Current drone applications are limited to using drones for non-interactive tele-detection, "eyes and noses in the air". The following breakthrough is tele-interaction, "hands in the air". The MARS4Earth project aspires to develop the first autonomous and modular aerial manipulator that interacts physically with an outdoor operational environment in a safe, autonomous, efficient and cost-effective way. The research mainly focuses on the question of whether it is possible to develop a prototype of a modular and completely autonomous aerial manipulator that can physically interact with a realistic outdoor environment. In essence, the aerial manipulator acts as "arms and hands in the air", which can be used for both active and passive aerial interaction. The applicability of this technology will be demonstrated in three chosen application domains, inspection and maintenance (maintenance of offshore windmill and cleaning solar panels), agriculture (selective treatment of plants and sample picking) and Safety and Security (active firefighting). Funded by Netherlands Organisation for Scientific Research (NWO) (RAAK.PRO03.112).