SETI

A Private Trip to Alpha Centauri: Breakthrough Starshot*

Yuri Milner promises $100 million to research sending a fleet of laser-boosted nanocrafts to the nearest star.

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BreakthroughStarshot
Breakthrough Starshot

A fleet of laser-boosted nanocraft could be on their way to the Sun's nearest neighboring star, Alpha Centauri in a couple of decades. Breakthrough Starshot is the ambitious proposal announced by Russian internet entrepreneur Yuri Milner in New York today. As outlined by Milner, the idea is that a fleet of gram-sized spacecraft—StarChips—kitted out with diaphanous lightsails will be boosted into orbit and then blasted with a ground-based "light beamer" consisting of phased 100 gigawatt array of lasers. This would get the StarChips traveling at about 20 percent of the speed of light enabling them to reach Alpha Centauri in just over 20 years. According to the Breakthrough announcement of the project:

The Alpha Centauri star system is 25 trillion miles (4.37 light years) away. With today's fastest spacecraft, it would take about 30,000 years to get there. Breakthrough Starshot aims to establish whether a gram-scale nanocraft, on a sail pushed by a light beam, can fly over a thousand times faster. It brings the Silicon Valley approach to space travel, capitalizing on exponential advances in certain areas of technology since the beginning of the 21st century. …

Breakthrough Starshot aims to bring economies of scale to the astronomical scale. The StarChip can be mass-produced at the cost of an iPhone and be sent on missions in large numbers to provide redundancy and coverage. The light beamer is modular and scalable. Once it is assembled and the technology matures, the cost of each launch is expected to fall to a few hundred thousand dollars.

Milner plans to spend $100 million on the research and engineering program to demonstrate proof of concept for the project.

This is not the first time Milner has financed visionary projects. Last year he announced that he is bankrolling the Breakthrough Listen project with the Unverisity of California Berkeley. That project will use radio telescopes to search space for signals from extraterrestrial intelligences. He has committed $100 million over the next ten years to Breakthrough Listen.

Facebook founder Mark Zuckerberg and Cambridge University physicist Stephen Hawking will join Milner on the board of the Breakthrough Starshot project. The executive director will be Pete Worden, former director of NASA Ames Research Center. 

Bon Voyage!

*To those commenters who alerted me to this, many thanks (you know who you are). My apologies for getting to it so late in the day.

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  1. OT: I just had a look at Suderman’s article on the casual incompetence of the Trump campaign and the comments. Holy fuck Trumpsicles are complete fucking retards. They are basically proggies without the ‘social instinct’. Libertarians CANNOT afford to even associate with these worthless assholes. Have fun being the butt of jokes for several generations.

    1. Libertarians associate with you, so I think they have the ability to overcome some Trump.

      1. Trudat. πŸ˜‰

          1. \_(o-o)_/

      2. Thanks to the goodness I imbue them with by association. Your welcome.

        1. But not yours? Your certainly gracious.

          1. Geez, two “your” in a row. There truly is no hope for humanity.

    2. Nathaniel Branden’s Head returns! Where you been, buddy?

  2. I just don’t want to have to share a ship with those assholes from the Spartan Federation.

    1. I stand with Nwabudike!

  3. Space is about to get so scienced.

    1. “I’m gonna have to science the shit out of this.”

      Yeah, baby. I’ve got your science, right here.

  4. I am not a smart man, and I’ve had some drinks, but I feel like sending something that only weighs one gram into space balanced on a beam of light and hoping it reaches a system 4.37 lightyears away is a bit…optimistic. I know there’s nothing in space itself, but there’s a lot of stuff in the way. Wouldn’t something like a solar wind or passing debris field from some space junk be enough to knock this little thing off its beam of light or destroy it entirely? Even just a random floating rock? I don’t know how this stuff works, so maybe I’m just talking out my ass here.

    1. There is certainly risk of solar wind, but the likelihood of getting hit by a rock is pretty low. Consider that on asteroid belts, if you were on one asteroid, you wouldn’t even be able to see any other asteroids in the belt, they are so far away.

