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Project Bifrost: (Fission) Rockets of the Future?

timothy posted more than 2 years ago | from the ok-but-you-kids-be-careful dept.

Space 148

astroengine writes "Researchers from Icarus Interstellar Inc. and General Propulsion Science have announced their intention to pursue the development of Nuclear Thermal Rockets and other fission-based space technologies. The aim? To revolutionize space travel, ultimately paving the way to the goal of sending a probe to another star."

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Good luck (5, Insightful)

jonwil (467024) | more than 2 years ago | (#38772748)

Anytime anyone even thinks about mixing "nuclear" and outer-space (even radioisotope generators as used on many space probes) all the anti-nuclear groups kick up a huge fuss.

Unless this mob has something different they can use to convince the anti-nuclear mob that its safe, they will have a hard time actually launching anything without massive protest.

Re:Good luck (-1)

Anonymous Coward | more than 2 years ago | (#38772760)

Why don't you probe your nuclear asshole?

Re:Good luck (3, Insightful)

donscarletti (569232) | more than 2 years ago | (#38772874)

My opinion is if this thing blows up, it will kill the crew and pollute an area of space millions of kilometres from anything I personally give a shit about. This is pretty much the same end result as if a chemical rocket blows up. Sounds like a fantastic application for nuclear, makes good use of what nuclear is good at (fuel energy density) while minimising what it is bad at.

I figure, presumably after the engine actually works and has been tested etc. we put this thing in orbit without any fuel, make sure it's an orbit that will stay stable for at least 20 years if something screws up. We then send up the fuel in small amounts, so if anything goes wrong, the amount of poisonous uranium or plutonium or whatever released is not going to kill whatever forest or reef or city etc it lands on.

Then if something goes like really bad, we fire up the partially fueled engine and fly it into the sun. If not, we complete the mission.

Re:Good luck (2)

Bill Currie (487) | more than 2 years ago | (#38772916)

Then if something goes like really bad, we fire up the partially fueled engine and fly it into the sun. If not, we complete the mission.

Flying something into the sun is rediculously difficult (compared to Earth's orbit, the sun is pretty small). Much easier to just send the thing on its way and forget about it. If it's got enough delta-V to get it out of the solar system, we need not worry about it ever again.

Re:Good luck (2, Insightful)

donscarletti (569232) | more than 2 years ago | (#38773102)

From Wikipedia:

Earth orbital speed: 29.78 km/s

Sun's escape velocity at Earth (42.1 km/s)

Thus, the delta V to completely de-orbit from Earth's orbit is far lower than to escape the solar system. After de-orbiting, hitting the sun is quite easy, it just will tend to fall in.

Re:Good luck (4, Interesting)

Bill Currie (487) | more than 2 years ago | (#38773176)

Yes, the escape velocity is 42.1km/s. But anything in Earth's orbit already has a velocity of 29.78km/s (+/- a bit if in orbit around the Earth). This means that the delta-V required to escape the solar system from Earth's orbit is 12.32km/s. Less than half that required to de-orbit and fall into the sun.

This is actually a mistake that I make quite often (forgetting to factor in the current orbital velocity).

Re:Good luck (1)

WindBourne (631190) | more than 2 years ago | (#38774018)

who says that you have to hit the sun? Just let it fall slowly to the sun. Ideally, it can transmit information for a LONG LONG TIME as it heads there. Nothing better than allowing it to be a long life sat while on its way to oblivion.

Re:Good luck (1)

jeffb (2.718) (1189693) | more than 2 years ago | (#38774256)

I don't think you understand how "falling" works.

Earth is moving at about 30 km/s relative to the Sun. That happens to be just the right velocity to keep it in an orbit at a distance of about 150 M km.

Apply thrust along that same vector, and you go into a higher orbit. Apply thrust against that same vector, and you go into a lower orbit. Apply enough thrust against your vector long enough -- long enough to change your velocity by about 30 km/s, which is a heck of a lot -- and you eventually intersect the Sun's surface.

"Let it fall slowly to the sun" is a bit like saying "just pick up both feet at the same time, and until you put them down, you're flying!"

Re:Good luck (4, Informative)

Anonymous Coward | more than 2 years ago | (#38773206)

From Wikipedia:

Earth orbital speed: 29.78 km/s

Sun's escape velocity at Earth (42.1 km/s)

Thus, the delta V to completely de-orbit from Earth's orbit is far lower than to escape the solar system. After de-orbiting, hitting the sun is quite easy, it just will tend to fall in.

Hogwash. You do not know your stuff. Think before quoting Wikipedia.

As you have Earth's velocity of 29+ km/s already for free when departing from Earth in its orbit around the Sun, you are virtually "halfway to anywhere" (Robert A. Heinlein) when making it into Low Earth Orbit (LEO). Thus, the delta v needed for going from Earth surface to escape velocity out of the solar system is *much less* (~12.9 km/s) than for going to the Sun. In order to do the latter, you first need to get into LEO and then you need to decelerate from Earth's orbital velocity of 29.8 km/s to 0. So, your total delta v is around 40 km/s (!!!). More than three times than for going to infinity (and beyond ...). Good luck.

Hitting the Sun is anything but being "quite easy" (your words). That is the reason why it has never been done before.

Re:Good luck (1)

expatriot (903070) | more than 2 years ago | (#38773328)

You are right. It's very hard to hit the sun. You could do it with less energy than the 40km/s delta implies by doing multiple slingshots, starting with the moon.

Re:Good luck (3, Funny)

donscarletti (569232) | more than 2 years ago | (#38773776)

I like your style.

I'd be like the half-qualified director of NASA and would make this rousing as hell speech "do you want to be remembered as just some ordinary guy, or as the hero who flew a nuclear powered spaceship into the sun" and all of these cynical know it all guys would be like "you dumbass, you forgot to subtract Earth's orbital velocity from the Sun's escape velocity". And you'd be the promising young mathematician would would run to the front of mission control with a stack of paper and diagrams and be like "no, we need to launch this deadly broken nuclear spaceship at the moon first", then I'd smile and puff my cigar, knowing that everything would be awesome in the end.

