very useful for energy production, but very useful for energy storage.

Re:nuclear fusion?

[chalkyj]

Presumably it's not a way of generating power, but rather storing it. Who knows how efficient the generation of this plasma is, but you probably need to burn far more energy to create it than is produced when it is used.

Re:nuclear fusion?

[Dan East]

The purpose of this engine is to generate a very high speed ionized spray of lithium in a specific direction. How would that be converted into electrical energy? Generating kinetic energy (especially in space where waste byproducts just kinda go away) is extremely easy compared to generating electrical power.

Re:nuclear fusion?

[Chris Mattern]

We've had nuclear fusion working for over sixty years now. The trick has been containing it in a reactor for power generation. A fusion rocket might be easier to pull off--that's essentially just a semi-contained and directed H-bomb.

Re:nuclear fusion?

[badhbhcatha]

These are two different problems - they can't solve the problem of creating a sustained fusion reaction, but they can still use a low-frequency pulsed drive for space travel - it's not necessarily that different from the Orion concept, just executed in a very different way.

Re:nuclear fusion?

[Electricity Likes Me]

This. It's all about specific impulse in space travel - which is a very separate concept to net energy production. There's no problem spending a lot of energy making rocket fuels on Earth, when the big cost multiplier is launch mass.

Re:nuclear fusion?

[RevWaldo]

Creating a fusion reaction to create a very-hot-indeed metal plasma and spit the lot into outer space is one thing.

Creating a fusion reaction and containing the very-hot-indeed reaction inside a box, so you can draw off the heat to run a turbine, as multiple generations of despondent physicists will tell you, that's something else.

.

Re:nuclear fusion?

[Electricity Likes Me]

Worth noting, is that this concept is essentially the Orion engine without the heavy radioactives - the idea is essentially what we do in the hydrogen bomb.

Re:nuclear fusion?

[Waffle Iron]

High-speed ions would actually be easier and more efficient to use for generating electricity than conventional thermal energy. You set up an opposing electric field with a voltage that corresponds to the ions' energy in MeV, and capture them once they've slowed down. This creates a direct electric current at that high voltage, without the need for Carnot cycles, steam equipment, heat exchangers, etc.

One of the attractions of aneutronic fusion is that most of the energy is released in the form of charged ions that can be harnessed in this way.

Re:nuclear fusion?

[Electricity Likes Me]

High-speed ions would actually be easier and more efficient to use for generating electricity than conventional thermal energy. You set up an opposing electric field with a voltage that corresponds to the ions' energy in MeV, and capture them once they've slowed down. This creates a direct electric current at that high voltage, without the need for Carnot cycles, steam equipment, heat exchangers, etc.

One of the attractions of aneutronic fusion is that most of the energy is released in the form of charged ions that can be harnessed in this way.

Still depends on achieving efficient fusion. This doesn't have to be efficient - it's just a way of boosting the specific impulse you get from rocket fuel, using some other energy source (probably a fission reactor in a spacecraft) while also having a large enough impulse that it can get you around quickly. Ion engines are efficient - but you get up to speed slowly.

Re:nuclear fusion?

[roc97007]

erm... if they've got nuclear fusion working, couldn't they just forget about Mars and work on making it available as a power source to replace conventional powerplants to solve the world's energy needs?

I'm told we're fifty years away from that.

Re:nuclear fusion?

[cusco]

My understanding is that there was a re-examination in the 1970s by General Atomic into the original Orion project, but using a fusion power source rather than fission. The Pentagram immediately classified the report though, probably because they didn't want "the enemy" to know about the actual output of the small fusion devices, and it's never seen the light of day.

Re:nuclear fusion?

[Anonymous Coward]

Perhaps the promise of atomic age could resurface once a sufficient amount of churches devoted to the Anti-Christ is reached in the state of Washington.

Re:nuclear fusion?

[Anonymous Coward]

Lockheed Martin says 5 years for a working prototype and 10 for production. There's some speculation that their reactor is based on Bussard's Polywell concept and that the government is just stringing the Polywell development along at a snail's pace so that LM can be first out the gate.

Re:nuclear fusion?

[Anonymous Coward]

Specific impulse is only one leg of the tripod. You also need to worry about engine mass (including powerplant if not part of the engine) and net thrust. Having a thruster with a specific impulse of 100,000 seconds won't get you to Mars any time soon if it requires a 500T nuclear reactor to power it.

Is this...

[Anonymous Coward]

...Polywell?!

Re:Is this...

[Anonymous Coward]

Not in the slightest. As an earlier comment noted, it's sort of a fusion version of the Orion Nuclear Pulse Propulsion idea.

penis

[Anonymous Coward]

First. Penis

Re:penis

[Anonymous Coward]

First. Penis

Well, you are a dick, so there's that.

