Credit Card Sized Spacecraft Poised to Sail to Alpha Centauri

As a space-faring species, we’ve done a fair job of exploring and exploiting our local neighborhood. We’re pretty good at putting people and machines into orbit, but our galactic-scale signature is pretty tiny. Our radio signals are no more than 100 light-years away, and our farthest physical artifact isn’t even a light-day away from us 40 years after it launched.

Clearly we need to do a better job of getting out there, and that’s the goal of Breakthrough Initiatives’ Starshot program, which aims to launch a nano-spacecraft to Alpha Centauri and get it there fast. The program aims to build solar-powered credit card-sized spacecraft with sensors, cameras, communications, and even MEMS thrusters for attitude control. Motive power will come from solar sails catching laser light shined onto it from Earth, eventually accelerating the craft to 20% of the speed of light and reaching its destination within a generation.

The thought that we could start spreading ourselves out into the galaxy within the lifespan of most of the people on Earth is intoxicating. Sure, a wafer of silicon is a far cry from a sleek starship with powerful warp engines and all the finest appointments, or a gritty star freighter that can make the Kessel Run in less than 12 parsecs. But the laws of physics and the limits of engineering conspire to keep us mostly stuck at the bottom of a deep gravity well, and if this means sending fleets of nanobots across the galaxy in our stead, so be it.

And no matter what form our first galactic spacecraft take, you can bet that the Deep Space Network will be supporting the mission. For now, you can listen in on the program’s test satellites currently in orbit if you tune to 437.240 MHz.

74 thoughts on “Credit Card Sized Spacecraft Poised to Sail to Alpha Centauri

    1. No it won’t, because it’s only 4,37 ly to Alpha Centauri

      It will never catch up, because after 20 years the slower satellite has only 0.37 ly to destination, while the new satellite has to travel 10 times the distace just to catch up, and it can only do 5 times faster because we’re not allowed to break the laws of physics.

      By the time the old satellite is already at Alpha Centauri, the new satellite is less than half way in.

        1. No, they didn’t.

          Nobody ever said it was impossible to breach the sound barrier, because it was well known that many things – including airplanes – actually could do it. Their problem was that -propeller- aircraft couldn’t do it because propellers don’t work past the speed of sound.

          Likewise with the atom. The problem wasn’t theoretical but practical: atoms splitting were already observed so it was obviously possible.

          Meanwhile the speed of light is a question where theory agrees with observation: nothing goes faster than the speed of light, and there’s no practical proposition on how to get around it either. For the very understanding of how the universe works, something going faster than the speed of light is even metaphysically meaningless.

          As a proposition it’s similiar to saying “I want coffee that goes faster than blue.” You can send your engineers to work on that, but don’t hope much results any time soon.

          1. Yet it’s all about perspective…there are many projects in the works that desire to asymmetrically warp space/time. The occupants of such a craft would not perceive anything “special”, yet outside observers would see a craft(if they could see it at all, ie, your “metaphysical meaninglessness”) that is going many times the speed of light.The same theory you use to poo-poo Mike’s opinion, infers this is a possibility. The real question is if we can generate the power required to do so…just wait for the day we figure out how to “divide by zero”.

        2. The “light barrier” is a completely different animal from the sound barrier. The speed of light speed limit is enforced in a slick way by Mother Nature. As you gain speed, you gain momentum. Momentum is a form of energy, kinetic energy. And kinetic energy counts as energy/mass in terms of good ol’ E=mc^2 so, getting up to half of light speed is “easy”. It’s the SECOND half that’s hard! As you get closer to the speed limit kinetic energy builds up making it harder to push that ship. The good news is time slows down onboard in proportion to kinetic energy buildup. If you have a 10,000 ton ship doing ~90% the speed limit, it’ll have 10,000 tons of pure kinetic energy – and time slows to half.

          Please, don’t let a whacko grab the flight yoke! 10,000 tons of kinetic energy would pack quite the punch.

    2. That’s what they said in the 50’s already, well where are those spacecraft whizzing by those theoretical ones?

      Not that this isn’t daft, a credit card sized thing in interstellar space will neither be able to communicate back nor will it be able to sustain power, since away from the sun solar won’t work of course.

      1. The atom was proven splittable and thus didn’t live up to its name.
        Maybe… just maybe… one day we find a way to get things from A to B quicker than light can travel (even if bending time-space concept is more than pseudo-science).

