One of the world’s most powerful telescopes is to search for habitable planets around the closest star to help prepare for a mission by a fleet of spacecraft to visit them. 

The British-backed Very Large Telescope (VLT) in Chile will have its camera adapted to make it more sensitive to the faint light from distant alien worlds.

Last year a rocky, potentially habitable planet was detected orbiting Proxima Centauri, the faintest star in a three-star system known as Alpha Centauri.

Apart from our own Sun, Proxima Centauri is the closest star to us at a distance of just 4.2 light-years.

The discovery of a planet was announced just four months after a consortium of scientists and millionaires announced their Breakthrough Starshot project to develop fleet of miniature spacecraft, dubbed nanocraft, that could reach the star system within 20 years.

Physicist Professor Stephen Hawking announced the $100 million project which is supported by Facebook founder Mark Zuckerberg and Internet investor and science philanthropist Yuri Milner.

Current technology means a spacecraft would take about 30,000 years to get to the Alpha Centauri system. Breakthrough Starshot’s nanocraft are intended to be propelled by a beam of light pushing on tiny sails, just as ocean-borne ships were once driven by the wind.

While the Breakthrough Starshot team develops the space technology, astronomers will attempt to find out more about what planets exist in the Alpha Centauri system.

The camera being adapted to search for them is known as the VISIR (VLT Imager and Spectrometer for mid-Infrared) instrument. The telescope’s operators, the European Southern Observatory (ESO), have signed an agreement with Breakthrough Initiatives to carry out the modifications and provide telescope time away from conventional research to carry out a careful search programme.

ESO’s video about the discovery of a potentially habitable planet orbiting Proxima Centauri

Spotting an Earth-sized habitable planet around even the nearest stars is a huge challenge due to the overwhelming brightness of the star compared to the relatively dim planet.

The planets become “brighter” when viewed in mid-infrared light which detects the heat from their surface. But even then, the star is still millions of times brighter than the planets.

The VLT’s existing mid-infrared instrument VISIR will be able to cope with the blinding light from the home star if it is adapted. Technicians will enhance it to improve the image quality significantly using adaptive optics. They will also employ a technique called coronagraphy to reduce the star’s light allowing signals from potential rocky planets to be detected.

The VLT is actually an array of four giant optical telescopes, each with a main mirror 8.2 meters across, that can work independently or together.

Another awesome bit of kit attached to the VLT, and called KMOS, can study 24 distant galaxies at a time to learn more about the early Universe.

ESO is beginning construction of a much bigger telescope than the VLT with the equally unimaginative name of the European Extremely Large Telescope (E-ELT). With a segmented main mirror 39.3 meters, the instrument has the discovery and study of potentially habitable planets orbiting other stars as a major goal.