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Breakthrough Discuss: Initial Thoughts

The Breakthrough Initiatives conference I’ve just returned from, called Breakthrough Discuss 2016, had been a bit of a puzzle going in. Still bleary after an early morning arrival in Palo Alto, I was looking forward to getting to the Stanford campus for the first sessions the next day. Breakfasting at a small cafe near the hotel, I mulled over the possibilities. The emphasis was on astronomy, given the list of attendees, which included top names in the exoplanet hunt, but of course Breakthrough Initiatives is also funding a major SETI effort, so that would be a theme. And then there was the looming presence of the just announced Breakthrough Starshot.

Balancing all this out looked to be a challenge, but as it turned out, there was a strong cross-pollination among the various themes, with the Starshot — an unmanned flyby of Alpha Centauri and an infrastructure to sustain a further interstellar effort — woven into the proceedings. I knew I’d come back with material for a week’s worth of Centauri Dreams posts, but the level of presentations was so high and the insights so numerous that I’m thinking we’ll be talking about this meeting for some time to come. The challenge for me will be to weave ongoing news items into the background narrative the conference provides.


Image: Conference goers gather at Stanford’s Arrillaga Alumni Center just before the sessions begin.

The overall themes we would be dealing with were announced early. Jill Tarter was in charge of the SETI component, which focused on optical SETI and the detectability of directed energy systems, although in dealing with these issues you naturally get into broad questions of SETI strategy. Olivier Guyon, a coronagraph specialist who leads the Subaru Coronagraphic Extreme Adaptive Optics effort, led the sessions on exoplanet detection, which focused tightly on Alpha Centauri. Harvard’s Avi Loeb chaired the session on the Sun as a gravitational lens and gave a rousing conference keynote, one I’ll want to talk about in some detail later.

The gravitational lens was of particular interest to me. I ran into Claudio Maccone while checking into the hotel and we talked about the emphasis on a gravitational lens mission that was built into the program. Having championed the mission he’s been calling FOCAL for many years now, Claudio was clearly pleased at the attention the concept is now receiving. We’ve been talking about a FOCAL mission for years on this site with the assumption that it would involve a decades-long journey to the Sun’s gravitational focus, which begins at about 527 AU and for various reasons is best used a bit further out (more on this later). But now we’re talking about Breakthrough Starshot, a mission that could get to the focus in a matter of days.


Let’s back up a moment. The Breakthrough Starshot Concept uses the beamed power of a massive phased laser array to drive small sails to one-fifth of the speed of light in mere minutes. That gets you to Alpha Centauri in about twenty years, a mission time that compares suitably with other lengthy missions already in our portfolio, most especially Voyager. If we built the infrastructure to make this happen and solved the innumerable details that make it so difficult, we could get payloads to the gravity focus not only to conduct surveillance on our first target star, Alpha Centauri, but also to operate as a communications bridge between the Earth and Centauri A and B. Because as we’ll see, even a tiny transmitter can be detected at interstellar distances when you’re taking advantage of the massive magnifications at the gravity focus.

Image: Pete Worden, executive director of Breakthrough Initiatives, discussing the goals of the conference as it begins.

Thus FOCAL suddenly becomes a mission enabling technology in its own right, with not only a huge scientific payout but an engineering application for sails we might send out within a generation. But can we send them? At the Yuri’s Night festivities held at Yuri Milner’s estate, core Breakthrough Starshot participants discussed the mission and did a Q&A session with the audience, led by Milner himself. I’ll have more on all this as this series of reports continues, but for now, realize that a key part of the presentation was a list of 19 challenges the concept must overcome. How to build the beamer itself. How to power it up. How to ensure sails are not blown off its beam. How to get data back to the Earth. How to cope with interstellar dust.

As became evident in the discussion both at the Yuri’s Night party and during the conference at Stanford, no one is taking these problems lightly. The $100 million that Milner has put forward toward Breakthrough Starshot is to be used to dig into these key questions, to stress the concept to the breaking point, identify its weaknesses and learn how to resolve them. Will there be a genuine show-stopper somewhere in this investigation? At this point we can’t know, but we’ll have the research funding now to identify them if they are there. And as we are talking in generational terms, we’ll also identify the trends that may make the improbable possible.