        Are there scientists/engineers trying to break the “light-speed” barrier?
        CERN maybe?
        Or trying to find a loophole in physics and the speed limit of the universe?
        Or is this century just too busy making IoT toilets/toasters, taking selfies, arguing and watching soaps to bother educating each other on such matters?

        1. The speed of light is intrinsically linked with causality.

          Consider that time doesn’t exist as such. If you were God, the entire universe and all that exists may run its course just in the snap of your fingers, but for anyone within the universe it is an immeasurably long time because they still have to go through all the motions and that is what they measure as time: time is the relative order of events, and from that order of events arises the apparent speed of light. Without that speed limit you could experience effects before their causes.

          So “going faster than the speed of light” is patently nonsense.

          1. Do you have sources to back up that statement?
            I have heard it quoted that faster than light travel could cause paradoxes many times but, I have never seen it explained.

          2. Cause: Past,
            Effect: present/future

            “Consider that time doesn’t exist as such”:
            Thus basically, you may of said Jordan Maxwell was right that Ra is Jesus because modern language (specifically modern English) was known well in ancient Egyptian times you know sun god thus son god thus son of god???
            since without time, therefore the future and past is all the same and one…. Nothing. So how would things happen (motion) in a time-less alternate reality?


            Seriously, Time is the only reason we don’t see the effect before the cause….There is no going back in time… Just viewing the effects of time:

            Photo – effect of light caused chemical reaction etching darker/lighter patches in either broad band form (B/W) or narrow band form (colour),

            Burials, memories, etc… History: what happened before now… not due to light

            Watching space: Same as looking at history…. We’re just looking at the carcass remains of a bunch of emitted photons from various sources.


            Read [This] the first answer basically says somewhere within it, light travels back in time (something to do with electron recoil)…. and that back in time light has to wait anywhere between immediately to several years in order “to complete its circuit”.
            That sounds like nonsense written there, as that would mean what we see could in fact be happening in the next 1K years! Therefore meaning we’re already seeing the future by anything between now to several years simultaneously.


            And… who is this god-guy out of no-where “flicking his fingers”?
            Also, does his ability to think vs see vs click his finger indicate something faster than his finger flick (god’s light faster than god’s finger flick?)?

            Time is the reason cause before effect… Don’t try to invent a, “god out of nowhere”… bad enough wrapping our heads around a “Universe out of nowhere”

          3. The speed of light is intrinsically linked with causality.

            So “going faster than the speed of light” is patently nonsense.

            Not at all! There is this thing called “proper time“, which basically gives us a gift of travelling any place at any “proper” speed, even higher than c, even infinite, if we agree with two inconvenient facts: first, that destination look upon arrival may vary … drastically … from what is depicted on travel prospects and marketing material, and second, your friends and family back home will never see your vacation photos … because they will be departed by then, unless meanwhile they all were on round trips with exactly same proper time as you, too.

            So basically, we can’t live as we do now and “just” add interstellar travel, but theoretically there is a lot we could do within laws of physics as they are, if we change our ways to adapt to them.

            So essentially, if we assure causality breakage, we can travel faster than the speed of light. We already can communicate gibberish (no information content) instantaneously, using quantum entanglement. I am sure that as soon as this sinks in public common base of knowledge we will see as many “solutions” for “FTL communication” as today there are for “free energy sources”. They will all fail of course (in Physics, the house always wins, no exceptions nor strikes of luck), but like some of the attempts on overunity energy machines, some of them may uncover some interesting techniques useful for something less ambitious.

          4. Sheesh. Just mentioning the impossibility of FTL brings all the nutjobs out of the woodwork.

            >”We already can communicate gibberish (no information content) instantaneously”

            That’s an oxymoron. Entanglement doesn’t communicate. The proper interpretation is that the property being entangled is not -real- which means that whatever the measurement made, the information about what result you got, can be altered later to agree that the entanglement happened. It shows up as “spooky action at distance” only when you compare the results, as if history was re-written to agree that entanglement did happen.

          5. >”Not at all! There is this thing called “proper time“, which basically gives us a gift of travelling any place at any “proper” speed, even higher than c,”

            No it doesn’t.

            The proper time interval for an object travelling at speed equal to or faster than light would be an imaginary number. For lightlike objects, the concept of proper time breaks down.