I'd pay my $8 to see that movie, I really would.

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38773888)

Obligatory soundtrack
http://www.youtube.com/watch?v=v5_0iZQ-TuA

Set the Controls for the Heart of the Sun
Pink Floyd

Re:Good luck (1, Interesting)

donscarletti (569232) | more than 2 years ago | (#38773360)

So, I mention de-orbiting (WRT the Sun) something already IN earth orbit, then you add in the delta V to get into LEO _again_, clearly distorting the number to prove your point. Also, you suggest needing to go to zero, which is untrue, if something enters the corona it will be decelerated, the corona takes about 2 degrees of arc in the sky meaning an elliptical orbit will be just as good, which does not require zero orbital velocity.

Re:Good luck (3, Informative)

CrimsonAvenger (580665) | more than 2 years ago | (#38773490)

Also, you suggest needing to go to zero, which is untrue, if something enters the corona it will be decelerated, the corona takes about 2 degrees of arc in the sky meaning an elliptical orbit will be just as good, which does not require zero orbital velocity.

Dropping something into the corona of the sun from LEO....

Okay, assume that that requires us to get down to ~3,000,000 km (about four times the radius of the sun).

orbital speed up at this end of the hohmann ellipse is ~5900 m/s.

If we assume our orbital speed in LEO is about 7100 m/s (corresponding to an escape speed of about 10 km/s), then a single burn of about 18800 m/s is required to reach the corona of the sun.

Note, for reference, that from the same LEO, solar escape speed requires ab out 8800 m/s deltaV.

No matter how you slice it, it's easier to just toss something out of the solar system than it is to toss it into the sun...

Re:Good luck (2)

donscarletti (569232) | more than 2 years ago | (#38773682)

OK, that all checks out, in truth I _had_ forgotten that I could subtract the earth's orbital velocity from the sun's escape velocity (also the spacecraft's orbital velocity, but that would work for both escape and de-orbit). So, I would like to change my position ever so slightly to say: "throwing something hazardous into the sun is awesome and _worth_ the extra deltaV".

Re:Good luck (1)

WindBourne (631190) | more than 2 years ago | (#38773970)

You have to be kidding. Far easier to point it at the sun and go in, or simply point it retrograde, slow down speed relative to earth and allow the sun to pull it in to either venus, mercury or itself.

Re:Good luck (1)

Patch86 (1465427) | more than 2 years ago | (#38774840)

I won't answer it again (siblings posts have done a far better job of it than I could), but to sum up- no. That isn't how space works.

Re:Good luck (1)

Anonymous Coward | more than 2 years ago | (#38775831)

Could it also be ridiculously difficult? I don't know what "rediculously " means.

Re:Good luck (1)

sourcerror (1718066) | more than 2 years ago | (#38773048)

"My opinion is if this thing blows up, it will kill the crew and pollute an area of space millions of kilometres from anything I personally give a shit about. This is pretty much the same end result as if a chemical rocket blows up. "

You mean like the Challenger and Columbia? Except with nuclear fallout. I know the reactors in spaceships are usually much smaller than a nuclear plant, but this is definitely bigger risk than a chemical rocket.

Re:Good luck (4, Interesting)

BlueStrat (756137) | more than 2 years ago | (#38773408)

You mean like the Challenger and Columbia? Except with nuclear fallout.

What, are you a Flash Gordon fan!?

Nobody designs even a chemical-powered interplanetary spaceship to land it's main mass (including it's main propulsion system) on a planet surface. That's what landers are for. Even Apollo used a Lunar Module to land on the moon and a small Command Module for Earth re-entry.

This thing would be assembled in orbit and would never land on a planet. For something like a nuclear-powered interstellar spaceship, I imagine most of the construction would be done in low Earth orbit and then moved to a parking orbit at a La Grange point for final departure preparations, including loading the nuclear fuel.

I think you understand this, but are allowing your nuclear fears to cause you to post ridiculous and unrealistic scenarios in an effort to fight the idea of nuclear-powered space propulsion systems.

Strat

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38773662)

Well, what about using Biofuels? And also, if the crew was vegan, it would save a lot of energy on food! Meat take a lot of energy to produce, each time you eat at KFC it's the same thing as drinking half a barrel of petrol!

GAIA!

Re:Good luck (1)

BlueStrat (756137) | more than 2 years ago | (#38774338)

Well, what about using Biofuels? And also, if the crew was vegan, it would save a lot of energy on food! Meat take a lot of energy to produce, each time you eat at KFC it's the same thing as drinking half a barrel of petrol!

GAIA!

Biofuels!?

But...but...

We'd have to wait until we find aliens to give carbon credits to!

I'm surprised at your irresponsible environmental attitude. It's reckless plans like yours that will result in an AUW catastrophe (Anthropomorphic Universe Warming) and completely destroy the natural course of entropy! [shudder]

You make baby stars cry.

Strat

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38775456)

Coffee.

Nose.

Keyboard.

Bastard!

Just keep the muzzies out of it (0)

Chrisq (894406) | more than 2 years ago | (#38773552)

My opinion is if this thing blows up, it will kill the crew and pollute an area of space millions of kilometres from anything I personally give a shit about.

Just keep the muzzies out of it Imagine the ground zero hole if they flew that thing into New York.

Re:Good luck (1)

petes_PoV (912422) | more than 2 years ago | (#38773792)

pollute an area of space millions of kilometres from anything I personally give a shit about.

Though in space things don't stay where you put them - they have an annoying habit of forming closed orbits (unless they're going fast enough). So the area of space that you personally don't give a shit about could soon find itself on an intersecting path with a person, place or planet that you do have some small gravitational attachment to.

