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Print 51 comment(s) - last by PrinceGaz.. on Nov 30 at 4:02 PM
The Voyager 2 space probe should be crossing another milestone any day now.

Shortly after Voyager 2's 30th anniversary in space, the probe is set to achieve another milestone in its journey; it is expected to cross the termination shock in late 2007 or early 2008. The termination shock is a spherical area that surrounds the solar system where solar winds slow to subsonic speeds.

Though launched 10 days later, Voyager 2's sister craft, Voyager 1 crossed the termination shock in December of 2004, three years ahead of Voyager 2's projected arrival. The earlier crossing was due to a shorter trajectory out of the solar system.

The prediction comes from physicist Haruichi Washimi at University of California, Riverside. Washimi used a global magneto-hydrodynamic simulation in conjunction with data from Voyager 2 to give the window where the probe will likely cross the boundary. The simulation is a "method that allows precise and quantitative predictions of geometric disturbances caused by solar activities," according to a release at UCR.

"This is the first time the termination-shock position has been forecast in this way. After it crosses this boundary, Voyager 2 will be in the outer heliosphere beyond which lies the interstellar medium and galactic space. Our simulations also show that the spacecraft will cross the termination shock again in the middle of 2008. This will happen because of the back and forth movement of the termination-shock boundary. This means Voyager 2 will experience multiple crossings of the termination shock. These crossings will come to an end after the spacecraft escapes into galactic space," explained Washimi.

Launched August 20th, 1977, Voyager 2 has seen four planets -- Jupiter, Saturn, Uranus and Neptune -- and their moons on its way out of the solar system. The original Voyager missions where slated only to visit Jupiter and Saturn, along with their largest moons. The extraordinary success of the missions convinced NASA to extend Voyager 2's mission and use gravitational boosting to propel it towards Uranus and Neptune.

Though still operational, the natural decay of the plutonium fuel on the craft has forced shutdown of several systems to keep it operational. At launch, the Radioisotope Thermoelectric Generator pumped out 470 watts of power, but by 2001, output was down to a meager 319 watts. Both the Voyager crafts are projected to have enough fuel to continue operations until about 2020.

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Very cool...
By ChristopherO on 11/28/2007 5:26:53 PM , Rating: 2
It's good to see these probes still being useful to science after so many years. I'll occasionally check the Heavens Above site to see their current position, etc.

Given that I'm not a physicist, and I don't keep up on drive technology... Is it possible to build a vastly faster probe than the Voyager series?

I remember something about an ion drive that was tested a few years back. It was the space-based equivalent to getting propulsion from a leaky faucet. I think it bled off a very small stream of ions, but did it with a huge degree of force, so the cumulative impact of months of propulsion was a very significant velocity.

I'd like to see probes out to the Kuiper belt, but I just don't see that as being too feasible since the nuclear fuel needs a significant life span, plus you have to factor in a decade of electronic usage without failure.

We definitely need a faster drive in order to reach the further planets in a reasonable amount of time. Given that, we should be able to get there and undertake higher-quality science.

The Voyager probes might be providing data, but realistically it's just a drop in the bucket compared to what they could previously accomplish. There has been some sensor failure, some have been shut down to power, so at this point there are only a couple instruments, the primary computer, and the heater online.




RE: Very cool...
By ChristopherO on 11/28/2007 5:30:57 PM , Rating: 2
Oh, and kudos on the Ilia photo... That was one awesome movie. Actually my favorite in the series. Khan / First Contact might have been the most exciting, but TMP was definitely the purest in regards to science fiction content. TMP was more 2001 than Star Wars.


RE: Very cool...
By wordsworm on 11/29/2007 4:51:44 AM , Rating: 4
Hogwash. Star Trek IV was the most scientifically pure of them all. If the whales ever stop singing, we're all doomed!


RE: Very cool...
By marvdmartian on 11/29/2007 9:38:14 AM , Rating: 2
Agreed. Props to Levi for the photo (and those of us old enough to remember it's significance).

Oh, and since no one else has mentioned it, this thing passed URANUS!!! ;)


RE: Very cool...
By masher2 (blog) on 11/28/2007 5:35:46 PM , Rating: 3
> "Is it possible to build a vastly faster probe than the Voyager series?"

Sure; it just requires nuclear power. However, since the 1963 nuclear test ban treaty, the US has lost all interest in nuclear propulsion for spacecraft.


