In 2045: Alpha Centauri

We’ve talked about project Breakthrough Starshot which aims to send a solar sail probe to Alpha Centauri within 20 years. A little basic math and knowing that Alpha Centauri is 4.3 light years away means you are going to need to travel over 20% of the speed of light to make the trip in that time. Some new papers have proposed ways to address a few of the engineering problems.

The basic idea is simple. A very small probe is attached to a very large sail. But calling it a solar sail is a bit of a misnomer. The motive power for the sail would be a powerful laser, which provides more reliable power to the tiny probe’s propulsion system. The problems? First, the thin sail could tear under constant pressure. The answer, according to one of the papers, is to shape the sail like a parachute so it can billow under pressure.

The other problem is not burning the sail up. Space is a hard environment to dump waste heat into since radiation is the only way to transfer it. Another paper suggests that nanoscale patterns on the sail will allow it to release waste heat into the interstellar environment.

Small Lightsail Will Propel Cubesat

If you read science fiction, you are probably familiar with the idea of a light or solar sail. A very large and lightweight sail catches solar “wind” that accelerates a payload connected to the sail. Some schemes replace the sun with a laser. Like most things, sails have pros and cons. They don’t require you to carry fuel, but they are also maddeningly slow to accelerate and require huge sails since there isn’t much pressure produced by a star at a distance. So far not many real spacecraft have used the technique, IKAROS was the first back in 2010. However, this month should see the launch of a crowdfunded cubesat that will use a solar sail to move to a higher orbit.

The 5 kg satellite built by Georgia Tech students is about the size of a loaf of bread. Once in orbit, it will deploy solar panels and a square solar sail nearly 20 feet long on each side. Despite the nearly 350 square feet of area, the sail is less than 5 microns thick. You can see more details about the mission in the video below.

Credit Card Sized Spacecraft Poised To Sail To Alpha Centauri

As a space-faring species, we’ve done a fair job of exploring and exploiting our local neighborhood. We’re pretty good at putting people and machines into orbit, but our galactic-scale signature is pretty tiny. Our radio signals are no more than 100 light-years away, and our farthest physical artifact isn’t even a light-day away from us 40 years after it launched.

Clearly we need to do a better job of getting out there, and that’s the goal of Breakthrough Initiatives’ Starshot program, which aims to launch a nano-spacecraft to Alpha Centauri and get it there fast. The program aims to build solar-powered credit card-sized spacecraft with sensors, cameras, communications, and even MEMS thrusters for attitude control. Motive power will come from solar sails catching laser light shined onto it from Earth, eventually accelerating the craft to 20% of the speed of light and reaching its destination within a generation.

The thought that we could start spreading ourselves out into the galaxy within the lifespan of most of the people on Earth is intoxicating. Sure, a wafer of silicon is a far cry from a sleek starship with powerful warp engines and all the finest appointments, or a gritty star freighter that can make the Kessel Run in less than 12 parsecs. But the laws of physics and the limits of engineering conspire to keep us mostly stuck at the bottom of a deep gravity well, and if this means sending fleets of nanobots across the galaxy in our stead, so be it.

And no matter what form our first galactic spacecraft take, you can bet that the Deep Space Network will be supporting the mission. For now, you can listen in on the program’s test satellites currently in orbit if you tune to 437.240 MHz.