It’s been nearly a decade since NASA’s Kepler mission first launched. Beginning in 2009, the Kepler spacecraft watched hundreds of thousands of stars within our own galaxy, measuring the total amount of light output for each one and searching for any minuscule changes. By mission’s end, Kepler and its add-on mission, K2, had discovered thousands of new planets around stars beyond our own, including a significant number of Earth-sized, potentially habitable worlds.
If Kepler showed us that our galaxy was full of planets, then its successor mission, TESS — the Transiting Exoplanet Survey Satellite — will reveal the transiting worlds around the closest stars to our own. If there’s an Earth-like world that passes in front of its parent star relative to our line-of-sight, TESS will reveal it. For the first time, we’ll be sensitive to the “holy grail” of planets right in our own backyard.