Image: Discussing Breakthrough Starshot with the audience during the Yuri’s Night celebration.

I have many thoughts on all this, but tomorrow we’ll start digging into the conference proceedings to see how Alpha Centauri shapes up as a target. As the nearest stars, Centauri A and B are irresistible targets, two stars each capable of hosting habitable planets, not to mention planetary possibilities around Proxima. But how much do we know about the system, and what are our next steps as we try to find out whether interesting planets are actually there? These issues and FOCAL’s contribution to an interstellar mission will take up much of the week. And that leaves us with optical SETI to examine by week’s end and the implications of beamed energy. If we use beamed power to propel spacecraft, can we detect others who do so?


Comments on this entry are closed.

  • Giulio Prisco April 18, 2016, 10:30

    Re “[Breakthrough Starshot] could get to the focus in a matter of days… we could get payloads to the gravity focus not only to conduct surveillance on our first target star, Alpha Centauri, but also to operate as a communications bridge between the Earth and Centauri A and B.”

    That’s an awesome idea, and a gravity lens -based communications link to Alpha Centauri could be the best way to receive Starshot data, but it seems that we should get to the focus by other means, since the Starshot mission concept doesn’t include deceleration. Or am I missing something?

    • Matt April 19, 2016, 1:07

      I think there would be a lot of value to a FOCAL type mission that uses gravity lensing. However this project does not seem like the right way to do that. To use gravitational lensing the telescope would have to stay at the proper distance from the sun. In other words it would have to be a larger space craft with a way to slow down once it got where it was going, and rockets and fuel for station keeping.

      So I don’t think the 1 gram chips traveling at .2c are going to do that. However it might be worth funding and building a separate project to put a telescope permanently at the gravitational focal point.

      • Giulio Prisco April 19, 2016, 10:59

        Yes, that was my point, a gravitational lens observatory pointed to Alpha Centauri could be a useful and perhaps a key part of Starshot, but it could not be launched with the same technology used it Starshot.

    • Eniac April 22, 2016, 9:15

      No you do not have to decelerate. The focus is not a point, it extends away from the sun as a line. You do have to have some maneuverability, though, to stay exactly at opposition with your target at all times.

      A radio communication device can potentially be very small. An optical communication device, on the other hand, would need to be a telescope with an aperture of around 10cm, so you can separate the focused radiation from the much more intense light coming from the sun itself. The focused light will appear to come from a ring around the sun, known as the Einstein Ring, which will be rather small at that distance and will require the 10cm aperture to resolve.

      An imaging mission would be similar to a communication device, but either moving around to acquire light from different directions at different times, or multiple devices to do the same at the same time. Or, a little bit of both.

      A gravitational focus mission would be a great application for intermediate versions of light beam sailing technology, where getting there in a few years would be ok and the demands on the sail and laser much less.

      • Matt April 22, 2016, 14:54

        You really want to slow down. Yes, the focal point is as a line, or a tube, but it is not infinite. The area that focuses on what we want to see is limited. Remember that the spacechips are moving at .2C.

        I don’t think the fast moving 1g space ship is the right thing to be the telescope at the focal point.

        • Eniac April 22, 2016, 18:17

          It is a line, not a tube, and it does extend to infinity. The amplification factor may go down with distance, but only gradually. Also, I was talking about space chips that don’t go 0.2 c. Space chips that might be launched well before we have that extreme capability. If it takes a few years to get there, we can observe/communicate for many decades without slowing down. It is a perfect way to test out sail beaming concepts in a much easier regime. To test communications, we’d need to send two chips in opposite directions.

          • Giulio Prisco April 23, 2016, 0:38

            Great points!

            “It is not necessary to stop the spacecraft at 550 AU. It can go on to almost any distance beyond and focus as well or better. In fact, the farther it goes beyond 550AU the less distorted the collected radio waves by solar corona fluctuations…” (Maccone, Mathematical SETI, 12.3)

            It would be interesting to see calculations and system simulations for a Starshot spacecraft (chip + sail used as antenna to receive data and transmit data back to Earth), moving at a range of relativistic speeds.

