DARPA defined Very Low Earth Orbit (VLEO) as orbits less than 450 km, or roughly 280 miles, in altitude. Low Earth Orbit, by contrast, is 2,000 km or 1,200 miles. The benefits of being in Very Low Earth Orbit include, according to DARPA, “improved spatial resolution for optical imaging, higher signal-to-noise ratios for radar and lidar systems, improved geospatial position accuracy.” These all let cameras and other sensors on the satellite better observe activity on Earth below, and communicate those observations more quickly and accurately. In addition, DARPA suggests that it’s cheaper and easier to put a satellite into VLEO, noting “greater launch vehicle insertion capability, and mass, volume, and cost savings.” Even more importantly than all of that, because VLEO is so close to Earth and so far from other satellites, the low satellites can get away with less radiation protection, and are generally out of the path of most orbital debris.