Will it be added to ...

[Anonymous Coward]

Will it be added to Kerbal Space Program?
Can't wait to have a generator and fusion reactor!

Re:Will it be added to ...

[X0563511]

The Deep Space pack (and whatever that electrical pack is that goes with it) already have a nuclear reactor and ion engines.

Re:Will it be added to ...

[Anonymous Coward]

Nice! I downloaded it just to try it, but I guess I'll have to buy it since it's a good product :)

Re:Will it be added to ...

[X0563511]

Highly recommended. The mods really help too.

British Sci-fi reference

[Anonymous Coward]

Just do not let anyone with the demeanour of Brian Blessed captain the mission.

Re:British Sci-fi reference

[khallow]

DIVE!!!!

Re:British Sci-fi reference

[jamiesan]

Do you want to live forever?!

Required electricity

[schneidafunk]

How is the electricity produced in the space ship for the nuclear fusion, would it also be nuclear? "The capacitors are hooked up to a giant magnet that houses the chamber where the fusion reaction will take place. With the flip of a switch, the capacitors are simultaneously triggered to deliver 1 million amps of electricity for a fraction of a second to the magnet, which quickly compresses the metal ring."

Re:Required electricity

[Anonymous Coward]

Their stated cycle time is 1 minute. Article says they fire for a "fraction of a second" to compress the metal rings, so the peak power generation needed would be 2-3 orders of magnitude lower than the instantaenous power usage. Small scale fission reactor like the sort on a nuclear submarine would do the trick. Or a radioisotope thermal generator: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Re:Required electricity

[MightyYar]

You put a big paddle wheel off the back and run generators with it.

Re:Required electricity

[Electricity Likes Me]

You could probably run it off solar power, but I believe NASA has been looking to get approval to launch nuclear reactors into space again. NERVA-type engines still have inferior Isp compared to most of the fusion concepts out there - and whatever else it may be, using a fusion-based combustion chamber is going to be easier to make safe then a nuclear lightbulb type design. No need to shotgun blast a bunch of uranium into space/orbit/the atmosphere.

Re:Required electricity

[Anonymous Coward]

If they have megamp class switches, they could be running a power type focus fusion system. Ive seen people doing the design specs for fusion powered aircraft and spacecraft using this principle.

Re:Required electricity

[Anonymous Coward]

if it's ionised and pulsed power generation isn't a oroblem.

Re:Required electricity

[LordLimecat]

I desperately hope that they use this solution-- it sounds both reasonable and exceedingly amusing to watch.

Re:Required electricity

[Hentes]

You could run it off anything if you limit the reaction rate accordingly. The problem is that the generated energy has to be stored in a roomful of capacitors, which won't fit on a rocket.

Re:Required electricity

[Electricity Likes Me]

Depends how heavy that room is. And I suppose, how heavy the fuel is - you could justify launching a large, one-off ship that you then only have to send up fuel for. A 90 or 30 day trip to Mars would mean you'd be able to run regular missions shuttling between the two.

Re:Required electricity

[Anonymous Coward]

Bingo. For a space mission they would optimize on capacitor energy density. For lab work they would use the cheapest capacitor available that does the job without regard to space/weight considerations.

They article specifies a million Amps for a short duration (but fails to specify the duration or voltage needed). Here's a 2000A, 5 KG ultracapacitor. 1 million amps at 16V is achieveable in 2500 KG with a 1 second long burst. http://www.maxwell.com/products/ultracapacitors/docs/datasheet_16v_series_1009363.pdf

The "roomfull of capacitors" in a rocket doesn't sound too farfectched to me.

Re:Required electricity

[BaronAaron]

They have a infographics that gives a lot of nice details.

Mars Mission
Power Source: 180 kW solar array
Spacecraft Mass: 16 MT
Payload Mass: 61 MT
Propellent Mass: 57 MT

Re:Required electricity

[MightyYar]

Also, once they get a few miles out, they can open up the slot machines.

Re:Required electricity

[Anonymous Coward]

The rule against nuclear reactors in space is not of terrestrial origin. I don't think they'll get approval.

Re:Required electricity

[Anonymous Coward]

For lab work they would use the cheapest capacitor available that does the job without regard to space/weight considerations.

And along those lines, many plasma experiments uses capacitors that have been passed down and reused for many experiments, frequently ending up older than many of the researchers working on the project. The last time I talked to a large capacitor manufacturer to check on the specs of some we had been using, I learned that not only were our caps over 40 years old, but that their current generic/economy line had almost 4 times the energy density per volume for the same kind of capacitor. You could probably get even more energy or power density by changing to a different kind of cap or getting one specifically designed with that parameter in mind.

