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Breakthrough Starshot: Focus on the Sail

Who knows why and when we’re going to remember things? In the bus on the way to Moffett Field for the second morning of the Breakthrough Starshot meetings, I found myself thinking about Poul Anderson’s The Enemy Stars (1959). I had a paperback edition with a beautiful Richard Powers cover when I was a boy. What haunted me on that drive was the memory of what was written on the back:


They built a ship called the Southern Cross and launched her to Alpha Crucis. Centuries passed, civilizations rose and fell, the very races of mankind changed, and still the ship fell on her headlong journey toward the distant star. After ten generations the Southern Cross was the farthest thing from Earth of any human work – but she was still not halfway to her goal.

Breakthrough Starshot doesn’t plan to take that long to reach one of the Alpha Centauri stars (Alpha Crucis, by the way, is not one of them, but a multiple star system that is a part of the beautiful asterism known as the Southern Cross). The immensity of a journey between the stars still astounds me, after all these years of writing about it. At Moffett Field’s Building 18, we would be talking about ways to cross such gulfs. And while the long result is always at the back of your mind, it was time here in the Bay area to start talking about what can be done soon.

I have discovered that bilocation — being in two places simultaneously — is impossible. In the meetings at Moffett Field, I wanted to listen and take notes in each of the subcommittees, but stayed with just one, the sail group, because it seemed the best way to get a sense of the process as it worked itself out over the three days. Tough choice, because my respect for laser group leader Bob Fugate (New Mexico Tech) is immense, and I wanted to see how he and his team would deal with the early conceptualization of an unthinkably vast laser beamer. I also wanted more of the overview that Kevin Parkin’s systems engineering group was constructing.

Fortunately, our sessions frequently coincided as the subcommittees reported back to the full group, and it was possible to keep up to speed. The days were long, the debate fast-paced and productive, taxing my powers as a note-taker. But something Greg Benford said in the early going kept resonating with me throughout the meetings. “Nature bats last,” Greg commented after explaining his thoughts on beaming energy to a sail. In other words, we can produce idea after idea, but ultimately they’re going to be tested in simulations and in the laboratory, and we’re going to wind up with what works, not necessarily with our preconceptions.


Image: Did I mention that it was crowded when the full group met? This is from the first day of meetings, with several of the people from Breakthrough Listen also on hand to report on their own sessions.

Working on the Sail

We know what the long-term plan is: To develop and build a system that can deliver a payload to the Alpha Centauri system, said system to be perfected within a 20 to 30 year time frame, followed by 20 years of interstellar flight and a data return period of another 5 years. The plan is to send not one but many of these probes. In fact, if we are able to build a suitable beamer, we’re creating a reusable deep space infrastructure. Now, sitting in the board room at Moffett Field with afternoon sunlight slanting across the table, the sail committee was talking about the ‘short’ run, a 5-year period of technology development designed to lead to a prototype.

Technology development involves deep study of the concept, followed by simulations leading to laboratory work, and we were helped in the early sail discussions by the fact that Jim and Greg Benford, along with the University of New Mexico’s Chaouki Abdallah, had already performed laboratory work on microwave beamed sails using lightweight, highly temperature resistant carbon fiber. Out of this work’s simulations and experiments, the 4-meter sails envisioned for Breakthrough Starshot can grow conceptually and with new rounds of experimentation.

We have a sail that must achieve 20 percent of lightspeed and survive an intense period of acceleration lasting merely minutes. This is a craft that must be able to operate more than 20 years, given travel time and data return, and the sail that carries the payload must demonstrate stability on the beam, meaning that the slightest imperfection in design could cause it to simply be flung off-course. Moreover, the sail must be readily deployable, and it must be able to withstand the rigors of launch from Earth. The choice of materials for the sail flows directly from these requirements. Did I mention that we need to use the sail to return data to Earth? And that dust particles in the interstellar medium are a serious issue, though thought manageable?


Image: Work going on even during the breaks. This is mostly the sail committee, with Jim Benford at left, Breakthrough Starshot executive director Pete Worden, Greg Benford, Rafael Fierro, and Greg Matloff. I believe that’s Roald Sagdeev just behind Rafael.

We know that a beamed sail can be stable under a beam if it is spinning — the Benford/Abdallah lab studies have already demonstrated this (bringing the sail up to its initial spin, which involves sail deployment issues, is a key requirement). New rounds of simulation will be looking at matters like the best sail shape. A spinning conical shape is preferred, with the payload distributed in the lower part of the sail, which must be built so that a net sideways force tends to restore the sail onto the beam rather than pushing it off. The spin imparted to the sail comes from initial deployment, as previously demonstrated in tests at JPL. The sail becomes stabilized against pitch and yaw, but the center of force must always be above the center of mass.

This last, by the way, is why a rocket is not stable. The center of force is actually below the center of mass in this case, a situation we don’t want to see on the sail, which is why the payload cannot be placed on top of the sail. And given the power levels the team plans to put onto the sail, we have to identify issues that have so far escaped us. “In terms of beam-riding and stability,” Jim Benford noted, “we are going to learn new problems we have not thought of yet. That’s why we have to get to experiments sooner rather than later.”

The sail committee debated these matters much of the afternoon on the first and second day, a team involving Lou Friedman (Planetary Society), Mason Peck (Cornell), Starshot director of engineering Pete Klupar (who would move between sail and laser meetings), Kelvin Long (i4IS), Zac Manchester (Harvard), Raphael Fierro (UNM), Greg Matloff (CUNY), Chaouki Abdallah (UNM) and both Benfords. Jim Benford, who chaired the sail meetings, pointed to the need for experiments both vertical and horizontal, the vertical to test stability and spin, the horizontal to test acceleration.