RE: Very cool...
By creathir on 11/28/2007 5:51:04 PM , Rating: 5
Which this baffles me. With all the environmental concerns of carbon based fuels, you would think nuclear power would be investigated further. I suppose I am a crazy one, but I am of the ilk that beleives we could perfect the process so much that it would be someday possible to use small amounts for fuel cell type of power systems, even for automobiles.

I guess its just pie in the sky ideas though...

- Creathir


RE: Very cool...
By BlackBanna on 11/28/2007 10:13:30 PM , Rating: 2
NASA and the EU have been working on Ion drives.

http://nmp.nasa.gov/ds1/tech/ionpropfaq.html

similar principal of a nuclear fueled one.


RE: Very cool...
By Shadowself on 11/28/2007 6:06:51 PM , Rating: 1
Look up the JIMO (Jupiter Icy Moons Orbiter) among other missions. NASA is still actively exploring these possibilities. They are just not actively funding the build of any of those reactors.

The 1963 treaty has nothing to do with a loss of interest in nuclear propulsion. It's cost.

Nuclear propulsion will happen -- just not soon.


RE: Very cool...
By Chernobyl68 on 11/28/2007 6:12:39 PM , Rating: 2
well, that and environmental cost. The tree huggers always point to "what happens if it blows up on launch"


RE: Very cool...
By Zurtex on 11/28/07, Rating: 0
RE: Very cool...
By AsicsNow on 11/28/2007 9:46:21 PM , Rating: 2
The difference in safety however is that Nuclear powered space ships could leave the atmosphere slowly with a constantly supplied thrust, which is much safer than the extreme amount of energy expended in a very short time frame by chemical rockets. So basically the you're risk is much lower of an accident happening, which should help balance out the more problematic aftermath of a nuclear powered spaceship exploding on liftoff. (it'd also be TONS safer for returning into the atmosphere because they don't have to worry about the risky ass aerobraking procedures since they could simply reverse thrust over the ocean and come down in a much more controlled manner)


RE: Very cool...
By howtochooseausername on 11/28/2007 11:06:10 PM , Rating: 2
You need to accelerate above 9.81m/s2 to leave the atmosphere. Exactly which nuclear powered engine produces that kind of thrust? Or are you just assuming that such an engine exists?


RE: Very cool...
By CyborgTMT on 11/29/2007 2:21:15 AM , Rating: 2
You are assuming vertical take off - I don't see why conventional means could take a craft into the upper atmosphere like a plane then kick in the nuclear engine to boost into space.


RE: Very cool...
By howtochooseausername on 11/29/2007 10:40:32 AM , Rating: 2
The upper atmosphere still isn't high enough (~40mi, someone correct me on that). The craft would still need to generate a lot of thrust at that height.

F=Gm1m2/r^2. I forget the value of G, but r is the distance between the two masses m1, and m2.
So you know that F = 1/2 m2*dv where dv is the change in velocity, and m2 is the same as the previous mass.

Anyways, no, you'd have to be fairly high up, past the mesosphere before the thrust produced by current Nuclear engines would be able to overcome Earth's gravity.


RE: Very cool...
By Cerberus29 on 11/29/2007 10:59:56 AM , Rating: 2
G is 6.67 x 10^-11.

Just finished doing gravitational fields in Physics. :D.


RE: Very cool...
By Chernobyl68 on 11/28/2007 6:11:40 PM , Rating: 3
The voyager's are moving very fast becaue of the multiple slingshots they've gotten from the planets they've visited. They're pretty much just moving on inertia now.


RE: Very cool...
By regpfj on 11/28/2007 7:13:03 PM , Rating: 3
Check out this kick-ass idea for 1/10 c travel from ARPA, propelled by our friend the atom.

http://www.damninteresting.com/?p=679


RE: Very cool...
By howtochooseausername on 11/28/2007 11:14:48 PM , Rating: 2
I think in 71 NASA stopped further investigation of Nuclear thrust. Prior to that the AEC assisted in funding some of the research that NASA did.

It was not the nuclear test ban treaty that killed it, but people's fear of nuclear weapons. Considering that nuclear missiles were targeted at the US and minutes away from launch, a justifiable fear. Now that we aren't threatened by MAD, it might be worth re-investigating Nuclear propulsion.