Re:Required electricity

[OolimPhon]

You plan to send a submarine to Mars?

Re:Required electricity

[Lithdren]

Why not? They're not that different from space ships in many ways.

Both must keep high pressure and low pressure areas seperate and protected from one another. Both must supply the crew with life support functions and the ability to communicate. Sure keeping the ocean out vs keeping the atmosphere in is different, but thats a structual question, functionally it's pretty similar.

By far the largest difference is a sub doesn't have a weight limit anywhere near as strict as a space ship, but that's more of a technology and material science issue. I could see someone who built submarines having some insight into how to build a space ship.

Re:Required electricity

[Anonymous Coward]

MT doesn't mean ... megatons? That would be ridiculous.
The sketch of the spacecraft looks like it masses a couple hundreds tons, tops.
If not, I have no idea what MT could mean.

Re:Required electricity

[cusco]

Just its power plant. They're extremely well-designed and quite safe.

Re:Required electricity

[Lord Lemur]

Metric Tons?

Re:Required electricity

[Shotgun]

It worked for the Yamamoto!

ON STAR...BLAZERS

http://en.wikipedia.org/wiki/Star_Blazers

Re:Required electricity

[Anonymous Coward]

Damn! thanks.
I read too much SF.

Re:Required electricity

[Anonymous Coward]

Why not? They're not that different from space ships in many ways.

Both must keep high pressure and low pressure areas seperate and protected from one another. Both must supply the crew with life support functions and the ability to communicate.

Won't work, submarines are designed to keep pressure out, not in. Also a modern submarine electrically breaks oxygen off of seawater for the crew to breath. I'm sorry but there is no seawater in space.

Re:Required electricity

[Anonymous Coward]

Since this requires amplifying a magnetic field, I believe a flux capacitor should do the trick. Should be able to get new old stock Delorian parts off ebay.

Re:Required electricity

[Sardaukar86]

The rule against nuclear reactors in space is not of terrestrial origin. I don't think they'll get approval.

That's just silly. No nuclear technology in space?

What are they afraid of? Radiation?!

Re:Required electricity

[angel'o'sphere]

The unit "metric ton" is written just 't' and not 'MT'.

I don't see how.

[140Mandak262Jamuna]

I don't see how putting five blades on the front and one more blade at the back and slightly above is going to improve things much. Going from two blades to five, increases the efficiency, I can see. Each stroke is like five strokes using a straight-edge. But at this point we are beyond the optimum in the law of marginal returns.

Wait, you are talking about Gillett, aren't you?

I thought I'd never see good things from Redmond.

[master_p]

But apparently there can be good things from Redmond, like nuclear fusion-powered spaceships :-).

a small grain of sand...

[sabt-pestnu]

As Silicon Dioxide (silica, a component of sand) is not noted for its fusing properties, I was guessing that the fusion would be from more typical materials: hydrogen, or perhaps helium.

And while liquid hydrogen technology is well developed, liquid helium is a bit more difficult, and metallic hydrogen even more so. A "grain" of (metallic) hydrogen seems a bit beyond expectation. A grain-sized amount of hydrogen, I'd believe. But a tank of granulated metallic hydrogen?

Re:a small grain of sand...

[dAzED1]

Is English not your first language? (honest question, sometimes nuances can be lost) "As small as a grain of sand" is just a phrase, used to denote something tiny. Sounds like a word or such just got left out of the phrase - I can assure you they're not trying to use actual sand for fusion. Redmond may have nutjobs living there, but doing that would be beyond even them.

Re:a small grain of sand...

[AndreyFilippov]

Lithium deuteride ( http://en.wikipedia.org/wiki/Lithium_hydride#Lithium_deuteride ) can look like a grain of salt literally - it is just not as clear as NaCl.

Re:a small grain of sand...

[Lithdren]

"Honey can you pass the Lithium deuteride?"

"You know you shouldn't eat that stuff so much hon, it's bad for your heart. Remember what the doctor said..."

"Yeah yeah, I know it gives me bad hydrogen gas, but it tastes so good!"

Re:a small grain of sand...

[sabt-pestnu]

I was, rather, pointing out that "small as a grain of sand" has little meaning when referring to gasses, where the amount of material depends on the pressure involved; it has rather more meaning when describing liquids and solids, which are much less compressable.

This type of fusion was worked on 35 years ago

[InterGuru]

The Trisops machine at the University of Miami.