  • Alex Tolley April 18, 2016, 11:02

    It would be ironic if this apparently attractive approach to probe propulsion is not used by alien civs precisely because it is a potential giveaway to galactic predators.

    Sounds like it was a great conference. I look forward to reading the reports on CD.

  • Andrew Higgins April 18, 2016, 11:41

    Much of the coverage of Starshot keeps asking, “Why Alpha Centauri?”, “Is Alpha Centauri the best target?” These questions seem to miss the point: Starshot would enable launching probes on a daily basis, and as long as they are within view of the ground-based laser, there is no fundamental reason why *all* nearby stars could not be targeted. After the Transiting Exoplanet Survey Satellite mission, we should have dozens of interesting targets within 20 ly.

  • djlactin April 18, 2016, 12:59

    “…but the level of presentations was so high and the insights so numerous …” Is there any chance that they will become available on the net?

    • Eniac April 22, 2016, 9:18

      Luckily we have our man on the ground to report…. :-)

  • Charlie April 18, 2016, 13:48

    So the very obvious question to you; why is this particular symposium (if you wish it to call it that) a CLOSED to the general public ??
    I mean is, there is an attempt to engage the public in meaningful discourse regarding all this and they hope to get support, it would seem that they would want to have a broad spectrum of an attendees. I can understand that if there is limited broom and all that to have people that is one thing, but it’s hard to believe that that is the reason that they would not want to have people who would be able to engage in the process.
    I’ve always found these restrictive processes to be somewhat annoying to the general public and a sort of a slap in the face, so to speak. The general public is good enough when tax dollars are wanted for these far-flung missions, but heaven forbid that the general public should show up when only the elites are there.

    • Michael April 19, 2016, 14:46

      That’s the risk when capital is at stake, although money is slowly coming forwards I am worried that they will become closed entities for the elite with money and not those with the most skills. I will be very dispointed if they start asking for money to access information about space for profit, I doubt, if say an asteroid is mined near the earth they will give any info on its composition for instance other than basic info about it.

  • James April 18, 2016, 15:27

    Are there any discussion of doing FTL research?

    • Eniac April 22, 2016, 9:26

      Yuri is a physicist, so he’s probably convinced it is best to stay within the speed limit.

  • Michael April 18, 2016, 15:40

    Just had a thought, if we used a ring of transmitters or a central laser transmitter with laser reflecters on the light cone to the SGFP’s, say at earth’s orbit the beam would be bent to parallel without having to go to the SGFP. This should allow a reduced power requirement of transmission to the other star system. The same could be used in the other star system to allow return signals.

  • Andrew Palfreyman April 18, 2016, 16:54

    As Claudio pointed out to me in email in response to my suggestion that we try and synthesise a gravscope apeture closer to home than the grav focus:
    He said that we can synthesise a gravscope at earth orbit, but it suffers the drawback that it can only look at stars on the ecliptic.

    I am still bound to ask:
    Can we do it off-ecliptic using active navigation? Perhaps leveraging off eLISA tech for accurate positioning?

  • Andrew Palfreyman April 18, 2016, 17:07

    The idea of a swarm of spacechips is not only good for overall system reliability via massive redundancy, but has a couple of other advantages:

    1. It increases our total time at the target system. Each spacechip will arrive with a slightly differing entry vector to the target system, and will thus not only increase our total data capture time, but also enable us to see the destination system from differing viewpoints. So a little bit of deliberate spread is a good thing.

    2. Reducing required spacechip transmit power and increasing spacechip datarates are both desirable characteristics and are enabled by the use of a data relay between the target and Earth. Here’s a quick example calculation:
    The ISS is about 500 (metric of course) tons so we can launch 50 tons consisting of 5 gm starchips, over time no problem. That’s 10 million starchips total. If we space them equally from here to Alpha Centauri, that’s an inter-chip distance of about 4 million Km. The relay comms idea should be doable for this toy example.
    Let’s do a sanity check ion that spacing based on the Starshot published parameters (60 Kgee, 100 GW). v = a t so t = v/a = 0.2*3*10^8/6*10^5 = 100 seconds. Coasting for 100 seconds at 0.2c covers a distance of 6 million Km
    It hangs together quite nicely.

