Can We Really Get to Alpha Centauri?

In a previous episode, I said that traveling within the Solar System is hard enough, traveling to another star system in our lifetime is downright impossible. Many of you said it was the most depressing episode I’ve ever done .

The distance to Pluto is, on average, about 40 astronomical units. That’s 40 times the distance from the Sun to the Earth. And New Horizons, the fastest spacecraft traveling in the Solar System took about 10 years to make the journey.

The distance to Alpha Centauri is about 277,000 astronomical units away (or 4.4 light-years). That’s about 7,000 times further than Pluto. New Horizons could make the journey, if you were willing to wait about 70,000 years. That’s about twice as long as you’d be willing to wait for Half Life 3.

But my video clearly made an impact on a plucky team of rocket scientists, entrepreneurs and physicists, who have no room in their personal dictionary for the word “impossible”. Challenge accepted, they said to themselves.

In early April, 2016, just 8 months after I said it was probably never going to happen, the billionaire Yuri Milner and famed physicist Stephen Hawking announced a strategy to send a spacecraft to another star within our lifetime. In your face Fraser, they said… in your face.

Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity's first interstellar voyage. Credit:
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit:

The project will be called Breakthrough Starshot, and it’s led by Pete Worden, the former director of NASA’s AMES Research Center – the people working on a warp drive.

The team announced that they’re spending $100 million to investigate the technology it’ll take to send a spacecraft to Alpha Centauri, making the trip in just 20 years. And by doing so, they might just revolutionize the way spacecraft travel around our own Solar System.

So, what’s the plan? According to their announcement, the team is planning to create teeny tiny lightsail spacecraft, and accelerate them to 20% the speed of light using lasers. Yes, everything’s made better with lasers .

We’ve talked about solar sails in the past, but the gist is that photons of light can impart momentum when they bounce off something. It’s not very much, but if you add a tremendous amount of photons, the impact can be significant. And because those photons are going the speed of light, the maximum speed for the spacecraft, in theory, is just shy of the speed of light (thanks relativity).

You can get those photons from the Sun, but you can also get them from a directed laser beam, designed to fill the sails with photons, without actually melting the spacecraft.

In the past, engineers have talked about solar sails that might be thousands of kilometers across, made of gossamer sheets of reflective fabric. Got that massive, complicated sail in your mind?

Now think smaller. The Starshot spacecraft will measure just a few meters across, with a thickness of just a few atoms. The sail would then pull a microscopic payload of instruments. A tiny chip, capable of gathering data and transmitting information – these are called Starchips. Not even enough room for water bear crew quarters.

A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives.
A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives.

With such a low mass, a powerful laser should be able to accelerate them to 20% the speed of light, almost instantly, making a trip to Alpha Centauri only take about 20 years.

Since each Starshot might only cost a few dollars to make, the company could manufacture thousands and thousands, place them into orbit, and then start bugzapping them off to different stars.

There are, of course, some massive engineering hurdles to overcome.

The first is the density of the interstellar medium. Although it’s almost completely empty in between the stars, there are the occasional dust particles. Normally harmless, the Starshots would be smashing into them at 20% the speed of light, which would be catastrophic.

The second problem is that this is a one-way trip. Once it’s going 20% the speed of light, there’s no way to slow the spacecraft down again (unless the Alpha Centaurans have a braking system in place). Just imagine the motion blur and targeting problems when you’re trying to take photos at relativistic speeds.

The third problem, and this is a big one, is that the miniaturization of the spacecraft means that you can’t have a big transmitter. Communicating across the light years takes a LOT of power. Maybe they’ll connect up into some kind of array and share the power requirement, or use lasers to communicate back. Maybe they’ll relay the data back like a Voltron daisy chain.

Even though the idea of traveling to another star might seem overly ambitious today, this technology actually makes a lot of sense for exploration in our own Solar System. We could bugzap little spacecraft to Venus, Mars, the outer planets and their moons – even deep into the Kuiper Belt and the totally unexplored Oort cloud. We could have this whole Solar System on exploration lockdown in just a few decades.

Even if a mission to Alpha Centauri is currently science fiction, this miniaturization is going to be the way we learn more about the Solar System we live in. Let’s get going!

37 Replies to “Can We Really Get to Alpha Centauri?”

  1. You are missing one huge problem. The military-political problem. That laser array would be a weapon that could clear near space of any and all satellites. I doubt that the major powers would stand by and allow it to be built. The obvious solution would be to build it on the lunar farside out of line-of-sight view of earth orbit. But that would add a whole new complexity to the project.

  2. “NASA’s AMES Research Center – the people working on a warp drive.”

    Two things:

    1) It’s “Ames”, not “AMES”. The center is named after Joseph Sweetman Ames, it’s not an acronym.

    2) NASA is not and has never been working on a warp drive, not at Ames, or any of the other centers.

  3. Of course we can get there. I go all the time. Why don’t you ask something meaningful like, “When are they finally going to fix that leak in the men’s room of the McDonald’s on Fleeptor Street on Arglax 7 in the Gamma Quadrant?” — Miss Thorb, substitute 4th grade teacher from Mars, currently on assignment in Topeka. (To see aliens jump off the page of her new book and walk around your desk, visit:

  4. Before we go nuts sending chip-sized spacecraft all over the solar system, lets send a few out to Mars and see how effective they are at acquiring data and sending it back to Earth.