Trisops was an experimental machine for the study of magnetic confinement of plasmas with the ultimate goal of producing fusion power. The configuration was a variation of a compact toroid, a toroidal (doughnut-shaped) structure of plasma and magnetic fields with no coils penetrating the center. It lost funding in its original form in 1978.
The configuration was produced by combining two individual toroids produced by two conical pinch guns, located at either end of a length of Pyrex pipe with a constant magnetic guide field. The toroidal currents in the toroids were in opposite directions, so that they repelled each other. After coming to an equilibrium, they were adiabatically compressed by increasing the external field.

Disclosure: I am one of the authors of the cited paper in the article and the author of the above Wikipedia article

Re:This type of fusion was worked on 35 years ago

[Anonymous Coward]

I haven't had a chance to look at the Trisops description too closely, but it looks relatively similar to various other force free plasma experiments that have been on going for a while now too, short of maybe the external magnetic mirror field instead of flux conservers like a lot of other opposed gun configurations use.

Re:This type of fusion was worked on 35 years ago

[Anonymous Coward]

Yeah, reminds me of SSX at Swarthmore or HIT-SI at Washington (assuming those are still funded... I'm a few years out of date on that). And I remember something similar being done at UCLA once upon a time, and some talk of doing colliding spheromaks at Caltech. Or in more general some of the work being done by General Fusion or colliding FRCs by TriAlpha.

What powers the fusion drive?

[DerekLyons]

What's not clear in the article is how they plan to power the drive... I seriously doubt solar will be sufficient (mostly due to the low insolation at Mars), which means nuclear. Which means *heavy*.

Re:What powers the fusion drive?

[Electricity Likes Me]

The real question is could you do an Earth launch with this? Because the "heavy" equation changes a lot if we could actually use something like this to get into space in the first place.

Re:What powers the fusion drive?

[X0563511]

OK, think about those ridiculously high watt lasers. Recall how those are pulsed?

So is this, with a period of a minute or so. (large amount of energy in a tiny period of time, with a long 'idle' phase between). A traditional fission reactor or RTG could be used to charge the capacitor system for this, as well as the other ship systems.

Re:What powers the fusion drive?

[Anonymous Coward]

...or even traditional solar collectors as long as we aren't talking about extra-solar travel. Thinking about inner solar missions, such as Mars, Venus, Saturn and even Jupiter. Think about all the asteroid mining opportunities, and using this method of propulsion to move some of these larger catches into Earth orbit...

Solar becomes even more viable the closer we move towards the sun.

Re:What powers the fusion drive?

[seyfarth]

Star Trek has already answered that question. The mother ship is built in space and never leaves space. This changes a lot of structural requrements. It needs to be able to survive micro-meteorite impacts and the stress of whatever accelaration is involved. There would need to be shuttle craft to land on Mars. Initially these might be fairly crude like the lunar landers. With time we would develop better reusable shuttle craft.

Building a mother ship in space would require the development of a lot of systems in space. It might require off-world mining to avoid the huge cost of moving materials into space. I predict that I won't live long enough for that advanced a technology to develop, but I expect that people will make it to Mars during the next 30 years. Maybe I'll see some nice pictures on youtube.

MOO2

[Anonymous Coward]

Man... Fusion Drives, Plasma Drives, Ion Drives... now I really want to play Master of Orion 2.

Bob Lazar

[Anonymous Coward]

Might sound wacky but Bob Lazar somewhat discusses the traveling technology behind the crafts he worked on and it sounds just about 2 levels above this.

The downplay of current tech

[khallow]

From the article:

âoeUsing existing rocket fuels, itâ(TM)s nearly impossible for humans to explore much beyond Earth,â said lead researcher John Slough, a UW research associate professor of aeronautics and astronautics. âoeWe are hoping to give us a much more powerful source of energy in space that could eventually lead to making interplanetary travel commonplace.â

[...]

NASA estimates a round-trip human expedition to Mars would take more than four years using current technology. The sheer amount of chemical rocket fuel needed in space would be extremely expensive â" the launch costs alone would be more than $12 billion.

That's not true at all. Chemical rockets work as well. And with the Falcon Heavy in the near future, there's no reason to pay $12 billion in launch costs for a Mars mission, even if you use chemical rockets.

Note also the phrase "take more than four years". That makes it sound like it takes two years to come and go from Mars. It really only takes six months with chemical rockets (plus some time for attaining Mars orbit, there's probably not going to be a direct landing on Mars due to the high risks of aerocapture) The reason it would take that long is because humans would be staying on the surface of Mars for at least two years. I doubt even instantaneous travel would cut off more than a year and a half.

The more reasonable 90 day passage to Mars would takes six months off the travel time plus reduce the time needed to get into Mars orbit. It would also enable trips at any time rather than just during the most optimal trajectories. This really is the key constraint of chemical rockets.