To get moving quickly, the sail committee decided to identify and contact industrial, academic or governmental research groups that can be of help, with a workshop on sail materials as soon as the end of September. Work on simulations can likewise begin quickly, with sails tested in a vacuum under a variety of accelerations. If the laser for this early testing cannot be provided in that timeframe, microwaves can be a stand-in, with a variety of advantages of their own. Meanwhile, the analysis, simulation and fabrication will involve multiple contracts, with down-selection at the end for the best solution to the complicated sail requirements.

As I mentioned the other day, a Request for Proposal (RFP) is already being drafted — we worked on this the last day of the meeting, at the hotel. Results on that should begin to emerge in the spring of 2017, even as Breakthrough Starshot begins trade studies that will help in the evaluation of these proposals. The RFP will help to select the people who can do the first round of studies. Stability testing on the sail can begin relatively soon, Jim Benford said, while developing the requirements for acceleration will depend on chosen contractors.


Image: Late in the morning of the last day, the sail committee, consulting at the hotel with laser subcommittee leader Bob Fugate. From left, Greg Benford, Mason Peck, Zac Manchester. I think that’s Wes Green (Tau Technologies) just behind Zac, then Jim Benford, and Bob Fugate. Not visible at the end of the table: Greg Matloff and Rafael Fierro.

Deep Space Reminiscences

With Anderson’s The Enemy Stars still bouncing around in my head, I joined the Starshot team for an evening at a local restaurant. I was fortuitously placed directly across from Olivier Guyon (University of Arizona) and Slava Turyshev (JPL), which led to conversations about all of us and how we got involved at an early age in space. I always ask the scientists I talk to about this, and it invariably generates discussions about long-remembered favorite books and movies. Few of us have just one key driver, and I can recall films like Destination Moon as well as the Anderson novel among numerous other books and short stories.

Guyon recalled the Fantômas books, a long series by various French authors involving wild plots and inventive gadgetry — with an anti-hero main character to boot. Turyshev had read some of these in the Soviet Union and had even built his own versions of some of the unusual technologies, like a flying car with retractable wheels. Novels were my own introduction, especially the Heinlein juveniles, and Jim Benford jumped in with his own reminiscences of such titles as Have Spacesuit Will Travel (for me, it was Starman Jones). Amidst all this, Ed Turner (Princeton) and I squeezed in a talk about his travels in Japan.

Conversation flows easily after days of data crunching and analysis (wine doesn’t hurt, either). But the size of the project was something that stayed with me throughout these meetings, and it was only reinforced by the memory of Heinlein and science fiction’s Golden Age. Walking back to the hotel on a fine Palo Alto evening with Claire Max and Kevin Parkin, I found myself pondering the audacity of a star mission. “They built a ship called the Southern Cross and launched her to Alpha Centauri…” Name aside, it’s the plan, though the ‘ship’ is nothing like Anderson’s. It’s small, sail-driven, and can be sent out in swarms. It will need to travel 4.2 light years, fully 260,000 AU (if Proxima is the target, another 10,000 AU or so if it’s Centauri A or B). And what put me in an irresistibly light mood was the thought that the physics does not preclude it. The engineering, though, is another matter, and a key focus of all these deliberations.


Comments on this entry are closed.

  • Roger Wehbe September 2, 2016, 14:08

    The sheer size of the distance is mind boggling

  • Neil S September 2, 2016, 15:04

    Was there talk of the disposition of the sail during the later parts of the trip? Once the laser (or ?) is off, the sun might give a little additional boost at first but it would soon be negligible. Then the sail out in front just becomes a bigger target for dust or larger particles, and gas would tend to fold it back around the payload (assuming the shrouds aren’t rigid). Might it be possible to wind the sail in and use it, bundled somewhat, as leading-edge protection? And how stable is the orientation of the payload? How stable does it need to be? And if the sail is to be used for communication later does it need to be in front at the end of the trip?

    • Paul Gilster September 2, 2016, 16:29

      All these are good questions, but most have not been discussed at this point so much as identified as major issues. There has been talking about adjusting sail orientation to minimize dust impacts, though there is more concern, from what I’m hearing, with damage to the payload than the sail itself. Right now, though, the focus is on the next five year period, and some of these issues are being slated for later discussion. Communications is a huge issue that will get plenty of focus soon.

      • hiro September 2, 2016, 17:13

        Mr. Gilster, it’s best to use “non-solid/soft electronic circuit” covered by several thin layers of Tungsten-Titanium alloy as the shell for the “artificial brain” of the StarChip, the experts in the field could give an educated guess about the advances of non-standard electronic circuits in late 2020s. I think testing the concept in the region > 550 AU from Sol around 2030 should gain enough data to analyze any unexpected problem, the real experiment is launched in the same decade.

    • Jim Early September 2, 2016, 22:59

      At the velocities under consideration the gas and dust will pass through the thin sails with virtually no damage. Only the payload needs protection, and that appears possible.
      The sail will probably be essential for communication and for use as optics during the target fly-by.

    • Michael September 2, 2016, 23:55

      The sail if edge on would give an equivalent 1m of material protection to the centre, that’s a lot. If the sail was edge on and curled up like a cigar the ‘starchips’ would be in the centre, now depending on the amount of rolling up the protection would be better than leaving it open to the cosmic ray issue, maybe 20 microns. The problem then would be how to control the opening and closing of the sail.

      It might be better to have a few dummy reflective sails launched ahead first, they will be fairly cheap, in front of the other stream of sails to absorb the impacts. The first few sails will only be used take the hits and then move to the side on approach of the star system. Some other sails will be used as communication reflectors to and from the sensitive observer craft following behind.