Added to which, if the engine does go <bang> then it's hard to say which pieces will go in which directions, and at what speed - so making any predictions about where they'll end up a little bit impossible.

The only safe way to do it is to stash the rocket at a Lagrange point and fire it from there, in a direction that will never let its orbit (powered or unpowered) intersect with Earth's.

And as for flying it into the sun - make sure there are no pesky inner planets anywhere near. One small orbital perturbation and that whole radioactive mess could miss the Sun and come swinging back to make a meteor shower you really wouldn't want to get too close to.

Re:Good luck (1)

camperdave (969942) | more than 2 years ago | (#38775460)

And what, exactly, can blow up on a nuclear rocket?

Re:Good luck (1)

symbolset (646467) | more than 2 years ago | (#38772908)

Indirect Toynbee tile reference. +1 for the reference, +1 for subtlety. I don't get mod points any more for some obsure reason, so this is what I can do.

Re:Good luck (5, Informative)

dkf (304284) | more than 2 years ago | (#38773010)

Anytime anyone even thinks about mixing "nuclear" and outer-space (even radioisotope generators as used on many space probes) all the anti-nuclear groups kick up a huge fuss.

Sucks to be them, then. Any time you push beyond the inner solar system, you need some sort of nuclear power to get electricity, as you can't burn things or use hydroelectric or wind-power. You can use solar panels in the inner solar system, but the further out you go the less practical that becomes. IIRC, solar is a no-go much beyond about the orbit of Mars, even for relatively low-power applications. High thrust engines are not low-power!

What's more, as long as you're outside the Earth's magnetosphere, any nuclear explosion is exceptionally unlikely to contaminate Earth (or the Moon) as the solar wind will push all of the small particles out to interstellar space. Yes, you could be hit by a large piece even so, but that would be amazing bad luck; space is damn big.

Re:Good luck (1)

athe!st (1782368) | more than 2 years ago | (#38774402)

By way of counter example, the Juno [wikipedia.org] Jupiter mission uses solar panels for it's power rather than RTGs. They would generate 12-14Kw at earth but due to the distance to will only produce 486W at Jupiter.

Re:Good luck (1)

kelarius (947816) | more than 2 years ago | (#38774518)

Yes, you could be hit by a large piece even so, but that would be amazing bad luck; space is damn big.

It's not up to luck if there is an explosion in LEO, if something in orbit dies it WILL eventually make it to the surface one way or another, that's just the nature f orbit. The concern is that those large pieces of the spacecraft would be radioactive and an explosion in orbit would undoubtedly send them back into our atmosphere. While the actual fallout from an explosion wouldn't likely cause any damage (the Earth's magnetic field protects us from far worse than nuclear fallout on a daily basis)) any debris left over from the probe and especially the reactor sections would likely be very irradiated and would poison wherever they landed/flew over, and since re-entry can cover a distance of thousands of miles I think you can imagine what kind of damage that could cause.

As has been discussed before fueling and launching the probe from a La Grange point or Lunar Orbit would be the safest way to do this, using chemical rockets to provide the initial thrust to fire it out of our immediate orbit will help to minimize this risk. Now getting the fuel into orbit is a bit trickier, you would need to send small amounts of fuel multiple times and I believe it could be performed safely, we already have casks used to transport nuclear material and these are already proven to be capable of withstanding large forces so I'm not too terribly concerned about that as long as most of it's launch transit occurs over ocean)

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38774584)

space is damn big.

How big? Please use number of football fields as a reference.

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38774678)

You are absolutely right. It's very safe out there beyond the magnetosphere. Problem is, the most likely fail is between ground and near earth orbit.

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38773190)

This thing coumes up since the 1960s every now and then. So I assume they will fail. Again. As previous attempts have failed. NASA and ESA had looked into it. The British had looked into it. And all present concepts are not going to work. They want to solve it with new technology. But, the previous attempts failed because the concepts are flawed.

Re:Good luck (1)

0111 1110 (518466) | more than 2 years ago | (#38774008)

What attempts were made exactly? Citation desperately needed. IIRC, Orion was canceled for political, not scientific, reasons. Nuclear propulsion is the only means we have of traveling interstellar distances in any kind of reasonable time frame. In what way are the concepts flawed?

Re:Good luck (1)

newcastlejon (1483695) | more than 2 years ago | (#38774942)

What attempts were made exactly? Citation desperately needed.

They did some testing with scale models and conventional explosives. I'm very sorry but I can't seem to find the Youtube link, but if you want a citation and you have a large library try this:
Freeman Dyson, Disturbing the Universe (New York: Harper and Row, 1979)

Re:Good luck (1)

newcastlejon (1483695) | more than 2 years ago | (#38774988)

Just to clarify, I'm saying that they did some tests, not that those tests showed the concept to be impractical (though they may have).

Re:Good luck (1)

jeffb (2.718) (1189693) | more than 2 years ago | (#38775220)

You're talking about Orion, not NERVA. This fission-rocket proposal is the same approach as NERVA.

Re:Good luck (1)

jeffb (2.718) (1189693) | more than 2 years ago | (#38774324)

And by "failing" or "not working" I presume you mean "running for nearly two hours straight, including nearly half an hour at full design power".

NERVA worked. It could've put humans on Mars in the time that it took us to send the Shuttle program limping into LEO. The main "flawed concept" was the notion that the US had the political will to see it through.

My college roomate's father worked on the NERVA project back in the 60's. I don't know how he ever got over its ignominious cancellation. I'm not sure I ever would have managed it. I hope he's still alive to witness its rebirth.