RE: Very cool...
By Treckin on 11/28/2007 11:45:42 PM , Rating: 3
This is totally false...
If you want to find out why, do your own damn research, im sick of citing websites and wasting my time researching things I already know to show people...

Up until only 1985 they had a fully functional nuclear engine in the New Mexico desert.

There are also even better ways to achieve velocities faster than an inertial gravity engine, such as Ion drive, solar wind, hydrogen collection etc. Some are obviously better candidates for different missions than others.


RE: Very cool...
By ChristopherO on 11/29/2007 1:11:12 AM , Rating: 2
This is rather frustrating. From what I understand, the benefit of nuclear propulsion isn't as great as one would think. Basically it seems the nuclear reaction takes place of the oxidizer, which leaves you a liquid fuel (hydrogen). More or less, you get twice the propulsion from a given weight of fuel. It's not "revolutionary" since we're not talking about exponential gains in efficiency, but a 100% improvement isn't anything to sneeze at. Of course that's an over simplification.

I've been watching Mars Rising on the Science Channel and they've been talking that almost all the long-term plans for returning to the Moon and Mars feature a nuclear drive. Anyway, the show is obviously simplifying things, but it is interesting to see what NASA and the ESA have on the drawing board.

Mars Rising has been quite good. DirecTV has it on VOD, you need an HR20 HD DVR and it has to be hooked up to broadband... I've downloaded 4 of the episodes so far.


RE: Very cool...
By spluurfg on 11/28/2007 9:02:23 PM , Rating: 3
Ion drives are working on probes right now. Look at Deep Space 1. The efficiency of an engine in space applications is generally measured by specific impulse. This measures the change in momentum per unit of fuel.

Liquid fuel rockets tend to have very high acceleration, but lower specific impulses, where as ion engines are the reverse. This is due to the fact that while ion engines put out much less force but use tiny amounts of fuel, while rocket engines spit out huge amounts of force at the expense of tonnes of fuel. This means that with liquid fuel engines, much of the payload is fuel. Thus over a long timeframe (i.e. years) ion engines are generally better at achieving higher speeds if you aren't changing directions much.


RE: Very cool...
By Goty on 11/28/2007 10:08:50 PM , Rating: 2
Ion propulsion has actually already been used to propel satellites. The first (I believe) was Deep Space 1, which launched in 1998.

You've got the mechanics a little backwards with regards to how ion propulsion works. Each of the ionized gas atoms is propelled at high speed from the satellite, the act of which produces a very small force which, over time, allows the satellite to achieve amazing speeds.


RE: Very cool...
By ChristopherO on 11/29/2007 1:03:55 AM , Rating: 2
That's what I meant, each ion was a little force, but relatively speaking they left the space craft with a huge amount of force for a single ion (relatively speaking). Those drips really added up...

Ah, I knew it was already used in a test platform. I couldn't remember the craft name. That should have occured to me, as I remember chuckling at the time thinking that some of the engineers must have been DS9 fans, lest the name would have never been selected.

But I digress. I didn't know the cumulative effect of the ion drive. I didn't know what sort of velocities we were talking about. The Voyager probes are moving quite fast, but that's the result of I don't know how many gravity boosts. Plus they've had the solar wind at their backs, so I would think that would also act like an ion drive given the great distances.


RE: Very cool...
By spluurfg on 11/29/2007 10:23:00 PM , Rating: 2
I believe the effect of solar wind would be fairly small by comparison since it consists mostly of subatomic particles, where as an ion drive such as in deep space one ejects xenon ions at very high speeds (around 26mi/sec).

Using a sail to use solar wind was definitely considered as a method of space travel, but at one astronomical unit from the Sun (ie the distance between Earth and the Sun) the force supplied by solar wind is only 9 newtons per thousand square meters of sail, creating a number of technical challenges. As you can imagine, with only a surface area of a few square meters, at a distance of many astronomical units from the Sun, solar wind would probably have little effect on Voyager 2.


great technology
By TSS on 11/28/2007 5:32:52 PM , Rating: 2
that something can make a journy that long and harsh and still work, by any measurement, is a great piece of technology.

i wonder how fast space development goes though. it would be great irony if we end up picking up either voyager 1 or 2 ourselves in the far future. the famous golden plaque with humans and the location of earth on it, *the* first outreach into the universe, stored in some very futuristic yet somewhat dusty museum. on earth. watched by humans.