  5. in my heart i have felt the pain of wanting to fly and never die! but in my mind i have been there a thousand times.

  6. The speed of light is approximately 700 million miles per hour. 20% is approximately 140 million mph. It doesn’t seem like we will be doing manned intersteller space travel anytime soon. WARP speed acceleration would squish the human body like a bug hitting a windshield.

    1. Accelerating at 1G, it would take about a year to reach 99% the speed of light. We all experience 1G living on the Earth’s surface. There would be no difference physically

    2. Also someone had a report recently about a large boundary layer for each galaxy with extremely high temperatures and great breadth. Don’t plan on visiting Andromeda points anytime soon.

    3. Here are some numbers for you. A spaceship leaving Earth under a constant acceleration of Earth gravity (32 feet per second squared) would require about one year to reach the orbit of Pluto, and would then be traveling at approximately the speed of light.

  7. After buying my new car, I was planning to drive to Alpha Centauri by myself, since I’ve never been there, however, before doing so, I checked with my auto insurer, AAA, for additional maps, and such, but, regrettably, I was informed they do not have any facilities there, and as such, they would not would not extend my coverage to that local. Thus, I’ll have to change my itinerary and settle for the Grand Canyon or someplace less distant.

  8. I’ve been there before, and I can tell you, in no uncertain terms, Alpha Centauri is an inhospitable destination for anyone wishing a warm vacation. It’s way too cold for me and the wife. As such, next vacay we’ll just plan on staying in our own Solar System. Plus, my AAA car insurance will not cover us outside our Solar System.

  9. Solar Sails and laser beams, to infinity and beyond. Give me a break. This is nonsense that is trotted out by a branch of science that is 1) eager for funding so their jobs can go on and they can retire well; 2) these same are outside of the loop for black-ops that are ultra secret, so much so that Congress is not reported to. Those lads are working on the real propulsion systems to get us out of the solar system. And no, you cannot send a news crew to any of their locations and ask for an interview. That doesn’t mean that evidence is missing. Just harder to isolate.

  10. The concept of faster space travel is certainly intriguing but as you state, the speed of light is the ultimate finality unless things like wormholes prove to be what we would like them to be. Moving around the universe at a percentage of the speed of light makes interstellar travel very, very long term and difficult. What we ignore is that if it is that difficult for us, it is just as difficult for the “aliens” out there. The distances are immense and until the finality becomes just another speed bump, it is highly unlikely that we will meet an alien anytime soon.

  11. The obvious way to slow the spacecraft down is turn the light sail around and use it as a parachute. The interstellar medium does indeed have enough particles to slow the spacecraft to controllable speeds; likewise the parachute will absorb enough energy for radio transmission power.

    What bothers me is the control system needed to maintain focus on the sail during acceleration and second, can we really build a perfectly reflective light sail.

    Nevertheless a fascinating possibility which I hope there are people available who can make it happen. I would certainly donate to the effort.

  12. If we cannot come out with far more advance propulsion system and fuel, we will not go far. Also we need to think about what we define about habitual planet. Life will develop and advance according to that particular planet. It is passible aliens doesn’t breath on oxygen and need liquid water, but other air and liquid to survived. It is also possible they need lighter or heavier gravity. Aliens may also develop far more advance communicate technologies than what we develop on Earth.

  13. This subject again. I get tired of going through the “accelerate for 388 days at 1G to the speed of light then face the other way decelerate for 388 days back to stop”…. speil…. With the magical drive system that hasn’t been invented yet…. I think you’d only be half way across. You’d have to go 5 or 600 days of 1G acceleration and then 5 0r 600 days of same deceleration. You wouldn’t vaporize or go back in time. They used to think that about breaking the sound barrier too.

  14. Why not just have a set of orbital solar concentrators focusing the sun’s output ’round the clock, “bugzapping” (as you call it) the little fellas without the atmosphere and rotation of the earth to worry about? And it’s fairly arrogant to claim that Milner and Hawking read your article and said, “Gee, I never thought about any of this until Fraser Cain dreamt it up; I’d better get cracking!”

    1. You want the light finely-tuned to a wavelength that isn’t absorbed by the sail; only lasers can provide that. But it wouldn’t work anyway. Flying through the Local Bubble, there are enough dust grains to destroy even a Whipple shield equipped sail in a matter of hours. At 60,000 km/s, a 1 meter sail would hit dozens of grains of dust per second; most of them only a few molecules in size, but something like one seriously big (100 nanometers) every minute, that would put a healthy sized hole in the forward shield. In one hour it would be in tatters, and in a few months, even the payload would be seriously eroded.

  15. AJ’s rule: If UFO’s are real, then interstellar travel is ridiculously easy (we just havn’t found out how yet). If it’s not easy, then the energy/time needed would be daunting for a type 4 civilization. Especially considering we are just one more unremarkable piece of real estate not worth visiting. It’s just our hubris that we are special when it’s clear we are not the center of the universe or anything else.
    Other option is UFO’s are us from the future which would explain the interest.