Re:Good luck (1)

Truekaiser (724672) | more than 2 years ago | (#38775078)

it wasn't because we lost the will. it's because our leaders chose immediate gratification due to our biology and political structure rather then a long term plan that for them at the time, 52~ years ago, which may or may not of payed off at LEAST 20 or 30 years later and in a minimal fashion without a more of a pay-of until now or at most 2020.

they chose to scramble for the remaining earth bound resources and a nonsensical fight against a ideal(communism then, then replaced with terrorism now so the same people can profit). rather then spend the same money, effort, and natural resources to set up the basic earth-moon & possibly martian infrastructure so for at least some natural resources we would have a bigger supply. that in turn has closed the window for this species to be be anything other then one which stays on it's own planet or planet with a occasional mission maned or not to their moon/moons and neighboring planets. even a colony ship is out of grasp as we do not have the resources to spare to build the infrastructure to make one in orbit.

i think, the best one can hope for is that the next intelligent species that evolves on this planet after about 250 million years(wither it be our decedents or some creature that is alive now) from now if their timing is as fortunate. will use their natural resources which resulted from our activity(oil and nat gas since they are renewable on a 'geological time scale' the massive plankton blooms we are causing due to our influence on climate will become their oil under the same processes that the Carboniferous era gave us ours.) and the earths plate tectonics bringing more to the surface within reach of any species more wisely and use this one time natural gift to propel them to the stars. Ironically our situation is rather like a bird in a egg, to the bird they have a lot of food in that embryonic sack, it's normally just enough to fuel them more or less to break through their egg. it's just that we are a bird who has seen this large natural resource and chose, foolishly, to stay with it. because we did not have the will nor the long term thinking to use it to get out of the egg after we stuck our beak out of the shell and did not find any more.

Re:Good luck (1)

DerekLyons (302214) | more than 2 years ago | (#38773428)

Anytime anyone even thinks about mixing "nuclear" and outer-space (even radioisotope generators as used on many space probes) all the anti-nuclear groups kick up a huge fuss.

Yes, look at the fuss kicked up over New Horizons and Curiosity... Oh, wait there wasn't any.
 
Seriously, this myth (about anti-nuclear activists) needs to die in a fire. Over time, the protests have gotten quieter and quieter and come from ever further out on the lunatic fringe - until, over the last few years, they've become essentially silent. (Cynics among the space community think this is because the Usual Suspects in such protests became busy with Anti-Bush/Iraq protests and have moved on to the Occupy movement.)

Re:Good luck (1)

CrimsonAvenger (580665) | more than 2 years ago | (#38773502)

Yes, look at the fuss kicked up over New Horizons and Curiosity... Oh, wait there wasn't any.

Probably because noone told them there were RTG's on those spacecraft. It's not like they glow from radiation, after all (and I suspect that many of the anti-nuke whackjobs really do believe that "nuclear" power plants/etc GLOW)....

Re:Good luck (2)

WindBourne (631190) | more than 2 years ago | (#38774062)

Derek,
Sending up small amounts is now accepted. Sending up the amount needed for NERVA would drive the same group that objected to the IFR batty. ANd yes, they would protest.

But there is a simple solution. Send up a small processing/breeder unit to space, and then send up safe uranium. At that point, it gets bred to plutonium and allowed to be used.

I wonder if a NERVA can be used to land on the moon? If so, that would become a truck. I noticed that Japan found Uranium on the surface, though quantity was unknown.

Re:Good luck (4, Insightful)

BoRegardless (721219) | more than 2 years ago | (#38773548)

Nearest Star = 4.2 light years. At the moderate speeds we would be able to generate to accelerate, but then an equal amount of fuel to decelerate to enter orbit around such a star in time measured in something larger than 10s of thousands of years at survivable speeds that don't erode the probe down from "plasma erosion" like you have with a plasma jet cutting machine.

Helium, Hydrogen and Protons and electrons hitting any metal or ceramic surface at huge speeds eventually cut through, even if only in thousands or tens of thousands of years.

A signal back from the probe would then take 4.2 light years to reach back to earth......if it didn't hit the smallest little rock or ice chunk along the way, which is a real undetectable possibility, and at the high speeds it takes, those would be fatal.

I understand the thrill of the thought process and the income if you are on the program and getting paid.

As a taxpayer, it leaves me as cold as intersteller space.

Re:Good luck (1)

ColdWetDog (752185) | more than 2 years ago | (#38773712)

As a taxpayer, it leaves me as cold as intersteller space.

It leaves me with a warmer feeling than most of the things we spend our money on. Er, excuse me, we spend our kid's and grand kid's money on.

Your cold hearted appraisal of the issues certainly has validity, but stuff like that hasn't stopped us in the past.

Re:Good luck (2)

0111 1110 (518466) | more than 2 years ago | (#38774066)

Where are you getting your data from? The hydrogen in interstellar space is very sparse and what little there is might be scooped up and used for fuel with a magnetic scoop. A super-Orion sized craft could reach speeds of up to about 0.1c. At that speed Alpha Centauri is only 44 years away. The chances of hitting a macro sized object in interstellar space are low. The vast majority of matter in the galaxy has already clumped into solar systems.

Re:Good luck (-1)

Anonymous Coward | more than 2 years ago | (#38774378)

Actually, the nearest star which is not our Sun is 4.2 light years away.

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38774682)

Couldn't you use quantum entanglement to send the signal back to earth instantly?

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38775394)

No.

Re:Good luck (1)

Patch86 (1465427) | more than 2 years ago | (#38774738)

Citation needed, on the travel time aspect.

Project Orion (the 1970's attempt at a thermonuclear rocket) would have take 44 years to reach Alpha Centauri (assuming a fly-by with no deceleration time, and excluding 36 days worth of acceleration to it's top speed). A long time by human standards, but a very very long way short of "10s of thousands of years". If you launched one today, you could get your first pictures back in almost the same amount of time as between Apollo 11 and today. That's travelling about 10% the speed of light.

There was also Project Daedalus, which was a similar concept using fusion rather than fission. That could go 12% the speed of light, and was not really that much less practical than Orion.