RE: great technology
By GeorgeOrwell on 11/28/2007 6:12:07 PM , Rating: 3
So brightly did shine American genius and the desire to build the best. Today, we are left with only the pursuit of profit; there is no quest for greatness, no heart that guides the craftsmanship.

To paraphrase Sir Edward Grey:

"The lamps are going out all over America. We shall not see them lit again in our time."

If you are an American, savor this moment. With today's America nothing more than a nation of illiterate, immoral and obese idiots, it is folly to think we will reach again as far.


RE: great technology
By retrospooty on 11/28/2007 6:57:57 PM , Rating: 2
Hey now, we are not ALL illiterate, immoral and obese idiots... But I do see you point. Far far too many of us are, and they vote too :(


RE: great technology
By DEVGRU on 11/29/07, Rating: 0
RE: great technology
By sweetsauce on 11/29/2007 1:12:15 PM , Rating: 1
...And bible thumping conservatives. See what i did there, yeah.


RE: great technology
By Merry on 11/28/2007 7:04:16 PM , Rating: 2
What you need is a common enemy. The Space program itself, both Russian and American was born out of conflict and rivalry, indeed the Germans started it in the first place out of the desire to destroy such a common enemy.

Perhaps, therefore, no such feats of engineering are produced is down to the fact that, in an era of increasing globalisation there is no real common enemy, merely enemies in trade, hence the pursuit of profit.

It is not to say, however, that such an enemy should be another nation state, for example the Industrial Revolution (arguably) was born of the pursuit of providing for the needs and wants of a nation, thus attempting to rid the nation of a common enemy, that being want. (Although the 'revolution' itself started agriculturally in order to support an army at war with the French).

So there you go, perhaps in order to do great things again you should find yourself a common enemy because there sure as hell isnt any profit to be made out of launching space probes and such, so the free market on its own wont help.

I should probably stop drinking now and maybe get on with my real Political Thought essay....


RE: great technology
By Ringold on 11/28/2007 7:40:46 PM , Rating: 4
quote:
so the free market on its own wont help.


Thats what I expected, I just didn't know where it'd pop in to your post. You really ought to get stripped of your ECO credits. :P

http://www.bigelowaerospace.com/
http://www.scaled.com/
http://www.spacedev.com/
http://www.spacex.com/
http://www.planetspace.org/lo/index.htm
http://www.sea-launch.com/
http://public.blueorigin.com/index.html

That's hardly a comprehensive list, those are simply the ones I've got in my favorites.

Also, Bigelow offers 3/4 billion for a ship:
http://space.newscientist.com/article/dn12836-bige...

Meanwhile, Obama recently said he wanted to delay NASA's Constellation program by 5 years to "pay for" education spending if he were President.

In fact, go forth, my sad Keynesian friend, and embrace the fact you're entirely wrong about the free market not helping:
http://www.space-frontier.org/NewSpaceNews/

Mmmmmmmm! A warm bath of capitalism, most of which would go on if these firms never saw a single red American tax-payer funded cent of welfare.


RE: great technology
By Merry on 11/28/2007 8:13:20 PM , Rating: 3
Damn, busted :p I do have a bit of a soft spot for Keynes actually, I find that some arguments for considered governmental interventionism in some areas, particularly regarding key infrastructure quite compelling.

As for your point regarding private space companies, i'm well aware of their existence, however, there is no way they will ever (in my opinion of course) be able to produce big feats of engineering in areas in which there is little profit to be made, such as space exploration, particularly regarding probes etc

I'm not trying to say there is no role for the free market, such a sentiment would be foolish, i just think that in order to attract such private investment there has to be some sort of incentive. Perhaps the Hoover Dam is a good example of such a process.

I think the trouble is that people, indeed countries, get bogged down in economic 'ideology', for want of a better word. I see it here all the time. There is. and nor can there be, 'the best way', only the 'best way at a given time in a given circumstance' . So in effect I put it to you that all economic 'ideologies' are flawed be they Keynsian, Classical or neo-classical as they are only good as a means of prediction and explanation in the circumstances to which they were born, and may just as easily be proven wrong at any time by any unforeseen circumstance.

Perhaps thats just a long winded way of saying 'i'm a bit of a pragmatist' really.


RE: great technology
By Ringold on 11/29/2007 1:33:57 AM , Rating: 3
It's okay. I can spot a Keynesian from 10 parsecs.

