After more than 10 years in orbit, the first Copernicus Sentinel-2 satellite, Sentinel-2A, is still finding new ways to contribute to Earth observation. With its younger siblings, Sentinel-2B and Sentinel-2C, now leading the mission’s core task of delivering high-resolution, ‘camera-like’ images of Earth’s surface, the European Space Agency is pushing Sentinel-2A beyond its original remit.
At the beginning of the exoplanet age, the goals were fairly simple. The first was to find as many of them as possible to flesh out our understanding of the exoplanet population. The second was to determine if any were in the habitable zones around their stars. The definition of a habitable zone was necessarily simple in the beginning. Any planet in the right distance range from its star to allow liquid surface water was considered to be in the habitable zone.