        2. There are plenty of theoretically possible (Alcubierre) or plausible ways to bend space it’s the energy involved in such endeavors that’s holding us back.
          Without fusion, a Dyson swarm and laser or maser power link, or some heretofore unknown energy source, we just can’t accelerate fast enough for more than a one way trip or generation vessel.

        3. Faster than light travel is not a problem that needs solving, not at the moment at least. Within our current understanding of physics, there are massive improvements to be made to propulsion technology. Current engines are slow and cumbersome on even a solar system scale. On interstellar distances they are next to useless. Just getting anywhere near the speed of light, say 0.2c or 0.5c, will be a massive feat of engineering.

  1. This long-discussed kind of spacecraft is fast but have no way to brake in the targeted solar system. It will pass through it way too fast and will be of little interest. Solar sails should be much more usefull to move asteroids to improve mining operation in our solar system.

    1. If you aim it well, the sail can brake down with the radiation pressure from their sun and with any luck be captured in orbit around some planet. The thing about interstellar travel is that when you’re very far away from bodies of gravitation, even the tiniest, most insignificant impulse will alter your course by millions of miles at the end of it.

      1. If the acceleration power is given by our sun and a giant laser, it will be difficult to brake with only a star on the other side. All the laser power has no counter part.

        1. I might be wrong, but isn’t the acceleration produced by a solar sail actually produced by the number of photons hitting the solar sail, which decreases by radius squared with the distance to the point light source. (Our sun is basicly point source. Of course this isn’t true for the laser light source.) So if you aim (directly) for the other star, it’s just a mater of how close you get to the other star to get enough photons to counteract the initial acceleration.

          1. Precisely.

            If you hit dead-on, eventually you will get close enough to the star that the radiation pressure stops the craft – provided it doesn’t vaporize from the heat first or tear apart from the flying particles.

            In any case, if your craft is smart enough, it can also do gravity braking which is the opposite of the slignshot effect. After it just slightly misses the sun, it can shoot in any arbitrary direction depending on how close to the sun you can manage to survive.

    2. The solar sail will have a hole in the centre. Once max speed is attained, the sail will begin to slow as pressure mounts on the other side, the card will fly straight through. It should use its microthrusters to target a body in the target system, if it can do so. It should then deploy another sail to its rear, to slow it down from 0.2c. I don’t know how well using the thrusters will work when there is a solar sail behind, I presume it’ll be okay due to the minute pressure on the sail, but a ship of this size will have so little fuel…

      In insides of the sail need to include a lightweight solar power coating.

      They need to launch thousands of these, so that one or two actually don’t sail straight through the target system and get caught by something interesting.

    1. Go out the door on a clear night, point yout phone up at the sky and snap a photo.

      That’s about all you get, because a credit card sized probe doesn’t have the power budget to communicate more than about a single shitty VGA picture, and since you can’t steer it with 8½ years of communications delay, the picture you snap will be on a timer off in some random direction and probably won’t show anything but the background stars.

  2. Does it have a stealth mode? It wouldn’t give us much of an advantage if it would encounter aliens and give our existence away years before we get to know it. That would be tactic of the ‘fait accompli’. That tactic only works if you’re prepared for (all) the consequences of your action. If you’re not prepared for the consequences, then you’re just spreading chaos. In general, that’s the moment that people start to die.

    1. Also, if your credit card accidentally hits a planet at 20% of lightspeed, I think it could make a considerable hole into somebody else’s property. It weighs 4 grams, at .2 C (59958491.6 meter/second). According to the physics calculator, the energy on impact will be 7190041429894.5 joule. Quite considerable. About 1500 kilograms of TNT, if I’m not mistaken. I think those aliens would talk about that for quite some time. They might even think that somebody purposefully threw a bomb on their heads. :)

      1. It will burn up in their atmosphere like any old space rock. We get meteors carrying megatons of energy that streak down the sky into a trail of smoke, and since 70% of earth is oceans, and of the rest a great deal is uninhabited, we just don’t notice the bombardment – there’s nobody around to see it.

          1. Weight is not the only parameter in this equation. 10 grams without moving has 0 joules of kinetic energy. 4 grams at .2 C has 7.2 trillion joules of kinetic energy.