  • john walker September 2, 2016, 15:21

    Thanks so much for your hard work as Starshot correspondent , Paul.
    I hope this project produces hard data soon. I’m really itching to see experimental numbers. Until that’s available, a few theoretical papers would tide me over fine. ;)
    In order for the timeline to work though, I think this will have to be a 20 year long nonstop sprint. Hope everyone’s eating their wheaties.

  • Sanford Zane Meschkow September 2, 2016, 15:34

    I admire the guts of the team members to tackle this project. At the speed these instrument packages will be moving I think one could arrange a test of the entire system, beamer, packages, and all, by doing a flyby of Pluto or a more distant body in the outer solar system almost over a short working vacation. Fantastic!

  • Charlie September 2, 2016, 17:28

    “The sail becomes stabilized against pitch and yaw, but the center of force must always be above the center of mass.”
    Why ? Don’t follow this at all, if I understood mechanics at all, if the force doesn’t pass through center of mass you impart a rotation as well as a translation. I know you’re not a physicist, anybody you can ask?

    • Paul Gilster September 2, 2016, 18:02

      I’m sure some of the physicists here will weigh in to answer your question better than I can. So I’ll ask them.

    • Robert L September 4, 2016, 8:12

      I am not a physicist! But I think this from NASA clarifies the point https://spaceflightsystems.grc.nasa.gov/education/rocket/rktstab.html

    • Michael September 5, 2016, 0:28

      With the electronics concentrated at the centre it will have more mass there that will cause the outer part of sail to bend in a way that makes the centre of mass below the plane of force from the beam.

  • Charlie September 2, 2016, 17:35

    $100 million pledged by a Russian, any ideas as if this is a sufficient amount to begin any type of concrete hardware type of development? What about cost of the remaining experiments and theory work, who pays for that? Any further word as to who will be the principal investigators and will it be an international effort? How serious are they to actually go ahead with this project and proceed to an actual flight? And finally are they going to have a dry run in which a dummy probe, for example is accelerated to some other body other than a target star in which the flight can be evaluated. While the object is still in the solar system?

    • Paul Gilster September 2, 2016, 17:58

      $100 million launches the effort to come up with the concept, produce simulations and laboratory work and push the idea forward, but it’s certainly not enough to fly the mission. I believe the website calls $1 billion the amount needed for a prototype. Breakthrough is estimating $10 billion for the actual mission, a number that seems unrealistic to me — I think with the kind of technologies that need building here, the cost will be much higher. We will see if further funding can be found through philanthropists, but I don’t know anything about that effort. Yes, I’m told the project is international, if by that you mean scientists working on it from various countries and contracts to be let out around the globe. We’re still in early days for that, though. And I have heard nothing about what kind of early test mission might be done at this point. Yes, I do believe they’re serious. The questions really involve the kind of engineering all this will require, which has huge unanswered questions, and many of them.

      • Michael September 3, 2016, 7:05

        ‘Breakthrough is estimating $10 billion for the actual mission, a number that seems unrealistic to me — I think with the kind of technologies that need building here, the cost will be much higher.’

        I don’t think it will be that much greater than $10 billion as we have all of the technology now, it just needs integrating into a system. By sinking money in programs that have knock on effects like MHD’s and FEL tech money spun off from that can be paid back into the program. Even a small scale system can start producing money like suborbital payload and personal effects launches.

  • Michael September 2, 2016, 17:37

    ‘Fortunately, our sessions frequently coincided as the subcommittees reported back to the full group, and it was possible to keep up to speed. The days were long, the debate fast-paced and productive, taxing my powers as a note-taker. ‘

    I thoroughly believe Paul with your abilities of getting to the greatest space stories of our time that if aliens where to land on the White house lawn you will be the first person near the spacecraft’s landing gear feverishly taking notes!

    • Paul Gilster September 2, 2016, 17:59

      Michael, very kind of you! Many thanks. I hope you’re right ;-)

  • Sanford Zane Meschkow September 2, 2016, 18:40

    Charlie is thinking along the same line I am: the use of some mission within the solar system to stress test the whole setup. One test mission might be to shoot a flock of Starshot probes out of the system along the plane of the ecliptic where we have a pretty idea of the density of dust and gas and use the results of any degradation of the probes to extrapolate the effects of the dust and gas between here and Proxima and then upgrade the design accordingly if needed. My background in astronomy isn’t strong enough to know if Proxima flares randomly or periodically. It sure would be a shame for a sudden flare to fry all the probes just as they were passing through the Proxima system. Perhaps it might pay to fire a flock of probes past our sun during a flare at the proper time and distance to test their resistance of the strength and duration of the flares that Proxima might generate.

    • Ashley Baldwin September 3, 2016, 7:24

      For the derail Kipping et al published on arxiv on Proxima’s flares. The day of its planet’s discovery. They used the MOST telescope to measure . I don’t know about pattern but it has smaller flares multiple times each day and severe flares very frequently , many per week. All pretty nasty .

  • Joe September 2, 2016, 18:51

    Great article Paul! Please do a similar article on the camera and ideas for transmitting data. Developing a camera that can take a clear picture while moving 60,000 km per second is going to be quite a challenge. So is transmitting the pictures 4.3 ly back to Earth.