At this point, it is worth noting that there are other viable near future propulsion technologies as well. A key one is electric propulsion which can be solar or nuclear powered. It has a good mass fraction and travel times. Solar sails could be used to ferry radiation-immune loads over very slowly.

Re:The downplay of current tech

[Electricity Likes Me]

It's all about how much mass you can move though. More mass means more people, resources, landers arriving at Mars per trip, or more fuel which you can then blow on shorter trip times.

We obviously can technically do it - but being cost-efficient and speedy are not solved challenges.

Re:The downplay of current tech

[SlippyToad]

We had NERVA in the 1960's. Well, we still do, now. It would also take us to Mars.

The issue is not the technology. We have had the technology to do Mars and reasonably for over 30 years. It is national willpower and getting our priorities sorted out.

Maybe NASA can program Curiosity to look for gold, or oil, on Mars. Then we could use the military to invade. That seems to be a project Americans can easily get behind, over and over again, regardless of the total lack of results.

Sci-fi not so sci-fi?

[Anonymous Coward]

First.. fusion reactors, next, manufacturing spaceships in space (cool designs, no need for rocket fuel, as big or as small as you want), third.. terraforming, fourth.. galactic travel

Anyone want to make a guess on how long it'll be? 50 years? 100 years? 150?

Fart power...

[Ashenkase]

"could" take us to Mars as well.

Unfortunately, harnessing fart power has proven much more elusive than fusion power.

Terrible ride quality

[flyingfsck]

So, this thing will go WHUMP! once a minute? It will be the most annoying and uncomfortable journey ever and forget of sleeping.

Re:Terrible ride quality

[mill3d]

Could having many smaller units fired at close intervals help with the neck-breaker problem..?

Re:Terrible ride quality

[Anonymous Coward]

They could dampen it with a fluid - in space maybe an aerogel?

Re:Terrible ride quality

[Anonymous Coward]

Which is why you build a nice set of shocks between your engines and your crew compartment. The simplest one to think about would be a sliding joint with an actuator controlled to put a constant outward force between the two halves - the front half can't tell that the back half has even changed direction so long as you don't hit the limits. In practice you'd get something you can notice, but I'd not call that uncomfortable.

Shock absorbers are very, very well-understood machines.

Re:Terrible ride quality

[mutube]

I've wondered about this before, maybe someone more enlightened on the physics can clear it up.

If you add shock absorbers (I'm hypothetically imagining a giant spring mechanism to keep it simple). As the fusion reaction provides forward force, the spring will compress absorbing the impact and lessening the discomfort for the crew module. Then it un-compresses releasing the energy.

But half that energy is going back in the direction of the fusion reaction (assuming it's a short-lived pop). Aren't you losing half your efficiency to dampen the impact? Is there an alternative?

Either bullshit, or too important for NASA

[Animats]

These guys are claiming to have controlled thermonuclear fusion above breakeven. That's huge. No one has ever done that. If it works, we have a new major power source. They write: "Now, the key will be combining each isolated test into a final experiment that produces fusion using this technology". That's a Nobel prize if they succeed.

This is too important to let NASA fuck up.

Re:Either bullshit, or too important for NASA

[Andy Dodd]

Actually, they're not. What they're creating is more akin to uncontrolled thermonuclear fusion.

Pretty much mini-bombs without the fission primary. Still pretty much bombs though. Usable for a rocket, not usable for electrical generation.

Also, even if it doesn't achieve breakeven, it may still be able to achieve very good Isp - e.g. lots of thrust per gram of propellant mass.

We could call it Project Pluto!

[RandomFactor]

Seems like an appropriate name for a very fast nuclear powered vehicle where we don't have to worry about disposing of the exhaust left in its wake right?

linux fipth

[Thud457]

I don't we can ensure that Redmond is destroyed if they launch from Bellingham.

Are they using 'fusion' as a noun?

[invid]

Only a small amount of fusion is needed to power a rocket – a small grain of sand of this material has the same energy content as 1 gallon of rocket fuel.

Fusion is a process, not a material.

Re:Are they using 'fusion' as a noun?

[invid]

And for you grammar nazis, I meant 'proper noun'.

Re:Are they using 'fusion' as a noun?

[invid]

Alright, I've just been to Wikipedia and what I really meant was 'concrete noun.' I've really got to go there first before I post anything.

We already had this ability in the 1960's

[SlippyToad]

It was the NERVA rocket. it wasn't fusion, but it was a nuclear-powered rocket, and it would have easily made Mars our bitch.

It was canceled to, fucking get this, no seriously, wait for it. It was canceled TO SAVE THE BUDGET because the politicos at the time were afraid a successful Mars rocket would "drag" the US into this huge "space program" where we'd explore the solar system and stuff. And that would cost a lot of money.