          2. @ReTepV

            Even if the meteorites have no velocity in the direction of Earth, Earth is cruising along it’s orbit at 30km/s. They’re cosmic bugs on a windshield.

          3. >”10 grams without moving has 0 joules of kinetic energy. 4 grams at .2 C has 7.2 trillion joules of kinetic energy.”

            Many weigh kilograms to tons. The Chelyabinsk meteor observed in 2013 had 1.8 Petajoules of kinetic energy which is 1,800 trillion Joules.

        1. That’s assuming that those aliens are on a planet with an atmosphere. Or at the least with an atmosphere of mainly nitrogen and oxygen. But they could be settlers on a planet without an atmosphere, an outpost of their civilisation. Like the one we will soon have on Mars, if everything goes according to plan(s).

    2. Imagine that by the time those satellites reach Alpha Centauri, we have already invented faster travel than .2 C, and we have met aliens, and are in diplomatic talks with them to determine our mutual boundaries, etc. By then we will have long forgotten about these satellites.

      …until one of them, by bad luck, smashes into one of the aliens’ planets, the aliens accuse us of bombing them, and we spiral down into the first war between humanity and aliens.

      Someone should write a book about it. :D

          1. I can take fantasy as fantasy, and mythology as mythology, but science fiction is usually just bad because it’s trying to shoehorn reality into supporting impossible premises and faulty logic, which results in stupid plotholes and bad writing. It’s like watching reality TV where you can actually see the producers whispering instructions to the actors, and even though you know it’s not really really real anyways, that’s just killing the mood.

            I mean, if you say “Look, there’s this zero point energy that is actually possible”, then I’ll point out that “if such zero point energy was possible, your universe would have blown up aeons ago because if it’s so easy to access it should be everywhere”… etc.

            If you say “It’s magic, I ain’t got to explain shit”, then I can suspend my critical judgement.

          2. Or to put it otherwise, do you know the difference between fiction and fantasy?

            Fiction is all about the plausible, so it aims to convince you by explaining its plausibility to tell a compelling story. It takes a subject matter like, “what if Hitler was still alive?” and spins a detective story around that. Fiction is a conspiracy theory that you know isn’t true, but it’s so good that you want to know how it works out.

            Science fiction at its best works because it doesn’t venture too far off from the possible, where the reader can still go “yea, I can see how that would work”. Good sci-fi has robots and spacecrafts and all that jazz, but it has the good sense to stop where it’s still winning, rather than force some insensible voodoo to make its conclusions.

            Fantasy on the other hand is all about the impossible, and seeks to substitute reality with that which cannot be, for its own sake. It’s talking trees and hobbits, or space planes that go pew pew in vacuum and blow up death stars, and it doesn’t need to make sense because it isn’t trying to convince you that it all actually works. It’s just turtles all the way down.

            The problem is that most sci-fi authors don’t have the intellectual integrity to keep to fiction. They start with a fantasy premise, some “singularity uplifted society” or faster than light travel, and then use this fantasy as their god of the gaps to bridge the story, like introducing an actual ghost into a Sherlock Holmes novel. From there it just goes downhill as we are forced to watch Sherlock apply knowledge and reason to the unreasonable and unknowable.

            So, bad sci-fi is actually fantasy masquerading as fiction, which fails on both accounts because fantasy shouldn’t need explaination – that would be just boring exposition that doesn’t serve the story – while fiction absolutely depends on it.

      1. Back up a bit. What makes you so sure the thing would reach the surface, rather than vaporizing on contact with the atmosphere?

        Assuming it didn’t vaporize, what would lead the aliens to conclude it was an artificial object, let alone an intentional bombing? The “craft” would be the kind of obliterated that’s hard to study.

        Even if they did realize it was artificial, given that both our species would at this point have proof that intelligent life exists in our galaxy beyond our respective worlds, would it not be just as reasonable to assume the object came from a third party?

  3. Here’s a thought. Don’t move the CC sized object but instead find a way to create a field around it that stops the effects of gravity and other forces acting upon it. Much like hydrophobic coatings do with liquid. it stays put and lets the universe come ti it. Sounds far fetched but then using a laser to power something that is traveling that distance from earth has about the same chance of success. as for communications we are nearing an age where the speed of light is no longer an obstacle and tests have already been done using “spukhafte Fernwirkung”, spooky theory.

