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Breakthrough Starshot: Mission to Alpha Centauri

Here on Centauri Dreams we often discuss interstellar flight in a long-term context. Will humans ever travel to another star? I’ve stated my view that if this happens, it will probably take several hundred years before we develop the necessary energy resources to make such a mission fit within the constraints of the world’s economy. This, of course, assumes the necessary technological development along the way — not only in propulsion but in closed-loop life support — to make such a mission scientifically plausible. I get a lot of pushback on that because nobody wants to wait that long. But overall, I’m an optimist. I think it will happen.

Let’s attack the question from another direction, though, and leave human passengers for a later date, as Yuri Milner’s Breakthrough Initiatives, aided by Stephen Hawking, is doing today in a New York news conference. What if we talk about unmanned missions? What if, in fact, the question is: How soon can we put a scientific payload past another star? Let’s not worry about decelerating — this will be a flyby mission. Let’s build it as soon as possible using every breakthrough technology we have at our disposal. How long would it take for that mission to be developed and flown?


Milner, a philanthropist and investor who was an early backer of Facebook, Twitter, Spotify and numerous Chinese tech companies, tells me his goal is to ‘give back to physics’ in developing just such a mission. Part of that giving back is the $100 million he has already put forward to support SETI, a ten-year project that will produce more telescope time for SETI than any other. Milner is also the founder of the Breakthrough Prize, issuing awards in physics, life sciences and mathematics. But in many respects this third Breakthrough Initiative is the most daring of all.

Time for the Stars

Breakthrough Starshot is an instrumented flyby of Alpha Centauri with an exceedingly short time-frame, assuming research and development proceed apace. Milner is putting $100 million into the mission concept, an amount that dwarfs what any individual, corporation or government has ever put into interstellar research. A discipline that has largely been the domain of specialist conferences — and in the scheme of things, not many of those — now moves into a research enterprise with serious backing.

Could an Alpha Centauri flyby mission be developed and launched within a single generation? I think it’s quite a stretch, but it’s the best-case scenario Milner mentioned in a phone conversation over the weekend. He’s enough of a realist (with a first-rate physics background) to know that the challenges are immense. Even so, he sees no deal-breakers.

Let’s walk through the case and see why he finds reason for optimism. “There are major advances that we can now turn to as we develop this proof of concept,” Milner says. “Twenty years ago, none of these things would have been available to far-thinking scientists like Robert Forward. But now we can put them to use and test their possibilities.”

If you’re thinking of an interstellar mission in the near-term, there is really only one choice of propulsion: The beamed sail. Sails have the advantage of known physics, laboratory experiment and actual deployment in space. We could talk about fusion for some indefinite point in the future, but at present, we don’t know how to do fusion even in massive installations on Earth, much less in the tight confines of a spacecraft engine. Interstellar ramjets are a far-future unknown — they may act more effectively as braking devices than engines, according to recent research. Antimatter is nowhere near readiness for propulsion, either in production methods or storage. Chemical rockets fall victim to the mass/ratio problem and are useless for fast interstellar journeys.

That leaves us with sails carrying very small payloads. To cross the 4.37 light years to the Centauri A and B system, Breakthrough Starshot proposes small spacecraft, taking advantage of advances in nanotechnology to reduce payload size. Think Moore’s Law and the reductions in size and cost that have accompanied the vast increases in micro-chip power. “Moore’s Law,” says Milner, “tells us that now is the time.”

StarChip is the Breakthrough Initiatives’ name for a payload measured not in kilograms but grams, a wafer that carries everything you would expect in a fully functional probe. ‘What was once a 300 gram instrument is is now available at three grams,” Milner continues. “What was 100 grams is now 0.5 grams. This is the trend we are riding.”

The StarChip payload includes cameras, power supply, communications equipment, navigation capabilities and photon thrusters. And it would be thrown across the interstellar gulf at 20 percent of the speed of light by a sail that is itself a miniaturized version of the sails Robert Forward used to discuss. Forget the thousand-kilometer sail (much less the continent-sized sails of the science fiction dreamer Cordwainer Smith). Milner’s team believes we can now talk in terms of a laser-driven lightsail that is no more than 4 meters across. This is actually smaller than the first deployed sail craft, the Japanese IKAROS, which boasts a sail measuring 14 meters to the side.

Advances in metamaterials and additional research should be able to produce, Milner believes, a 4 meter sail whose own weight is tallied in grams, and whose materials allow fabrication at a thickness of a few hundred atoms. A sail that small makes its own statement: Clearly, it’s not going to be under the beam for long, which means we need to focus a great deal of light on it for a very brief time. Lasers are another technology that benefits from rising power and falling cost. The trick here will be to create ‘phased arrays’ of lasers that can scale up to the 100 gigawatt level. A phased array involves not one but a group of emitters whose effective radiation pattern is reinforced in the desired direction by adjusting the phase of the signals feeding the antennae.

This is classic Bob Forward thinking rotated according to the symmetries of our new era. Milner aims for a beamer technology that is modular and scalable. And it fits into a larger infrastructure. Breakthrough Initiatives talks about bringing a ‘Silicon Valley approach’ to the problem of interstellar flight. Build a StarChip that can eventually be mass-produced at no more than the cost of an iPhone. For the Alpha Centauri mission, whenever it flies, is itself a proof of concept that could lead to multiple destinations. And if the cost can be driven as low as Milner believes, then we can think in terms of redundancy, with StarChips sent in large numbers to return a full characterization of any destination system. Assemble the light beamer and, as the technology matures, the cost of each launch falls.

These are ideas that are at once familiar but also exotic, for while Forward talked about enormous power stations in close solar orbit to power up his banks of lasers (and a huge Fresnel lens in the outer system to focus the beam), Milner thinks we can build a ground-based beamer at kilometer scale right here on Earth. I was startled at the idea — surely efficiency favors a space-based installation — but Milner’s point is that he thinks we can begin to launch interstellar craft before we have the technology to build the kind of power station Forward envisioned. If you’re serious about a launch within a few decades (again, it’s a best case scenario, and a dramatic one), then you build an Earth-based beamer and use adaptive optics to cancel out atmospheric effects.


