Or is it? There is a plan in the works, bankrolled by Russian entrepreneur Yuri Milner, to send a probe to our nearest star system, Alpha Centauri, by the end of the century. Named "Breakthrough Starshot", the goal is to launch thousands of ultra-light miniature space probes and propel them with the velocity of one-fifth of the speed of light. This proposed mission is perhaps one of the most ambitious currently being undertaken anywhere in the world.

The Alpha Centauri system, made of three stars, is just over four light years away - that is, light from the stars takes over 4 years to reach us. When you look at this star system, you are seeing it as it was four years ago. You can find Alpha Centauri quite easily in the southern sky - look for the brighter of the two "Pointers" near the Southern Cross.

If we want any chance of getting there within a lifetime, we need to go a significant fraction of the speed of light - millions of kilometres an hour. The fastest probe built so far, the Solar Parker Probe, will only reach 700,000km/h.

Breakthrough Starshot aims to accomplish this through two technologies. The first is to use an extremely small and light spacecraft, no bigger than a fingernail. This way, we can accelerate these objects very quickly to very high speed. For instance, you can throw a cricket ball much faster than a basketball. These lightweight spacecraft would have huge solar sails, about 5m wide, to propel the spacecraft. The plan is to have a gigantic fleet of thousands of these probes, so that if one collides with some dust on its journey, we have many backups to continue onwards.

The second technology is to use lasers, and a lot of them, to give the spacecrafts a push. We are talking about an array, spanning many kilometres, of lasers that produce a combined power output up to 100 gigawatts. This is roughly the same as the peak power consumption of the entire country of France. These lasers would blast the sails on the spacecraft for about 10 minutes, like wind on a sailboat, providing an acceleration of 10000 Gs. Once this spacecraft gets going, it should reach Alpha Centauri in 20 to 30 years. A long time, but a lot better than 75,000 years it would take current rockets.

Breakthrough Starshot was initiated in 2016, and leaps in technology have been made, including by some groups in the Research School of Physics at ANU. There is a long way to go, though, so while science fiction looks to be ever closer to reality, we still have to wait patiently for some time yet.