Spacemen urge NASA to build nuke ship for Mars trip Mars has given nuclear spacecraft engines a new lease on life, with nuke ships being named as a top priority – along with electrical propulsion – in a new report that recommends what NASA should focus on in coming years. The two propulsion systems prioritized in the 468-page report by the National Research Council (NRC) – …
Even if I have felt great excitement with space exploration starting with Sputnik and perhaps finishing with the moon landings, but how could the exploration of Mars, a completely worthless planet, in any way prevent Mankind's downfall. If we are concerned with Mankind I think we should concentrate on Mankind on this planet. Then again you are right "Mankind's short sightedness may well be its downfall", true from the very beginning, but that has nothing to do with Mars.
Am I being mean, I think I need a beer.
Far from being "worthless" Mars is the only really viable place for Mankind to colonise, as it is (in astronomical terms) just next door, and has the potential to be terraformed using current or near future technology, to the point where living on the surface could be possible within a few generations. Contrast with the Moon where any colony would always be confined to artificial structures, and at the mercy of the low gravity (which has deleterious effects on human bodies).
It's all very well the boffins going "ooh look at star such-and-such, it's got goldilocks planets which can support life!" the reality is we are not sufficiently advanced to even consider travelling to any of these.
You say "I think we should concentrate on Mankind on this planet."
Yes, but we are in the classic "all the eggs in one basket" situation at the moment, where firstly, any extinction level event (whether from orbital impact or through our own foolishness) would wipe us all out, and secondly, we are running out of room and resources.
We either need to drastically limit the population growth in some way, or find another planet to move to. Doing this now, before it's too late, would seem sensible. But as you and the previous poster have said "Mankind's short sightedness may well be its downfall".
Colonising Mars would certainly be one mean job, and terraforming on a scale that would make the planet's surface habitable would take something on the order of thousands of years, if indeed it would be possible (can Mars's gravity keep an atmosphere?), however, living in large underground caves or bubbles in large enough numbers for humanity to survive an Earth catastrophe would be possible.
Of course the key to that, especially with much less solar irradiation for plants to grow etc, is massive amounts of power, and that means nuclear power on a gigantic scale
Not to mention the fact that Mars is not massive enough to hold onto anything other than a very thin atmosphere. Even if you managed to replace what is there (mostly CO2 IIRC) with a nice nitrogen/oxygen mix, you'd still asphyxiate pretty much straight away. Trying to hold onto a thicker atmosphere would be a fool's errand, as you would be continuously losing mass to space. Assuming you had some miracle technology that could convert rock into breathable gases, you'd essentially be subliming the planet away into space, making the problem worse as you waste more and more mass.
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While what you say is generally true, I think that you probably reach the limits of diminishing returns utilising that and solely that.
The planet is already at a point where significant swathes of it do not have sufficient fresh water for the population as it currently stands - look at Australia. While you are right that innovation is often bred from this, there is only so much we can do, and the negative effects of these innovations are often not well understood and do not come to the forefront until significantly later.
You ask:
"Why hasn't the last century of geometric growth in population resulted in a 'Malthusian catastrophe'?"
I answer:
Possibly because at that time, the planet was underpopulated and, thanks largely to the Dark Ages, not as technically advanced as we potentially could have been. The last century brought massively increased population growth and invention to support that. We may well have now 'caught up' as it were.
Could it be we are now at the point of saturation?
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Or as Kenneth Boulding put it: "Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist."
Even if you assume we out-innovate any obstacle to growth, fundamental physical laws will get us rather soon: http://physics.ucsd.edu/do-the-math/2011/07/can-economic-growth-last/
The total carrying capacity of earth, population-wise has nothing to do with why people are unhappy with the current population growth. If yo want to sum it up, when population grows, we find the changes made to feed them result in changes to the earth and previously uninhabited areas that we do not like.
We're nowhere near population saturation. We have not even begun to exploit all food sources. When we run out of plankton to eat, or CHON-burgers, then it might be an issue. Any words to the contrary are just histrionics. However, the changes we've already made have been unsettling enough to generate a reaction, and justifiably so. If population growth means that we render an excessive number of species extinct (I wouldn't mind if mosquitoes went extinct) and that we turn treasured environments and habitats into cultivated space, we as a species lose a lot of things that we should come to regret.
We, of course, should be better stewards of this particular planet. The development of interplanetary resources is the single best way to do this without also putting restrictions on people that won't be followed, or that are counter productive. For example, if intelligent people are concerned about population growth, and forbear having children in order to do their part, then the earth will eventually be overpopulated by the slightly dense that just "didn't get the memo". They were probably watching some trashy reality show at the time and couldn't be bothered...
Even in circumstances where legislation forces the population as a whole to reduce itself, cultural issues arise to confound the best-laid plans. "One Family, One Child" turns into "One Family, One Boy, now that he's 18, where are the girls?"
On a positive note, the people lamenting the loss of the old-growth forest in the US should know that there is more forestation in the US than there was in pre-Columbian times.