Image: A wide-field view obtained with an Hasselblad 2000 FC camera by Claus Madsen (ESO), of a region around the Southern Cross, seen in the right of the image (Kodak Ektachrome 200, 70 min exposure time). Alpha Centauri is the bright yellowish star seen at the middle left, one of the “Pointers” to the star at the top of the Southern Cross. Although it appears here as a single ‘star,’ it is actually comprised of the G-class Centauri A, K-class Centauri B, and the M-dwarf Proxima Centauri. Credit: ESO/Claus Madsen. Original here.

All this will be subject to tightly focused research, which is what the $100 million is for, but what Milner hopes to see are nano craft delivered to orbit and then boosted on their way with a 30 minute laser ‘burn’ that, reaching 60,000 g’s, drives the sail to 20 percent of the speed of light. That makes for roughly a twenty year crossing to Alpha Centauri. With a craft this small, data return is highly problematic, and in fact I think it’s one of the biggest unanswered questions Breakthrough Starshot will have to face (well, this and the challenge of interstellar dust, and key questions related to sail design and the sail’s ability to stay on thee beam during acceleration). The sail is itself the antenna on a craft of this design, and Jim Benford told me in conversation that it will have to be shaped to one-micron precision. Even so, powering up the system to send imagery and data to Earth is going to be tricky. It will be fascinating to see what kind of solutions emerge as this research gets underway, and what alternative methods may be suggested.

Even so, and granting the cost reductions digital technology makes possible, Breakthrough Starshot embarks upon a multi-year research and engineering phase that will focus on building a mission infrastructure. Creating the actual mission will demand a budget comparable to the largest scientific experiments of our time. These are no small aspirations, but what drives them is something that interstellar studies have never had at their disposal: A dedicated, enthusiastic, well-funded effort with the participation of major scientists.

“We have an advisory board of twenty, including Freeman Dyson and other top scientists,” Milner added. “$100 million will be spent in coming years as we look toward concept verification. Multiple grants should flow from this, research and experiments. We need to complete the initial study and see if building a prototype, perhaps at a scale of 1/100, is then the next step.”

At the very least, we can expect the research behind this project to spin off numerous useful technologies, all of which should be applicable not only to star missions but to in-system exploration, along with, potentially, a kilometer-scale beamer that can double as a large telescope for astronomical observations. And while I doubt we can look at interstellar missions within the next few decades (I am open to being convinced otherwise), I believe that the timing for a fast flyby of Alpha Centauri will be considerably advanced by this work.

There is much to be said about all aspects of the Breakthrough Starshot concept, and as you would imagine, I’ll be covering this closely, beginning with a trip later this week to the Breakthrough Initiatives meeting in California. That meeting will have a large SETI component growing out of Milner’s prior commitment of another $100 million, which is already being translated into active observations at the Green Bank observatory in West Virginia. But as you can imagine, the Alpha Centauri mission will be under discussion as well as the research effort begins to be assembled. What spins out of this will keep us talking for a long time to come.


Comments on this entry are closed.

  • Marc Millis April 12, 2016, 12:27

    WOW! With that level of support, I’m looking forward to what will be brought to fruition. To have seen, over the years, so many refinements in the estimates and details (material and energy options), it will be great to see that progress put to a test. This could be cool.

  • Alex Tolley April 12, 2016, 12:31

    IMO, this is definitely the way to go for a fast mission, assuming the technical hurdles can be solved. What I also like is that the approach scales. We can run any number of lower power lasers and slower moving sails to targets in the inner and outer solar system to test instrumentation and control, while reducing the size and cost of the probes. At some point we can then start send out probes, perhaps in swarms, to the nearer stars, as proposed.

    As for communication, it might even make sense to have a receiver probe in the outer system to use gravitational focusing to receive signals from the probes doing stellar flybys. Can we use propellant-less propulsion to decelerate too like Forward’s sail designs? Or perhaps electric or mag sails?

    I’d be interested to see proposed designs for 4m sails massing just grams, yet able to withstand 10’s of thousands of g’s without vaporizing.

    Exciting times.

  • DJ Kaplan April 12, 2016, 12:34

    By “photon thrusters” do you mean the sail?

    • Paul Gilster April 12, 2016, 14:21

      I need to clarify this as well, as the materials I’ve seen imply thrusters on the StarChip. But a lot more information is becoming available, so more on this will follow.

      • Csaba Saghi April 13, 2016, 8:55

        They are most likely just for attitude control and small course modifications.

  • Giulio Prisco April 12, 2016, 13:26

    Just watched the webcast. Awesome news. Paul, thanks for this article, and I look forward to your next one, What spins out of this will keep us talking for a long time to come indeed!

  • Odd-Bjørn April 12, 2016, 13:55

    You omitted fission-powered propulsion from your discussion, why? I’m thinking of something like a naval reactor (minus all the heavy shielding that won’t be needed on a space probe) driving a big ion thruster.

    • Paul Gilster April 12, 2016, 14:23

      Mostly because if we’re talking a mission any time soon, we would have to get past the political hurdles — not to mention the technical ones — of getting giant reactors available for ion propulsion in space. Milner and team think the small sail is the fastest way to get this launched.

      • Ashley Baldwin April 12, 2016, 17:49

        Absolutely . The VASIMR advanced ion drive which is designed to provide far more boost than any other such proposal to date has got bogged down with suggestions it would require a 4000 tonnes reactor to function . Even with decades of uninterrupted acceleration , it still wouldn’t even come close to providing the significant fractions of “c” required to reach Alpha Centauri in a life time even with multiple flybys and a mother of all chemical launchers . ( good for Kuiper belt though ) .Laser boosted sails are the only option in even the medium term. Hopefully a $100 million of research will mature the concept sufficiently for others to pick up the baton. A very good start though.

        • Antonio April 13, 2016, 9:36

          “The VASIMR advanced ion drive which is designed to provide far more boost than any other such proposal to date”

          *Sigh* That hoax again… Several ion thrusters in the market have much more Isp than VASIMR!

          • Brett April 13, 2016, 12:27

            True, but they’re at lower power levels. HiPEP would have beaten VASIMR on ISP, but it’s only designed for power output in the 20-50 KW range. As far as I can tell, you can’t just hook up a bigger power source to it and scale up further.