Re:Good luck (1)

the gnat (153162) | more than 2 years ago | (#38775128)

Project Orion (the 1970's attempt at a thermonuclear rocket) would have take 44 years to reach Alpha Centauri (assuming a fly-by with no deceleration time, and excluding 36 days worth of acceleration to it's top speed).

That was Freeman Dyson's calculation of what sort of extreme the technology could be pushed to; it's by no means a sure thing. However, the Orion drive was vastly more complicated (and expensive) than the nuclear thermal rockets they're talking about in the article, which would never be able to get to anywhere close to 1% of light speed. The big difference is that an NTR engine was actually built and worked at one point, whereas Orion was never more than blueprints. Also, an NTR is something that a private company could theoretically build, whereas Orion requires setting off repeated fission explosions, which only a handful of governments know how to do - and which in any case genuinely would cause an uproar.

Re:Good luck (1)

khallow (566160) | more than 2 years ago | (#38775106)

Nearest Star = 4.2 light years. At the moderate speeds we would be able to generate to accelerate, but then an equal amount of fuel to decelerate to enter orbit around such a star in time measured in something larger than 10s of thousands of years at survivable speeds that don't erode the probe down from "plasma erosion" like you have with a plasma jet cutting machine.

[...]

As a taxpayer, it leaves me as cold as intersteller space.

Well, it's a good thing then that you aren't paying for it. I imagine people who live much longer than we do, would have a different take on the value and cost of such things. But they'll get to use their own money for that. Nuclear-powered propulsion has more practical uses within the Solar System than without.

Re:Good luck (0)

Anonymous Coward | more than 2 years ago | (#38774834)

I hope you know that space is already very radioactive. The sun is just one massive fusion reactor which emits tons of radiation. Nuclear space technologies have been flying since Apollo and were used on every moon mission. We just sent a plutonium powers rover to Mars in November...We have contributed not even a teaspoon full in comparison to our sun.

Car analogies (2, Insightful)

Anonymous Coward | more than 2 years ago | (#38772774)

Brad Appel of General Propulsion Sciences frames the situation in more familiar terms: "To look at it another way, imagine you are planning a road trip from New York to Los Angeles and back. Except, there are no gas stations along the way -- you need to pack all of the fuel along with you. Using a chemical rocket to send humans to Mars would be like making the road trip in a cement truck. You might barely make it, but it would be one enormous, inefficient, and expensive voyage. Using an NTR, however, would be more akin to taking a Prius. It'll make it there comfortably, and it can go a lot further too."

A terrible car analogy quite worthy of Slashdot. Bravo.

Space travel is nuclear! (0)

englishstudent (1638477) | more than 2 years ago | (#38772784)

Just do the testing at Fukushima. Can't get much worse than it already is.

Re:Space travel is nuclear! (1)

WindBourne (631190) | more than 2 years ago | (#38773944)

Nope. Chernobyl is where you want to go. However, if doing something like NERVA, I will be happy to have it tested in my state. After all, it was designed here. The fact is, that NERVA is exceptionally safe.

Painted red and whote in hommage to Hergé ? (1)

Hamsterdan (815291) | more than 2 years ago | (#38772796)

Re:Painted red and whote in hommage to Hergé (5, Funny)

maxwell demon (590494) | more than 2 years ago | (#38772844)

I think your title was damaged by a radioactive particle.

Reminds me of an old Joe Haldeman short Story... (0)

Anonymous Coward | more than 2 years ago | (#38772824)

...The Mazel Tov Revolution, in which a bar is launched on a rescue mission by the simple expedient of strapping on fission-powered rocket engines (using hot, radioactive lead as the reaction mass) and driving it off a cliff and hoping it didn't go splat.

just bomb everything (0)

Anonymous Coward | more than 2 years ago | (#38772830)

just go with the old project Orion (http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29) if you have to use fission, its still the most effective one.

Re:just bomb everything (1)

DerekLyons (302214) | more than 2 years ago | (#38773536)

just go with the old project Orion (http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29) if you have to use fission, its still the most effective one.

To the extent that something that's never been tested can be said to be 'effective' sure.
 
Seriously, Orion has gained a reputation all out of proportion to reality. Few people seem to realize that not one single significant component has ever been built, let alone tested at even the most modest scale. None. Zero. Zip.
 
Yes, I know about the scale models they built - and they're roughly as relevant as an R/C car is to Formula One racing. The R/C vehicles 'proves' that a four wheeled vehicle can operate, but doesn't have an IC engine and the stresses on the suspension are orders of magnitude below those the Formula One racer experiences - not to mention the vast differences in aerodynamics. The same is true of the Orion scale models. They had no pusher plate or shock absorbers. They depended on the atmosphere to produce the propulsive shock waves. Etc., etc..
 
While it's true there are no obvious show stoppers, there are a lot of unanswered questions - particularly in the behavior of the pusher plate and the shock absorber system.
 
Also, few people realize the whole craft is designed around nuclear weapons of a type that don't exist - extremely small, extremely light, highly efficient, very clean (I.E. most of their yield was from fusion rather than fission) fusion weapons. Dyson and his team had very little access to nuclear weapons design details (something less than is publicly available today), and thus were relying on shaky assumptions about the direction of nuclear weapons research and the capabilities of nuclear weapons.

legal? (4, Interesting)

kaspar_silas (1891448) | more than 2 years ago | (#38772842)

Sounds exactly like 1955s project Orion. And similarily to it I don't think they can actually legally work on this idea due to international nuclear regulation. In particular the comprehensive test ban treaty. Because after all what you are designing is something very like an icbm with a "dirty" warhead. I god damn guarantee if Iran openly worked on this the US would bust itself to attack ASAP.

Re:legal? (5, Informative)

Anonymous Coward | more than 2 years ago | (#38772932)

Nothing at all like Orion. This is using hydrogen as the reaction mass, heating it with a fission reactor. Orion uses nuclear bombs set off repeatedly behind a fscking huge steel plate.

