Yuri Milner breakthrough mission to Alpha Centauri Options

[Guest_mcmcmc_*]

https://breakthroughinitiatives.org/about

Laser-powered nanocrafts headed to Alpha Centauri:

Breakthrough Starshot is a $100 million research and engineering program aiming to demonstrate proof of concept for a new technology, enabling ultra-light unmanned space flight at 20% of the speed of light; and to lay the foundations for a flyby mission to Alpha Centauri within a generation.

Which are the engineering challenges?
http://breakthroughinitiatives.org/challenges/3

Yuri Milner twitter feed (official?): https://twitter.com/yurimilner

[Gerald]

I'm asking about the ratio of energy of the laser beam converted into kinetic energy of the probe (relative to Earth) by presumably mere momentum transfer of the photons of the laser beam being reflected by the light sail.
In a first calculation, I think, that one can rely on the figure of 6.6 N/GW provided in the paper as an upper limit. So, this is about physics, assuming perfect engineering.

In the case of Sedna, it may be possible to simplify the technical overhead by first sending the probe to the sun, then unfolding or pointing the light sail, and exploiting the inverse square rule for a push by radiation pressure of up to more than 10,000-fold the 9.08 µPa at 1 a.u.. It's of course challenging for the electronics to survive temperatures of more than 1000 K close to the sun or within an intense laser beam, as well as temperatures of few 10s K in the outer reaches of our solar system, Transport to the sun can be within a heat-protected capsule, but then the nano probe needs to be exposed to the intense radiation.