I'm not sure what one might call the current.. pseudo-consensus. Friedman has a lot of currency; it helps that those nations who followed the Chicago school of thought did better than those who stuck with Keynesian theories. He's not infallible, though. Top-down macro management by the government, though, and the idea that government can actually respond the way Keynes suggested with fiscal policy, is shoved aside entirely as mathematical hubris.

But economics like Meier, while distancing themselves from Kenyes & Marxists (two peas in a pod on one dimension), point out the most successful economies: those with governments that encourage infrastructure, increase human capital (education, like those Asian Tigers), and promote law, order, and freedom for corruption. It makes me a little uncomfortable, but smart government investment in private industries early in the development of a nation is also beneficial, but of course we're far beyond that here.

As far as space goes, I think grand technological solutions are typically unnecessary; Occam's razor applies to economics, too. Scaled Composites craft was.. pretty simple, it seems. Big rocket, little body, flies high. The space shuttle was a grand technological solution -- and came with it a grand price tag. In terms of getting people out 'there', the markets can and are doing that, and they're doing it on time tables that ought to me making NASA engineers weep.

But of course, there is no profit in stargazing, checking out Pluto, etc. I fully support NASA's unmanned science missions, the NSF, etc. I surely won't argue that. We're not too far apart, but the blanket idea that markets wouldn't help us leave Earth, and I assume thats the real long-term goal, living sustainably off world, bust my pop-off valve.


RE: great technology
By cambit69 on 11/28/2007 11:09:49 PM , Rating: 2
today our common enemy is terrorism


RE: great technology
By dluther on 11/30/2007 9:19:59 AM , Rating: 2
quote:
today our common enemy is terrorism


Please, allow me to retort.

"Terrorism" is not our enemy, "terrorists" are our enemy. And really, when you distill that down to its purest component, our enemy is a small group of people who are united against us for various reasons. It's a distinction that people absentmindedly repeat until any reason or logic is blurred into complete background noise, so that any dissenting opinion or action is lumped in to a single, all-encompassing label whose true meaning has long since been lost.

To be completely frank, "terrorism" is what won our country's freedom from England and alleviated it from the Indians for our settlement. So I would say that "terrorism" is our enemy only when it works against us, not for us.

The point I'm trying to make is that terrorism is the result of a condition, and it seems that people don't have much of a memory when it comes to declaring war on conditions. Check our progress on the "war on poverty", the "war on cancer", the "war on illiteracy", the "war on drugs", the "war on hunger", the "war on homelessness", and yes, even the "war on terror". We really don't seem to have such a good track record when it comes to wars on conditions.

Think about it.


RE: great technology
By Ringold on 11/28/2007 7:19:59 PM , Rating: 3
You're right -- government may not reach such a level. A founding American principle is that the government is not something to venerate, cherish or even hardly to honor. It is the individual which they felt must be venerated, and it's the American people that make America great, not whatever member of the military industrial complex is getting a welfare checks this decade.

In that respect, the individual pursuit of profit is consistent with every economic agents desire to acquire the best life, to maximize his utility to the best degree he is willing to work to achieve. The constitution essentially asserts the unlimited rights of the individual to seek this.

This drive, however, is also already well on the way to delivering us our first commercial space station, operating with the same model as a strip mall does. Paid for by the US government? Nope. Try a hotel tycoon, with his own money and zero interest in government money.

And after that? He's already working on designing the equipment necessary to move regolith on the Moon to cover a a lunar base for radiation protection, a base which he can easily construct at a lagrange point and lower to the surface. Some people have expressed interest in mining the moon for resources, if possible. There's a lot of commercial interest in low-gravity and free-vacuum conditions, since apparently vacuums are expensive to create on Earth. Before you discard the above as pie-in-the-sky, you'll note the successful launch of, I believe, two completely functional test modules. Oh, and based on technology discarded by the almighty government.

Already, private enterprise can pop people in to space safely, regularly, and with minimal maintenance on their space craft. The US government has been at this game for half a century and can't boast what Scaled Composites did virtually overnight by comparison.

Perhaps the first boots to hit Martian soil will leave the imprint of General Electric, and they'll plant the US flag only after the US government coughs up a some millions of bucks for the favor. Frankly, that doesn't bother me in the least. At least a commercial presence someplace such as the Moon would be permanent, productive, and conducive to further growth just as the original colonies in North America ultimately were. Not to mention, they too were Public-Private ventures.