As was pointed out these magical system don't work or have very bad effects of other areas.
For example from Central_Valley_Project link you provided:
"Despite the benefits of the Project, many CVP operations have resulted in disastrous environmental and historical consequences. The salmon population in four major California rivers have declined as a result, and many natural river environments, such as riparian zones, meanders and sandbars no longer exist."
In other words to live one lifestyle, others had to pay. This will eventually cause enough trouble to trigger wars or the collapse of societies. Man has been changing his environment for millennia, but the repercussions are only now being felt in some areas.
Go back a few centuries and the vast majority of Europe was covered in forests as dense and diverse as those in the Amazon, our ancestors got away with deforesting a continent as most of the planet was still mostly untouched. If that gets repeated in South-America, Africa and Asia the effects could be devastating all round.
Going purely by what I see as your incredible naivety on the real world issues, I assume you also believe in the Sky Fairy and/or Intelligent Design. Where as in reality; humans are just animals, a few slightly more intelligent than most other species, but the same basic rules apply. When the resources needed to live run low we either kill or steal from our neighbours or die off.
The one difference between us and the other species, is that we should be smart enough to stop breeding beyond what can be sustained, and before we need to fall back and act like all the other critters on this planet.
Quite like your text, I also liked the book "The read planet".
But Mars is to small, too cold, and does not have anything to support human life. There is not enough water and there is no shield against radiation, nill, nothing.
The way we have managed (and sometimes failed) to send probes and satellites to Mars is fine.
But to send humans there I just cannot see as anything more than a political decision.
It was that way with the moon too.
I would leave Mars to China as far as landing humans is concerned. I believe the political gain would be nill.
I would support an international Moon base, for assembling larger satellites and so on.
But the one thing that intrigues me from this Mars book was the space lift or space sling.
That I could support. It would be fun to know if we had the technology and the money to build one.
When it comes to those planets in other solar systems it is quite clear that we would first send unmanned stuff there before any space ship with humans on board.
I like science fiction very much but you have to leave at least on toe attached to this earth.
And yes if Mars seems to be a good home some day, then we must have fucked it up real bad.
Australia comes to my mind, and then again not at all, not not.
The author is not emphasizing that this is a publication driven from NASA's OCT. The OCT hasn't driven a report with this level of specificity in years. It doesn't mean that NASA is confident that it will secure funds to achieve these goals, but that the NASA administrator was confident that he wouldn't be fired for daring to conjecture on such an expensive level.
Looks to be an interesting read. The budgetary requirements for enacting these proposals seems far away. The USA does need to pay down the massive debts assumed in the August 2008 financial meltdown.
Yes, Footfall was a good 20-30 years after the concept of Orion. Freeman Dyson wrote a paper in the 60s on using thermonuclear devices to achieve interstellar voyages - you can be sure the maths and physics stand up! Carl Sagan pointed out that this would be a rather clean way of disposing of nuclear weapons inventory.
Erm... I hopes that he added "Once the rocket is far from earth gravity well"...
Project Orion was on the same line as those "Civil engineering nukes" - a good idea as long as you don't mind the radiations.
Disclaimer : Don't take me wrong - I'm not of the "nuky=baddy" team, and I'm in favor of the developpement of "clean" NTEs...
And admit that after hundreds of billions of dollars the poverty level hasn't really changed that much along with the fact that the major reasons for a lack of food in the third world are corrupt regimes that prevent markets from working and/or a lack of cheap energy to produce said food.
As Blackhawk Down shows, it's not the US military budget taking bread from the mouths of toddlers in the third world, it's more like the African warlord's military budget that is killing people.
Recently a branch of the Kenyan civil service estimated that the country could support almost 300 million people. That's twice the population of Russia. At the minute Kenya's population is ~41 million.
Anyway. So you decide to divert the entire world's military budget to feeding people. Then what? Will people suddenly become virtuous, industrious, _and_ peaceable? There is vast wastage in all military budgets and we should spend more on disaster relief and development, but spraying resources around will not magically solve the world's problems.
NTR is a pain and it has limited Isp. Sure, cooling is a little easier because your reaction mass carries the pile's heat with it, but at ~2000sec you're still going to need a lot of reaction mass and time to get to Mars. Just let it die. Focus on compact nuclear electrical sources and solve the reactor cooling problem. You'll be a lot better off in the long run.
One may indeed assume it is not a vacuum. When it ends up as part of a nuclear reactor cooling scheme, one might plausibly call it an 'oven', though perhaps 'kiln' or even 'furnace' might be more appropriate.
High efficiency radiators in a vacuum are plausible, but exceedingly non-trivial to engineer. One of the better designs looks like a spray of low-vapour pressure coolant; the droplets having a large surface area for radiation, and as they won't boil away to any significant degree you can catch em in a scoop to return em to the coolant loop. Does away with all the mass and inertia of a really big solid radiator system, certainly. Not quite as straightforward as an open-cycle nuclear reactor though.