    • Ashley Baldwin September 3, 2016, 5:34

      That’s a good point. The LORRI instrument on New Horizons which has been upgraded for inclusion on Europa Multi Flyby as the Europa Imaging system , is specifically designed for fast flyby imaging of dim targets . We’ve all seen its majestic images of Pluto, but the many pictures it took of Jupiter’s moons and especially Io enroute are equally captivating especially when you consider the speeds and great distances involved .( millions of Kms as the moons were all poorly postponed at the time of New Horizon’s Jipuer encounter ) . The flyby speeds ? About 13kms/sec. LORRI had an aperture of 8cms . There’s a lot of work to be done but the first key steps have at least been made. A difficult problem though as it is challenged by the physics . The ” seeing power” or angular resolution of any imager telescope is given as Resolution ( in m) = (1.22 x wavelength ) aperture ( in m) . The 1.22 is the lowest number possible in this equation assuming that the telescope is functioning at its most efficient or “diffraction limit” which is generally the case for space based telescopes as they have no turbulent atmosphere to content with . The only potential problem is imperfections in the construction / mirror design. Segmented mirrors, due to the nature of their design , need more assistance to reach the diffraction limit than monolithic , from the use of additional corrective mirrors . The fraction / percentage of diffraction limited imaging a a telescope reaches is expressed asthe Strehl ratio ( telescope resolution / diffraction limited resolution ) . Before adaptive optics on large ground based scopes this might have been as low as 10 % on ground based scopes thanks to mirror imperfections and atmospheric turbulence . Since the introduction of adaptive optics the best scopes with the Large Binocular telescope leading the way , regularly get Shrehl ratios above 80% with the LBT reaching an unbelievable 90% under the best viewing conditions . The ratio can drop as low as 60 % though and this helps illustrate the big advantages of space telescopes like Hubble despite its smaller size .

  • Patrick September 2, 2016, 22:44

    Might the whole swarm be used as an interferometer? That’s a much bigger camera. Or have I made a dumb mistake?

    By the way, what a wonderful site this is. Been one of my go-to’s for a while.

    Now I have to track down a copy of The Enemy Stars.

    • Paul Gilster September 3, 2016, 7:08

      Interesting you mention that. I just looked over a new paper from Avi Loeb on interferometric uses — it’s “Interferometric Measurement of Acceleration at Relativistic Speeds,” and can be found as a preprint:


      Perhaps it could be applied to Starshot.

      • Patrick September 3, 2016, 15:27

        Well then, I guess my work here is done. :)

  • Robert G September 3, 2016, 11:27

    Has anyone considered instead of thinking along the lines of functionally distinct dumb sail and smart ‘payload’ chip, simply printing the payload circuitry directly onto the sail itself? Organic compound printable circuitry has been under study for at least twenty years. Might this have some advantages?

  • Paul Gilster September 3, 2016, 11:58

    It’s an interesting thought, Robert, and reminds me of some of Robert Forward’s ideas (Starwisp, for example).

  • Al Jackson September 3, 2016, 12:57

    I remember reading Poul Anderson’s The Enemy Stars as “We Have Fed Our Sea” in Astounding 1959. It was a ‘young’ Poul Anderson who used his background in physics and a keen ear for poetic prose to create some of the best science fiction ever. What I liked about this story was the idea of sending a robot ship with a matter transceiver aboard. I can’t recall an earlier version of this idea. Was there? I am sure it was used after Anderson’s story, for interstellar travel… that is ( I know matter transmitters were). I like it because it conformed to Special Relativity. The photon riders would experience zero lapse of time between receivers and transmitters. The ship was STL. Very cool!

    • Patrick September 3, 2016, 15:23

      Just started it. Good book!

      Have had a similar idea in my head for a few decades–sort of a combination of von Neumann probe and the matter transmitter. May have read it in Drexler’s Engines of Creation? The kg-sized payload somehow decelerates in the target system and lands on any convenient source of raw materials, energy and low gravity, i.e. a small asteroid in a close orbit. The payload is a nanofactory and yes I know that’s hand-waving at the moment, but we *are* discussing interstellar flight! It has enough onboard programming to gradually bootstrap itself into a larger, more capable facility and builds, among other things perhaps, a large antenna using solar power and regolithic metals and organics. Now, with a nanofactory and a radio (or laser?) receiver in the target system, we can transmit “build instructions” for the facility to make much more complicated machines such as telescopes, in-system probes and landers, theoretically even humans or human-equivalent agents. The foundations of a whole new civilization, in essence.

      Hope that’s not too crazy for this site!

      • Gregory Benford September 4, 2016, 21:53

        Maybe not crazy enough! But fun, yes.

        • Patrick September 5, 2016, 14:25

          You, sir, just made my year, because you’ve been one of my favorite science fiction writers since I was a teenager. Thanks!

          My next question is, could the swarm, or part of it, use a gravitational slingshot and/or low-altitude sail deploy over Proxima to redirect to one or both of the other stars? The Centauri Grand Tour.

          • Michael September 6, 2016, 10:32

            They will be going too fast at 0.2 c to be slung by any significance towards A-B centauri. I doubt using the magnetic field would help either as it would more than likely melt the probe.

      • john walker September 5, 2016, 9:07

        Been thinking along the same lines for years. Only my iteration has higher storage capability meaning no further communication is necessary. ;) I heard Philip Lubin from UC Santa Barbara in an interview recently and got the impression he has had thoughts along the same lines. I wonder how many other academics dream of this type method of interstellar colonization.

      • john walker September 5, 2016, 9:33

        Although it raises clear ethical questions, if a promising ecosystem were discovered, it could be thoroughly analyzed via locally synthesized machines with the goal of determining if and in what form the “creators” should be subsequently produced with the goal of colonizing.

      • john walker September 5, 2016, 9:38

        If the system were robust enough for the long haul, terraforming a lifeless world would of course be morally less problematic.

      • john walker September 5, 2016, 11:00

        Rambling on…
        The synthesis capabilities needed are so advanced, it’s likely that by that time so much will have changed here in the social context that interstellar colonization may no longer be regarded as desirable. Who can say?

