Slashdot Mirror
Nuclear Fuel For Superfast Interplanetary Travel
jdoire writes: "Using a thin metallic film of americium-242m, a rocket could reach Mars in only 2 weeks. This is made possible because the nuclear material could be used both as a source of energy and as a propellent material, making the engine very efficient and light weigth. Check ScienceDaily for the full story."
The article is slashdotted, but from the Slashdot description, it sounds like we're talking about a radioactive substance that would be expelled for a reaction force. Is that right? If so, then it sounds like you don't want to be anywhere near or downwind of the smoke cloud this thing makes when it takes off.
I hope I'm misinterpreting this, because my first reaction is: "Gee, that's stupid." I mean, it doesn't sound as bad as Orion, but still...
---
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
Yes, the length of an efficient Hohmann orbit is a lot greater than the straight line distance to Mars. But with a travel time of two weeks, efficiency goes completely out the window; you would be practically taking a straight line path.
.1 G.
.15 G figure is probably more accurate, and even a wide margin of error wouldn't change the answer to the "would I be pureed by this acceleration?" question.
Calculating the actual orbit is a non-trivial task, but I recall that for the outer planets, at least, the straight line approximation mghiggins did wouldn't be very far off (in terms of relating travel time and acceleration) for a constant-thrust ship of even
Also, I'd assume "trip to Mars in 2 weeks" means when Earth is passing closest to Mars in it's orbit, so the
I want to see us go to Mars, but I don't want us to rush it. I am sure that you have taken note to the backlash that NASA took when it lost several probes in a row. Those were unmanned and they got reamed big time. Imagine what the public would do if NASA lost six astronouts while enroute to or on Mars. Chances are good that NASA would either get axed or be so horribly crippled from budget cuts that it might as well be dead. Although the technology we have currently is capable of sending manned missions to Mars, we need to do more research and more testing and patience before we can achieve a SAFE mission to Mars. I am sure we will get there, and within my lifetime. Why, because it is one of NASA's priorities. Right now they are spending most of their budget on the ISS, as you know, which IS necessary. I personally believe that having a working space station is as necessary as sending someone to another planet. Once they are done with the ISS then they can move onto providing more time and funding to the Mars project.
Disclamer - Opinion of Person
Getting americium isn't that impossible, but it is dificult. The steel and metals industry uses americium to gauge the thickness of metals.
In fact the company I work for now probably has a few pellets from many years ago. I don't think they are of this isotope, but still, it can be found.
Oh, BTW, if it wasn't mentioned, the half life of Americium-242 is about 16 hours. It's relatively easy on the environment. However, Am-241 has a half life of 432 years. And to make matters worse, Am-243, the most stable isotope has a half-life of 7300 years.
Wow... I guess space travel has come a long way since I went to sleep last night!
--
SecretAsianMan (54.5% Slashdot pure)
Washington, DC: It's like Hollywood for ugly people.
Math isn't your strong suite, is it?
150,000mph / 60 = 2500 mp minute
2500 mpm / 60 = 41.66 mps
BTW - that 150,000 mph figure - is that supposed to be peak velocity, or something else?
That's a pretty good posting Hemos, but what department is it from? Hemos: "The" department.
What good is it to have tiny nukes if we have no ability to deliver them to other planets, where hostile alien races are sure to be setting up a similar attack on us? We must strike first to establish humanity's supremacy in the galaxy, and a super-fast spaceship with horrifyingly destructive weapons is the first step.
Phallic Symbols in LOTR
True and false. There ARE in fact things we can put together out of carbon which are superior to any petroleum-based lubricant. Unfortunately, no one has done so commercially. This is mostly because it's expensive. You can see pictures of buckyballs here. CMU has a buckyball project. So does SUNY. You could make your own fullerenes. There are a number of fullerene-related patents.
That last page produces the real gem: this patent is for a "Magnetic recording medium comprising a solid lubrication layer of fullerene carbon having an alkyl or allyl chain". The abstract reads:
There are further supporting references. The Buckyball: An Excruciatingly Researched Report (which gives its references at the bottom) contains this quote:
Of course, I don't know that anyone's actually assembled such a molecule. I located an article called Just Rolling Along which discusses tungsten disulfide, which is similar to buckyballs. It is, however, expensive to produce, and difficult to make in quantity; This is what we're waiting for. Incidentally, I did find one article that gave hope for this, under the heading "Cheap Buckyballs". Amusingly enough (to me) the anchor tag is named "cheapballs". I guess when you're hopped up on this much sugar all kinds of things are funny. If anyone has access to the text of "Journal of Organic Chemistry, March 8" perhaps they could help out here.