Instead, we killed the NERVA rocket and saved our budget for Vietnam, which was a roaring success that paid incredible dividends . . . . oh, fuck.

Anyway, this is nice to hear, but I'm not going to hold my fucking breath. Our national priorities are far too ass-backwards for something forward-looking like a Mars mission. I suspect the first people to land on Mars will likely be an international team, and America will be riding along in the back begging for a look out the front window from time to time.

Re:We already had this ability in the 1960's

[Anonymous Coward]

It was canceled to, fucking get this, no seriously, wait for it. It was canceled TO SAVE THE BUDGET because the politicos at the time were afraid a successful Mars rocket would "drag" the US into this huge "space program" where we'd explore the solar system and stuff. And that would cost a lot of money.

Rightfully so!

How can you even think of wasting money on such trifling nonsense, when we have yet to fully explore the many ways in which we might horrifically kill brown people?

'sides, Mars is the "Red" planet. You're not some kinda Commie, are you?

Re:We already had this ability in the 1960's

[T.E.D.]

I went online looking to debunk this, but frankly its essentially true.

Some further sad facts: In all of history there have been 12 human beings to set foot on another planet. The youngest of them is now 77. Most of them are still alive (probably thanks to the extreme physical fitness required of astronauts), but the day is not too far off when they start dying, and we will be left with no living people who have visited another planet. Most US citizens were not born yet when this was going on.

Space exploration is not something we are actively doing, but part of our history, joining its place alongside the Civil War and Lewis and Clark as "things to bore kids with in US History". If we tried doing it again, we've lost so much capability that it would probably take longer to accomplish, and cost more. We might as well post the poem Ozymandias next to our old Apollo artifacts in the museums:

I met a traveller from an antique land Who said: Two vast and trunkless legs of stone Stand in the desart. Near them, on the sand, Half sunk, a shattered visage lies, whose frown, And wrinkled lip, and sneer of cold command, Tell that its sculptor well those passions read Which yet survive, stamped on these lifeless things, The hand that mocked them and the heart that fed: And on the pedestal these words appear: "My name is Ozymandias, king of kings: Look on my works, ye Mighty, and despair!" Nothing beside remains. Round the decay Of that colossal wreck, boundless and bare The lone and level sands stretch far away

Re:We already had this ability in the 1960's

[DerekLyons]

It was canceled to, fucking get this, no seriously, wait for it. It was canceled TO SAVE THE BUDGET

It was cancelled because costs were spiraling, performance decreasing, and a practical engine getting further away every day.

Re:We already had this ability in the 1960's

[caywen]

Plus, god forbid we leak radiation into space. Keep space black!!

Re:We already had this ability in the 1960's

[kermidge]

Also, in part, due to the increasing resistance of the nukaler nutters who protested against just about anything having to do with nuke stuff. Except of course for X-ray machines when they needed them. It was around this time that "Nuclear Magnetic Resonance" was re-named "Magnetic Resonance Imaging" so that hospitals could continue to have a useful diagnostic apparatus, and there began sweeping cutbacks in commercial power nukes due to greatly-increased costs for environmental and safety studies, and financing, and construction costs; the issue of thorium cycle never arose, because the mind-set was still locked into uranium cycle for getting plutonium to build even more warheads.

(Circa '90 I read in Scientific American of three engineers at Hanford who, in early '80s I think, had worked out a no-melt configuration; they re-jiggered an idle reactor and ran their test. Closed the main coolant valve, watched the temp rise a bit, then slowly, steadily decline over the next three days, with no apparent damage or degradation to fuel elements, core, etc. Within a few months, their results were bureaucratically buried and they were transferred.)

If memory serves there were other issues with NERVA, among them packaging - shielding, configuration, controlling material degradation, and working out a complete mission package that made sense from an engineering and cost basis. Not finally, but another simple question was what to do with the whole thing. We'd lost the will to explore - the public and their representatives mostly didn't give a shit after Apollo; besides, robots were fine, so why bother going anywhere, to do... what?

All combined to make a perfect shit-storm that made it easy to just duck, run, find something else to not do.

Re:We already had this ability in the 1960's

[bjorniac]

That's no planet...

Re:We already had this ability in the 1960's

[Anonymous Coward]

Yeah, I am with you. I will start to believe we favor Science over War when they cut the DoD budget in half and put that money into NASA. Imagine what NASA could do with $300B. That is like one rocket system. (That was a sarcastic joke about NASA wasteful spending)

It would not be that bad for all the Defense contractors, most of them are also Space contractors.