By comparison, what does a NASA base on the Moon give us? Some highly paid astronauts sitting in an ISS-style boondoggle gazing at the stars and talking to elementary school classes by satellite, who then have to leave if the political situation turns against further funding of the dubious government venture?

Not that don't want NASA to try, but it does everything in regards to manned space travel in the most authoritarian, inefficient way possible. I wish NASA could be efficient and market oriented, but that's not in the nature of government.


RE: great technology
By jskirwin on 11/29/2007 10:20:41 AM , Rating: 4
Nice Romantic comment. Too bad it's wrong.

First a little context. Grey was speaking about Europe prior to WWI - a war he was attempting to stop. After the war was over in 1918, the "lights" came back on in most of Europe for two decades before going back out again between 1939-1945. While I am a Eurosceptic, I can't argue that the lights have been burning since the mid 1940's (although the rioters in France are doing their best to put them out again by burning libraries and books.)

So Grey's comment is dripping with romance - but it was wrong. No Dark Age (beyond a 10 year period of total warfare) descended on Europe, and all things considered Europe remains a dynamic center of progress and intellectual achievement.

What's wrong with the pursuit of profit - if that's what you're into? Profits lead to higher taxes which can then be used for the greater good? If you don't want to pursue profit... I just spoke to my son's grade school teacher this morning. I don't think she's in it for the money.

Not everyone in the US pursues MBAs and yearns to become a CEO of a Fortune 500 company - but they have the tools - and the freedom - to do so if that's what they desire. Pursuit of happiness and all that.

But that also means that some would rather sit on their butts and do just enough to get by. Do you or I have the right to force them to do otherwise? As long as my taxes aren't supporting them, then I have no problem with it. If you don't like it, what gives you the right to tell them what to do with their lives?

Predicting America's decline is big business and has roots in the 19th century when America was threatened by my Irish ancestors. We were supposed to outbreed the protestants and wreck America - which of course we did as the laws banning abortion, all non-Catholic religions, and the constitutional amendment mandating free whiskey attest to. Almost since its inception people have predicted America's decline, and it's usually coincides when another ethnic group arrives. Coincidence?

Meanwhile American universities have to reject qualified foreign students who want to come here. Most foreign graduates of US universities stay - leading to brain drains in countries throughout the Middle East and Africa. The American economy continues generating wealthy, jobs and increased living standards not just for Americans but for Indians, Chinese and yes, even Grey's Europeans.

Romantic sentiment is much more alluring than cold-hard facts. But reality abhors romance almost as much as nature does a vacuum.


Propulsion
By whoisnader on 11/28/2007 6:04:28 PM , Rating: 2
Actually there is another form of future propulsion and Star Trek kind'of jumped onto it to help explain how they travel from planet to planet.

Matter and anti-matter fusion, or perhaps more likely electron and positron fusion. Collect enough positrons from an accelerator and store them in a container surrounded by magenetic field. Then the idea is that when a positron interacts with an electron, they fuse to convert %100 of their mass to energy. This would have to be the most efficient energy source and would require very little of it to power any probe. I think the comparison is something like a kilogram of matter and a kilogram of anti-matter is enough to power a small state for a year with no pollutants generated as a result of the reaction.




RE: Propulsion
By Chernobyl68 on 11/28/2007 6:14:24 PM , Rating: 2
yes but the energy required to make the antimatter in the first place is pretty large. You can't mine for antimatter... :)


RE: Propulsion
By Shadowself on 11/28/2007 6:22:00 PM , Rating: 1
The best, high velocity propulsion system is the one described in Roddenberry's second space series attempt, Starship. I say "attempt" because IIRC even the pilot was never completed.

The system described (and actually was based upon many scientific papers of the time) uses an extremely large magnetic ring to focus the interstellar "dust" (mostly hydrogen) into an extremely small volume as the ship moves through space. This produces a sustained fusion reaction behind the craft which in turn produces significant thrust. Thus the craft does not have to carry any propellant with it to support this type of propulsion. The interstellar "dust" provides everything you need.

The problem is that -- in reality -- this type of propulsion is only viable at very, very high velocities. You need to get up to high enough velocity that the interstellar medium has enough mass in it so that as you pass through it you obtain enough mass to sustain the reaction. The interstellar "dust" consist of, on average, roughly only one atom per cubic centimeter. Damn little.