          • Angelo Genovese April 13, 2016, 12:35

            Which ones? ;-)

          • Ashley Baldwin April 13, 2016, 13:07

            ISP is great over time , and indeed there are other concepts that offer more but not necessarily thrust though and that’s what gets your speed up quickly which is what is needed here.
            Other theoretical magnetohydrodynamic concepts may top it on thrust too but haven’t had the massive investment of dear old VASIMR, which is what is so annoying as I’m sure this is a field to pursue , certainly for the solar system out as far and deep into the Kuiper belt though probably not further .
            Hopefully we will see things move on rapidly once the first mission with the much improved NEXT drive takes place , likely New Frontiers 4 in 2024 for which the engine is offered as a free option.

  • Vignesh R April 12, 2016, 14:07


    I have a basic doubt. The mass of an object will increase if the object travels at 20% of the speed of light. So how will they handle the acceleration of the relativistic mass ?

    • Paul Gilster April 12, 2016, 14:21

      Mass increase at 20 percent of c is exceedingly minor.

      • Scott Gordon April 13, 2016, 4:42

        About 2% increase only (Formula for the increase as a fraction, is 1/sqrt(1-v^2/c^2)-1 where v=speed vs Earth and c=speed of light; v/c=0.2 here)

  • Robert April 12, 2016, 14:11

    I think the project will end up funding an education center where kids will go on school field trips to learn about science. But that’s about it.

  • Matt April 12, 2016, 14:14

    It is very exciting to see this idea getting real money behind it. Even if it does not fully succeed it will bring a lot of progress.

  • Neil S April 12, 2016, 14:17

    Let me try to be the first one to say it: Space Chips.

    • Michael April 12, 2016, 15:46

      A major pain with thin membranes is that radiation affects them badly, however some stand off shields, launched ahead, of thicker material will aid in there protection. Either way around this problem still leaves the enormous amounts of energy required.

      • djlactin April 13, 2016, 8:34

        Another option is to fold up the membrane like an umbrella after the thrust stage. Or to discard it altogether.

        • Michael April 13, 2016, 9:20

          Fold it up like cigar might be easier.

      • DJ Kaplan April 13, 2016, 13:02

        A new material like grapheme may provide that shielding in a light weight. Stay tuned.

  • James Stilwell April 12, 2016, 14:28

    You’ve about got to the bottom line here…
    Without politics in the equation we are going nowhere…
    Your group already has the technology ready for expansion…
    Getting to Alpha Centauri is commendable…
    We’ll need a JFK to launch…ergo, the March 16th post of 2016 —the problem of arrival—and the many valid comments–sets out of bounds the fusion ramjet…another way must be chosen…
    A great post…

    • Javier Garcia April 13, 2016, 5:42


      I dont want this to take this into politics, but it is true that the world needs good leaders, and presently they are nowhere.

      Maybe it is also that we live in a different kind of society than JFK.

      But without the right leadership, there is a lot of noise instead of a beautiul melody.

      • Robert Del Rosso August 25, 2016, 22:50

        I just discovered this today, Aug 25th, 2016 !!!

        I am neither a Politician nor a Space Chip Designer, but if you have $100 million from Yuri Milner and maybe Bill Gates and Paul Allen and Elon Musk and Larry Ellison “Chip” in, then why do you need to worry about what “Politicians” say?

        Is the American or Russian or Chinese President going to say: ‘DON’T GO?”. Even if he (or SHE) said so, why do you have to listen to them?

        Even for an Alpha Centuri Flyby in 20 years, this is Great!


  • Greg Matloff April 12, 2016, 14:53

    Dear Paul
    It is exciting to see this research funded. The largest technical issue will be the thermal problem. Power levels in the laser/maser beam will be enormous. In the best case, for a 30-nanometer thick aluminum sail (the thinnest non-transmissive aluminum sail), about 8% of the power from a yellow laser beam will be absorbed by the sail. Getting rid of this without melting the sail will be a very major challenge. It will be interesting to see if anyone can overcome this.
    Regards, Greg

    • Michael April 12, 2016, 15:38

      Cooling is going to be a major issue as you state but perhaps we can integrate it into a large habitat that uses the thermal excess for normal operations, perhaps a probe manufacturing station whose soul function is launching probes.

    • Matt April 12, 2016, 16:24

      I don’t know if a melting sail is a problem. It might be a good thing. Melt the sail off and use the masts as antenna. Of course the sail would have to last long enough to accelerate the spaceship, so that might still be a problem.

      Anyway having some funding for working on these problems is great.

      • Matt April 13, 2016, 11:06

        On further reading I see that they are planning on using the sail as an antenna. So burning up the sail would actually be a problem. That hardly seems like the hardest problem in the project though.

    • Eric Hughes April 12, 2016, 19:01

      I think Greg may be understating the problem. Above a certain intensity of electric field as carried in the propulsion beam, the atoms of the sail material will spontaneously ionize. The mechanical strength of a plasma isn’t very high.

    • Andrew Higgins April 12, 2016, 19:27

      RE: …about 8% of the power from a yellow laser beam will be absorbed by the sail.

      This is addressed in Lubin’s “A Roadmap to Interstellar Flight”, available here: :

      “Laser coatings on glass already can achieve 99.999% reflectivity or absorption of less than 10^-5 . We have started working with industrial partners and have designed a “roll to roll” process that is a multi-layer dielectric on plastic that achieves 99.995% reflectivity (in design).”

  • Thomas Goodey April 12, 2016, 15:08

    “At the very least, we can expect the research behind this project to spin off numerous useful technologies…”

    The laser could be used for blasting into oblivion pretty well anything in Earth orbit, and probably much further afield.

    • Ivan Vuletich April 13, 2016, 0:03

      Which just sparked a thought, if a laser array that big is every built, could it be used for laser launches of conventionally sized payloads to LEO?


      • Thomas Goodey April 13, 2016, 8:11

        According to the description, the laser array would be built to supply an enormous amount of power in a very short time, so as to accelerate the craft at circa 60,000 g. I don’t think that an array of that type would be able to supply power for the ten minutes or so needed to launch to LEO. The demands for cooling would be huge.

        • Patrick Sawyer April 13, 2016, 14:31

          But, think about LEO applications for so much power… Space debris removal? Send up a satellite with a steerable mirror, and use only a few of the laser emitters from the whole array, and use the mirror to focus them on small space debris. It’ll either vaporize it outright, or it’ll turn the side facing the laser into a plasma rocket, which you could easily use to deorbit the junk. No more Kessler Syndrome to worry about.

