Humankind has long pondered upon the ambition of becoming a multiplanetary species. While much of our realistic focus resides right here in our own solar system, there’s no escaping the fact that it won’t last forever. If humankind ever wishes to persist longer than the solar system we live in, this will require not just becoming a multiplanetary species, but a multi-system species in which we inhabit other systems besides the Sun’s.
The closest system to our own is Alpha Centauri, and while it may be the closest, it’s still no walk in the park to get there. Alpha Centauri resides 4.2 light-years away from Earth, and while that may seem like a small number at first glance, it’s important to remember that a light-year is the distance that the speed of light travels in one year. Consequently, the aforementioned figure translates to around 24,690,230,000,000 miles.
So just how far away is 24 Trillion miles? To put that into perspective, it would take a spacecraft like NASA’s Voyager moving at 38,000 miles per hour nearly 70,000 years to get there. Obviously, that’s way longer than a human lifespan. That said, it’ll take a lot more than current technologies to get us to Alpha Centauri as quickly as we’d like.
One promising idea is that of solar sails, which are quite literally giant sails. They would be incredibly thin – hundreds or thousands of times thinner than a trash bag – and they would need stretch several miles across. These sails would capture light photons traveling through space, such as those being emitted by our Sun, and then use that energy to propel the attached spacecraft through the vacuum of space. After the sail moves too far away from the Sun, lasers could theoretically perpetuate its propulsion through interstellar space.
This concept has yet to be tested in full-scale in outer space, but it shows promise. Moreover, any spacecraft tethered to a solar sail would purportedly be capable of moving close to the speed of light, cutting the 70,000-year transit time down to a mere 20 years.
It’s definitely a long way off from becoming a reality, but it should be interesting to see whether this concept ever comes to fruition and matures. After all, science and humanity could one day depend on it.