A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away

Post by drdrey » Sat, Apr 16, 2016, 6:54 AM UTC

slg wrote: post #129

dysfunction wrote: post #121

Earlier quoted context omitted.

We wouldn't be able to see the probe itself, rather we'd see its laser. The planet outputs (or reflects) vastly more total light than the laser, but the laser is pointed directly at the receiver and can output more light in that specific direction than the planet does. Plus, to get interesting data about the planet we need to get quite a lot of light from it, whereas we can get data from the laser over time by pulsin…

>The planet outputs (or reflects) vastly more total light than the laser, but the laser is pointed directly at the receiver and can output more light in that specific direction than the planet does. So then the problem is that you need a laser than can hit a 1 km^2 target from 40 trillion km away?

Post by jessriedel » Sat, Apr 16, 2016, 6:24 PM UTC

vacri wrote: post #210

jessriedel wrote: post #48

Earlier quoted context omitted.

Agreed on the extreme skepticism warranted. I am imagining these "solar sails" to be essentially spherical, both for structural reasons and so that their response to applied laser power does not depend on orientation. The electronics in precision guided mortars in the US army survive 50,000g. http://proceedings.ndia.org/C347/Davis.pdf (This is only for the fraction of a second when they are fired, and I don't know ho…

> The electronics in precision guided mortars in the US army survive 50,000g And then are immediately 'disposed of'. That is, quite literally, a fire-and-forget problem; those electronics don't have to keep working for months or years.