  • Tom Mazanec April 12, 2016, 15:23

    This could make a good flyby of Telisto (if it actually exists).

    • Adam April 13, 2016, 17:27

      Just what I was thinking :-) If we can do an occultation study of its atmosphere then we’ll know if we can aerocapture a slower, bigger probe.

  • Wojciech J April 12, 2016, 15:33

    A fascinating and inspirational proposal. I can see it gathered interest in the media and should bring more understanding of exo planets research to the public, as well as freeing interstellar travel from realm of fantasy in common perception.
    One thing that interests me is radiation, how could such small computers be protected? Combination with mag sail for own field protecting them? Since the project envisions sending 1000 probes or so as I understand, would it be possible to use outer swarm to shield probes “inside”( if such formation is possible of course).Of interest could be software for quadrocopter swarms(google it, they do amazing stuff in coordination together). Could solar sail have dual purpose and has research been undertaken on it? For example using it as communication antenna.
    As to probes themselves I wondered if they could communicate with each other increasing their processing power.
    Very, very exciting news.Although I believe that in 30 years we should be able to see other planets using advanced telescopes, a probe would be amazing.

  • Andrew Palfreyman April 12, 2016, 16:08

    Yes yes yes yes yes!!
    That’s the way to go.

    Launch costs (my bugbear aka StarTram/Skylon) don’t really play here because of the tiny mass. At Musk’s touted $2K/Kg, the launch of one SpaceChip would cost less than a Starbuck’s frappuccino :)

  • Frank Smith April 12, 2016, 16:15

    Wow! This is great news!

    But, given the power of Moore’s law, would it not be better for that $100 million to be put into a Foundation and let it grow? 4% interest a year is $400,000 a year. Take $100,000 a year and pay for studies and management. In a hundred years 3% interest would get you $1.9 billion leveraged by Moore’s law, which should pay for a serious probe…

    The average compound growth of the stock market for the last 100 years or so is about 10%, which is about 7% adjusted for inflation.

    7% a year would make the Foundation worth about $860 billion in a hundred years. You’d probably have to spread the money across multiple banking systems to keep the government from grabbing it. Maybe Switzerland, Japan and Singapore.

    • Giulio Prisco April 13, 2016, 2:56

      With this approach you keep waiting forever and never do anything.

      Why should you buy a new computer or phone now instead of waiting one more year for a better and cheaper one? But if you wait one more year, then the same logic says than you should wait yet another year. And then yet another year…

      If you really need a new computer or phone, just but the best that you can find now. I think we need an ambitious starshot now, for the mental health of our species.

  • FrankH April 12, 2016, 16:20

    This is exciting news, despite the technical issues. It does remind me a bit of David Brin’s “Existence”

  • Tulse April 12, 2016, 16:29

    Hey, Centauri Dreams got a mention at The Atlantic!

  • Guillem April 12, 2016, 16:34

    Wow! Really exciting and thanks for the context as well.

    If they can put a macroscopic object at 0.2c, that would be huge already. Imagine the possibilities, all solar system bodies and the solar gravitational focal at reach within weeks. Quick numbers say that a mass of 1 g at that speed would have 1.8 10^12 J, which is ~ 0.3 Ktn. A pretty respectable kinetic weapon as well…

    ps. Hopefully they can spare a few ‘SpaceChips’ to Proxima too ;)

    • Nathan Currier April 12, 2016, 19:49

      A SpaceChip that goes past Proxima could then become a transmitter along Proxima’s gravitational focus, which would beam to a receiver along the Sun’s gravitational focus. Proxima also has good alignment with Alpha Centauri A and B, but the probe would still pass 600 AU from the binary, thus making power and communications difficult. The A+B probe could store data and use A or B to focus the signal, but their orbital motions will make only a temporary alignment with the Sun. The best alignment will be around 2060, when the stars will have little relative motion as seen from Earth.

      • Nathan Currier April 15, 2016, 0:48

        Never mind, Proxima is not well aligned. 2.2 degrees angular separation as seen from Earth. That would correspond to a 10000+ AU flyby distance from A+B. The point about the year 2060 still applies.

  • Adam April 12, 2016, 16:51

    If the SpaceChips can be pointed with sufficient accuracy, then they might produce a usable Sail-Beam, pushing a much larger vehicle.

    Of course this all requires a decent power supply available to the Beamer system. That’ll be interesting to watch as it evolves.

    • Ashley Baldwin April 12, 2016, 17:39

      And there lies a good point. Accuracy. Gaia’s dramatic improvement in stellar cartography falls a long way short of what is needed for any Alpha Centauri flyby missions. Even sub percentage accuracy amounts to tens of thousands of AUs over “just” 4.3 light years .
      Meantime it’s ridiculous that despite all the exoplanets discovered so far we still don’t know for sure that there are any planets in the trinary Alpha Centauri system.( though hopefully that will change soon for Proxima through the RV approach at least with Alpha Centauri too later if all goes well thanks to Gaia’s astrometry ) .
      But no specific plans to do so. Even WFIRST cant target a binary system as things stand either with a coronagraph or starshade .Tangible targets make for a big statement( and more funding ) . Something to aim for especially if in habitable zone. And it doesn’t have to be expensive. The ACE-sat 0.45m telescope concept could cover the entire “zones of orbital stability” around both Alpha Centauri A and B , never mind the large combined habitable zones within, and was only submitted as a $120 million “Small Explorer” programme. Based on Kepler style “one direction” style observation from a stable Earth trailing orbit .
      Needs some key technology maturing but nothing dramatic , and will hopefully become an important option for next decade . It includes “multiple star wavefront control ” software it uses to simultaneously image around binary stars . Once perfected this could easily be downloaded into of WFIRST ,even after launch allowing its much larger 2.4m mirror to search the Alpha Centauri system ( and other binaries too) for planets , though it would require an extended observation period to get the small Inner Working Angle ( how close to the star it can see) and high contrast needed to see Earth mass planets in the habitable zones of both stars .

  • Enzo April 12, 2016, 16:51

    Surely you could test a lot of the technologies by sending the probe to remote locations of the solar system first (Uranus, Neptune,Sedna,etc.).
    If it’s capable of returning any useful information, it would be very useful and it won’t need to go to 0.2c to do that.