Now if we gave the $300B to Space X they could have monthly round trip missions to a permanent station on Mars by 2015.

Sounds like they have a BS degree

[frovingslosh]

As in Bullshit

Fusion rocket could take us to mars?

[Anonymous Coward]

Yah, so could the fairy f*kin' god mother

Impossible

[Anonymous Coward]

All technologies that can be discovered have been discovered. How many laws of the universe does this perpetum mobile violate?

Let me guess - in 20 years?

[xanthos]

We are talking about fusion here so of course it perpetually will be available in 20 years.

Re:Let me guess - in 20 years?

[Teresita]

We are talking about fusion here so of course it perpetually will be available in 20 years.

It's a real toss-up which will come first:

1. Fusion power
2. Artificial intelligence
3. The Year of the Linux Desktop.

Re:Let me guess - in 20 years?

[Anonymous Coward]

We are talking about fusion here so of course it perpetually will be available in 20 years. It's a real toss-up which will come first:

1. Fusion power

2. Artificial intelligence

3. The Year of the Linux Desktop.

Hey, Duke Nukem Forever made it off the list. Anything is possible.

Re:Let me guess - in 20 years?

[jafac]

you're not factoring-in relativity. Fusion will be available in 20 years, unless you approach the speed of light, using a fusion drive, in which case, time slows down, and fusion will be available at some point further in the future.

Re:Let me guess - in 20 years?

[Anonymous Coward]

If you approach the speed of light, using a fusion drive fusion will be right there burning your ass off.

Typo?

[2gravey]

Shouldn't that read "Fusion Rocket Could Blow Us To Mars". No, I did not RTFA. Who has time for that.

Interesting thing about a fusion rocket...

[davebooth]

So suppose this works as described and we have a functional method of initiating pulses of controlled fusion in a rocket engine that when vented out the nozzle produces usable thrust. Let's make that nozzle thinner and a bit more tubular than conical - a few hefty magnets around to to keep all that fusing stuff in a nice thin stream. While we're at it lets anchor the other end of the rocket to something HUGE that the thrust isn't going to have a prayer of shifting. Except here we call it recoil, because if you have made a fusion rocket you have also created the other staple of grand space opera... A plasma cannon :)

Re:Interesting thing about a fusion rocket...

[Anonymous Coward]

You might run into some problems with it very quickly dispersing once it goes beyond the magnets you are using to confine it, and in the process becoming much colder and more diffuse. And how much damage it will do might be a lot less than expected, unless you can get an enemy to stay at point blank range for a while and use it more like a welding torch. Otherwise, it might be one par with trying to weaponize a giant fan after seeing an airplane or airboat.

Re:Interesting thing about a fusion rocket...

[DirtyLiar]

Ramping up the chemical rocket process to deal with containing and redirecting plasma is not the only way to take advantage of nuclear processes.

Fission could be used to produce what is basically a steam rocket. Water would be relitively cheap, since it is one of the most plentiful things on earth. Water is also one of the best shealds against radioactivity, so we could use water as fuel that had previously shielded our astronauts against cosmic and solar radiation in the second half of the trip out, to brake the ship for Mars orbit.

A more 'out there' option is to use nuclear bombs (either fission or fusion), to directly push the ship. The drawbacks to this is a probably jarring ride, and the probable resulting damages to ship, crew and cargo that would go with it. A 'continous' stream of micro-bombs that might be able to simulate a 'smooth' ride would present a whole new set of problems, starting with making bombs small enough, and reliable enough, with enough power to move the ship, all the way up to creating a system that could reliabily move enough of them continously for months without a single catistrophic break-down.

Clearly

[ThatsNotPudding]

(my favorite is the Focus Fusion experiment)

Clearly a Ford man.

Acceleration? Braking?

[Lawrence_Bird]

And how not to kill all involved? No mention of that in the article from my quick read.

Re:Acceleration? Braking?

[DirtyLiar]

Without reading the article:

Accelleration is easy, depending on the technique you use to capture / redirect the energy.

1) Heat exchange: You use the heat of the process to vaporise a substance (like water), and that is released out the back of the vehicle.

2) Direct physical redirection. Small bombs are released behind the vehicle and a physical sheild that redirects the explosion, and protects the vehicle. The force of the explosion pushes the vehicle forward. Unless the people are stupid, the bombs will vary in size so that the initial explosion (or any others) will not kill the astronauts, but still allows for reaching enourmous speeds.

Decelleration / beaking / slowing down is simply a matter of spinning the the ship 180 degrees, and do the same things you did to accelerate. Start this early enough, and you will slow down in time to orbit mars.