You're right about there being international nuclear regulation that may stop it, though - if I recall correctly, there are legal hurdles to even test-flying nuclear reactors up to orbit and all kinds of international agreements following near-misses with both soviet and american test reactors in the 60s.

Re:legal? (1)

WindBourne (631190) | more than 2 years ago | (#38773928)

nope. Not from a treaty POV. We send up reactors all the time. NERVA has ZERO issue going. Orion is a different matter. Those are technically bombs on there. The treaties prevent that from going to space, though I suspect that if we got ALL of the signatories to agree to it, we could do it. And I have serious doubt that we could get that, except when an asteroid or some other major threat were in-bound to earth (and in light of how America's CONgress is acting, I would guess that even with a massive alien invasion coming in, that we would get a number of nations or even extremists that would object to orion).

Re:legal? (5, Informative)

cbhacking (979169) | more than 2 years ago | (#38773036)

Nuclear thermal rocket != nuclear pulse rocket. The latter is the classic "Project Orion" engine, utilizing super-critical explosions for propulsive force. The former is actually more akin to a traditional chemical rocket, in that it works by expelling reaction mass from thruster nozzles. However, the energy of the reaction mass is imparted by heat generated in critical or sub-critical (but not super-critical) nuclear reactions. You can use any number of materials for this reaction mass, though the popular ones are hydrogen and water. Neither is inherently harmful, nor is there any reason they would need to pick up radioactivity from the reactor (any more than the cooling water which cycles through the heat exchangers of nuclear electrical plants or naval vessels becomes radioactive).

The test ban treaty has nothing to do with this. Nuclear pulse rockets are certianly forbidden by the test ban treaty - after all, they are literally exploding nuclear bombs as part of the engine's normal operation - but there's no reason nuclear thermal rockets would be that I can see. The argument about a "dirty warhead" is potentially valid (in that some would claim it, not in that it would be a plausible danger when you consider we already have nuclear-tipped ICBMs). However, there's no law or treaty against launching radioactive material into space. In fact, quite a few of our space probes and planetary rovers use radioactive thermal generators.

Compared to chamical rockets, nuclear thermal rockets have a vastly higher specific impulse, which is to say that a given quantity of reaction mass (rocket fuel or hydrogen flowing past a reactor) can produce a greater thrust (simply put, higher efficiency). This is due to their (much) higher exhaust velocity. Remember, E (in Joules) = mass (in kg) * velocity (in meters/second) squared. If you divide both sides by kilos (fuel or reaction mass), your energy per unit of reaction mass becomes a function of v^2. In other words, doubling the speed of the reaction mass will get you four times as much energy for a given unit of reaction mass.

Since the amount of thrust you can get out of the quantity of reaction mass that can be placed on a spaceship is the current limit on spacecraft range, speed, and payload, increasing that efficiency has the potential to revolutionize space travel.

Re:legal? (1)

Lord_Naikon (1837226) | more than 2 years ago | (#38773882)

I think you make some mistakes in your calculations. First, it's E = 1/2 * m * v^2. Secondly, the force the engine generates is proportional to m*v (impulse). The energy required to create an impulse of m*v is indeed 1/2mv^2. In other words, as the amount of thrust doubles, the required energy quadruples. Hence the need for a nuclear reactor. Basically energy efficiency is lower for high velocity rocket engines. In this case that is not a problem because this engine doesn't require much mass to operate resulting in high specific impulse (but low energy efficiency). Normally though, in chemical rockets, it is a tradeoff.

Re:legal? (1)

cbhacking (979169) | more than 2 years ago | (#38774430)

The factor of 1/2 is irrelevant here - I'm not talking in absolute quantities (and arguably shouldn't have given actual units at all) but in ratios. E/m (energy per unit mass) is a function of v^2. Since energy is relatively cheap (especially with a fission reactor), but mass is hideously expensive, you want an engine with the highest possible exhaust velocity, as that will maximize the E/m ratio very quickly.

Impulse is another story entirely. Impulse mesures the strength of the engine, not its efficiency. For high impulse, you typically want a relatively low velocity and high mass - this applies to everything from modern chemical rocketry (which is powerful enough to lift itself off Earth directly, something only a few even theoretical high-efficiency rockets can do) to early cannons (which used a heavy shot to maximize the impluse transfer they could get out of the limited energy of low-grade gunpowder).

Specific impulse (Isp) is the impulse as a function of mass flow. High Isp does not neccessarily mean high impulse - ion drives have excellent Isp, but push so little mass that their actual impulse is very weak - but it is one of the most popular measurements of efficiency for a rocket. In essense, it addresses the question of "If we are unconcerned with energy cost, how much mass do we have to consume to get us there?" (although "get us there" is actually much more complex in a real-world system).

Of course, extremely high Isp engines do tend to be energy-limited; not necessarily in the ability to supply it, but in the ability to move and dissipate it. In the case of nuclear thermal rockets, the limit is quite literally the melting point of your reactor assembly (including its controls and containment). That's still enough energy to accelerate a good quantity of mass to a truly absurd velocity, though - giving enough impulse to allow (among other things) more than 1G of thrust while still having a sufficient Isp that distant destinations and round-trip journeys become practical.

Re:legal? (1)

WindBourne (631190) | more than 2 years ago | (#38773936)

oops. I should have read yours first. You are correct.

Re:legal? (0)

Anonymous Coward | more than 2 years ago | (#38774944)

If you read the description of Project Bifrost on Icarus' website you'll see that they are also charged with reassessing Project Orion, and nuclear pulse. There's a fine line to draw between weapons and spacecraft. Just look at ICBM's - they are technically weapons, but we used them in space as heavy lift manned rated vehicles...

Re:legal? (1)

jamstar7 (694492) | more than 2 years ago | (#38773040)

Orion was the one you set off nuclear bombs under a heavy plate as a thrust mechanism. BiFrost is basically an upgraded NERVA system, from what little I can gleam from the article. Not a lot of hard science in it.