  • Larry DePuy April 12, 2016, 16:52

    20 years to Alpha Centauri. Outstanding!! Milner and Musk have given new meaning to the letters M&M. My disgust and envy of the very wealthy does an abrupt about face with these men. I get the vicarious thrill of their work and can’t praise them enough. As space research is so slow and I am 68, my hope is a cure for aging will come in time for me to live long enough to see what the future brings. Space research is just now getting interesting. I don’t want to miss any of it. I think a cure for aging will put an end to the “multi-generational ship” theory. Although Calico has been quiet, Helen Blau at Blau Labs Stanford has rejuvenated healthy human skin cells in the lab, so whole body rejuvenation is not far away. Treated shin cells replicated 40 times, while the control cells senesced. The way things are now, you can only wait 20 years for a project, so many times and then poof you are gone. I think aging and death are a really bad ideas.

  • Joe G April 12, 2016, 17:04

    Very exciting news… I still worry about the power requirements to transmit info back to earth, and the physical limitations of transmitters the size of a chip…
    Perhaps thousands could be deployed acting as repeaters , strung out in a line between the two systems … Not sure where the economic break even point would be, where it costs just as much to send one “big” powerful probe vs thousands of chip ships…
    In any case, this is a very encouraging step… Im confident the technical problems can be solved.

    • DJ Kaplan April 13, 2016, 13:07

      I wonder about that too, although I don’t see it as a barrier, but as a question: What’s the smallest and lightest transmitter we can build today that will send a signal from AC? I doubt that it’s even been designed yet.

    • Patrick Sawyer April 13, 2016, 14:35

      Or, if you have them strung out over several light hours, you can buffer the data along the line, then time the message so that each probe fires it at the same time. They’d be turned into a massive linear phased array antenna.

  • Thomas Goodey April 12, 2016, 17:17

    I don’t understand why this proposal is even being discussed. It is crassly obvious that the intense blast of laser radiation would blow the tiny probe and sail into incandescent gas in an instant. How can reputable scientists lend their prestige to such dreaming?

  • Kolyo April 12, 2016, 17:40

    That’s amazing news !!!! Waiting for it for more than two decades !!! Of course there is a lot of work to be done before proving the concept possible at all, but I think that this will be the giant step toward making this thing happen. I think we all should colaborate and help from all field of technology, nanotech, laser science, matherial science, electronics and communication and if we increase the size of investment we can make it in 2-3 decades !!!

    • Giulio Prisco April 13, 2016, 3:20

      I am 58 and I won’t see the end of the mission, but I will start exercising more so perhaps I can see the launch ;-)

      I hope there will be opportunities for volunteer citizen scientists to participate in some ways.

  • Harry R Ray April 12, 2016, 18:06

    Paul Gilster: Is a COMPLETE LIST of presentations and discussions at the upcoming Breakthrough Initiatives SETI conference available yet. I am wondering if Philip Lubin was invited to discuss his blockbuster paper, “The Search For Directed Intellegence.” The Benfords have always favored MICROWAVE beaming over laser beaming, and I assume that if a mission is attempted within a decade or two, that this WILL be the energy source. But, Lubin argues that in the NOT TOO DISTANT FUTURE, laser beaming will become a lot more economical than microwave beaming, and that we should PRIORITIZE spectrographic analysis of stars OVER listening at microwave frequencies. I wonder if the Benfords have a REBUTTAL for this? ALSO, can ANYBODY answer the question I posed in a PREVIOUS COMMENT, which is: The Bouquet OSETI observatory saw NO EVIDENCE of pulsed laser emission coming from the vicinity of KIC8462852, but were they even EQUIPPED to look for CONTINUOUS LASER BEAMING(case in point: lightsail leakage)?

    • Harry R Ray April 12, 2016, 18:30

      OOPS> I guess they DO intend to use lasers instad of microwave AFTER ALL! All the more impetus for everyone who reads this to google “The Search For Directed Intellegence”. and read the PDF ASAP! I really hope Lubin’s “DE-STAR” proposal gets funded by Breakthrough Listen!

      • Paul Gilster April 12, 2016, 20:17

        Yes, this is a laser-beamed mission. As to the schedule of the upcoming Breakthrough meeting, I don’t have it yet, but Lubin is a part of Breakthrough StarShot and I assume he’s going to be speaking.

      • Adam April 13, 2016, 17:31

        Hi Harry
        Both Lubin & Jim Benford are involved, so no doubt they’ll be discussing the relative merits of frequencies aplenty.

  • Andrew Norman April 12, 2016, 18:29

    Hi Paul

    Congrats on another definitive article on a fascinating subject! Any idea how closely associated Lubin at UCSB will to this project? He’s been talking about a very similar idea for years, and gave a good SETI Talk on the subject awhile back. In fact, I remember thinking “This is brilliant, why isn’t everyone talking about this?” It’s amazing what money will do.

    • Paul Gilster April 12, 2016, 20:18

      Lubin is closely involved with Breakthrough StarShot, and I assume will be speaking at the upcoming conference.

    • Javier Garcia April 13, 2016, 6:35

      One of the reasons or not being at the front of all the newspapers by now, is that a lot of people think: “look what rich people do with their money when they dont know whatelse they can buy”.

      We must realize that, for many people, spending $100M on the starrace, when people is dying from hunger, war, climate change, etc, looks awful.

      We better take it into a different light: focusing on the benefits for the human being this coul bring.

      • Thomas Goodey April 13, 2016, 8:09

        We don’t have to satisfy everybody on the planet. Those naysayers are fools.

        • Giulio Prisco April 13, 2016, 9:42

          Re-igniting our cosmic inspiration and optimism is a benefit for all human beings. This is one of those projects that can inspire young people all over the planet to look at the stars and do great things here on earth.

          The world is interesting because there are different people with different priorities and goals. Some work for peace, some develop medicines, some create great literature and art… and some build stairways to the stars. All are needed.

          Kudos to Yuri Milner for putting his money to great use for us all.

      • Larry April 13, 2016, 12:40

        We have collectively spent trillions of dollars on “the poor”. It hasn’t helped them one bit, and in fact may have made them worse off. It has certainly increased their numbers, though. Their problems will not be solved by showering them with more money, grants, gifts, benefits, subsidies, etc. If we refuse to invest in anything else until the problem of every poor person has been solved first, then humanity will never accomplish anything, ever.

