Microlensing search for planets

Using gravitational microlensing, a space-based wide-field imager could carry out a search for planets with greater sensitivity than any other technique. Because the amplitude of the microlensing signature is independent of planet mass, the survey would extend down to Mars-mass planets, at least a decade below other techniques. While most sensitive to planets in the so-called “lensing zone” (roughly 1-5 AU from star), the microlensing technique probes planets over a broad range of separations, and is the only method that is sensitive to free-floating planets. It is also the only technique capable of conducting a planetary census at a wide range of Galactocentric distances.