I never thought I'd live to see this.

The Russian billionaire Yuri Milner, who last summer committed $100 million to boost SETI searches to a new level (Breakthrough Listen is now busily underway), announced on April 12th, along with a lineup of distinguished scientists, a new, far more ambitions $100 million project. Breakthrough Starshot will conduct research and development toward accelerating insect-size interstellar probes to 20% of the speed of light, driven by a 100-gigawatt laser array on Earth. The tiny probes would scout exoplanets up close — and report back across the light-years.

The "nanoprobes" would take only 20 years to get to Alpha Centauri, at least the ones that survive (a dust particle along the way would be fatal). As each zips through the system, a tiny camera and atmosphere analyzer are to grab pictures and data on any planets there. Then — hold on now — it would transmit this data the 4.4 light-years back to Earth using a "compact laser." The total mass of each probe, including power supply, camera, sensors, processors, fine-navigation thrusters, and that amazing transmitter, is to be just a few grams.

The laser array would boost this delicate snowflake of a thing out of Earth orbit with an acceleration of 25,000 gs, delivering the force to a lightsail purely as radiation pressure. It will have to do this without vaporizing the lightsail and the probe, which will have to be incredibly super-reflective. Such intense power is required to push the probe to its cruising speed in just two minutes, before it gets beyond good laser range. The lasers would then take a day to recharge their batteries (from a dedicated power plant), before sending off the next probe, and the next.

For years now, blue-sky engineering analyses of the sort that I've seen presented at science-fiction conventions have concluded that while this technology is rather beyond us at present, it could come into reach if Moore's Law continues and if materials science and ultra-micro manufacturing develop as hoped. And if lasers keep getting more powerful and cheap. Milner's $100 million will go toward investigating whether all of this can be made to happen.

Milner says his team has looked into “20 challenges” facing engineers. “Each one could have been a deal breaker, but it looks like we found a reasonable path forward for each.”

If such a system becomes possible it might cost $10 billion to build, suggests Breakthrough Starshot's impressive roster of experts. That's in line with the biggest big-science projects today. Once everything is up and running, the launches themselves would be cheap: maybe $100,000 each.

At this point there's really nothing more I think I should say. You can read heaps of news coverage; start with the New York Times, which was super-quick off the mark, and continue with The Atlantic's interview with Milner. For technical information to geek out over, and the case for plausibility, you want the Breakthrough Starshot website.

Milner says such a system might be ready to fire off its first interstellar probes in 20 years (I'd multiply that by 10, myself). Considering the travel time for the probes and for the returning data, Milner says he hopes to see the first closeups of any Alpha Centauri exoworlds in his lifetime. He's 54.



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April 13, 2016 at 3:42 pm

You mentioned discussions of this sort of ultra-low mass interstellar probe concept at "science-fiction conventions". For readers who haven't heard of this before, the general idea of tiny spacecraft driven to the stars on intense beams of light has been bouncing about for decades. One version, known as "Starwisp" was described by the incredibly creative aerospace-engineering genius Robert L. Forward as early as 1985. R. L. Forward is also a science-fiction author. The "Starwisp" concept is covered in a brief Wikipedia page: https://en.wikipedia.org/wiki/Starwisp.

While there are enormous technical challenges, this project is well within the realm of known physics. IT CAN BE DONE. We could see a fleet of tiny spacecraft launched to Alpha Centauri within 50 years. The physics is not prohibitive. But what about the economics? While the technology required for this mission is advancing rapidly, remote-sensing technology is also advancing rapidly, and ultimately the pay-off of this interstellar flyby mission may be a very hard sell. For the enormous price of this spacecraft mission, it's very likely that far more science could be accomplished with large space-based telescopes. And such scopes could observe hundreds of nearby stars, not just one. Ultimately, this mission will fly only if is portrayed as the beginning of things to come --the initialization of a future of interstellar exploration.

Frank Reed
Conanicut Island USA

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Peter Wilson

April 14, 2016 at 9:09 am

It will be easy to test.

Alpha Centauri A and B orbit each other in a plane, inclined at some angle, theta, to Earth. Fire two test probes away from the plane of the solar system, one at an angle theta, the other at theta+180 degrees. If they send back useful information about here, it could work there.

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April 15, 2016 at 4:21 pm

I don't believe a word of it. So this chip is going to be able to send pictures and data from the star to here. Yea, sure.

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Seth Jarvis

April 15, 2016 at 4:44 pm

I need an explanation of how a radio weighing at best a gram, and without an aimable parabolic antenna, is expected to transmit data back to Earth. Power source?

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April 15, 2016 at 5:39 pm

That is amazing. I would love to still be around when this takes place. As you all can see, that star has been a favorite of mine since I was a kid. I saw it while I was in the Army and stationed in Hawaii. I was on the Big Island on guard duty under a beautiful sky at about 6000 ft. of elevation when I saw it.

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April 16, 2016 at 3:23 am

Say these bitty probes really can be accelerated to 0.2c. Imaging and gathering data would be quite a challenge.

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April 18, 2016 at 5:32 am

> Then — hold on now — it would transmit this data the 4.4 light-years back to Earth using a "compact laser."
Um, HOW? A laser or maser bright enough to be seen 4.4 light-years away would need to be practically as bright as those sending the probes from Earth. Better to think of a way to get the probes to act together to produce a single integrated laser signal. Or send a few heavier probes with powerful lasers & (separately) solar power arrays.
The political problem with this proposal is that a 100-gigawatt laser array, with fast precision tracking of moving objects, would be a fearsome weapon against anything line-of-sight in the air or space, out to the distance of the Moon. To be allowed, it'd probably have to be under UN control.
Rather than having to come up with light thin lightsail material so reflective it won't be vaporized by 100Gw for 2 seconds, it might be easier to put the lasers in orbit or on the Moon, solar-powered, so they wouldn't be diffused by Earth's atmosphere & could provide a narrow beam on target for much longer. Or to get the most intense solar power, at the poles of Mercury, as suggested in at least a couple of SF novels.
Other than those "minor" engineering & political problems, it sounds quite feasible, & I heartily encourage the project.

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April 19, 2016 at 5:38 am


Now where are my Jules Verne books?

... Bob

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Alan MacRobert

April 19, 2016 at 9:40 am

Jules Verne never thought this big.

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April 20, 2016 at 3:37 pm

The potential for the proposed laser array to be turned into a weapon is far too great and will put a kibosh on this project. Sorry. Sure, the array could be used to propel such a probe or even de-orbit space junk or vaporize an incoming NEO! BUT given the inevitable possibility of the array being usurped for military purposes and given the perpetually unstable political environment here on Earth - no way. Put the laser array on the far side of the moon is one suggestion I've heard, but is a non-sequitur. Simply orbit a mirror around the Moon to reflect the energy to vaporize Wall Street? Moscow or Beijing? Nope... it ain't going to happen...

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