      • sglover April 13, 2016, 16:10

        I think yours is a good point. Naturally, it brought out some of the local social Darwinists, whose wisdom always boils down to, If only the poor would die off quietly, we’d be spared so much unpleasantness.

        But anyway…. In Milner’s defense, these days there are oligarchs throwing away multiples of his $100 million on yachts. At least he’s spending his money on something with real cultural and scientific value, rather than grotesque narcissism.

        However, I think I’d put the technical efforts into things like telescopes in this solar system. Even aside from the immense challenges of this effort, for the first time there are questions of interstellar politics to consider. I doubt very much that there’s any sentient life in the Centauri system (or anywhere beyond earth, frankly), but of course we don’t know. Is it really wise to send shotgun blasts of relativistic pebbles in the general direction of every place we’re interested in?

        • Alex Tolley April 13, 2016, 17:20

          Only a probe can provide local data that needs direct measurement. If this idea could really be implemented for $10bn, then that cost is comparable to the James Webb telescope. This shouldn’t be “either/or” but “and”.

  • Tom Mazanec April 12, 2016, 18:45

    This system could send a probe and get back data within a century of stars within 5 parsecs. There are at least 56 such destinations:

  • Brett Bellmore April 12, 2016, 19:06

    I was interested that one of the rationales for placing the laser array on Earth was that doing so made it impossible to *aim* at anywhere on Earth. One of the biggest problems with beam propulsion has always been that whole “First we build a Deathstar” thing.

    But locating it on the far side of the Moon might be a better choice, in that it accomplishes the same thing, only for near Earth assets to, and gets around having to get the beam out through an atmosphere. It would probably go well with the proposed Lunar equator solar power array.

    A big issue, though, is once you’ve gotten this small, absurdly light probe to another star, how do you get any information back from it? That’s not an easy task.

    • Thomas Goodey April 12, 2016, 19:35

      It doesn’t make it impossible to aim at satellites, though.

      And why would you want to deprive yourself of any capability, including aiming at somebody you don’t like? Try selling that to the Government.

      But of course the laser array should be positioned on Earth, because that will be far far cheaper than trying to build it in space or on the Moon. The atmospheric losses pale into insignificance when the cost aspect is considered.

    • Eniac April 15, 2016, 6:59

      That, and feasibility. We are far from being able to lift the components of a giant laser like that from Earth, and even further from being able to produce them off Earth. Anything other than basing the laser on Earth would have to wait until AFTER the industrialization of space, and we won’t see that one in just a few decades. This part of the proposal is remarkably clever.

  • Michael Chorost April 12, 2016, 19:40

    Fascinating idea. I saw the NYT article and I knew there would be a good discussion of it here. As for the problem of beaming data back to Earth, maybe they could join together into a kind of parabolic dish after flyby, using the light of the star to generate energy? And as for the problem of the laser vaporizing the SpaceChips and sails — well, I don’t know about the sails, with such tenuous material, but maybe the SpaceChips themselves could have ablative surfaces, such that the laser would vaporize them and give them an extra kick of speed. Anyway, a fascinating idea!

  • Astronist April 12, 2016, 20:04

    I’m skeptical about the value of an undecelerated flyby probe. Breakthrough Starshot will need to ask whether such probes can really acquire more data than a large telescope in the Solar System. Any planets in the system will be much the most interesting part of it, for which detailed close-up observations from orbit will be preferable. The most interesting aspect of any planets is any possible indigenous biology, for which one wants cameras, microscopes, mass spectrometers and so on located on their surfaces. Still, it’s a nice try, and let’s see what they can come up with.

  • Eric S. April 12, 2016, 21:02

    One of the interesting things is the ‘residual’ capability this has for more ‘mundane’ tasks… like more massive items sent thru the solar system. This should also give the DE-STAR folks a real shot in the arm.

  • Al Jackson April 12, 2016, 21:15

    About the only viable orbit debris removal project NASA has studied and is studying is with ground-based lasers. Maybe some joint talking should be done.

    • DJ Kaplan April 13, 2016, 13:13

      Indeed, our fleet of commercial satellites are at risk. You’d think there’d be some willingness to pony up some Latinum.

  • Geir Lanesskog April 12, 2016, 22:09

    This sounded great, until I thought about more. Twenty years of flight-time for a second of utility. Why not spend the funds on developing a swarm telescope the size of a planet and keep it here in the solar system – like the TPF on steroids. A lot less technical challenges and you could keep reusing the components, and improving or expanding them.

    I know it’s not an either/or – somebody else could do that, but if it was my money, I’d go for the telescope.

    • Wojciech J April 13, 2016, 10:43

      That is my stance as well, however testing this as a proof of concept is a good idea.
      It would be interesting to use this as precursor to solar gravitational lens telescope mission.

  • Ivan Vuletich April 12, 2016, 22:30

    Assuming that the sail survives the launch largely intact, how much deceleration could you get by diving straight at Alpha Centauri A for instance?

    You could use one of the earlier probes to provide better targeting information to a later probe, similar to the chain of repeaters that Joe G mentioned.

  • Mike Fidler April 12, 2016, 22:35

    Let’s see, a launch every two minutes, Alpha Centauri A, Alpha Centauri B, Proxima Centauri, Barnard’s star, Planet nine, Pluto, Titan. That’s a lot of interesting places to go and just how big of a payload could be sent to places in our Solar System? How long would it take to reach Planet 9?

    • Harry R Ray April 13, 2016, 9:48

      Obviously the relatively NEARBY missions mentioned above will happen a LOT sooner than the grand finale, because the 100+GW phased laser array will be online much earlier than 20 year reliability nanosats. Here is my itinerary and the mission names. FIRST: PIAD, which stands for Pluto In A Day(Alan Stearn, are you in?). SECOND: TIAF or TIAM, which stand for Telesto In A Fortnight and Telesto In A Month, depending upon which part of its orbit it is in(if there really IS a planet nine, and if it is is discovered in the next few years. Now, HERE ARE MY ADDITIONS: THIRD:JERI , which stands for Jupiter Extremely Rapid Impact. It seem likely to me that to have a really CLOSE encounter with the stars in the Alpha Centauri system, you would have to hit a roughly Jupiter-sized “bullseye” at roughly Jupiter’s distance. What better way to practice than to hit Jupiter ITSELF(would a one fifth lightspeed penetration of Jupiter’s cloudtops by a spacecraft as SMALL as these proposed ones cause a flash detectable by ground based telescopes, and if NOT, JWST or HDT)! FOURTH: EEHL, which stands for Europa Extremely Hard Landing. There have been proposals in the past for a “Deep Impact” type mission so that an orbiter can collect ejected debris for study. A MAJOR concern has always been the possibility microbes of Earth origin SURVIVING the impact and polluting Europa. No need to worry about THAT when the impact is at one fifth lightspeed! And LAST, before the MAIN EVENT, ARPA, which stands for Asteroid Rubble Pile Anaihlation. A one fifth lightspeed collision with such an asteroid may produce an ENTIRELY DIFFERENT UOTCOME than the PROJECTED one for a much slower impact.