      100 GW lasers are no joke. I’d be concerned with the Russian government taking over the project and using it to burn up objects in orbit.

      1. I know the odds really are astronomical but I guess I’m just wondering about the random gram-sized bits of space debris that are probably in abundance between here and Alpha Centauri. I guess if you’re going to shotgun thousands of these things in the hope that one gets there, then sure, it might work. I’ll believe it when I see it.

        You hear that Yuri? That’s a challenge.

        1. There really aren’t any gram sized bits of space debris in interstellar space. There isn’t even that much of it in the Solar system.

          1. I can’t even get a ping pong ball into the cup in beer pong, so something like this is beyond my comprehension.

            1. The trick is getting drunk enough to focus but not too drunk to throw the game. Having a Russian backing this project seems like a good start.

        2. Average density of the universe is about 1 hydrogen atom per cubic meter. Could you hit something? Yes. Will you hit something before you win the Powerball? Almost certainly no.

        3. Well, that’s the point of sending a bunch of small, cheap probes rather than a big expensive one. They’re assuming a number of them are going get taken out before they make it. They’re playing the odds here…

      2. As for the Russians burning up space debris…that’s probably a good thing given how much crap is floating around up there.

        1. If only we can be sure that Putin will be focused on debris and not communication satellites.

    2. Its just statistics about getting hit; everyone plays a shitty lottery. Interstellar space is even emptier than interplanetary space though, and interplanetary space is empty for the most part. At speeds this one-gram thing is hypothesized to travel (~.2c), if it hits anything even bacteria-sized the kinetic energy would be something like a MOAB’s worth of boom.

      1. That’s the reason my concern here is what the effect on the target might be. There’s probably no intelligent life in the Alpha Centauri system, even if there are planets, but I’d hate for us to the the interstellar equivalent of the redneck neighbor firing a shotgun through the front window just to see if anybody’s home…

        1. We definitely don’t want to alert the Trisolarans that we exist.

    3. Once you clear the Solar system you don’t have to worry much about that. Though space is not entirely empty. You can find about 1 electron or proton per cubic centimeter, on average.

      I’m more curious how they plan on doing course corrections. There won’t be any realistic way to track the probe, and I would guess that it’s too small to have built in navigation if it really is gram-scaled.

      FWIW, they don’t seem to plan on stopping. It will be a fly-by. Mostly because there is no way to stop it.

      1. I am also curious how it is to communicate with earth. 1-watt transmitter or whatever isn’t going to get it done from light years away, even with DSN, even with a mega-upgraded DSN. It must hypothetically use the sail as an antenna.

        1. I’m not entirely sure what “gram-scale nanocraft” actually means. It must have an antenna capable of getting some pictures back. It will have a camera (they talk about it in the “challenges” section, namely how fast it will have to slew to track a planet doing a flyby at 0.2 c). If there is no way to get information back then it’s sort of pointless.

          1. FWIW it’s worth, from the website:

            Capturing images of a planet, and other scientific data, and transmitting them back to Earth using a compact on-board laser communications system.

            Using the same light beamer to receive data from nanocrafts over 4 years later.

            Interesting. I wonder how much collecting area you would need for laser communication across 4 light years.

            1. It also sounds like they want to do optical interferometry over a kilometer scale (I’m guessing baseline). That’s hella cool, and would be huge for optical astronomy. Also a technical challenge and expensive in it’s own right.

              1. Whycome you usin’ such big words?

                1. They want to make a bunch of smaller telescopes work like a bigger telescope πŸ˜‰

              2. Hmmm. I guess they are all aimed one way, so such a scheme would theoretically work. The whole array would have to aim at single targets for duration of mission (years) though. Maybe slew back and count the kids for a given target every couple months? Watch the numbers dwindle over the years. Very interesting, innovative idea no matter.

        2. I suspect that there won’t be any communication. But, they could use the laser like radar to track it. So, as the probe got further away, the delay would be longer, and by the time it got 4 light years away, the delay in tracking the probe’s position would be four years.

