Today, the European Southern Observatory announced an agreement with Breakthrough Starshot, A group dedicated to sending hardware to return data from the nearest stars. The agreement would see Breakthrough Starshot fund the development of new hardware that would allow the ESO’s Very Large Telescope to become an efficient planet hunter. The goal is presumably to confirm there’s something in the Alpha Centauri system worth sending spacecraft to image.
Breakthrough Starshot’s audacious plan involves using ground-based lasers and light sails to accelerate tiny craft to a significant fraction of the speed of light. This would allow the craft to visit the stars of the Alpha Centauri system within decades. The company’s goal is to get data back to Earth while many of the people alive today are still around.
Getting meaningful data requires a detailed understanding of the Alpha Centauri system, which is where the new telescope hardware will come in. Last year, scientists confirmed the existence of an exoplanet orbiting the closest star of the three-star system, Proxima Centauri. But we’ll want to know significantly more about the exoplanet, its orbit, and whether there are signs of any other planets in the system before we send spacecraft. The other two stars of Alpha Centauri are also worth a closer look.
But imaging planets around other stars is exceedingly difficult, given that they are (in interstellar terms) exceedingly close to their host star, which drowns out any light originating from the planet itself.
The new hardware will be a modification of existing equipment. The Very Large Telescope is actually four eight-meter telescopes capable of being operated as a single unit. One of these (Unit 3, named “Melipal”) has hardware called VISIR, for VLT Imager and Spectrometer for mid-Infrared. VISIR can separate infrared light into its component wavelengths, which can tell us something about either the source of the light or any objects in between that absorb light of these wavelengths.
Exoplanets turn out to be best to image in the infrared since they often glow with heat, either left over from their formation or due to absorbing light from their host star. But VISIR isn’t specialized for planet hunting. For that, it will need a chronograph, which will blot out the light from the star and make planets easier to spot. VISIR will also need adaptive optics, which can compensate for distortions created by the atmosphere. (The Very Large Telescope may be 2.5km above sea level in a desert, but the atmosphere still poses problems.) And it will likely need additional vibration dampening equipment.
Fortunately, we already know in principle that this plan works. The Gemini Planet Imager has been attached to a similarly sized telescope, and it can perform what used to require days of imaging in a matter of minutes.Regardless of Breakthrough Starshot’s goals, you can bet astronomers will be happy to have a second instrument with those capabilities available.