  • Stan Erickson April 12, 2016, 23:40
    • DJ Kaplan April 13, 2016, 13:24

      Good thoughts. And when the laser is turned off, and assumed thrust has been applied, then there is light from the sun, which is probably impacting the sail. Hopefully this doesn’t throw the craft off course.

      1000s of questions.

  • Rafik Bourne April 12, 2016, 23:45

    Great news that hopefully will see breakthrough advances over coming decades.

    On the practical side of things we have a program of development over a generation, around 30 years, a velocity goal of 0.2c, around 22 years, and return communications around 4 years. Total time of roughly 56 years.

    Hawking is unlikely to see a launch with that timeframe, Milner is unlikely to be around to see any return communication from AC and Zuckerberg will be in his late 80s. Very altruistic for them to take on such a program that children or grandchildren will enjoy seeing the fruits.

    What it could give us is a defined science/engineering goal that will be a challenge for two generations with lots of intermediate goals such as the outer solar system, Kupier belt, Oort cloud and the Sun’s gravitational lens at 550 AU.

    My question is if the sail survives launch can we use it to slow the SpaceChip for the last 5-10 years of the journey? Even if we could get down to 0.1c on arrival we would have twice as much time to collect data during the flyby.

  • Marshall Eubanks April 13, 2016, 2:21

    Send a swarm of femtospacecraft, use optical communications with good shared clocks (so they jointly send last pulses in very narrow time windows) and wait 1-2 months after the flyby (i.e., travel order 500 AU out) to use the host star as a gravitational lens to greatly amplify the optical signal back on Earth. (For best results, the lasers should be tuned to an absorption line in the stellar spectrum.) This wouldn’t work in the radio, as the corona near the star would be too dispersive, but it should work just fine in the optical or the near-IR.

    • JohnHunt April 14, 2016, 9:37

      Some pretty good thoughts there which could make this proposal more doable. Perhaps if there were a concept revision process which allowed the input of ideas were crowd sourced and a selection process to incorporate good ideas, this proposal could be significantly enhanced in the near-term. Perhaps StarShot 2.0.

      • Marshall Eubanks April 20, 2016, 14:07

        Pete Worden told me that they will issue a call in due course. Until then, the “best way to get involved is to make an input on the appropriate topic on our web site: http://breakthroughinitiatives.org/Initiative/3

        • Giulio Prisco April 21, 2016, 4:26

          Thanks, I had missed this. I signed up and posted a first comment:

          “Re ‘Okay, this is going to INCREASE costs substantially but I think for good reason: Put it on the FAR side of the moon!…’

          I think this option should be considered. It’s likely to more than double the overall cost of the project, but the establishment of a moonbase on the far side – which could double as an astronomical observatory and other uses – is a worthy goal in itself and could attract its own funding.

          NASA, ESA and other space agencies have preliminary plans for a farside moonbase. While unlikely to significantly contribute to Starshot itself, the space agencies could be persuaded to contribute to the establishment of the moonbase, including transportation. Perhaps Starshot could be the catalyst that makes a moonbase happen.”

          It’s good to have an official open forum to discuss the project. However, their forum software seems rather poor, without threaded comments and all the features that we expect these days. Perhaps they could be persuaded to consider Centauri Dreams as a complementary unofficial forum?

  • Malcolm Davis April 13, 2016, 3:12

    I think this is a good place to start. There are clear technical challenges, but if its possible to get a nanoprobe (or better yet, lots and lots of nanoprobes networked to work as one more sophisticated probe) to Alpha Centauri within the next few decades, and send back some useful data, including high resolution imagery, then that is worth doing. If we look at what New Horizons could do at Pluto, and the excitement that caused, imagine the excitement if this probe could over the next 50 years send back images of new worlds orbiting Earth’s nearest neighbour? Furthermore, there is no reason to stop at Alpha Centuari? Why not send similar probes to Sirius, Tau Ceti, Barnard’s Star and Ross 248 at the same time?

    This technology has obvious application for deep solar system missions too – Pluto in a few weeks sounds very good, and it would be possible to get a probe out to Planet Nine within a reasonable time frame.

    • Thomas Goodey April 13, 2016, 8:08

      If the system would actually work, obviously it would be used for very large numbers of successive launches. The cost of the actual craft would be inconsiderable as compared to the cost of the launch array.

    • Larry April 13, 2016, 13:06

      One of my concerns is how much useful visual information could be obtained. A 100mm diameter telescope yields ~1 arcsecond resolution. New Horizons carried a 200mm diameter telescope. The optics on this chip ship would be perhaps 2 or 3 mm. The mission would in part be used to find and photograph planets, and it’s very unlikely that there would be any close flybys, so this could be the equivalent of trying to photograph our own planets from earth using a cellphone camera without any telescopic aid – you would get dots a pixel or two across with no detail. I assume we’ll learn more about the proposed technology in time.

  • Moebius April 13, 2016, 5:54

    MIT apparently developped a ‘perfect mirror’. Maybe a technology that can be used to prevent the sail from melting:

    • Thomas Goodey April 13, 2016, 8:07

      I don’t believe anything is perfect. The power that this tiny craft is being asked to reflect is so gigantic that, even if only one millionth was not reflected but was converted into heat, the craft would be whiffed in a microsecond. Remember, it would have almost no heat capacity. The root of the problem is that the acceleration is postulated to be extremely high.