          1. That kind of ranging would only get you radial distance. But I don’t know how much precision they need. They want to do a flyby close enough to snap some useful images or get other data, not put it into orbit.

            But they definitely want to do communication.

          2. The beam would be too diffuse years before that happened. Even a tiny beam divergence turns into a huge wavefront over such length scales. Just remember the rules of diffraction:

            1) Big parts of the lens/aperture modify the fine parts of the beam.
            2) Small parts of the lens/aperature modify the large parts of the beam.

            #1 means that if you want to finely focus something you want a big, big lens, dish, etc. The good news is that we can use this to our advantage by creating a synthetic aperture. As long as we’re careful with the phase information, we can sample (or emit) from two or more widely spaced points to create an artificially large aperture. I expect that is how they would have to have these things communicate. But that all assumes you can get a significant power source, sensor, and computer into a 1g payload. I’m not holding my breath on that.

            1. It sounds like they are currently thinking of doing communication with optical lasers. Aperture synthesis at 0.1 micron wavelengths? Is that possible?

              1. Shortest frequency of visible is ~.47 microns, longest is ~.8.

                1. “Boring factors of order unity.”

              2. Just come up with X-ray lenses. πŸ˜›

                I think we’re in Fresnel territory here. On the plus side we’d get some red shifting on the way out!

              3. I would be really interested to see how they plan to power and collimate a beam sufficiently to survive a light-years long journey — all in a gram sized package.

                I’m no expert, but I doubt we can do it today with a minivan sized package.

    4. Huh. I posted a (for me, anyways) well-thought-out reply and the squirrels appear to have eaten it. Hopefully it doesn’t get shat out on somebody else’s thread…

      1. Nuts. I’m interested. Damn you squirrels.

      2. That’s why I type lengthy replies in NotePad or Word and then copy-paste to the site. If something goes wrong, I still have it on my Clipboard or the original editor.

        1. real men compose in vi.

  5. I really appreciate private individuals spending money on their star-shots, but man I wish they spent that $100 Million on something more beneficial to space habitation.

    $100 Million would go a long way to developing a private presence in mid earth orbit.

    1. Some bigger steps towards Mars would be nice.

      1. Personally, I think Mars is even too much.

        The biggest challenge to space exploration right now is gravity wells. It costs fuel (and therefore money) to get payloads out of gravity wells.

        Libertarians know that the major way to get a brisk colonization is to get meaningful economic value. Both sides of a trip need to generate economic value. We have near earth asteroids and freefall in high earth orbit where mining and microgravity manufacturing COULD make it economical to maintain a lasting presence.

        If you are going to spend money to bootstrap a space colonization, spending a bunch of money to get off this rock, travel for months, land on another rock, then spend a huge amount of money to lift out of that gravity well again makes the ROI pretty well. OTOH, that money would be better spent getting habitations on the Moon or, even better, in orbit around earth. In the Orbital Debris article earlier this afternoon, I mentioned how important a space tether in orbit would be in giving us a reusable method for gaining higher earth orbits.

        The key is moving away from these “Moonshot” prestige goals that are popular with the public and instead moving towards real investment in the infrastructure necessary to get earth-bound people and tools out of the gravity well.

        1. Depends on your goals. If you are looking for a viable space economy, I agree. If you’re trying to get young people inspired about the next big technological revolution, or to make a world-historic discovery, then “starshots” are probably the better way to go.

          1. We’ve been playing that game for 50 years. All it gets you is what we have today- unless you can spend orders of magnitude more to do the next big thing, everyone goes “Meh”.

            You want inspiration, look at the Gold Rush. Millions of people pouring west because they saw how they could change their own lives by hopping in a wagon.

            Make it so that a 5%er can spend money to get payload into space and I guarantee you we will inspire people with REAL stories of how small companies are making due in many different forms of space exploitation. (And space SEXploitation, iykwim)

            1. And space SEXploitation

              I’m picking up what you’re throwing down.