"Most of what we know as radiators work by convection or conduction, neither of which will operate in a vacuum."
Just because a household appliance is called "radiator" it does not mean that it really is one.
Radiating heat into space is quite possible. In fact, that's how we get the heat from the Sun here on Earth. The space is black = very cold and radiating into space is actually the best way of radiating heat, as one can easily deduce from how cold it can get here on Earth on a clear night.
Even inside our atmosphere, as you heat things beyond a few hundred degrees C, radiation becomes the main component of heat transfer.
So, dumping heat into space without throwing away hot mass is very much possible and the hotter the stuff you want to cool is, the more efficient it is to use radiation to cool it down.
There's plenty of other cool things in the research pipeline. Open cycle gas core NTR springs to mind, or weirder things like fission fragment reactor based things. Both are likely to be better than a couple of thousand seconds. The important thing is that practical work be done on these various designs rather than purely theoretical... like most nuclear technologies we've more or less failed to innovate in the last 30 years (or longer!) because of their bad reputation and image.
That said, I'm terribly keen for mini-magnetosphere plasma propulsion sails to work. That would be all kinds of awesome.
The library of the Physics department of the Helsinki university of Technology used to have (or still has, haven't visited the place for decades) a collection of documents on microfiches about the NERVA. I came across them as a student while looking for something else, and wondered what they were doing there, as Finland certainly did not have a nuclear rocket programme going on. Maybe when the project was terminated, NASA wanted to ensure its results are not lost and sent copies of all unclassified documents to university libraries around the world?
Which means that if a country with no scruples about reactors in space (the Chinese, say) wanted to send a nuclear-powered ship to Mars, they wouldn't have to start the research from scratch. I for one would really like to see such true spaceship to be be built in my lifetime, no matter who does it.
I don't know if they would work as well as Uranium reactors, but if a nuclear rocket could be based on the LTFR molten salt reactor, nearly all the fissile material could be Thorium, which presents a much smaller risk of radioactive contamination in the event of a catastrophic failure. This might obviate one of the major objections to nuclear rockets.
If I understand correctly, the ability of a nuclear reactor to provide the necessary energy for a long period of time with a small fuel mass means that a much larger amount of propellant (the stuff shipped out the back) could be carried instead of chemical fuel. This means that a long, slow thrust could be used instead of the present method of maximum thrust for a very short time.
"But unfortunately, as has been proven in scientific and technological debates ranging from climate change to evolution, reason often takes a back seat to entrenched beliefs and constituents' fears, interests, and ideologies."
Indeed, as has been shown many times in El Reg, which continues to spew reactionary climate change ravings -- with comments turned off, as Andrew is afraid that reason might rear its ugly head near his articles -- to please its sponsors. Not to mention the pro-SOPA garbage they tried to push on us not too long ago.
Mine's the white one with the burn marks on the sleeves.
I think you probably meant sarcsasm, though people tend to use 'irony' instead as they feel it makes them sound clever.
"-- with comments turned off, as Andrew is afraid that reason might rear its ugly head near his articles --"
No-one has reason to fear that from 99% of the pompous asses who post here, my friend.
" Not to mention the pro-SOPA garbage they tried to push on us not too long ago."
Dates? Ideally, links to the articles? *Some* evidence rather than bringing up a topic you think will get the aforementioned asses on your side?
"Mine's the white one with the burn marks on the sleeves."
Advertising your untrustworthiness around naked flames doesn't speak well of your intelligence and automatically makes you less credible. But Homer Simpson likes nuclear stuff too, I suppose ...
@Alister: maybe for terraforming but there alternatives to colonizing Mars. You could construct an O'Neil cylinder on the stable Lagrange points. By their design O'Neil cylinders are scalable enabling humanity to colonize space. They are easier to build and there is a technological path from our current space capabilities. It starts with a Bernal sphere which will be used to house miners and geoengineers to mine asteroids until we get enough materials to build the cylinder. Which should be used to develop and perfect environmental engineering enough that you can replicate the conditions of earth in space. Eventually you may consider colonizing other planets.
http://en.wikipedia.org/wiki/O%27Neill_cylinder
http://en.wikipedia.org/wiki/O%27Neill_cylinder
Nice to see that nuclear is receiving some attention. However NERVA, I think was seen at the time to have shortcomings that would affect scalability and continuous development. A much more elegant and effective thruster was the DUMBO reactor. Having said all that, the end result of all this new enthusiasm will very likely end up like the UK Nuclear Energy Proposals and result in endless talk and absolutely no action.
In reading the previous replies I'm rather glad that I share a forum with so many rocket scientists who know a thing or three - my education about the subject has improved dramatically just by reading the responses to this one very informative article. It's so much better than having to hang out with political retards who haven't got a clue.
Thank you everyone for bringing me up to speed on such a fascinating subject. Maybe someone could advise where I can get one of these fusion engines - I have a spare De Lorean in the back garden and as I understand the current situation a nuclear powered car wouldn't be subject to road tax (but I guess the yearly MOT might be a tad expensive).
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