The more difficult second level requires a flight of 180 seconds followed by a landing on simulated lunar terrain, complete with rocks and craters.
更困难的第二个级别，要求飞行180秒，接着在遍布岩石和陨石坑的模拟月球地形上降落。
2
Also new is a 3d map of Mars, which includes high-resolution images from NASA, 3d terrain data, and annotations for landing sites and other interesting features.
此外Google Earth还提供了火星的3d地图，并附有来自美国航空航天局的高分辨率照片。
3
In order to achieve safe landing in a region of complex terrain with high scientific value, future planetary landers must have the capability of autonomous obstacle detection and avoidance.