              I don’t think these approaches are mutually exclusive. If space can be made profitable, it will happen (it’s starting to). And big philanthropic efforts can focus on the less profitable stuff aiming at the existential questions. Anyway, I’m 100% for it (though I am admittedly pretty biased).

              1. I agree.

                That said, think about the Internet. When the web first started, yes there was big money in a bunch of web companies, but the vast amount of early revenue was in the infrastructure companies- the Nortels, Ciscos and carriers. Those guys made bank building the infrastructure that Google required before it could rise.

                I understand philanthropy but until we have businesses not just building rockets but transportation networks, we are a long way off and moonshots won’t fix that.

                1. And the ADC’s and other fiber companies enjoyed about 6 months of a bubble before it popped badly on them. So what is in space that we can’t get (easily) get here? Well, platinum group metals from an NEA. Uninterruptible solar power. Communication relays and observation posts. That’s kinda it until you get to the whole concept of having another habitable location just in case or He3 for fusion that we can’t quite do yet.

                  I’m as space nutty as they get, but the business case just isn’t there yet.

                  1. Everyone went through the bubble. That bubble was caused by a massive influx of money from the fed in an attempt to avoid the asian flu. Nevertheless, the point remains that the leaders in revenue from the mid 90’s through the early ’00s were infrastructure builders.

                    There are near earth objects with $10 – $100 Billion in harvestable metals. Other NEAs can be harvested for in orbit fuel.

                    The business case is obviously difficult. However, the business case become much easier when you can reduce the cost of LEO-to-GEO from 2x to 1.1x.

                    This is why I continue to focus on a LEO bosting infrastructure- it makes all that other investment much easier to make.

        2. The big question for future in space – on Mars or anywhere else – is how tolerable alternative gravities are. We know zero-g sucks for our biology, to the point we know it is not practical for earthlings to live in zero-g long term; indeed offspring born and raised in such an environment could very well be trapped there, unable to mechanically support themselves in earth gravity.

          But what about .38g (Mars)? Or the Moon (~.17)? Are the problems of bone loss etc. encountered in zero-g a linear thing, or does, say, ten percent gravity keep one’s biology ready for 1g? Nobody knows answers there, and those answers define what people wind up doing in space long-term, and how they go about it.

          1. Heinlen covered that in Mistress. The answer is that you can’t easily survive back on Earth after living on the moon, but you do get to sleep around a lot.

            1. The Moon is a problem. Mars probably not.

              1. Aye, she is harsh.

            2. you do get to sleep around a lot

              — sure, if you marry them all

            3. Heinlen covered that in Mistress.

              He might have written about it, but he sure didn’t cover it. It was written 3 years before the first moon landing, so he didn’t do anything but speculate.

              1. I was just trying to work an anarcho-capitalist group-love reference in there, and you guys have to be all literal about it. You won’t be invited to my Alpha Centauri parties, for sure.

                1. It’s alpha centparty time.

                  UNS UNS UNS UNS UNS UNS UNS UNS

          2. I am willing to bet that creating and supplying a space habitat that provides near 1 gravity would be a factor of ten cheaper than creating and supplying a moon base and a factor of 100 cheaper than a moon base.

          3. If meat puppets are still the way we transport our consciousness in the future, then our species will probably branch off into different species for different environments. Some will be closer to each other that others, like people living on similar size planets will be similar.
            It also depends on if relativistic speeds can be reached. With no cross pollination, you’d think that, eventually, any isolated planet would evolve a different species.

            1. Meat puppets? But where do bad folks go when they die?

              1. They go to a lake of fire and fry.

        3. Space elevators, man. Or a StarTram:

          https://en.wikipedia.org/wiki/StarTram

    2. He is specifically trying to fund projects that are BIG in scale. He wants to inspire the next generation the way the Apollo missions did. By comparison, Mars is incremental.

    3. I wonder how much, really, it would cost to set up a moon base research station. Could it be done for 100 million? 10 times that? It doesn’t seem like to should be that hard. The supplies, of course, are the biggest expense. However, it seems like it could work. I’ll get right on this.

