If humans ever do leave this solar system, most probably they would not do it aimlessly. More likely they would set a course for some distant waypoint, some other solar system perhaps, to visit, or maybe settle down. When they do so, there is a good possible chance that the new planet-hunting spacecraft of NASA would have discovered the destination they choose.
Known as the Transiting Exoplanet Survey Satellite, the instrument soon would hitch a ride to space abroad one of the SpaceX’s Falcon 9 rockets. There, from a highly unusual orbit, TESS would lead a search for the planets beyond our solar system also more ambitious than the one mounted by Kepler Space Telescope, its predecessor, by seeking rocky alien worlds in our immediate galactic vicinity.
Like that of Kepler, TESS is designed to identify small dips in the light emanating from the stars. Those dips could serve as clues that an orbiting planet is motioning across the face of its parent star, avoiding some of its light from reaching the spacecraft in a phenomenon that the astronomers call a transit.
The use of the transit method by Kepler fundamentally changed people’s view of the universe. Thirty years ago, the astronomers knew of only nine (currently eight) planets-those who comprise our solar system. Throughout the ’90s the scientists found a handful of planets orbiting the other stars; but as recently as a decade ago, it still was unclear if the so-called exoplanets were rare or commonplace in the galaxy. Even the prevalence of potentially habitable worlds was not known.
But Kepler that launched in the year 2009 changed that in a big deal. It surveyed only a tiny patch of the sky. But inside that tiny patch, Kepler has discovered, more than 2,300 exoplanets, dozens of which could host liquid water. By Kepler’s sampling, now the astronomers believe that the planets of the Milky Way could outnumber its stars and that our galaxy could be home to many billions of habitable worlds.