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If you are a fan of science fiction, you have probably read or seen a lot of stories that involve interstellar travel. Like, they are called "Star" Wars and "Star" Trek for reasons. And we might be getting a little closer to making interstellar travel a reality. Just not for humans. Last week, Russian entrepreneur Yuri Milner announced that he was heading a project called a "Breakthrough Starshot". The plan is to use giant lasers to propel tiny spaceships to Alpha Centauri, our next door star system, and collect a bunch of scientific data. Getting this, right now theoretical, plan to work will take decades of research and probably tens of billions of dollars. But, with some more advanced technology and a lot of problem solving, we might be able to do it.

Interstellar travel is hard because space is *big*. Alpha Centauri is the closest star system and it's about 4.4 light-years away. That's 41 trillion kilometers. So, to get there from Earth, we would either need to travel for a very long time, or travel very fast. If we tried to go to Alpha Centauri using the technology we currently use in space travel, like rockets powered by propellants, it would take, like, 80,000 years. Which is not super practical. But Milner and the Starshot team want to try the other option and build spaceships that go really fast. Like, a significant fraction of the speed of light, fast.

There's a lot of work that needs to be done to make this happen, but there are a lot of people supporting this endeavour, including physicist Stephen Hawking and laser propulsion expert Philip Lubin. Specifically, the team's plan is to build very tiny spaceships, about the size of a postage stamp, and then push them through space using a bunch of lasers here on Earth.

If the idea of propelling small spaceships with giant lasers sounds familiar, it's because we talked about it a few weeks ago. It's called photonic propulsion, and it's based on the fact that light can have enough pushing power to propel certain kinds of spacecraft. When the laser light (which is made of a concentrated beam of photons) hits a special kind of reflective sail attached to a spaceship, it transfers some of the momentum and pushes the craft forward.

The team wants to use this concept to get their tiny spacecraft moving fast enough to shorten the trip to Alpha Centauri to just a couple of decades. So, their grand plan is to build a huge array of lasers here on Earth, which would combine into one big beam. The laser would fire in pulses and accelerate the stamp-sized starship to about 20% the speed of light. Around 20 years later, those starships would get to Alpha Centauri, take measurements as they flew by, with the nanotechnology inside, and then send the data back to Earth.

If all goes very well, they might be ready to launch as soon as the 2030s or 2040s, but there are a lot of big challenges here. For one thing, they're building the laser here on Earth, instead of in space, because it's a lot cheaper. But when you fire a huge laser through the atmosphere, all of those gas particles weaken and distort the beam, which means that you have to account for less pushing power and potentially slower speeds.

They'd also have to be careful to not hit anything in space, that might fly between this incredibly powerful, possibly 100 gigawatt laser beam, and the spacecraft, like satellites. Plus, their tiny spaceships would have to be able to withstand the beam without melting and stay stable as they're zooming through space. Not to mention, they have to be able to survive running into interstellar dust at 1/5th the speed of light without being blasted apart. The ships would also need things like a reliable and strong enough power source, as well as an effective way to communicate with Earth from so far away. Technology that we don't have yet, on that small of a scale.

And these are just a few of the issues that need to be solved and the team definitely has their work cut out for them. And a lot of fundraising to do. Milner's initial $100 million investment is still only a fraction of the billions of dollars necessary to develop this project and all the related technology. It's a big task, and one that's going to take a lot of planning, and development, and time, and money. But if we ever want to visit other stars, even just with tiny robotic probes, we have to start at some point. Might as well be now.

Thanks for watching this episode of SciShow Space News and thanks especially to all of our patrons on Patreon who help make this show possible. If you want to help us keep making episodes like this, you can go to Patreon.com/SciShow and don't forget to go to YouTube.com/SciShow and subscribe. [rumbling sound in the background] We're going to move to a new studio soon, where it's quieter. That's loud.