  16. Imagine if some guy who didn’t ever work at propulsion laboratories or have any degrees, was so intrigued by the concept of a ship smoothly accelerating to light speed and down again, that he thought up a prototype of a mechanical drive system you could bolt to the output shaft of a Bell helicopter for example…. instead of the rotor. And it would take the power of the motor turning and direct it in a direction without needing atmosphere molecules to push against. And the thing didn’t have to many more parts than the rotor blade cyclic and wasn’t that much more complex of a mechanical assembly.

  17. Certainly a very tough technical challenge. I hope they give it a shot.
    This topic has really inspired (for me, anyway) a desire to understand the incredible distances involved, even to our nearest star buddy. (My apologies for ranting at your writers!)
    Really looking forward to the JWT and what it may see.
    in other news I got a great Craigslist deal on a telescope this past weekend…. not a great quality reflector, but enough to enjoy the stars and let my imagination fill in the rest.

  18. The speed of light c is NOT a “speed limit” for motion between heavenly bodies. We know this to be true because we observe Doppler redshifts as great as z = 6.3 for the recession rate of distant galaxies, which indicate velocities relative to us that exceed c. The constancy of the line element ds postulated by Einstein’s special theory is not required to ensure that c remains constant in all frames. It is instead the constancy of the phase phi that is required where phi = k dot r minus omega dot t, at any location r and time of observation t for a wave number of k and a wave frequency of omega, The conundrum of space travel will disappear when the scientific community is able to question the infallibility of Einstein’s invariance theories,

    1. I don’t know what that has to do with this project, but such shifts don’t indicate superluminal velocities at all, or even in the case of Newtonian physics for sound. If a receding police car were emitting a 1000 Hz tone, it could be reduced to 1 Hz or less if the car was nearly reaching the speed of sound; but not exceeding it.

      1. Forget the sound analogy. Light travels freely in a vacuum, whereas sound does not and is a disturbance in some medium. This article assumes that the speed of light c is absolute and cannot be exceeded. But that is an error which has led to a lot of silly proposals such as lightsail spacecraft. An intelligent discussion of timely travel to some star such as Alpha Centauri must address whether or not the speed of light can be exceeded. The definition of z is z = omega-emitted divided by omega-observed minus 1 for a light ray emitted by a star, and a value of z = 6.3 indicates a speed greater than c. See, e.g.,

  19. Slowing the probe down is quite possible. The sail would simply have the ability to re-align its sail in opposition to the star as it approaches, causing the incoming photons to push it in the opposite direction, acting as a brake. The nice part about alpha centauri is that there are multiple stars to steer towards and multiple opportunities to slow down based on how the trajectory is altered. The probe would ave to have to computing power to auto-navigate this far from home. The likelihood of instant destruction by space dust is a real concern, which is why multiple probes should be sent. Has anyone made a rudimentary calculation about what the odds are of this happening? This would in turn affect how many probes should be sent,

    1. There is ~ 1 particle, <100 nanometers in size, per running 1,000 kilometers of 1 meter cross-section. At 0.2c therefore, there will be 60 strikes per second (c=300,000 km/s). Most of these will be only a few molecules in size, but even that may have an impact on a membrane <1 micrometer in thickness. A little bigger, and you will get micropunctures big enough to locally interfere with the reflectance of the presumably diachroic mirror-surface.
      Even assuming the extremely dubious claim that the diachroic integrity over the entire meter or more of sail at the time of manufacture such that the staggering flux of the (even monochromatically tuned) lasers is able to be sustained at such reflectance at every point on the surface, even sub-micron punctures would present a local breakdown in the reflectance/absorption fraction and the laser would then tear away at those poorly reflecting hole-perimeters in seconds, or even milliseconds.
      The only recourse then is to reduce the flux and extend the propulsion phase. But the thing must still hold up under the dust-flux that much longer. Now we’re talking many strikes by ~100 nanometer grains and the sail would quickly be full of holes, as would a Whipple shield.

      Elon Musk’s Hyperloop has a better chance, which is next to nil.

      1. P.S. Once the propulsion phase is completed, of course, the sail no longer matters, and in fact could be collapsed into a compact form directly in front of the probe as a protective barrier.

        I forgot to add an answer to the question ‘how many would have to be deployed?’ I’d say ‘All of them.’, and leave it at that.

  20. May I suggest a book, “The Discoverers,” by Daniel Boorstin. This scientific dogma that you preach is ego-based and not accurate historically. In my opinion, there will be new discoveries in the upcoming decades that will cause a complete recalculation of the universe. My guess is that a new dimension will finally be proven that changes the distances that will be measured by actual distances and/or a totally different view of the universe as it actually is. The paradigm will shift once again and the academics will have to completely change their tunes, once again. It’s funny how that has happened over and over throughout human history, but certain scientists still have the audacity to shout never. Your friend, Albert Galileo Copernicus Newton

  21. Light sails are of course an old idea explored in science fiction. That doesn’t mean they are nonsense. As for decelerating, see for example “The Mote In God’s Eye” by Niven and Pournelle.

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