Breakthrough Starshot, the Stephen Hawking-backed initiative to look for aliens in the nearby Alpha Centauri star system, announced Wednesday it had pulled off its first ever successful spaceflight. Not that anyone would easily notice: The tiny test probes that just went into space measure 3.5 by 3.5 centimeters and weigh only four grams.

The successful test happened late last month, when Breakthrough Starshot launched a series of what it calls “Sprites” — the smallest functional space probes ever designed, which comprise of a single circuit board — into low Earth orbit. Although only half the size of a Post-It Note, the Sprites possess an array of solar panels for energy, computer and sensors to collect and process data, and radio instruments to send signals back to scientists on Earth.

These Sprites are the first step towards the development of similarly tiny “StarChips” — nanocraft capable of traveling the 4.37 light-years to Alpha Centauri to look for signs of extraterrestrial life and planetary habitability within the binary star system. The goal is to improve the design so the team can fit decent scientific instruments onto a single, ultra-small chip that can be flown into space.

sprite breakthrough starshot
The Sprite design.

All the nanocraft will be able to do is take a few pictures of the star system as they zoom by, and they will be going incredibly fast. The StarChip design is propelled using a solar sail, which pushes the probes into the far reaches of deep space at one-fifth the speed of light. It’s still unclear whether this laser-driven technology is actually possible to build and operate, among other big questions about the feasibility of the mission.

If Starshot is successful, it means hundreds or even thousands of these cheap nanocraft can be launched towards Alpha Centauri and its exoplanet Proxima B and look for signs of life. The astronomy community has been generally very optimistic about the potential for Alpha Centauri to host a habitable world — for humans or for extraterrestrials.

You've read that, now watch this: "Arrival Language"