Scientists think there might be one or more Earth-like planets in our nearest star system, Alpha Centauri, 4.37 light-years away. And to find out for sure, an organization is funding a new instrument to hunt for such worlds – ahead of a possible mission to the star system in the 2030s.
This is thanks to an agreement between the European Southern Observatory (ESO) and the Breakthrough Initiatives. The latter is working on a mission to send small spacecraft called "nanocraft" to Proxima Centauri, the third and faintest star of the Alpha Centauri system, as part of their Breakthrough Starshot initiative.
To get to the Alpha Centauri system, Breakthrough Starshot would involve equipping these tiny chip-sized nanocraft with large laser sails. A powerful laser on Earth would then be fired at the sails, accelerating the mini spacecraft up to 20 percent the speed of light. At this speed, the journey to Alpha Centauri could be made in just 20 years.
Working with ESO, the Breakthrough Initiatives (backed by Russian billionaire Yuri Milner) are going to provide funds to upgrade an instrument on the Very Large Telescope (VLT) in Chile. Called the VLT Imager and Spectrometer for mid-infrared (VISIR), the instrument – as its name suggests – observes stars in mid-infrared wavelengths, allowing the presence of a planet to be noticed by lowering the brightness gap between the star and the planet.
However, planets still appear millions of times dimmer than their host star, even with this technique. So this latest development will see the Breakthrough Initiatives pay for upgrades that use adaptive optics and coronagraphy to reduce the stellar light. The latter involves using a coronagraph to block out the star’s light, making planets easier to spot. As part of the agreement, ESO will begin looking for planets in the Alpha Centauri system from 2019.
Of course, we already know of at least one planet in this system. Last year, it was announced that a planet called Proxima b had been found around Proxima Centauri, and it may be an Earth-like world. This revelation came shortly after Breakthrough Starshot was announced, adding excitement about the mission. A separate initiative, called Project Blue, is attempting to directly image planets around the other two stars in the system, Alpha Centauri A and B, by 2022.
Observing planets on our cosmic doorstep would be a major breakthrough. We've found thousands of planets elsewhere in the galaxy, but having worlds tantalizingly within reach would be hugely exciting. And, who knows, we might just go there in the not too distant future.