  • Ashley Baldwin April 18, 2016, 18:45

    Alpha Centauri imaging Satellite . “ACE-sat” . Indisputably the leader of the gang.

    A silicon carbide , off axis 45 cm telescope with a built in high performance PIAA coronagraph with precision wavefront control provided by a combination of small MEMS ( microelectromechical ) actuator driven deformable mirrors and a sophisticated Multi Star Wavefront Control ,MSWFC ,algorithm which blocks stray light from one star as the other’s system is imaged for planets (Alpha Centauri A and B approach each other as close as just 11 AU , just further than Saturn’s orbit round the Sun) . All from a Kepler inspired Earth trailing orbit allowing two years uninterrupted stable imaging of just Alpha Centauri.

    Twenty thousand pictures of A and B simultaneously that allow precision mapping of any planets’ orbits and subsequent subtraction of any imaging defects or “speckles” which don’t follow the classic Keplerian path displayed by the planets . Possible because the telescope is ONLY devoted to Alpha Centauri during its primary mission , which is Small Explorer funded at just $120 million in order to justify its important but narrow scientific focus . (Cf JWST where a maximum of observation time is granted to exoplanet science )

    The coronagraph delivers a respectable 1e8 contrast that is then boosted by the thousand times necessary by extensive image manipulation on mission completion . “Post processing ” . The better this is the less the pressure on the coronagraph to deliver and with increasingly demanding stability required ( with “thermomechanical” stability easily the biggest obstacle to progress in exoplanet imaging telescopes ) as coronagraph performance increases, the easier ( and cheaper ) the telescope construction . The resultant 1e11 contract is more than enough to image down to Mars sized planets and in conjunction with the imaging stability allows the observations to get in very close to the central star . A small “inner working angle ” or IWA ( along with contrast the two features that define high performance coronagraphs ) .More than enough to image the entire habitable zone of BOTH stars simultaneously and most of their stable orbit zone ( circa 2.5 AU radius ) .

    The mission itself hasn’t yet been improved as its pivotal technology has yet to reach a sufficiently high level ( roughly Nasa grade TRL6 minimum) of maturity . But all areas are progressing fast largely due to the WFIRST mission that will spend a year looking for shorter periods at many planets as part of its 2020s primary mission and may even if lucky discover an Esrth like planet if nearby . Thanks to its binary nature , Alpha Centauri is ironically not currently on the target star list though as ACE-sat’s MSWFC is software driven , it could conveniently be downloaded right up to and even after launch . Possibly the perfect follow up to ACE-sat. Timing will be vital too.

    No spectrograph but the telescope observes in five separate wavelength “bands” which allows rudimentary characterisation and especially the ability to see the ” Rayleigh scattering ” believed to be typical of Esrth like atmospheres which would be reinforced by the planet lying within a habitable zone. Adding a spectrograph would be possible with greater funding ( as would a larger aperture ) provided by either Medium Explorer Funding or should Small Ecplorer be increased as proposed by a recent Nasa review , to $170 million.

    The key is finding planets in the Alpha Centauri system and especially in the habitable zone as thus would immediately act as a catalyst for larger characterising telescopes. “Project Breakthrough” could in turn act as the catalyst for ACE-sat itself . The ACE-sat design itself can extrapolate to a very reasonable 1.5m which would be enough given Alpha Centauri’s proximity, especially if it was given months or years to collect light to analyse .

    Cubesat technology could offer an even easier solution. After years of development JPL/MIT are launching the 8cm aperture 6U prototype transit spectroscopy prototype telescope, ASTERIA , in June . Easily convertible with the introduction of a mini coronagraph and ultimately scalable up to 30 cm apertures for significantly less than $10 million if mass produced . A “swarm” of such telescopes working in tandem could characterise individual star systems over years from easily reached low Earth Orbit and be launched as a cheap add on to big payloads.

  • Ivan Vuletich April 19, 2016, 2:39

    As for the interstellar dust issue. I wonder if the humongous laser launcher could be used to clear out a probes flight path within the inner solar system at least.