        Hard to predict how advanced technology will morph our social fabric.
        However, I expect that within 100 years there will have been or will be concerted attempts at social engineering with perhaps the explicit aims of rooting out the more destructive aspects of our inherited behavioral baggage. Dangerous no doubt, but a future society may regard it as expedient. Our evolution will be accelerated, directed. Initially, of course in order to optimize longevity and minimize physical disease risk. Later, to minimize psychological disease. Beyond that, the choice could be made to attempt to permanently reduce the danger of violent deviants. Not in the form of a therapeutic response to singular acts of crime, but profilactically through universal genome engineering. Inconceivable in the near term. And questionable even in the middle term. But, given decades more advancements, generational taboos may fall coinciding hopefully with greater perspectival sophistication. No sudden reckless gambit based more on hope than science. Desirably a mature acknowledgement of our need to encode civility(for lack of a better word) into ourselves instead of forever relying on the ultra thin film that we give the same name today. Sounds awfully, old-futurist? Maybe. Given the sorry state of the world, with unending rampant and violent tribalism(my preferred catchword for ethnocentricity, nationalism and religious bigotry) we and the other species of this planet have long suffered under the unbridled continuation of our He-man heritage far beyond it’s usefulness.
        In the far future the process of genetic manipulation may eventually fracture our homo sapien homogeneity into various subtypes and potentialy into radically different species.
        You’re right, Dr Benford this is fun!

        • Patrick September 5, 2016, 14:34

          Agree, we are now effectively in a race between “traditional” human technological aspirations and advancement, and the unfathomable AI version. All bets are off. Unfortunately it’s difficult to discuss posthuman/AI thinking on a merely human forum!

          • john walker September 5, 2016, 19:10

            AI is the buzzword in today’s media. And it is a highly worrisome prospect. The scenario I sketched above is strictly biological. Predicting potential developmental pathways which incorporate synthetic intelligence are I dare say even more complex. Certainly more error prone. The reason being that our biological “nature” offers us halfways familiar behavioral laws from which a limited number of extrapolations can be made. This despite the plethora of philosophical discussion points that run parallel.
            Throw in “advanced” ai and the equation becomes at least for me very difficult to bend my mind around. I don’t read SF nor do I peruse discussions on Techno/Transhumanism. I just read the political news and follow a little scientific research. So, my thoughts on the future suffer from a lack of enrichment from others doing the same. That said, it seems to me that ai may at it’s core be as you said “unfathomable”. At some point in the not all too distant future, ai algorithms will of course optimize themselves. Logic processes will eventually become opaque for us due to their sheer complexity. AI will be inscrutible. And no human experts will be 100% certain of the ai’s intentions nor perhaps even capable of understanding it. Physically isolating such “beings” and limiting data input will only work in the short term. Eventually the temptation to unshackle the creative power will become irresistable. Whether ultimately our only salvation lies in the “singularity” is hard to say. It depends whether our impulse to exploit every advantage at our disposal despite deficient understanding remains intact. As always, crises and catastrophes will help mold our tactics, but the thought that the reach of ai can be effectively regulated something like WMD proliferation is an error.

        • Joe September 7, 2016, 23:31

          “a concerted attempts at social engineering with perhaps the explicit aims of rooting out the more destructive aspects of our inherited behavioral baggage.” This reminds me of an old Larry Niven story where this is exactly what future humans did. And then the Kzin showed up…

  • Andrew Palfreyman September 4, 2016, 8:58

    Is it too soon to start putting together that laser beamer? Where can progress be followed on this? It’s an incremental build, so it can start out small.

  • David W Cummings September 4, 2016, 10:46

    I’m sure that one of the variables factored into the planning of this mission is the changes (and likely majfor, game-changing breakthroughs) in materials technology that will take place in the next 5-20 years, changes that we can only now speculate about now. I predict that the final sail will be very different from what we could build today.

    The possible characteristics of a Super Sail:
    1. Maximum absorption (or responsiveness) to the accelerating laser beams.
    2. Ability to morph characteristics after 20% light speed is reached (no longer needs to be optimally responsive to laser beam acceleration).
    3. Maximum communication effectiveness with minimum vulnerability to dust impacts. Maybe morphing into a net once it is beyond the reach of the accelerating laser beams.
    4. Morphing characteristics controlled by some kind of self-repairing nano technology.

    Maybe things like this, maybe things we can’t foresee at all. Whatever the sail will look like in 2026, or 2036… it will be far different than what it would look like if we built it today… because of ongoing development and likely major breakthroughs in material technology.

    • Project Studio September 4, 2016, 18:29

      re: ability to morph
      There has been some discussion of this capability on the breakthrough challenges pages; for example, describing experiments on Mir with temperature responsive materials that self-transform.

      I think this is an engineering challenge best started on early. The gram-level payload and communications requirement means that components need to have multiple applications. Unless the same shape can suite both beamed sail and laser-communications reflector the sail will need to morph its shape. Wondering if there are plans to test driving a parabolic sail shape? (watch out for the reflected beam, though)

      • Michael September 5, 2016, 10:18

        A parabolic reflective sail pointed towards us will defocus the beam back to us.

  • Steven Torry Rappolee September 4, 2016, 22:03

    The laser transmitter and these nano spacecraft if passing through our system would we even know of it? Thoughts of “knowing the world” come to mind

  • PW September 5, 2016, 20:28

    very hard to get excited about a data return of over 50 years.
    A time span like that really means that the technology/propulsion needs to be brought forward.
    Go back to the drawing board and find the physics and the propulsion to do something better than this.

    • Moebius September 7, 2016, 4:43

      Easy to say. Have you found the physics to do better than this? If yes, please share them to the world.
      Currently some of the best physicists from around the globe are working on it. Be assured that if they believed they could find a better way in a reasonable amount of time, they would not support Breakthrough Starshot and they would propose and support another concept instead.
      0.2c was not even imaginable before the recent progress of miniaturisation and is still not imaginable now without relying on possible technological breakthroughs in the next decades which will overcome the challenges listed on the project’s website. Thinkers are already thinking ahead of existing technologies, current physics are not likely to be broken or to change dramatically anytime soon and we’d better get used to work with laws of physics that do not particularly tend to make interstellar flight quick and easy. After all, we don’t see alien ships coming to visit us every week-end so it is probably not that simple.