      1. The cost of the Apollo project was around $25 Billion or $135 Billion in 2005 dollars. All told, it consumed nearly 1% of GDP at its height. So it would be extremely expensive.

        Half the problem is that it we keep spending money on getting people to spots that cost a lot to reach. If we instead spent that money on building infrastructure that could get people cheaply to geostationary orbit, it would be a far better use of resources.

        1. To be fair, that was NASA. NASA has the exact opposite of cost controls. But I agree, 100 million is low-balling it.

        2. Sure, but that was #1, a government program and, #2, with 1960s tech. How much do you think it would cost amazon to get to the moon? Bezos has already got $500mm in it, but is having successes. It could build on this investment, not re invent the wheel. (Especially with competing companies.)

          1. Not trying to dismiss you, but Bezos has invested $500 million to get payloads to low earth orbit.

            Getting a payload to Geostationary Orbit costs about 2x- with associated increases in complexity and risk. Getting from GEO to a lunar transfer is probably another 3-5x.

            Those are based on the per-lb cost of transfer- not including the R&D, so it isn’t totally transferable.

            My only point is that we spend all these resources on moon shots rather than trying to cut the costs. If getting from LEO to GEO was cut in half, how would that change things?

            1. My biggest problem with the space elevator is the risk. Imagine a catastrophic failure due to terrorism, weather, accident, whatever. That nanotube, or whatever, cable crashing around the equator could be an existential threat to mankind.
              Other than that, an elevator to a LaGrange point would be awesome.

              1. You can create space tethers that do not reach to earth at first. These tethers would extend from Mid earth orbit to low earth orbit, and Geo to Mid Earth orbit. Interestingly, these would also be feasible without near future technologies like carbon nanotubes. Kevlar has the tensile strength to be one of these tethers

                Payloads could be launched conventionally, couple with the tether and be lifted into the next orbit where they could ladder up. Theoretically, such a network could deliver cargo to and from the moon with relative ease.

                The cost to the tethers is orbit-keeping fuel. Every time the tether lifts a mass, its orbit decreases a little. The amount depends on the mass of the tether. The good news is that you can use much more fuel (and cost) efficient ion engines (or similar) to lift the tether over a period of weeks before each payload reaches it. Additionally, the tethers could catch payloads in higher orbit (i.e. payloads returning from the moon) and lower them to lower orbits back to earth. In doing this, they would actually lift themselves a little bit instead of lowering.

              2. If it breaks everything above the break goes floating away quickly. Everything below falls back to the ground. Put your anchor point out at sea far from land on one side. Anything high enough up to do damage will burn up in reentry. Anything lower falls into the sea.

                It would go out to a geostationary location. No need to go out further. It’s cheap to transfer from there to anywhere in cislunar space.

                1. This is true Skippy, but again, we have been talking about a space elevator for decades and it remains “in the future” until such time as we can manufacture massively long carbon nanotube filaments.

                  On the other hand, space tethers made of Kevlar or similar materials and a 20 Kilometer inflatable space tower could be made with existing material technology and deliver payloads with only a short boost between the tower and space.

                  1. We don’t have materials with the tensile strength. Well, we do, but we don’t have them in 30,000km spools. I still do not like tethers in general. I would much rather just use a transfer tug. It’s kinda like buses and trains. Tug = bus, Tether = train. One is much easier to maintain and retask. Rendezvous is simpler too.

                    1. Just to clarify, my first sentence was in reference to space elevators and not tethers.

                2. cislunar

                  You transphobic shitlord!

                  1. Wouldn’t that be translunar? I don’t think I’m martian…

        3. If one adds NASA’s budget together from 1995-2005, one would be very, very close to that $135 billion 2005 dollar figure. And NASA did not build any 400-foot tall spaceships from scratch in that span; the money mostly bought more ancient rockets, and re-launched more ancient shuttles – losing one in the process. They also pissed some scratch away on Venturestar and flew nothing.