    1. Sadly, or good so arrow of time works, causality is preserved within the light cone. Entanglement is unpredictable random noise and communicates as much data as unwrapping two pokemon cards in two star systems and finding Pikachu. No information transmitted even though you know that light years away the other packet, when opened, contains the same card you hold.
      Causality violation sounds so damn novel but it would eff with our reality worse than the financial system’s favors for the wealthy.

      1. There’s three things that apply: causality, locality and reality. If causality is broken, events no longer follow from causes and physics becomes meaningless because shit just happens. It would be very curious and incredibly lucky, to have a universe with apparent laws of physics at all. If locality is broken, events across the universe can have instant effect anywhere, which has a similiar effect to the causality breaking in that all things can happen simultaneously and again physics breaks down because there’s no order of events anymore. Your universe goes “poof” and vanishes into a logical singularity.

        The universe as we know it can only tolerate the breakdown of reality – which is saying that not all things we observe are things as such. Cross two sticks and you get a cross, or close your hand and you get a fist – it is a thing not by itself but by relative definition. If we were naive scientists, or like a robot looking at a hand scrunched up into a fist, we’d think the fist is like a rock – that anything you do to it will not change its fistness. The we’d be completely baffled when the person opens their hand again. Where did it go?

        Likewise, the engangled property is something we observe to be, not something that -is-, and that very fact enables the correlation to happen.

        The trick is that the guys with the pokemon cards in two different star systems may very well pull out completely non-correlated cards for as long as they don’t interact with each other. As soon as they come together to compare results, it’s like putting the two sticks together and seeing a cross. What is real to you only appears to exist because of what information you hold about it, and so if your information content may change, or something is added to it, then your whole history may change retroactively.

    2. Gravity can be compensated only by a free fall, and overturned only by additional acceleration. For either to be sustained, you need to produce more spacetime along the axis at which gravity acts (we don’t know how to do it, but it happens in nature), and do it at a sufficient rate. Oh, and if we succeed, then we would trade one problem for another: how to get rid of that additional spacetime that got in our way?

  4. Why don’t more proposals for acceleration use the slingshot effect? Is it because all our planets rotate in the prograde direction, making it harder to use to ones advantage, exacerbated by the long orbital periods of the planets?

    In the reference frame of the heavy sling mass the craft is hyperbolically scattered with same initial and final kinetic energy.
    In the reference frame of the solar system the craft is massively accelerated. In order for the slingshot effect to work, the sling mass and the craft should have appropriate velocities (in the reference frame you want to consider the object as accelerated i.e. the absolute velocity of the craft being larger after than before). This is much easier to achieve if some of the available slings move in an opposing direction. This is also faster to achieve repeatedly if the slings are closer together orbiting a planet since the moons have shorter periods (in theory you can reuse the same with 2, 3 or more sling masses, possibly combined with Oberth effect of the planet for occasional and final course correction, the Oberth effect around the sun is of limited use because of solar heating, but here it is a planet so one is not limited in this sense). I presume I am somehow overlooking the reason for not using retrograde and regular moons, but we do have massive slings in the solar system that move in opposing directions: there are planets which have both prograde and retrograde moons, like the moons of why don’t we use these as slings?

    For example Triton is the heaviest retrograde moon, and has a period of ~6 days.

    There is of course a periapsis speed limit due to how close we can come to the moon during the gravity assist (due to its radius or atmosphere.)

    Can anyone point me to celestial mechanics paper/note/course notes which analytically derive maximum final velocity limits due to nonzero radius/atmosphere of the sling/oberth mass?

      Realize that you don’t change speeds. Your incoming speed (hyperbolic excess velocity) is the same coming in as
      going out. — in relation to the body you are orbiting.
      The velocity vecotr is just bent around the object. Now if what you are really interested in is your velocity
      relative to something else (sun?), then you add and subtract the vectors in the sol reference frame.
      You will pay attention to the turn angle and the impact parameters.

      As for a book, Everyone eventually buys a ‘BMW’ – Bate, Mueller, and White,
      Fundamentals of Astrodynamics, nice and cheap, the classic.

      Software ? maybe GMAT from NASA ? (free)


  5. Special relativity does allow FTL, however a power source from singularity is required and matter would meet its doom . More realistically powerful plasma engines hybridization with nuclear fusion would drive a spaceship to fifty percent light speed.

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