If you want a spacecraft that can explore beyond the solar system—and you don't want to wait decades for it to get there—you need one that can really move. Today's chemical rockets and solar-powered probes are downright poky on interstellar scales. Artur Davoyan has a completely different idea for how to accelerate a spacecraft to extreme speeds: pellet-beam propulsion.
Here's the gist of how it would work: First, you actually need two spacecraft. A probe blasts off on a one-way trip to deep space, while a second vehicle remains locked in an Earth orbit and fires thousands of tiny metallic pellets at its partner every second. The orbiting craft also either fires a 10-megawatt laser beam at the retreating probe, or aligns a laser fired from the ground at it. The laser hits the pellets, heats them, and ablates them, so that part of their material melts and becomes plasma—a hot cloud of ionized particles. That plasma accelerates the pellet remnants, and this pellet beam provides thrust to the spacecraft.
Alternatively, Davoyan thinks the probe could get thrust from the pellet beam if the craft were to deploy an on-board magnetic field-generating device to deflect the pellets. In this case, that magnetic action would push the craft forward.
Such a system could boost a 1-ton probe to speeds up to 300,000 miles per hour. That's slow compared to the speed of light, but more than 10 times faster than conventional propulsion systems.
It's a theoretical concept, but realistic enough that NASA's Innovative Advanced Concepts program has given Davoyan's group $175,000 to show that the technology is feasible. "There's rich physics in there," says Davoyan, a mechanical and aerospace engineer at UCLA. To create propulsion, he continues, "you either throw the fuel out of the rocket or you throw the fuel at the rocket." From a physics perspective, they work the same: Both impart momentum to a moving object.
(Score: 0, Disagree) by Anonymous Coward on Monday March 20, @12:16AM (1 child)
Yeah, I guess 175 grand is pretty realistic.. Doesn't matter how insane the idea is, and primitive besides, just make the sale...
(Score: 3, Insightful) by takyon on Monday March 20, @09:12AM
It's a typical award for a Phase 1 NIAC project. You get the money to investigate an idea and write a paper about it. I don't think there's any expectation of a prototype at that stage. It's a feasibility study.
https://en.wikipedia.org/wiki/NASA_Institute_for_Advanced_Concepts [wikipedia.org]
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(Score: 4, Interesting) by Runaway1956 on Monday March 20, @01:03AM (2 children)
Just capture the pellets aboard the traveling spacecraft - thus harvesting the kinetic energy of the pellets. Then feed the pellets to your ion rocket. I mean, if we're going to dream, let's dream big!
Meanwhile, where's the reaction mass coming from on the other end, when you might want to slow down, or even stop, to look around?
Abortion is the number one killed of children in the United States.
(Score: 2) by HiThere on Monday March 20, @01:13AM
If you only get up to 300,000 mph relative to Earth, you won't reach a stopping point in any reasonable amount of time. That's a good speed for a generation ship to go a, but (according to google) it would take 2,235.38876 years to go 1 lightyear.
(I only think it's a good speed for a generation ship, because I don't expect people to every want to get off. It's probably a bit fast, as by my concept they need to scavenge resources from the things they encounter as they travel, so they don't want to be going too much faster than the local drift.)
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 3, Funny) by Anonymous Coward on Monday March 20, @02:20AM
Please, this can't be serious. They saw one of those old MGM cartoons where the mouse shoots pellets at the cat with a toy machine gun to chase him off
(Score: 1, Insightful) by Anonymous Coward on Monday March 20, @02:16AM
Can't use the same mechanism for slowing down/ stopping unless you've already got something at the end right?
So might be fine for probes that you don't ever want to land intact or slow down to orbit somewhere, but not so good if you want to get to a lower energy orbit in Alpha Centauri?
(Score: 4, Informative) by bzipitidoo on Monday March 20, @03:24AM (16 children)
Decades? The article is complaining of waits of only a few decades? Really? Need a reality check.
If we could accelerate a probe to 0.1c, which I have read is about the upper limit that might be possible thanks to all the problems with even more speed such as blue shifting a whole lot of radiation into damaging ionizing territory not to mention the energy it would require and then the problem of getting only a brief look as such velocity would send the probe right past a star in a matter of days, would still take roughly 4 decades to reach the nearest star. Such a probe would be seriously miniaturized, like the size of a smartphone at most, maybe as small as a grain of sand. None of this 1 ton silliness.