NERVA basically pumps liquid hydrogen through a fission reactor core. The core heats up the hydrogen, it expands, escapes through the bottom of the reactor and the nozzle providing thrust. Think 'tea kettle'. It'll help you visualise it.

The best reaction mass for this concept is stabilized monotomic hydrogen ('single-H', as Heinlein put it).

Re:legal? (1)

gatkinso (15975) | more than 2 years ago | (#38773716)

Clearly you are either unfamiliar with Project Orion, or you didn't read the article.

What is this, a Tom Swift book? (1)

Shag (3737) | more than 2 years ago | (#38772884)

Paging the young inventor to the white courtesy phone, please.

Credibility (3, Insightful)

Extremus (1043274) | more than 2 years ago | (#38772894)

It would be easier to believe in these guys if they provide more technical details in how they pretend to achieve fission propulsion. As it is mentioned in the article, this is not a new idea. Is there any new development that could cast new light on the problem of fission propulsion?

Re:Credibility (0)

Anonymous Coward | more than 2 years ago | (#38772918)

There's other plans to use electric propulsion (of which there a few different designs) with a fission reactor to power it. But fission for thrust? Good luck.

Re:Credibility (2)

Oidhche (1244906) | more than 2 years ago | (#38773002)

We should've been using NTR for the past 30 years or so: http://en.wikipedia.org/wiki/NERVA [wikipedia.org] .

Re:Credibility (0)

Ofloo (1378781) | more than 2 years ago | (#38772954)

I don't think there asking, there telling us there going to do it.

Re:Credibility (1)

IntoMars.com (2554282) | more than 2 years ago | (#38773042)

This group will have an extremely hard time launching anything without massive protest from the anti nuclear groups. Pampers Diapers [intomars.com]

Re:Credibility (1)

0123456 (636235) | more than 2 years ago | (#38774604)

Is there any new development that could cast new light on the problem of fission propulsion?

What problem? We've built and tested fission rockets; the only problem is getting them into space when politicos would prefer to listen to the anti-nuclear luddites.

Nothing new (3, Interesting)

tsotha (720379) | more than 2 years ago | (#38773118)

There's nothing new here. It's another "study" rehashing technology that's been rehashed over and over for at least sixty years. And anyway nuclear thermal rockets don't address the biggest problem we have with space exploration, which is getting to orbit in the first place. Heinlein famously observed "Get to low-Earth orbit and you're halfway to anywhere in the solar system." But the converse is also true - no matter how good your deep space rocket is you're only half way to where you want to be.

Nuclear thermal rockets have a wonderful ISP, but they don't have as much thrust as chemical rockets, and they're heavy. Even assuming you wanted to use one for the first stage it probably wouldn't have enough thrust to do the job. And you wouldn't want to start one up on earth, either. They never did figure out how to keep bits of the radioactive core from breaking off and entering the exhaust stream,

Re:Nothing new (1)

Hentes (2461350) | more than 2 years ago | (#38773434)

You could build the ship in orbit thus circumventing those problems.

This is now antique technology (2)

drewsup (990717) | more than 2 years ago | (#38773142)

I was under the impression that the new Vasimir or Ion drives were WAY more efficient than this old tech. The only limiting factor is the size we currently them at.
Imagine an ion drive with 8 or ten modules, all powered by a fission reactor, it would start slow, but by the time it got halfway through the solar system would be cooking along at good clip. How fast is the potential ? No one seems to know, but a constant acceleration sustained for years would get you to a nice portion of C.

Re:This is now antique technology (2)

bejiitas_wrath (825021) | more than 2 years ago | (#38773226)

If we wanted to go to another star system far in the future would it be possible to build an electromagnetic ramscoop [wikipedia.org] ship or is that still in the realms of fantasy? Such a ship could get to the centre of the Milky Way galaxy in 25 years ship time, although 50,000 years would have passed by on Earth. The only question is what would the Earth look like politics wise in 100,000 years?

Would they have forgotten about you? What sort of technology do you really need to construct a ship to constantly accelerate at 1g and reach the galactic core safely, not to mention coming back.

Re:This is now antique technology (1)

gatkinso (15975) | more than 2 years ago | (#38773728)

I have read rebuttals to the ramscoop concept. Not sure if they are valid or not. One thing however that seems right: the amount of radiation produced by such a system is thought to be deadly to life. So such ships would have to be unmanned.

Re:This is now antique technology (1)

drinkypoo (153816) | more than 2 years ago | (#38774506)

At the point where we can actually do it, perhaps we can create an inverse field to protect crew. But they're theoretically plenty useful for unmanned probes, anyway.

Re:This is now antique technology (1)

WindBourne (631190) | more than 2 years ago | (#38773906)

This was already shown that the drag from the magnetic scoop was more than the energy that was derived from the particles. IOW, no.

Re:This is now antique technology (1)

stevelinton (4044) | more than 2 years ago | (#38774028)

Ramscoops, as described in the literature have basically two problems:

1. Getting protons (as opposed to deuterium or something heavier) to fuse at a decent rate requires conditions substantially hotter and denser than found in the cores of even quite large stars. Something more like the conditions met in shockwaves in exploding supernovae. Without this your ramscoop isn't much use.

2. The interstellar medium is very unevenly distributed. The sun is deep inside the bubble created by an ancient supernova, so there's not much to collect.

Something like monopole catalyzed proton decay might work to solve problem 1, if it happens, and if we can find or make some monopoles.

Re:This is now antique technology (1)

Oidhche (1244906) | more than 2 years ago | (#38773260)

Ion engines have wonderful Isp, but very low thrust. And it's not just that a journey with such an engine would be longer - low-thrust transfers are inherently less efficient than Hohmann transfers, negating some of the Isp advantage. Moreover, you couldn't reach a nice portion of c with current ion engines: their Isp is good, but not that good. Most of them only have at most a few hundred km/s of effective exhaust velocity, limiting the maximum delta-v to like 0.3%-0.5%c under any design with realistic mass ratio.