The real problem with this method then is you still need more conventional means to get up to that speed -- a huge amount of mass using any technology in use today or even planned for the next 25-50 years.


RE: Propulsion
By Ringold on 11/28/2007 6:58:08 PM , Rating: 2
Roddenberry had this in Star Trek, just a bit more fantastical; the Bussard Ram Scoops, the glowy red domes on the front of the warp nacelles.


Great ignorance
By wordsworm on 11/29/2007 4:43:29 AM , Rating: 1
For those of you who've suggested that nuclear propulsion is a good idea in space, I'd like to point out (I have too much time to waste) that a single accident 30km over the US would be enough to wipe out civilization as we know it. The electromagnetic pulse from one of those babies is enough to potentially send Americans back to the dark ages. EMPs are awesome.




RE: Great ignorance
By djc208 on 11/29/2007 7:29:36 AM , Rating: 2
You are assuming a nuclear explosion (i.e. the fuel reaches critical mass and starts an uncontrolled chain reaction). That takes a very specific type of setup to occur. The type of system used on voyager and the types of systems that would be used for propulsion would be thermal type reactors. Should they have a problem or the craft explode you would at worst create a cloud of radioactive material that would contaminate a large area, especially if it settled over land.

Not OK by any means but we're not lauching nuclear bombs into the air we're lauching small chernoybles (OK better than that but you get the idea). Even if an ICBM exploded due to a launch issue it's very unlikely it would cause a nuclear detonation but it still wouldn't be pretty.


RE: Great ignorance
By spluurfg on 11/29/2007 10:29:53 PM , Rating: 2
Incidentally, one of the most theoretically sound proposals for interstellar travel on human lifetime spans relies on detonating many large nuclear devices in rapid succession behind a spacecraft, which would be protected by a massive shield. Such a craft would essentially ride the explosions from the nuclear weapons and could theoretically reach Alpha Centauri in 50-100 years, or go to Pluto and back within a year. See the Orion project.

We'd just hope they would put some distance between themselves and Earth before firing it up.


RE: Great ignorance
By PrinceGaz on 11/30/2007 4:02:32 PM , Rating: 2
A nuclear EMP pulse from a large warhead would certainly be able to knock-out unshielded electronics over a continent-sized area, but would hardly send the country back to the dark ages. I'd imagine that most developed countries have plenty of well shielded equipment available for military and government use in emergencies that can survive such EMP pulses, which at the simplest level would simply mean locking it away in a near-perfect faraday cage until needed. There's nothing especially complicated in constructing a faraday-cage.


where solar winds slow to subsonic speeds
By lemonadesoda on 11/28/2007 6:32:05 PM , Rating: 2
There's not a lot of "sonic" activity (or ability) out there. What exactly does subsonic speed mean out in space (vacuum and therefore NO sound)?




RE: where solar winds slow to subsonic speeds
By McTwist on 11/28/2007 8:10:39 PM , Rating: 2
Space is nearly a vacuum. In fact it has roughly something like 3 atoms per cubic meter so there is a density and thus a speed of sound. When you calculate the numbers, it ends up being around 100 km/s.
http://en.wikipedia.org/wiki/Heliosphere#Terminati...
So the moral of the story is that somebody can hear you scream in space.


By CyborgTMT on 11/29/2007 2:30:48 AM , Rating: 2
Not really, even one of the random atoms got lucky enough to hit your ear drum, the vibration produced would be too weak to actually hear.


Cool ...
By deeznuts on 11/28/2007 5:27:47 PM , Rating: 2
Crazy stuff. What I'm wondering is, if it has to pass the term shock twice, because of the shifting of the boundary, does the boundary sort of "rear end" the V2 during its shift?




The Picture
By Griswold on 11/29/2007 4:35:14 AM , Rating: 2
Nice pick for the picture, considering thats Lt. Ilia from the first Star Trek motion picture that is centered around the Voyager space craft.

However, I think it was in Star Trek 5 where the klingon bird of prey commander blasts Voyager 2 to bits as target practice. ;)




Mag Sails
By Hellfire27 on 11/29/2007 10:53:44 AM , Rating: 2
I think a far more efficient way to move about the solar system would be to invest in Mag Sails. Once in space you theoretically wouldn't need any fuel and would just ride on the solar winds. All you would really need is power for the instruments and the magnetic field created by the "sails." Granted it may not be as feasible when you get further out of the solar system and into interstellar space.




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