      • Moebius April 13, 2016, 10:01

        The MIT’s article seems to be about a real perfect mirror (not a conventional metallic mirror). We’ll need the sail and the back of the chip to be a perfect mirror anyway or they will both be vaporised. If they’re saying “perfect” because it’s just maybe 99.999 % reflective for a given wavelength, well that’s a shame, but it’s still a good advance and we should push towards 0% absorption. We need to do it for only one wavelength anyway, as the laser is monochromatic. I don’t see how to overcome the problem of the craft being vaporised by the beam otherwise.

        • Bumblebee April 14, 2016, 5:54

          The problem here is the enormous Doppler shift from an object travelling at 0.2c.

          • Thomas Goodey April 14, 2016, 8:30

            That is also true. In any case, the idea of a perfect mirror with 100% reflection is a pure fantasy. Obviously.

  • Saint Aardvark the Carpeted April 13, 2016, 9:03

    My jaw dropped when I read this yesterday. Yes, the challenges are immense — but the idea, the *audacity*, is incredibly inspiring. I’m with Giulio Prisco — time to start exercising so I can see the launch. :-)

    And while I’m at it, many thanks to our host for his work in writing this up. This blog is always wonderful reading.

  • torque_xtr April 13, 2016, 9:06

    It’s so wonderful to see that amount of support!

    I wonder if they considered Sun’s gravitational focus as the aid for retranslation. If we can get 1 gram past Alpha Centauri at 0.2c, we can also get 3-3 orders of magnitude heavier payload on the focal sphere. This not only greatly reduces the antenna requirements (by dozen orders of magnitude maybe, and even DPSS laser may work!!) but also enables detailed reconnaissance of the target system (especially if the FOCAL gets there some years ahead, and it’s possible to send corrected research program).
    Wonder also if it’s possible to make graphene Bragg Reflector sail tuned for laser frequency, if a superconducting loop around the starwisp could act as a decelerator, and if it’s possible to navigate in the target system with a solar/magsail combination…

  • Jim Early April 13, 2016, 11:23

    We need to pay more attention to the limitations of a probe flyby at 0.2c The limited time and resolution will not be solved by nanotechnology. At a minimum we need to use the full size of the sail as the optical aperture to get useful resolution and to beam back data. I would agree with Astronist and Geir Lanesskog that the data potential of any probe should be compared with space telescope technology available in the same time period.
    To learn the basics of visible laser driven probes, I would recommend the work of Geoffrey Landis.

  • Andreas April 13, 2016, 12:08

    Can this system be additional used as a defense system against comets and asteroids?
    (Under the laser radiation, the surface of a body begins to melt and vaporize, and it is going to change of the fly trajectory)
    Maybe this “defense system” can be additional sponsored by some governments (politicians should be happy “we save the world” :-)

  • Alex Tolley April 13, 2016, 12:55

    Thinking further ahead, we use this approach with larger payloads to create seed ships that can create the laser arrays at the target stars, offering deceleration and return trip capability. Data encoded atomically can be sent back and forth between stars with high virtual bandwidth. machine intelligences can be similarly encoded and embodied on arrival, allowing fast transit times and zero perceived travel times.

    The “hard part” is decelerating that first payload to allow the building of the needed facilities at the target systems.

    In our own solar system, we can afford to send the heavy payloads needed to start the process, thereafter sending just the tiny payloads with data and intelligences. This would truly create a solar system that is open to rapid travel and thereby creating a cosmopolitan civilization, rather than just isolated human groups in O’Neill’s only able to communicate, but rarely physically traveling.

  • John Mccarthy April 13, 2016, 13:02

    If nano sized communications/navigation systems can be manufactured to fit inside of “black box” type nano casement systems for G force protection, the most sensitive elements can be protected and remain functional. The speed of nano repair systems could overcome some ‘impact’ incidences. Self replicating computer controlled devices are already in the works for backup necessities. The folks at Palo Alto are excited about this, no doubt.

  • Joe G April 13, 2016, 13:15

    If my math is correct, a probe traveling at 20% speed of light would cross the orbit of Jupiter in about 7 hours… the problem is how do you acquire a planet, and steer for it… I assume that, as the robot approached the system it could see the planets move across the background star field, a motion provided parallax… and be able to pick them out… far enough out, the probe could maneuver for a very, very close flyby (I’m thinking of really small optics akin to those found in a cell phone)… I’d advocate a flyby rather than a kamakazi approach… I’d hate for our first contact with an alien species to be the disintegration of the capital city of Hovering Squid World 97A, just for a cool robot selfie.

    • Harry R Ray April 14, 2016, 9:26

      You CAN’T steer these things. That’s why you would need THOUSANDS to be launched to even get a FEW DOZEN into the Alpha Centauri system. The REMAINDER would serve as com links. As for my proposed JERI mission, you would need a few DOZEN to get just ONE hit. BUT: That would give you the ODDS needed for the MAIN mission.

  • Joe G April 13, 2016, 14:07

    On the approach the probe would see planets as moving dots on a black bkgd… AI might be as simple as: look for moving dots… If 1 dot, steer for it… 2 or more dots, pick the bluish one, if no bluish one, pick the red one, if no red one, pick the biggest one… I’m this far away, parallax indicates to fire thrusters in this direction for X seconds…
    Small optics would require a close flyby… I think this is well within our current technology… Steering thrusters might be a problem with a craft the size of a cell phone… Might wing warping work with the membrane? Change the shape of the sail? Seems like making one side smaller might turn the craft but would it actually steer it into a new direction by say, 1/2 degree?

  • Geir Lanesskog April 13, 2016, 17:59

    I don’t want to poke holes in this, since I think it a really cool concept, even if I’d rather see it used closer to home (in other words – results before I’m dead), but the power requirements I saw quoted were 100 gigawatts.

    Not 100 GJ but 100 GW, I assume for the duration of each burst for each probe.

    If that’s truly what’s needed, and that math I can’t do right now, but, without the power tech breakthrough that Milner doesn’t expect, you would need the equivalent of 50 Hoover Dams or all 100 of America’s nuclear plants or a solar array the size of Rhode Island, along with the transmission infrastructure to make that work. And that’s assume a 100% efficient laser array. Or you’d need to store a smaller power input in capacitors or batteries the size of a small city. (Hmm, are we sure Musk isn’t backing this?)

    And then there’s the heat from that % of inefficiency. Nobody cares if it radiates out in space, but on Earth, that’s going to annoy the neighbors.