          1. I didn’t even get alien contact for my taxes!

          2. NASA exists almost exclusively as a jobs program. Oh, and global warming. Never forget global warming.

          3. IMHO, the biggest problem with NASA was that they tried to turn themselves into an orbital trucking company rather than a springboard for privatization of space.

            The shuttle was sold as a cheap reusable launch platform. They essentially bought an overpriced truck and got in the payload delivery business. So their business model centered solely around that with resulting business decisions.

            Consider that the External Tank from the shuttle could have easily been delivered to orbit at the same cost or cheaper. When the shuttle launched, it stopped firing its main engines prior to achieving full orbit. It then released the External Tank, where it would re-enter and burn up. Then the orbiter would fire hydrazine thrusters to get the rest of the way into orbit. Instead, if the shuttle continued into orbit, these massive structures would be there for building all sorts of orbital bases.

            But NASA wasn’t interested in that. Instead they optimized for delivering satelites to orbit. Not only did this keep us from making the capital infrastructure necessary for long term presence in orbit, but the subsidized launches effectively priced any private ventures out of the market. It took 20 years before any private concerns could get anywhere close to the subsidized prices.

            1. IMHO, the biggest problem with NASA was that they tried to turn themselves into an orbital trucking company rather than a springboard for privatization of space.

              I don’t disagree with you, but I think that was a necessary survival tactic. Note: not saying NASA has to survive to further space flight/exploitation, that’s a separate question and not one I’m attempting to answer here.

              What I am saying is that I think given reality, NASA turning it into a transport system wasn’t an open choice they picked from a list of alternatives, but a choice they were required to make it they were to survive/continue to be funded.

              They were in a position, until very recently, where the limits of technology made any exploitation which was big enough to create a new generation of space enthusiasts, monetarily infeasible. Even a manned moon mission is very expensive and that’s without building a base.

              And there’s not much desire to redo it to begin with. Everything else of course it’s just more expensive.

              So they were stuck – they couldn’t provide The Next Big Thing? because the costs far outweighed willingness to pay even if a sizeable percentage of Americans were enthused.

              So they set themselves up to be available for clandestine missions and what not.

      2. What’s the point of setting up a *manned* research base on the Moon?

        The Moon’s close enough for tele-work – want to do work on the far-side? Just orbit a couple small satellites to relay signals. Drop an unmanned lab and send up more stuff as needed.

        ISS is already providing pretty much absolutely no useful information at all. Beyond anything *human specific* all the stuff they’ve done up there could have been done remotely.

        Going there for the sake of going there is fine and dandy – as long as where not taking food out of people’s mouths at gunpoint to do it. And until you can make money up there that’s the only way it’ll get done.

        1. I think it may just be a token gesture. But it’s a grand token gesture. People need to see that we can accomplish something more than twerking and increasing taxes. It might inspire the non-luddites to once again dream about the stars.

          1. Except the non-luddites are already dreaming about the stars. We just don’t want to pay 100 times the actual cost to toss a couple people out somewhere where they pick their noses for a couple of weeks and then wander home with nothing to show for it except for bragging rights for our *politicians* to show how our country ‘is better’ than some other country because we can light really, really big piles of money on fire.

  6. First interstellar probe being in any way powered partly by decades-old coal-fired power stations is funny somehow.

  7. *To those commenters who alerted me to this, many thanks (you know who you are). My apologies for getting to it so late in the day.

    I guess that’s how Bailey does hat tips.

    1. Given speeds on display, obviously Bailey is not laser-powered.

  8. So how would they slow them down when they get to Alpha Centauri? I’m not sure they would be able to take decent pictures or make accurate measurements of things if they’re zipping by at 0.25c.

    And could a 1 gram probe have enough battery power to send much data back from 4.5 light years away?

    I don’t suppose you could squeeze many instruments into a probe that tiny, either, but that wouldn’t be a big problem if they’re able to send a lot of them, since they could all have different instruments.

    1. Sorry. That should have said 0.20c.

    2. The velocity would be less of a problem than the small size of the sensors themselves.

      That could be remedied (to an extent) if they were linked as a SAA.