  • Jim Strom September 6, 2016, 3:02

    Interesting to read about the detailed engineering problems that must be solved to turn theory into action.

  • ljk September 7, 2016, 9:34

    Allen Hall, Aerospace management and Information Technology Systems, sees Breakthrough Starshot as a pipe dream:


    There is a method of reaching the nearest star systems in something far less than the Voyager time to Alpha Centauri of 77,000 years. It uses technologies we have now; in fact, we were probably able to have this spaceship ready to go back in the 1960s:


    I am certainly not against Breakthrough Starshot, for it has already accomplished some wonderful inspiration. However, Allen’s critiques are worth noting. I am concerned that Starshot’s cost alone will be the prohibiting factor, one that no billionaire or even a group of billionaires may want to foot the bill on. Telling them that their payoff will be the thanks of future generations probably will not cut it.

    On the other hand, what I can still see happening is some really rich person (or China, maybe Russia) turning a planetoid (or maybe a comet?) into an interstellar ark, a multigenerational Worldship that they can reside over as king with a group of acolytes on a long journey to found a new world in another star system.

    They won’t have to pay Earth taxes among other motives for doing this. Think of the planetoid and comet belts as the space version of the Cayman Islands.

    Is this the start of such a plan:


    There is a real world precedent for what I state above. Biosphere II was originally built by a billionaire who created a cult-like following and designed the enclosed habitat as a way to plan and train for eventually founding his own colony on the planet Mars. See here:




    Rich folks (the One Percent), corporations, and the military industrial complex – that is how we got into space in the first place and what will keep us there unless something goes really wrong. Science has been used as the front to make the venture look good while it is simultaneously either ignored or used as a footstool. Remember, the USA and USSR’s first rockets evolved from the German V-2, which was designed to blast cities in World War 2, not explore space despite von Braun’s presumed wishes.

  • ljk September 8, 2016, 9:29

    Rummaging through the old NASA files for ideas….


    Who remembers the Thousand Astronomical Units (TAU) probe concept:


  • ljk September 9, 2016, 8:46

    September 08, 2016

    NASA NIAC E-sail Phase 2 Heliopause Electrostatic Rapid Transit System

    NASA Innovative Advanced Concepts (NIAC) had their 2016 symposium on August 23-25, 2016. Bruce Wiegmann, NASA Marshall Space Flight Center, Heliopause Electrostatic Rapid Transit System “HERTS”. E-sail phase 2 project:


    • Alex Tolley September 9, 2016, 14:34

      Very interesting presentation. The 2 cube sat test platform for launch out of the ecliptic plane was interesting. As always, some audience questions can illuminate issues, in this case the issue of the solar magnetic field influencing the density of the solar wind.

  • Michael C. Fidler September 9, 2016, 10:32

    I wonder if this would work!

    “A team of Chinese physicists has developed a new variety of light-based propulsion system with the ability to harness much greater forces than a conventional solar sail. The key, according to the Nankai University-based group, is in swapping out the mirrored sail—which captures photonic energy as radiation pressure in much the same way a regular air-sail captures wind energy—for a pure-black graphene sponge. Rather than reflect off of the sail, light is absorbed by the sponge, which converts that energy into propulsion. ”
    “Tremendous mechanical strength—despite being unimaginably thin, the material is bulletproof and many times stronger than steel—and extraordinary electrical and thermal conductivity.”


    • Alex Tolley September 9, 2016, 12:17

      So the issues I have with this effect as a propulsion system is that it works by ejecting electrons. So the graphene “sail” will become positively charged. It will either run out of electrons to emit, or start pulling them in from the surrounding medium, with unforeseen impact on the propulsion. OTOH, it may then become more like an electric sail and deflect solar protons enhancing propulsion away from the sun.

      Also, recall that this is not dissimilar to the Benford’s experiments of microwave beams on carbon sails that ablate off material allowing for fast acceleration while ablation can continue.

  • ljk September 14, 2016, 12:07

    I just hope that everyone working on Breakthrough Starshot is abnormal or something like that, because according to NASA Administrator Charlie Bolden, “normal people” cannot build rockets – only NASA can:


    The quote:

    “If you talk about launch vehicles, we believe our responsibility to the nation is to take care of things that normal people cannot do, or don’t want to do, like large launch vehicles,” Bolden said. “I’m not a big fan of commercial investment in large launch vehicles just yet.”

    And this:

    Despite the demonstrable efforts by both SpaceX and Blue Origin, Bolden nonetheless said that “normal people” cannot, or do not want to, develop large launch vehicles. What the administrator appears to be asserting here is that NASA is more special, or better, than those in the private sector when it comes to building rockets. This exceptionalism is curious, considering that NASA hasn’t actually built a rocket since the 1970s and the space shuttle and that the SLS is highly derivative of shuttle components, including its engines and side-mounted solid rocket boosters.

    • ljk October 11, 2016, 9:49

      We will see how long this lasts, and of course he is doing this with just months left in office – let the next President foot the bill, right?


      SpaceX still plans on beating NASA to Mars by at least one decade. Or are they now all going to work together? Is this a good thing or just a way to bog down the whole process for more decades?

      Pardon the pessimism, but when you grow up at the start of the Space Age with all its possibilities and promises, only to watch them get shot down and begged off for decades, it is easy to become cynical. Then again, maybe this is a new era for humanity. Although just a few years back, in 2012 to be exact, Newt Gingrich was openly mocked by all sides for proposing a manned lunar base by 2020, something that would have been announced with pride back in the 1950s and 1960s.

