Breakthrough Starshot is an initiative by the Breakthrough Institute to create microsized interstellar probes. yes, that's right, very small, very light space probes intended to be sent to another star. This whole project is funded by the backing of Yuri Milner, a venture capitalist in Silicon Valley. The idea is within 20 years, we could send very small spacecraft to stars other than our own in the galaxy.
The plan is for a mother ship to carry small, chip sized spacecraft into orbit, ones similar in size to the ChipSat. The whole interstellar spacecraft would weigh only a few grams. These would deploy a light sail, a reflective but very lightweight surface of about 2 meters by 2 meters. Once the sail is deployed, an array of lasers on Earth would shine on the sail.
The laser light would reflect off the sail and push the spacecraft causing it to accelerate very quickly to a fraction of the speed of light. The nano space probe would then fly for 22 to 44 years to Proxima Centauri, the nearest star and take pictures and potentially more. The data and images taken would take almost 4 1/2 years to get back to Earth.
The intent would be to fire dozens, if not hundreds of the space probes. The space probes would not stop at Proxima Centauri. They would be conducting a flyby only. Because they have very little control, in order to get good data and pictures. The cameras are planned to be only around 2 megapixels, so the images will not be great. However, with a very large number of them, good and interesting data can be had.
Starshot is very, very similar to Starwisp. Starwisp was proposed in 1985. Rather than using lasers, the idea was to use a maser. This is similar to a laser, but uses microwave light instead of infrared, visible or ultraviolet light like a laser does. There are some differences, but they are both examples of beamed power propulsion.
One of the biggest problems with the whole project may not actually be the technical side. There are challenges there, to be sure. Technology as a whole and in very specific cases for the space probes will need to be pushed forward hard. That's what Milner is paying for. On the other hand, there is a huge problem that I am having a hard time seeing how it can be overcome: the combined power of the lasers needed is enormous. So much so that the lasers would have the ability to destroy satellites in orbit.
The total output of the lasers is expected to be 10 gigawatts. That is over 1000 times the power output of the most powerful military lasers ever built. The combined output would be enough to almost vaporize a satellite. The damage would be done so swiftly, a nation wouldn't know what happened. Nations are already upset at the prospect of the militarization of space: look at the response to the idea of an American space force. If this was built or was started to be built, the world would flip its collective table. It is simply far, far too dangerous.
So, at it is, the idea is really exciting: would could send spacecraft to another star in less than 20 years! However, like Project Orion, it has a disturbing side and will probably be left incomplete.
As an aside, in good humor, had this been undertaken in the 1960s, we would have been calling in James Bond: after all, we have a rich Russian industrialist building a gigantic laser. Hmmm. ;)