  9. Pathetic Mammals! Your attempt at an intergalactic message in a bottle are quite amusing

    1. Fuck you, you homeothermic-challenged, bradymetabolic, non-lactating, fungus-susceptible, oviparous motherfucker.
      Actually, you probably never even knew your mother, she abandoned you before you were even born!

      1. Inter cultural insults can backfire if you don’t understand the other culture.

        For example – calling an Arab ‘father of a dog’ is a pretty bad insult. Calling an American that is taken almost as a compliment.

        Tell a lizard that his mother abandoned him and he’ll just be like ‘of course, what did you expect her to do? Shove a body part in my mouth and squirt in a bunch of fat?’

        1. True that, Agammamon.

          For example, if I replied: “More like shove a body part in your mouth and squirt in some protein. Booyah!,” Mr Lizard would be like “Thanks for the free protein, suckah!”

      2. That’s cold, d00d.

        Almost as cold as Lizard’s blood!

        BWAHAHAHAHAHAHAHAHAHAHA!!!

        Day-um! I *kill* me sometimes!

  10. Wow. 2nd comment eaten. In one blog post.

    I’m getting a complex.

    As I wrote previously (GO AWAY SQUIRRELS!), it would be ironic/hilarious if all the space dust/crap we know about turned out to be some other civilization’s attempt to do the same to us. We’d literally be plowing through each other’s “fleets” trying to send probes to distant worlds.

    I sense a short sci-fi story coming on…

    1. Heh, I actually rather like that.

    2. We’d literally be plowing through each other’s “fleets” trying to send probes to distant worlds.

      Nerd euphemism. Nice.

      1. I’m working on the all-time most abstruse masturbation euphemism. I think I’ve got a decent shot! **AHEM** If you know what I mean and I think that you do…

    1. Ogre crushing beer cans I’m rage? Oh yes!

  11. Stopping is easy, unfurl the light sail and dive into the star.

    Second Motie reference today!

    1. Never having done the math or seeing another’s derivation, I suspect the star isn’t sufficiently bright to do it in a single pass. You’d probably have to dive enough to capture into a high eccentricity orbit and that use future passes to get in to where the interesting stuff is.

      1. Would depend on ratio of light sail area to mass, I would think.

        1. But I think the brightness of the laser source would be considerably greater than the brightness of the star. Maybe you could do it with asymmetric accel/decel distances… Too lazy to wonder further than that.

      2. Send a mirror out first. That reaches AC and then, as it continues to fly out, you aim your lasers at it (causing it to accelerate away) and it reflects that beam at the probes causing them to slow.

        1. Lasers don’t work 4 ly out. See above.

          1. Yes they do.

            You need to choose your frequency and aperture size to manage diffraction limits on your spot size. But if you’re willing to accept some waste (ie light not hitting the target) and up the power that’s not an issue.

            As for targeting – you’re initially targeting a non-accelerating object that you know the position and velocity of. Its a non-trivial task to figure out where it will be in 20 years. It requires precise aiing, but figuring out where to aim is not difficult. And when you start beaming light at it, you will know where it will be in 4 years (when that light finally reaches it) and how fast it will accelerate and in what direction.

            Completely doable.

            The only issue is *if* there’s a problem there’s a 4 year lag before you know about it and another 4 years before you can correct so a lot of the aiming will have to be done ‘on faith’. But it can be done.

            1. Near IR (1 micron – good atmospheric penetration) beam with a 1000 km aperture gives a minimum spot size diameter of 49,919 m at 4.4 LY.

              This can be achieved either through a synthetic aperture setup across the country (and you get to build in *everyone’s* district – so yay for pork barrel politics?) and/or beaming up to a single large orbital mirror to combine and direct the individual laser beams.

              1. You’d obviously set up above the atmosphere – either at a Lagrange point or on the far side of the moon. Dealing with atmospheric distortion would likely kill this project, even if there were no absorption.