Re:This is now antique technology (1)

WindBourne (631190) | more than 2 years ago | (#38773900)

Sigh.
Ok, a VASIMR (a type of an ion engine) can drive an ion out at high speeds. HOWEVER, where does it get the energy to accelerate the ion from? Obviously from a generator or a solar collector. The problem with the solar collector is that not only does it add drag, it does not work as you get further and further from the sun. So, that leaves a nuke reactor. How much does it weigh? A lot. The real problem is one of efficiency and the fact that it will break down. To get electricity, you had to convert an element to steam and then run an engine that turns a generator. All of that is not just a loss of efficiency, but something that WILL burn out down the road. 50 years is a LONG TIME TO LAST.

Instead, it is far far better to simply use the nuke reaction to heat hydrogen to use it as a propellant. This is not just simpler in terms of mechanics. It is also a great deal more efficient. In fact, comparing NERVA to Orion, I will take NERVA. Again, it is simpler design. Simple wins for long term issues.

It all comes down to exhaust velocity + mass ratio (1)

stevelinton (4044) | more than 2 years ago | (#38774004)

Basic physics tells you that total delta-V for any kind of rocket comes down to just two things: how much of the ship you can throw away to get thrust (mass ratio) and how fast you can throw it (exhaust velocity). For mass ratios of less than say 1000 (ie ship at launch no more than 99.9% reaction mass at launch), and non-relativistic exhaust velocities, total delta-V is no more than 8-10 times the exhaust velocity. Exhaust velocity of chemical rockets tops out at about 3-5 km/s, nuclear thermal rockets get up to perhaps 10 km/s, ion and similar rockets at the moment do perhaps 40-50 km/s, although they could get much higher at huge cost in engine size and power and very low thrusts-- not so much a rocket as a particle accelerator!

Basically to get anywhere within spitting distance of relativistic speeds with a rocket you have to get MUCH, MUCH higher exhaust velocities which means some kind of direct nuclear propulsion (where the reaction mass is actually produced and heated in a nuclear explosion). Orion might manage one or two percent of lightspeed in principle, or better if you could replace the fission bombs with some kind of laser ignited fusion or matter-antimatter bombs.

Oh no! (0)

Anonymous Coward | more than 2 years ago | (#38773334)

This won't work either! Looks like you'll live here forever, Space Nutters!

It isn't what we need. (1)

sgt scrub (869860) | more than 2 years ago | (#38773492)

What we need is a reusable and reliable system to get objects out of earth's orbit. I would think the nuclear energy would be better utilized in a magnetic launch system. After that is established, then building an ORION/NERVA powered vehicle in space would be practicle. Using an ORION/NERVA powered launch rocket isn't my idea of a good start, so to speech.

Icarus? (1)

Anonymous Coward | more than 2 years ago | (#38773554)

Seriously?

Oh Please! (1)

rocker_wannabe (673157) | more than 2 years ago | (#38773626)

"Mass ejection" propulsion is so last century. Where are the darn warp drives? I say: "Go FTL or go home."

Warp drive off a planetary surface? (1)

jeffb (2.718) (1189693) | more than 2 years ago | (#38774380)

Oh, sure. "Nukes are too scary, so let's just goatse a big hole in space itself right next to an effectively unlimited reservoir of condensed matter."

Trivial to restart NERVA (1)

WindBourne (631190) | more than 2 years ago | (#38773702)

The problem is that we have so many left wingers that are gaga over the idea of nukes being launched into space. Yet, we could easily put up a small processing plant on either the moon or even in space, and simply send a safe form of Uranium up there to be processed and bred.

Legal? (1)

nurb432 (527695) | more than 2 years ago | (#38774470)

I thought this was banned by international treaty.

Missing Information from Article READ (0)

Anonymous Coward | more than 2 years ago | (#38774768)

It wasn't really explained in the article, but nuclear thermal rockets and fission technologies in general can be used in an interstellar mission, for purposes other than boost phase. They can be used for power or life boats. For the boost phase, you could use something like nuclear pulse propulsion, which Bifrost is tasked with re-assessing. I think NTR was highlighted because it's the most near-term technology that NASA has been putting more money into, for instance: in the new AES program (Advanced Exploration Systems) which deems NTR as essential.

Atomic rockets (2)

Patch86 (1465427) | more than 2 years ago | (#38774812)

Reminds me of one of my favourite geek-out websites:

www.projectrho.com/rocket/

If only more writers of science fiction television trash would spend just one afternoon of their life skimming that website...

Project in DARPA's Starship Program (1)

newsfan (2558102) | more than 2 years ago | (#38774982)

if you do your research, you'll notice that Icarus is charged with DARPA's 100 year starship program, which means that effectively Bifrost is going to be doing all things nuclear for DARPA in space

Rail gun on the moon instead? (0)

Anonymous Coward | more than 2 years ago | (#38775158)

My dad was talking about a rail-gun on the moon that could shoot small (few kilogram) sats at
some decent percentage of the speed of light. I didn't find anything else on the web about such
a thing, but the US military is getting pretty good at rail guns. With no atmosphere on the moon and
a relatively weak gravity well, seems like you could get some serious acceleration.

Seems to me that spewing out lots of small sats, with solar sail type propulsion and other
miniaturized components would be a good start to exploring the stars and outer solar system. Eventually, could
send progenitors of life (fertilized eggs, frozen micro-orgs, equipment to incubate them),
even if not living beings themselves.

Queller Drive (1)

smoothnorman (1670542) | more than 2 years ago | (#38775398)

Too bad they won't name it "The Queller Drive" (cf. http://en.wikipedia.org/wiki/Voyager_One_(Space:_1999) [wikipedia.org] ) a fun scifi plot device being that there's this space drive system that gets you there really fast, but unfortunately kills everything that's in its wake.
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