[Updated] Breakthrough Starshot

Interesting.

Internet Investor and Science Philanthropist Yuri Milner & Physicist Stephen Hawking Announce Breakthrough Starshot Project to Develop 100 Million Mile per Hour Mission to the Stars within a Generation
Breakthrough Starshot is a $100 million research and engineering program aiming to demonstrate proof of concept for light-propelled nanocrafts. These could fly at 20 percent of light speed and capture images of possible planets and other scientific data in our nearest star system, Alpha Centauri, just over 20 years after their launch.

Generally, the idea is nothing new: micro-probes with little lightsails propelled by a laser that stays behind. They describe the probe proper as “postage stamp-size,” with a 1 square meter sail. Where this differs from other proposals (like Forward’s “Starwisp”) is that Starshot consists of a lot of individual probes launched in a swarm.

Technical detail remains unpublished (and clearly needs a lot of development), but I’d guess that the individuals in the swarm will network together, so thay they can combine multiple low-resolution sensor data into a more detailed composite.

Getting the data back to Earth is tricky. The press release says the data will be transmitted “back to Earth using a compact on-board laser communications system.” The only way that can possibly work is if a large number of probes survive to reach Alpha Centauri so that they can synchronize a bunch of in-phase laser transmitters. That may be an iffy proposition for postage stamp-sized probes moving at 20% of lightspeed.

I’m not exactly sure what they mean by this: “Using the same light beamer that launched the nanocrafts to receive data from them over 4 years later.” Lasers aren’t receivers, but it may refer to using the collimation and adaptive optics part as a giant antenna.

Here’s the diceyist part of the job: a 100 gigawatt laser array. Not 100GW peak, but continuous power output. Though briefly; depending on the probe mass, they may get up to speed in hours. And the laser power would start much lower than 100GW, since full power aimed at those probes in orbit would vaporize them. Power will increase as the swarm gets farther away

Why’s that dicey? Read The Mote in God’s Eye. You’ll want to note the part where aliens fought wars to control the interstellar laser arrays to use as weapons. Granted, the Moties’ array was far larger, since it launched a manned Motied colony ship. But consider Navy tests in the mere 10-20 kilowatt range.

Imagine the Fourth of July fun you could have with an array 5,000,000 times more powerful. In CW mode. A lot more in peak pulse mode.

Weapons applications aside, they’re going to have fun putting a 100+ GW generator on that mountaintop. Or develop some astonishing storage systems.

More -ahem- power to them. It would be interesting to watch the development, the data gained just in interstellar space (much less at Alpha Centauri) would be invaluable, and spin-off tech would be almost unbelievably useful. And they’re doing it with private money, not your tax dollars.

Added, 4/13/16: Graphics and a little more detail. I’m pretty dubious of cramming cramming a camera, computer, laser transmitter, and a nuclear battery into a 1 gram package. Given the size, the battery would have to be betavoltaic, but which isotope? Tritium is a beta emitter, but has a half-life of just over 12 years, which I’d expect to be too short for an interstellar mission that requires sufficient power to beam a laser 4.3 lightyears after 20 years. Seriously, in such a small package, you need max output, but that typically means a short half-life.

That graphic claims the probes would get up to speed in 2 minutes. I’ll need to check the math, but I think that assumes full launching laser output from the start, which would mean vaporizing the probes.

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