The starship concept involves solar powered chips launched initially into orbit, then boosted to 0.2C by a ground based laser. They're cheap and tiny and launched in the thousands over the entire period the first probes are in flight, so you have a continuous chain of probes. The return signal is passed back along the chain to Earth. The probes steer using thermal effects and solar wind. Many probes work together to form a synthetic aperture array.
Since its 4.47 x 9.5 x 10 to the 15th power meters to alpha century, it doesn't seem feasible to form a communication chain of such tiny devices. How are they powered in deep space?
Presumably using light from the laser. I forget the exact numbers, but the proposed laser is on the order of hundreds of gigawatts. Even at 4 ly away, there should still be appreciable illumination from Earth.
Hundreds of gigawatts!? To my knowledge, there's never been a laser remotely that powerful that can emit for any constant duration.
The highest power laser [0] in the world currently is 2 petawatts and it can only fire for one trillionth of a second. Per the same article (not sure on validity) the entire world electricity usage is somewhere around 2 terawatts, so something producing a continuous 0.1+ terawatt beam would be an incredible cost that's simply impractical proposition any time soon.
I'm just jumping in here, but while we're in sci-fi land let me point out that this is usually not done from the Earth's surface (pushing 100 GW through the atmosphere is sub-optimal) but instead in near-Earth orbit, or from the Moon's surface, or something.
So, the power output of the Earth is not 100% relevant, it wouldn't be a load on the planetary grid.
Which makes it an even crazier proposition! The existing ultra high power lasers are so big in size that they'd currently be impractical bordering on implausible in space. To power it, we'd have to take every nuclear power plant on earth (plus another 2-3x more) and put them up in space. Seems likely, no? :P
The calculations you need are in https://www.youtube.com/watch?v=sImBlq542TQ
(his point is that lasers can be used for communications between solar systems, but the power calculations are similar for transport).
I'd be interested more about the steering (attitude control). Where did you find that? I don't see it in the article.
It seems like the dominant force here is going to be the radiation pressure of the laser hitting it, at least in deep space. There isn't going to be solar wind for most of this journey, they will be past the heliosphere and in the interstellar medium. But I guess all you need is for it to be correctly oriented when it reaches the distant star?