So in summary, there ARE better lubricants than those cracked from crude. They are not, however, currently on the market, as they are expensive and time-consuming to produce. However, science marches on, and we'll solve this problem, too.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Personally, I've always found the best way to achieve interplanar travel is to find a high level wizard who can cast the necessary spells. I like to visit the outer planes at least twice a year.
Coal fired power is evil, regardless of benefit.
Oil fired power is evil, regardless of benefit.
Natural gas power plants emit pollutants and so are evil too, regardless of benefit.
Geothermal and solar... hmmm... don't seem to work like greenpeace says.
So for the last ***10 YEARS***, not one new power plant was build in CA nor any expansion of existing plants.
Waaaaah! We have an enegry shortage in CA due to... uh.... yeah!.... DEREGULATION! Surely strict environmental laws are not to blame. And repealing then would be a right wind radical thing to do.
Let's lobby the DOE to force other states on the grid to sell us power at a mandated discount. They want to suck off the grid and pollute other states so they can have blue skies?!
Well, hey, CA, you download off the grid, you have to upload too. CA is no different than a w4r3z l33ch. If you want power, you have to get dirty... you have to pay for it just like everyone else.
Ma certo:
distance = 1/2 accelleration*time^2
The closest distance between Mars and Earth is about 100 million kilometers (I refuse to do this in miles)and want to cover it in a week
0.5*acc*(7*25*3600 second)^2=5*10^10 meter
Gives you about 0.27 meters/second^2 or about 1/40th of Earth's gravity. Peachy
Now, call me crazy, but people keep assuming that an in-atmosphere launch is a given when dealing with spacecraft. I doubt very much that this drive is intended for use in an atmosphere, and I know for a fact that both Project Helios and Project Orion were not intended for use inside the atmosphere of Earth.
But, since you mentioned them, I just want to comment on Projects Orion and Helios, related to this article by the fact they too were potentially great boons to space travel way back twenty years ago: Having become aware of the projects way back in the eighties because of a children's book(!) I began to research as much as I could on the projects. I really began to gather information when I got connected to the internet back in 1996. The internet is a wealth of information but in this case 98% of what you'll find will be either pure dross or pure fiction dressed up in science sounding terms. I'll add "in my opinion" rather than just state the above as a fact - IANASY (I Am Not A Scientist Yet). I've let my search lapse in the last few years mainly because of all the extra fake and useless info that appeared on the internet after films like "Deep Impact" which briefly mention Orion or Helios. But from what I gathered, the official reasons the projects were terminated rather abruptly were highly unlikely, the main one cited being the SALT (Strategic Arms Limitation Treaty) and SALT-II treaties with the Soviet Union. A second reason often given was that the '...radiation problem caused...[by the detonation of nuclear devices]...an unavoidable health risk[to the crew].."
Looking over the technical details I managed to track down, I do not believe this reason. Even with limited knowledge, most people would be able to proffer ways of protecting a crew from any major health risk - working only on a design basis. Fears of contaminating the Earth's atmosphere seem unjustified considering it would be possible to limit operation of either the Orion or Helios drive(for want of a better term) to an acceptable distance from Earth. I don't mean to spread paranoia, but at the very least the people who cancelled these projects were misguided - I leave any other alternatives up to your imagination!
I'm not an amoral person who puts science before people : NATO's use of DU(Depleted Uranium) based weapons is deplorable; fission is an unsafe and unnecessary technology for use in power stations; the use of growth hormones in livestock farming and relatively untested GM techniques in Agriculture is plain crazy in Western economies. The fact remains that Orion and Helios were two projects which shouldn't have been cancelled. I hope to goodness that, just because this new drive employs a radioactive isotope, it isn't designated 'too risky' out of hand - which seems to be a popular thing to do nowadays. (By the way, I know it's a different isotope, but check your smoke alarms....there's a good chance it contains Americium 241 (probably about 0.9 micro curie)
(By-the-by, if you're planning to look for info on Orion or Helios, try the following phrases "Advanced Propulsion Design", "JPL", "Helios" and "Orion" You'll also find that various university professors have, at one time or another, written papers on the subject - try contacting your local university's physics department. )
8)
Concrete analysis...
The G-force isn't that bad, actually.
brittanica.com tells me that the distance from Earth to Mars is between 56M km and 400M km, depending on the relative position of the orbits.