    • Michael April 19, 2016, 8:09

      If the space craft is fast enough there should be no problem, if not the region ahead will start to fill up again pretty quick due to the velocities of the particles. Also laser light needs to be tuned to the atoms and particles ahead it is attempting to move away or the energy will not be absorped.

  • Sascha Wageringel April 19, 2016, 6:42

    This is significant. The benefits of the concived FOCAL mission are considerable. The use of this approach for interstellar communication is a gamechanger. Most of my thinking went into the direction of in situ swarm array assembly for communication purposes. This approach is much, much better. Not only do we get the capability for reciving transmissions from distant star systems and the capability for driveless propulsion, we also get the most powerful telescope ever concived as a bonus. Solving three mayor problems in one stroke is too good to ignore it. The Heliopause Electrostatic Rapid Transit System seems interesting, too, it may be the case that we may not even need beamers.

  • Leonard Hunter April 19, 2016, 9:49

    “Because as we’ll see, even a tiny transmitter can be detected at interstellar distances when you’re taking advantage of the massive magnifications at the gravity focus.”

    If this is true, which I have no doubt, maybe this is one reason why we haven’t detect ET as yet, they are all listening to us already.

  • Brian McConnell April 19, 2016, 16:29

    Some thoughts on power beaming. I think this could really provide an economic basis for the project.

    As you know, SEP is being used more and more for interplanetary probes (DAWN for example). Limited power is a big constraint, due to long mission timelines required for gradual acceleration.

    What would be really interesting is if you could use power beaming to achieve gains similar to concentrated photovoltaics (> 100x amplification is routinely done). A 10KW array becomes a 1MW array when the beam is on. If that’s powering a cluster of hall effect motors running at 3,000s Isp, that works out to about 60N of force, enough to build up a lot of speed pretty quickly.

    What you would do then is send craft on a faster than Hohmann trajectory directly to their destination. Once out of the beam, the craft would slowly brake to intercept its target throughout the coast phase. Result: you only have to get the craft to LEO, and then can switch to electric propulsion from there.

    These spacecraft would also be on an evolutionary path toward the nanocraft needed for pure photonic propulsion. Similarly the power beaming infrastructure would start out in the 1-10 megawatt range, and could be scaled up from there. So the whole thing ends up looking like a chain of incremental improvements versus an all or nothing moonshot.

    The only fundamental limit I see here is heat rejection, but there should be plenty of strategies for mitigating that, such as:

    * tuning the lasers to match the peak conversion wavelength (more electricity, less waste heat)
    * using mirrors, metamaterials, etc to radiate heat away from the vehicle
    * if the array is small enough, feed cold propellent through its backplane for preheating
    * using active feedback (just monitor the spectrum of the target) to tune power output to automatically prevent overheating

    Ideally what you’d want to do is mass produce these power sails so they can be coupled to many different payloads. What I am picturing is an integrated solar array, radiator, and propulsion unit that functions as a tug.

  • Andrew Palfreyman April 19, 2016, 16:43

    The Heliopause Electrostatic Rapid Transit System, although ingenious, is in a totally different class. Instead of taking 16 days to reach the grav focus, it will take a decade or two. And there’s still the braking problem.

    Let’s take another look at that braking problem. The kinetic energy of a 5 gm spacechip coasting at 0.2 c is about 10^13 J. This is a mass-energy equivalent of 0.1 gm, a fraction of the all-up mass of the spacechip.

    I bet you know what I’m going to say next.

    A controlled set of backwards-directed matter-antimatter energy releases forward of the spacechip is capable of completely braking it from 0.2 c to rest. Perhaps, then, our attention should swivel to Penning traps that are light and last a couple of weeks?

  • Andrew Palfreyman April 20, 2016, 4:33

    On reflection, I should withdraw my remarks about antimatter braking. For after all, if we were to have that much control over that much antimatter in the first place, we’d already have an antimatter drive!

    Thus the braking problem to the grav focus from a coast velocity of 0.2 c appears to be as yet unsolved. A viable solution would be of great value.