Back in April, Russian billionaire Yuri Milner pledged $100 million toward a crazy plan to visit another star system.
The mission — Breakthrough Starshot — aims to get this done by propelling teeny, tiny spaceships to 20% the speed of light with powerful lasers.
Milner and famed physicist Stephen Hawking initially said their destination would be Alpha Centauri: the second-closest star system to Earth, located some 4.37 light-years (25.7 trillion miles) away.
But as far as anyone knows, Alpha Centauri is bereft of habitable worlds.
This is precisely why the recent and groundbreaking discovery of a nearby planet could switch things up for Starshot.
Astronomers on Wednesday announced they'd discovered an Earth-like and potentially habitable world, called Proxima b, circling Proxima Centauri — a red dwarf star that's closer than Alpha Centauri by about 1 trillion miles.
"The discovery ... provides an obvious target for a flyby mission," Avi Loeb, a physicist at Harvard University and a Starshot mission advisory committee chair, wrote in an email to Business Insider.
"A spacecraft equipped with a camera and various filters could take color images of the planet and infer whether it is green (harboring life as we know it), blue (with water oceans on its surface) or just brown (dry rock)," Loeb wrote.
The team hopes to "achieve a launch in 2-3 decades," says Loeb, and reach Proxima Centauri about 20 years later.
The photos, meanwhile, would take at least 4.24 years — the distance in light-years from here to the star — to get back to Earth.
Adding up that timeline, Starshot thinks it could take photos of Proxima b (plus whatever else its nanocraft encounter there) by the year 2060.
How to sail to a star
Milner said in April that Starshot will start out as a $100 million engineering proof-of-concept to design, build, launch, and propel a small fleet of iPhone-size "nanocraft" to Alpha Centauri in about 25 years' time.
Each nanocraft will contain a tiny spacecraft and a laser-light sail for propulsion. "This is the Silicon valley approach to spaceflight," Milner said.
The hypothetical spacecraft, called StarChip, will be built out of a "gram-scale" silicon wafer that's "carrying cameras, photon thrusters, power supply, navigation and communication equipment, and constituting a fully functional space probe."
Moving each StarChip along will be a Lightsail propulsion unit.
An array of powerful lasers called a "beamer" will take aim at the Lightsails, accelerating each nanocraft to more than 134 million mph.
'A sense of urgency' to reach Proxima b
At this point Starshot already has a prototype for the StarChip (pictured in Milner's hand at the top of this post).
It's smaller than an iPhone, and it will be backed with cameras, photon thrusters, power supply, navigation, and communication equipment.
But Loeb said the next 5 to 10 years of the project — and most of the $100 million — will be focused on proving the laser propulsion idea actually works.
From there they'll work on perfecting the tiny ships, Loeb said, noting that a beamer "could potentially launch hundreds of cheap, gram-scale spacecrafts per year."
"This will allow us to send a fleet of probes towards Proxima that could relay the images taken back to Earth more easily (from one spacecraft to the next along the line of sight to Proxima)," he said.
Noting that exisiting telescopes can't photograph the new planet, at least in a conventional sense, Loeb added: "The curiosity to know more about the planet (most importantly whether it hosts life) will give the Starshot initiative a sense of urgency."
Even if Proxima b doesn't support life, Loeb says it's still important to explore the not-so-distant world.
"The lifetime of Proxima is several trillion years, almost a thousand times longer than the remaining lifetime of the Sun," he said.
"Hence, a habitable rocky planet around Proxima would be the most natural location to where our civilization could aspire to move after the Sun will die, five billions years from now." (At least one sci-fi author thinks this is a horrible idea, though.)
A wealthy fan of space exploration
Milner's fascination with space and science runs deep.
The first man in space was cosmonaut Yuri Gagarin — who Milner has said he was named after.
Milner has also spent big money on science initiatives before, saying he wants to celebrate"intellectual achievement" in the same way we celebrate artistic and athletic prowess.
The Russian billionaire philanthropist has collaborated with Hawking in the past, too. In July 2015, the two announced a $100 million plan, called "Breakthrough Listen," to search the stars for intelligent extraterrestrial life.
Milner was even working on a PhD in physics before becoming a Silicon Valley investor, where he earned his fortune investing in companies like Facebook, Twitter, Spotify, and Groupon.
Today he funds some of the biggest science prizes out there, including the Breakthrough Prize, which Mark Zuckerberg also supports.
Kevin Loria and Lauren Friedman contributed to this post.