There is little difference between an explosion and a rocket. Don't believe me? Cut the end off a firecracker or ladyfinger, lay it on the ground and light the fuse. A flame will shoot out the cut end, and push the explosive in the oppisite direction. What makes a loud, forcefull explosion is (usually) a restriction around the explosive. Remove the restriction in one direction and the force will all rush out that side. The resistance is what causes the pressure to build up to the point where it breaks it's enclosure. The "bang" is created because the pressure builds up to the point that the pressure wave moves faster than the speed of sound.

Lastly, there is little lingering radioactivity from anything other than a ground explosion because the amount of material that can pick up radioactivity is limited to the bomb and shell it'self and a little bit of atmosphere. In a ground explosion, dust and dirt (and whatever has been pulverised) can carry vast amounts of radioactivity, and carry leathal amounts for melinia.

Luckily, a burst in space could only irradiate it's own mass, and the little bit of fallout that is created will be pulled by the earth's magnetosphere tword the poles, to become aroras. That which falls into the atmosphere will travel through and be disperced by the various winds, like all the other radioactive particles from the sun and beyond that rain down from the heavens every second of every day since the earth first solidified.

Re:Acceleration? Braking?

[DirtyLiar]

I forgot plasma, but it's basically like the heat exchange version, only with more magnetic shealding.

Keyword: Could

[Anonymous Coward]

Reality: Wont.

The basic engineering and physics have been known from more than 60 years. Still, the question comes to cost and return. The cost is still 'astronomical' the return near zero.

Many of the possibilities realized during the 1800s industrial revolution are still hopelessly out of reach for financial reasons.

Could/Would

[Anonymous Coward]

If my granny had four wheels she would be a bus and could drive me to work!

Um...

[Anonymous Coward]

'S'plain to me again how igniting nuclear fusion under my ass reduces my health risks? I must have blinked.

Well.....

[Anonymous Coward]

Little pink fairy wings and pixie dust could power us to mars too, but neither of those is a very practical solution today either.

Just wait

[Anonymous Coward]

A practical fusion rocket engine is only 30 years away!

Google Solve for X: Skunkworks Fusion

[catchblue22]

Here is a video of a scientist named Charles Chase who works for Lockheed Martin Skunkworks. The presentation is made at Google's "Solve for X". The video is 14 minutes long so I'll give an executive summary. Chase claims that his team has made a breakthrough in developing a small fusion reactor that will lead to a 100MW reactor the size of a truck trailer and of the complexity of a jet engine. The prototype they have built is a cylinder 1m in diameter by 2m long. In their experiment they put deuterium gas into a magnetically confined space and heat it up with radiofrequency energy. He infers that the confined plasma is reaching the conditions necessary for fusion to occur. The reactor is "high beta", with "beta" referring to the ratio of the magnetic field pressure to the pressure of the plasma pushing out. He says that the magnetic field strength in the reactor increases as you go out from the centre of the plasma, thus creating an extremely effective plasma confinement. He contrasts this with a Tokamak reactor, where the magnetic field is generated by the moving plasma itself, and thus decreases in strength out from the centre of the plasma. He says that this decreasing field strength is the main problem with Tokamak reactors and that it causes the confinement to be unstable. If the confinement becomes unstable, the magnetic field decreases, thus creating a negative feedback loop. This contrasts with his reactor design, that tends to create a far more stable plasma confinement.

I have a background in physics and what this man says in his video makes sense to me. It is of course short on details, but what would you expect for a short presentation. And you wouldn't expect a Skunkworks scientist to publish information in the same way as a university scientist. I have often puzzled in the past as to why we can't use an elegant method of magnetic confinement to achieve the conditions for fusion on a small scale. Tokamak seems an inelegant dead end. I think that if you can adequately confine the plasma, you have solved the energy balance problem that has plagued fusion reactors in the past.

Watch the video and see what you think.

Keshe Technology : KesheFoundation.org

[Anonymous Coward]

Steal from Keshe Technologies freely dispursed USB stick much?

Old Old news.

http://www.keshefoundation.org/

[Anonymous Coward]

Old Old news.

ho hum

[slick7]

"We can't solve problems by using the same kind of thinking we used when we created them." - A. Einstein

on the other hand...

[Anonymous Coward]

Fission rocket could get to Guam.

Yes...

[DirtyLiar]

... and old news (ancient in fact), will get you a free ticket to "No shit'sville".

The idea of using either fusion OR fission as a rocket "fuel" is nearly as old as the theiories of fusion and fission!

Some atomic rockets engines have even been tested. What's kept them out of space has been the attempt to proactively demilitarise space (to keep weapons out of space, especially nuclear weapons), and a fear of radioactive materials falling out of orbit for whatever reason, into your back yard.