A proposed Chinese mission would look for nearby potentially habitable alien worlds by launching a spacecraft to make ultraprecise measurements of how orbiting planets make a star wobble.

For this mission, called the Closeby Habitable Exoplanet Survey (CHES), the scientists would use a method called micro-arcsecond relative astrometry. This technique involves taking ultraprecise measurements of the positions and movements of stars compared with a set of background reference stars to detect the perturbations of a star resulting from the gravitational influence of exoplanets as they orbit their stars.

This method would provide estimates of the masses of exoplanets and the distance at which they orbit their stars, which, in turn, might reveal if these exoplanets have the potential to host life. The European Space Agency's Gaia space telescope is using the same method to create a 3D map of a billion stars in the Milky Way. (Other planet-seeking missions, such as NASA's Transiting Exoplanet Survey Satellite, use a different technique, called the transit method, which looks for dips in the luminosity of a star as planets cross it. However, this method requires planets to orbit edge-on with respect to the observer.)