Assuming constant +ve accn for the first half of the journey and constant -ve accn for the second half, and a two-week journey in total, this means an acceleration of between 0.15 m/s^2 and 1.1 m/s^2.
Since 1g = 9.8 m/s^2, these accelerations are tiny, and you'd safely avoid being pureed.
All opinions expressed herein are not my own; I haven't had free will since last year when aliens ate my brain.
If we have an affordable way to travel in months to the nearby planets, then the solar system and the stars are open to us.
the model is that of the Polynesians as they spread over the Pacific ocean. There plenty of small objects beyond Pluto that could act as stepping stones. never mind things like the asteroid belt. Earth crossing asteroids could suddenly become viable economic entities for carrying things between the inner and outer solar system
There are many problems of supply that would have to be worked out. But we could certainly build a network over time, terraform an asteroid or two, mine a comet for water. the challenges are formidable, but not out of the question.
"It is a greater offense to steal men's labor, than their clothes"
Your calculations would be great if you were flying from point A to point B in a straight line, but unfortunatately it's not that simple.
:) So not only do you have to worry about the eccentrities of getting into a Solar orbit at Mars' distance, but you have to time the process such that Mars will be there when you arrive. Depending on the positions of Mars when you leave terrestial orbit, this can be non-trivial.
:)
Firstly, you're moving about in Sol's gravity well, so you can't just point at Mars and pull the trigger. Instead, what you want to do is move into a higher (faster) orbit around the sun.
Secondly, Mars moves!
I Am Not An Orbital Mechanic, and perhaps someone who is could do the real math, but I think that the distance covered is far greater than you've assumed.
However, it seems to me that the accelerations involved are still not extreme. I may be wrong, but I think that a 1G acceleration gets you to Mars in ~ 2 weeks, taking orbital mechanics into account. 1G is a magic number, as it would simulate the gravity you're experiencing now - good for bone mass retention.
Want to learn about race cars? Read my Book
It's amazing what one neutron will do....
Am242: fuel to mars
Am241: Smoke detectors!
Paul_D
If this can be made praticle (and lord knows getting americium is damn near impossible!) it make the possability of space exploration more inviting and less risky. The time to arrive at our destinations is greatly decreased and the saftey factor goes up. Just think, a trip to the moon could turn into a "three hour tour".
I for one hope they make it work.
"Science is about ego as much as it is about discovery and truth " - I said it, so sue me.
If I were to endure a 2 week acceleration/deceleration trip to mars, given the distance, I'd be puree on arrival.
Karma karma karma karma karmeleon: it comes and goes, it comes and goes.
I think all these stories about pie-in-the-sky technology that we won't see for decades, if ever, is entirely the wrong direction to focus attention.
I want NASA to go to Mars, not in 50 years, not in 20 years...now, or 5 years ago even better. We have the ability and to go, we have a plan(Mars direct). All we need is some vision: from our representatives in Congress and from the public.
I'm sick of waiting and I'm sick of watching NASA shoot little AIBOs at that planet and then watching them crash and burn. Spend some money, build a good, safe ship, and send some people there. But for god's sake do it now. Everyone thinks it would be hard, and they'd rather it be easy. Well guess what, it will get easy, once we do it 100 or 1000 times.
And while I have nothing against ISS, that $60 billion could have got us a round-trip ticket to Mars, instead of Mir2.
Ok, so why are we still using gas-powered vehicles?
Nevermind, I'll answer that myself: because oil still exists in the Earth and therefore not every penny that can be made from it, has been made by the perto companies.
So if this nuclear material can be used to send a rocket to Mars in 2 weeks, then assumming it can be controlled and throttled, for how many years could it power a car running at 60 mph.
Here is a link to the same old story posted by michael yesterday.
Sure, we can go to Mars in a year or two with Mars Direct... but consider:
Fourty some years ago there were several methods for getting to the moon under consideration - among them were:
We went with Moon Direct - and sent 12 (14 if you count Apollo 13) people to the moon. Since then nothing.
Perhaps if we had gone the other way, we would have built the space station in LEO first. Used it as a staging point for missions to the moon and been left with an easy jumping off point for further missions to the moon, mars, and beyond.
I fear that if Mars Direct is the way we get to mars, you will be able to count the missions to mars on the fingers of one hand.
Americium and Neptunium should only be used for there god-given purpose. Cool little mini-nukes!
It is a waste of our precious scientists time trying to speed travel to Mars. First we must have popcan sized mini-nukes, then we can move on to such ungainly pursuits as space exploitation.