Centuries may be the shortest feasible time we'd have to wait for a probe to reach Alpha Centauri. Which brings up the problem of how to insure a probe could last that long. Thus far, we have little experience with designing any machine that can last over a millennium. Then there's the problem of whether the means and knowledge needed to receive the data would be ready when the probe at last arrives. A little civilizational collapse or just a moronic budget cut could easily throw away centuries of waiting.
(Score: 0) by Anonymous Coward on Monday March 20, @04:35AM (5 children)
Obviously we have to get way beyond light speed if we are going to be serious about space travel, even within the solar system. Navigation's gonna be a bitch also
(Score: 2) by takyon on Monday March 20, @09:06AM (3 children)
Deep freezed humans, a generation ship, or frozen embryos with robot gestation. Only one instance of one of them has to work, and you potentially have a stable foothold in another star system. If colonies continue to spread, the entire galaxy would end up filled with humans. No faster than light needed.
Billions of years later, humans could access the stars of Andromeda and some other galaxies because they are going to merge with the Milky Way.
FTL would be great to have, but it might not be necessary for interstellar travel, and it's definitely not needed for travel and asteroid mining within the solar system.
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(Score: 2, Insightful) by Woodherd on Monday March 20, @09:54AM (2 children)
Billions of years later? Humans have a very hard time planning for things they see coming a couple of decades out, and have only existed for less than some million years. In a few billion years, well, Reptilians may take another shot at the whole "evolve" thing, and become the dominant species on Gaia.
(Score: 0) by Anonymous Coward on Monday March 20, @09:46PM
Just make sure the wrong lizard doesn't get in
(Score: 1) by khallow on Tuesday March 21, @01:34AM
(Score: 0) by Anonymous Coward on Tuesday March 21, @03:42AM
(Score: 2) by mhajicek on Monday March 20, @04:57AM (1 child)
And by the time it gets there, we might have local sensors that can see the target better than the probe.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by turgid on Monday March 20, @09:07PM
But it would be fun trying.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 2) by PiMuNu on Monday March 20, @12:05PM (3 children)
> blue shifting a whole lot of radiation into damaging ionizing
You can strike that one off your list of problems. 0.1c does not blue shift anything much at all. Need to be up at 0.5c before blue shift is really a thing, 0.99c before it starts really pushing photon energy up.
(Score: 0) by Anonymous Coward on Monday March 20, @01:27PM (1 child)
Just trying to understand what's going on...
0.1C would blue shift 500 nm light to 450 nm light?
(Score: 0) by Anonymous Coward on Tuesday March 21, @04:07AM
(Score: 0) by Anonymous Coward on Tuesday March 21, @04:32AM
(Score: 2) by istartedi on Monday March 20, @06:14PM (3 children)
I don't think you even have to get to 0.1c for a really small piece of space debris to ruin your whole day. I think if we're ever going to make a run out there it's going to require redundancy. A swarm of ships, separated by distances large enough so that impact fragments from one won't reach another. Or perhaps one big ship with lots of air-tight doors for emergencies, assuming that space junk is more likely to pierce the hull cleanly as opposed to fragging the whole ship. Ideally, you simply hear a hiss once in a while, and are able to evacuate. Then a repair crew dons suits and fixes the damaged module.
Appended to the end of comments you post. Max: 120 chars.
(Score: 1, Funny) by Anonymous Coward on Monday March 20, @08:47PM (2 children)
Unless that hiss you are hearing is coming from your chest.
(Score: 2) by istartedi on Monday March 20, @10:38PM (1 child)
I actually thought about that later. Like, you're sitting there in your module having a casual conversation and then suddenly there's a dark hole in your companion's head and they stop talking, *and* you hear the hiss from both sides of the room. You have to be trained to just get out fast. Yet another reason to hate multi-generation ships. Who wants to raise kids there?
Appended to the end of comments you post. Max: 120 chars.
(Score: 2) by takyon on Tuesday March 21, @09:40AM
Someone who doesn't care about ethics, only the mission of getting humans established in another star system.
There could be serious consideration of the idea if we find some nearby Earth-like exoplanets, but it would be better paired with life extension and/or suspended animation.
If there is nothing good nearby that will be a real problem. Since an Earth twin 50 light years away instead of 10-15 ly multiplies the amount of mental and mechanical breakdowns experienced during the trip.
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