                Far side of the moon is probably most likely. Why? Because if you have a laser that is powerful enough for this mission, you have a death laser of mass destruction. Putting it in orbit would likely mean having it blown up by anyone who doesn’t feel like getting death-lasered and has rockets capable of reaching it. Putting it on the far side of the moon means it is no threat.

    2. Nah, just turn on your stasis generator and use the sun’s atmosphere to ‘aero’brake.

      1. Speaking of Slavers…

        Just don’t come to rest inside the corona. πŸ˜›

        1. Mixing of Nivenverses causes confusion.

  12. So, could “gram scale” refer to density? Ask these problems go away if you’re building a sail big enough.

    1. Nevermind, reread the article. But,a cloud of nano scale probes could be very large.

    2. StarChip: Moore’s law has allowed a dramatic decrease in the size of microelectronic components. This creates the possibility of a gram-scale wafer, carrying cameras, photon thrusters, power supply, navigation and communication equipment, and constituting a fully functional space probe.

      Lightsail: Advances in nanotechnology are producing increasingly thin and light-weight metamaterials, promising to enable the fabrication of meter-scale sails no more than a few hundred atoms thick and at gram-scale mass.

      1. I hate it when ppl think Moore’s Law is magic (see Kurzweil). And it stopped about 4 years ago anyway, although ppl will still argue about that.

        1. Moore’s law is not magic – but we’ve still not come close the the minimum possible size for electronic components. Only slowed down how fast we’re moving there.

  13. Zefram Cochrane will meet you there.

  14. Yeah, but what would it do when it gets there, and would we patiently wait 4-5 years to pick up some rediculously weak radio signal from it?

    1. I’ve patiently waited about that long for a booty call (one of the highlights of my life, BTW). So, yeah, sure, why not?

    2. 1. It would flyby the system in a matter of hours/days.

      2. Yes. The kicker though is could we *detect* those signals at the low power levels that an ‘iPhone’ sized probe will be able to do.

  15. This plan is just another one of those ‘let’s talk big so we can get a ot of headlines’ plans.

    1. 600,000 miles in 120 seconds = an acceleration of around 13.7 THOUSAND g. You have to build the probe to survive that – which means lots of extra mass that’s only needed for a short while and the means lot’s of extra power to push.

    2. Why 100 gw over 2 minutes and not over 2 years? Because to do it that way means that you’ll have to build a whole bunch of extra lasers and have a huge peak power – and since lasers are 20% efficient at best that means you’ll be dumping a huuge amount of heat in a short period of time. So now you have to pay for the cooling.

    3. Cost of power – especially if you’re trying to buy a lot in a short period of time.

    Then, once the boost phase is done, what do you do with it? Hopefully somebody else has a payload that needs boosting right away or your excessively expensive launcher is now worthless.

    Accelerate slower and the whole thing becomes cheaper. A two year acceleration phase? That could be done with *today’s technology. And the beauty of laser propulsion is that since the starship’s drive is *here* (on earth) you can always enlarge/upgrade it over the course of the flight. Get some extra money? Boost the probe for longer and cut the flight time.

    1. Then, once the boost phase is done, what do you do with it?

      Cha of course.

  16. As much of a tech buff as I am, I really fail to see what a visionary plan this is.

    Let’s say we can get these bots to Alpha Centauri in only 20 years. They have to communicate back to us, say everything goes perfect and it will take us 5 years to get that signal back.

    So, 25 years we are getting a signal back about … what?

    Are there any planets around the star? Being our closest neighbor, I’m sure we already know the answer.

    In 25 years, the tech we have today will be like the in today’s comparison, tech from 1815.

  17. Man, the Centaurans are going to be PISSED when their friendly welcome wagon ships on their way to bestow advanced everything on Earthlings get shredded to fuck by a bunch of sand going the opposite direction at 0.2c.

    1. Not as much as the Kzinti who come in to find our ‘propulsion and comunication laser’ is capable of cutting their ships in half at over an a.u. away.

      1. I can’t believe that it took the entire thread before someone mentioned the Kzin.

        This place has really gone downhill since Postrel.

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