A map of a Moon crater. A ‘lidar’ – the laser equivalent of radar – will be an essential part of ESA’s autonomous landing and navigation system for Luna-27. Leia (Lidar for Extra-terrestrial Imaging Applications) will scan the surface of the Moon with a laser for hazards such as slopes, boulders, craters and shadows. If the site seems too dangerous, the lander can decide to target a safer zone.