      We shall see. Does being an exclusive on CNN therefore make it legit? :^)

      • ljk October 11, 2016, 9:54

        Clearly the Apollo “Moon Shot” is trendy again – perhaps because this generation is finally realizing some “old” ideas were good ones abandoned for all the wrong reasons:


        Reminds me of when Medieval and Renaissance Europe started rediscovering the ancient Greeks and Romans and that begat a revitalization of European civilization and culture. Let us hope this renewed interest in exploring and settling the Sol system is in the same vein.

  • ljk September 15, 2016, 10:19


    Breakthrough Initiatives official to speak about the search for extraterrestrial life at ASU on September 20, 2016.

    September 14, 2016

    A key player in the search for intelligent extraterrestrial life will speak at Arizona State University. Simon “Pete” Worden, who is the chairman for the Breakthrough Prize Foundation and leads the spectacular Breakthrough Initiatives, will give the 2016 Eugene Shoemaker Memorial Lecture, 7 p.m., Sept. 20, in the Marston Exploration Theater on ASU’s Tempe campus.

    Worden, formerly the director of NASA’s Ames Research Center, is a recognized expert on space and science issues. He will describe some audacious plans to seek out life beyond Earth in a lecture titled “Shooting for the Stars: The Interstellar Breakthrough Initiatives.”

    “Whether or not we are alone in the universe is one of the oldest and biggest of the big questions of existence,” said Paul Davies, director of the Beyond Center for Fundamental Concepts in Science, which hosts the annual Shoemaker Lecture. “Given the ambitious goals of the Breakthrough Initiatives, we may soon know the answer.”

    Announced a year ago, the Breakthrough Initiatives is a program generously funded by the philanthropist Yuri Milner to search for intelligent life outside of Earth. It consists of Breakthrough Listen, a 10-year project to actively search for extraterrestrial communications; Breakthrough Message, to study the ethical implications of sending messages into deep space; and Breakthrough Starshot a proposal to use powerful lasers to propel a fleet of tiny probes to Alpha Centauri, a nearby star system.

    A target for Breakthrough Starshot could be a planet called Proxima Centuari b, an Earth-sized exoplanet that resides in the habitable zone of its host star in the Alpha Centauri system. The idea is to develop technology that will allow microchip-sized payloads to be accelerated to 20 percent the speed of light, enabling them to reach Alpha Centauri in about two decades.

    “Starshot is an audacious attempt to leapfrog existing space exploration by harnessing several new technologies,” said Davies. “The prospect of human probes reaching the stars within our lifetime is breathtaking.”

    Each year, the Beyond Center presents a special award to a leading scientist to honor the life and work of Eugene Shoemaker, who together with his wife Carolyn Shoemaker, pioneered research in the field of asteroid and comet impacts.

    The Shoemaker Lecture is free and open to the public, but reservations are suggested. For more information, go to http://beyond.asu.edu/, or call 480-965-3240.

  • ljk September 17, 2016, 15:44

    Interview: How to get a chip-sized spacecraft to Alpha Centauri and back

    16 September 2016

    By Tereza Pultarova

    In April this year, the Breakthrough Initiative funded by Russian billionaire Yuri Milner announced an ambitious plan to launch a chip-sized spacecraft to a neighbouring star system to image habitable planets. Pete Worden, the Breakthrough Starshot project’s director and former head of Nasa Ames Research Center explained the plan to E&T at the Space4Inspiration conference in London this week.

    Full interview here:


    To quote:

    E&T: Why do you want to go to Alpha Centauri?

    Pete Worden: We obviously had to figure out whether there is a place where to send these tiny spacecraft, whether there are any potentially life-baring planets around the nearest stars. So we launched another project, called Breakthrough Watch, which is looking into that.

    As serendipity would have it, scientists have actually detected what might be an Earth-sized planet in a habitable zone recently in the solar system of Proxima Centauri. Proxima Centauri is a star in the Alpha Centauri system and actually the nearest star, so we now have some place to go and we will be doing more work on that. It will obviously take a lot of time to get any data. If I am lucky, I will be still alive when the spacecraft is launched and then it would take another 30 years, to get the images back.

  • ljk September 29, 2016, 11:28

    An Animated Guide to Humanity’s First Interstellar Mission

    September 27, 2016

    Video by The Atlantic


    In a 1610 correspondence to Galileo Galilei, Johannes Kepler noted, “Ships and sails proper for the heavenly air should be fashioned. Then, there will also be people, who do not shrink from the dreary vastness of space.” Now, more than four centuries later, the Russian venture capitalist Yuri Milner is applying these principles to modern day space exploration.

    Human travel to our nearest star system, Alpha Centauri, will not be possible for many years, if ever. However, in the near future, robots might be able to make the trip in an inexpensive and scalable way. Using a solar sail, a nearly weightless spaceship and a powerful beam of light, probes could travel the 4 light years to Alpha Centauri in only 20 years. The most expensive piece of equipment, the beam of light, will stay on the planet, and each spaceship will cost only as much as a smartphone. With this scalable model, our earthly civilization might someday become truly galactic.

    Authors: Caitlin Cadieux, Erica Moriarty, Ross Andersen

    They did something similar to explain space travel to the general public in the 1950 science fiction film Destination Moon:


  • ljk October 11, 2016, 9:58

    Although it is by no means a star vessel, the technology of Lightsail 2 could be helpful towards developing real interstellar travel:


  • ljk October 11, 2016, 10:51

    Spreading our seeds across the galaxy:


    Is this maybe how Earth life happened? Are there other intelligences out there with the same idea? How far along are they with their own Genesis project?

