Hawking, Zuckerberg unveil $10B plan to reach Alpha Centauri in 20 years

A group called Breakthrough Initiatives, headed by Stephen Hawking, Russian philanthropist Yuri Milner, and Facebook’s Mark Zuckerberg, has maybe the most ambitious plan in human history: send a man-made mission to another star. This billionaire-funded project will involve a mothership, solar sails, super-lasers, and a swarm of near-light-speed probes no bigger than the common smartphone — if it ever gets off the ground, that is.

Dubbed Starshot, the idea itself is surprisingly novel given the amount of momentum it seems to have already. According to the plan, an Earth-based launch will put a “mothership” into space, loaded with about a thousand — yes, a thousand — interstellar probes described as roughly the size of an iPhone. These iProbes will disengage from the mothership, and each one will spread super-thin solar sails. Back on Earth, we’d then aim a yet-to-exist super-laser at these sails and blast them out in the direction of Alpha Centauri, our closest stellar neighbor.

According to their calculations, these tiny stellar sailors should travel about 600,000 kilometers in just two minutes, and at the end of this accelerating period will be traveling at up to a fifth of the speed of light. The beam loses coherence past this distance, so that’s what we’ll have to take. Alpha Centauri is just over four light-years away, so at 0.2c the team estimate their sail probes could reach Alpha Centauri in just over 20 years. Once there, they’ll user some sort of super-low-power propulsion system to reorient themselves, take readings, then beam those readings back to Earth. This would presumably be a part of Breakthrough Initiatives’ overall goal of finding alien life in the universe, but it could end up returning results that revolutionize just about any field within astronomy.

According to Milner, the big advances that make this possible have been in lasers, and the miniaturization of advanced computing and mechanical hardware. It’s only recently we could build the innards of these tiny starships, which will have to hold up to acceleration more than 60,000 times stronger than the force of gravity on Earth. Breakthrough has dubbed the eventual gram-scale starship brain they create the StarChip. Nice.

There are some very big and foreseeable obstacles to pulling all this off, however. First off, the sails in question would have to be extremely reflective to avoid being obliterated by their own super-laser — according to the New York Times, absorption of as little as a thousandth of a percent of the incoming energy would vaporize the sails entirely. They must also be incredibly thin and light, or ruin the whole concept of super small sat-lets, and rob the iProbes of their most meaningful advantage.

More problematic is the ground-based super-laser itself, which will have to deliver about 100 gigawatts of power for two minutes. That is to say, it would take five of the largest power stations ever created (China’s Three Gorges Dam), all focusing 100% of their energy on the laser, for two minutes straight. Put differently, it would take 15 of the largest American power stations (Grand Coulee Dam) doing the same.

That’s a bigger problem than it might seem, and one that could bring even the $10-billion upper spending limit for this project into question. The cost of the electricity itself isn’t really the issue — let’s pick a relatively low average cost per kilowatt hour of $0.10. At 100 gigawatts for 2 minutes, we’re looking at 3.33 repeating gigawatt-hours, or 3,333,000 kilowatt hours — let’s say $350,000. That’s achievable, for a billionaire, though costly over the thousand units this project is planning to send abroad in total. Actually getting that $350,000 worth of power all in one physical spot, over a two-minute span, is more problematic. Their plan says they will use natural gas plants to generate that power over time, store it with ultra-capacitors, then release it quickly to power the laser. They admit that the energy infrastructure for such a plan will be “challenging” to construct.

There are a lot of aspects of this plan that are either still up in the air, or which rely on an assumption of later scientific progress. They hope to solve these problems quickly, so we can get started on our 20-year journey as soon as possible — though we’ll still then have to wait another four or so years for the measurements from Alpha Centauri to reach us! Nobody truly knows what those readings will hold, from new theories of planetary formation to evidence of alien life. Still, we can rest assured that no matter what those readings say, if they do come back there will be no question that this was money very well spent.

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