A just-announced proposal for a $10 billion program to develop laser-propelled interstellar probes. The idea is to have a mile-wide ground-based array of lasers generate a whopping 100 gigawatts for two minutes to push tiny solar sails with a payload massing about a gram (comparable to the innards of an Iphone). In those two minutes the probe would be accelerated to 20% lightspeed, shooting past Alpha Centauri in about 20 years. It is estimated that Starshot would take 20 years to get going, so, when you factor in the time it takes for the message to get back to Earth, the first photos of A. Cent. from close-up won’t be available until 2060 or so.
The basic idea is not new. Lasers and microwaves have been suggested as “pushers” for sails for decades. Starting in the 1980s, engineers and scientists such as Robert L. Forward have suggested that advances in computer technology were such that probes could be made trivially small, meaning that it was possible to start considering power systems capable of sending probes to stars at good fractions of lightspeed.
The real trick would be developing a molecule-thick sail that won’t promptly vaporize when hit with a 100 gigawatt laser. This, to me, seems the most difficult part of the project. Next up would making a one-gram payload transmit useful data across the lightyears.
While not mentioned in the article, it seems to me that this vast laser array could, when not shooting microprobes to the stars, be used to power vastly larger launch vehicles into orbit, or perhaps “solar thermal” rockets leaving Earth orbit for, say, Mars.
So far no decent technical details, but the website for the project will supposedly eventually have tech reports.