  • ljk October 29, 2016, 12:53

    What’s the Most Stable Shape for an Interstellar Lightsail?

    Published: 28 Oct , 2016

    by Matt Williams

    In 2015, Russian billionaire Yuri Milner founded Breakthrough Initiatives with the intention of bolstering the search for extra-terrestrial life. Since that time, the non-profit organization – which is backed by Stephen Hawking and Mark Zuckerberg – has announced a number of advanced projects. The most ambitious of these is arguably Project Starshot, an interstellar mission that would make the journey to the nearest star in just 20 years.

    This concept involves an ultra-light nanocraft that would rely on a laser-driven sail to achieve speeds of up to 20% the speed of light. Naturally, for such a mission to be successful, a number of engineering challenges have to be tackled first. And according to a recent study by a team of international researchers, two of the most important issues are the shape of the sail itself, and the type of laser involved.

    The researchers include Elena Popova of the Skobeltsyn Institute of Nuclear Physics in Moscow; Messoud Efendiev of the Institute of Computational Biology (ICB) at the German Research Center for Environmental Health (GmbH); and Ildar Gabitov of the Skoltech Center for Photonics and Quantum Materials in Moscow. Combining their expertise, they conducted a study that examined various stability models for this proposed mission.

    Full article here:


    To quote:

    When Milner and the science team behind Starshot first announced their intention to create an interstellar spacecraft (in April 2016), they were met with a great deal of enthusiasm and skepticism. Understandably, many believed that such a mission was too ambitious, due to the challenges involved. But with every challenge that has been addressed, both by the Starshot team and outside researchers, the mission architecture has evolved.

    At this rate, barring any serious complications, we may be seeing an interstellar mission taking place within a decade or so. And, barring any hiccups in the mission, we could be exploring Alpha Centauri or Proxima b up close within our lifetime!

    • Alex Tolley October 29, 2016, 16:41

      So the spherical sail was slightly better than a conical sail. BUT the sail analyses needed the chip to be tethered behind the sail. This is a problem as it could get fried by the laser. Therefore I don’t know what value this analysis has based on the approach of using extremely high powered lasers to boost teh sail with very high acceleration. The sail material has to be an almost perfect reflector at the laser wavelength (that Lubin claimed existed and appears to be correct). But how is this to work for the chip and the tethers? The chip might be given a sail material reflector, but I don’t see how this can be done for the tethers.

  • ljk November 15, 2016, 11:46

    Anthropological reflections on space colonization

    Discussions of space settlement often focus on the technical issues to sustain a human presence beyond Earth. Babak Shakouri Hassanabadi notes that anthropological issues can’t be ignored if human settlements are to thrive.

    Monday, November 14, 2016


  • Alex A January 11, 2017, 11:00

    Have ‘pure’ solar sails been considered and ruled out?
    A ‘sun-diver’ solar sail could achieve 4.4% c via sunlight alone* (i.e. 100 year trip time). Big problems are (a) achieving low enough areal density (b) the sail surviving the high intensity sunlight (and resultant high temperatures).
    *Based on graphene sail diving to 0.01 AU distance from Sol at closest approach.

    • Alex Tolley January 11, 2017, 13:44

      Do you have a reference for that figure, because it is a lot higher than figures I’ve seen?

  • ljk March 9, 2017, 22:55

    Could Fast Radio Bursts Be Powering Alien Probes?

    Release No.: 2017-09

    For Release: Thursday, March 9, 2017 – 11:00 am

    Cambridge, MA –

    The search for extraterrestrial intelligence has looked for many different signs of alien life, from radio broadcasts to laser flashes, without success. However, newly published research suggests that mysterious phenomena called fast radio bursts could be evidence of advanced alien technology. Specifically, these bursts might be leakage from planet-sized transmitters powering interstellar probes in distant galaxies.

    “Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. “An artificial origin is worth contemplating and checking.”

    As the name implies, fast radio bursts are millisecond-long flashes of radio emission. First discovered in 2007, fewer than two dozen have been detected by gigantic radio telescopes like the Parkes Observatory in Australia or the Arecibo Observatory in Puerto Rico. They are inferred to originate from distant galaxies, billions of light-years away.

    Loeb and his co-author Manasvi Lingam (Harvard University) examined the feasibility of creating a radio transmitter strong enough for it to be detectable across such immense distances. They found that, if the transmitter were solar powered, the sunlight falling on an area of a planet twice the size of the Earth would be enough to generate the needed energy. Such a vast construction project is well beyond our technology, but within the realm of possibility according to the laws of physics.

    Lingam and Loeb also considered whether such a transmitter would be viable from an engineering perspective, or whether the tremendous energies involved would melt any underlying structure. Again, they found that a water-cooled device twice the size of Earth could withstand the heat.

    They then asked, why build such an instrument in the first place? They argue that the most plausible use of such power is driving interstellar light sails. The amount of power involved would be sufficient to push a payload of a million tons, or about 20 times the largest cruise ships on Earth.

    “That’s big enough to carry living passengers across interstellar or even intergalactic distances,” added Lingam.

    Full article here:


    To quote:

    To power a light sail, the transmitter would need to focus a beam on it continuously. Observers on Earth would see a brief flash because the sail and its host planet, star and galaxy are all moving relative to us. As a result, the beam sweeps across the sky and only points in our direction for a moment. Repeated appearances of the beam, which were observed but cannot be explained by cataclysmic astrophysical events, might provide important clues about its artificial origin.

    Loeb admits that this work is speculative. When asked whether he really believes that any fast radio bursts are due to aliens, he replied, “Science isn’t a matter of belief, it’s a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge.”

    The paper reporting this work has been accepted for publication in the Astrophysical Journal Letters and is available online here:


  • ljk March 10, 2017, 18:32