The European Southern Observatory — an international research organization that champions ground-based astronomy — plans to turn one of its giant telescopes into an even more superior planet hunter. Specifically, the organization’s Very Large Telescope, or VLT, in northern Chile is getting a hardware upgrade, so that it can better search for planets around the stars of Alpha Centauri, the closest star system to Earth. Located just over 4 billion light-years away, the triple-star Alpha Centauri system could be home to unseen, habitable planets — the closest possible places for life to exist outside our Solar System. If such worlds exist, ESO believes that VLT will be able to directly image them, by enhancing one of the telescope’s main instruments.
To help fund the upgrade, ESO has partnered with Breakthrough Initiatives, a program established in 2015 by Russian venture capitalist Yuri Milner to search for life throughout the Universe. Breakthrough Initiatives has a special interest in Alpha Centauri, as the organization has high hopes of sending a spacecraft there within a generation. The project, called Breakthrough Starshot, wants to transport a tiny vehicle to Alpha Centauri using a giant laser from Earth. Theoretically, photons from a powerful enough laser could propel the small vehicle up to one-fifth the speed of light, allowing the spacecraft to reach Alpha Centauri in just 20-plus years.
Unsurprisingly, Breakthrough Initiatives is very interested in finding planets within the Alpha Centauri system, since such worlds would make great targets for Breakthrough Starshot to analyze. And right now, astronomers know of only one planet at Alpha Centauri. Last year, a rocky, Earth-sized planet was discovered orbiting around Proxima Centuari — the smallest star within the system and the closest one to Earth. The discovery of the planet, named Proxima b, was extra enticing, since the world likely orbits in Proxima Centauri’s habitable zone. That’s the region around a star often referred to as the “Goldilocks zone,” since temperatures are just right for water to exist as a liquid on a planet’s surface. Liquid water is a critical ingredient for life here on Earth, so its presence on another planet may fuel life there as well.
The VLT’s upgrade, which will take a couple years to complete, will focus on a tune-up of the telescope’s VISIR instrument. It’s an imaging tool that observes celestial objects in the mid-infrared, a type of light that can’t be seen but is associated with the emission of heat. Looking for planets in the visible light spectrum can be tough, since the intense light from a star can overpower the faint light of any nearby planets. But observing these objects in mid-infrared can help to reduce the huge “gap” in brightness between a planet and its host star, according to ESO.
However, stars are still super bright in mid-infrared. That’s why the telescope’s VISIR instrument will need a few additional updates to be sensitive enough to pick up planets around the two remaining Sun-like stars in the system — Alpha Centauri A and B. VISIR will get a new sensor and will be updated so that it can employ a technique known as coronagraphy. It’s a way of blocking out the majority of light from a star, to better see the light of an orbiting planet. The instrument will also get a new “detector calibration device,” which will help make the telescope’s observations more precise. Once all the updates are done, ESO says it will allow Breakthrough Initiatives to use VLT for observing Alpha Centauri, potentially as early as 2019.
Of course, finding these planets at Alpha Centauri is just the first step, and there are still many unknowns about what’s out there. It’s possible astronomers won’t find anything at all, or the planets they do find won’t be located in the habitable zones of these stars. Plus finding a planet in a star’s habitable zone is far from a guarantee that the world hosts life. Proxima b, for instance, is so close to Proxima Centauri that it gets blasted with way more solar radiation than we receive on Earth. That’s not exactly conducive to the survival of life as we know it.
And then there’s the prospect of visiting these worlds, which won’t be an easy feat. Breakthrough Starshot still has many technical challenges to overcome before it can hope to send a spacecraft to Alpha Centauri within our lifetimes. For instance, interstellar gas and dust would likely cause such a spacecraft traveling at high speeds to deteriorate significantly on its way to Alpha Centauri, according to a recent study.
It’s all a big gamble, which is why ESO is grateful for funding to do an upgrade in the first place. “The probability that we’ll find a planet we can see is less than 50 percent. So there’s more of a chance we won’t see anything,” Markus Kasper, an ESO scientist, tells The Verge. “Normally this is something funding agencies don’t [fund], but Breakthrough Initiatives have created the excitement and resources to do these kinds of things.”