High Accuracy Radial Velocity Planet Searcher
Mayor's work focused more on improving instrumentation for radial velocity measurements to improve detecting exoplanets and measuring their properties. Mayor led a team to further improve ELODIE to increase velocity measurement accuracy to 1 m/s via the High Accuracy Radial Velocity Planet Searcher (HARPS) installed on the ESO 3.6 m Telescope at La Silla Observatory in Chile by 2003. Mayor led the team that used HARPS to seek out other exoplanets. In 2007, Mayor was one of 11 European scientists who discovered Gliese 581c, the first extrasolar planet in a star's habitable zone, from the ESO telescope. In 2009, Mayor and his team discovered the lightest exoplanet ever detected around a main sequence star: Gliese 581e. Nonetheless, Mayor noted that humans will never migrate to such exoplanets since they are "much, much too far away ... [and would take] hundreds of millions of days using the means we have available today". However, due to discoveries by Mayor, searching for extraterrestrial communications from exoplanets may now be a more practical consideration than thought earlier.