Answer:
Manned spacecraft are vehicles that can transport human beings outside the Earth's atmosphere. An unmanned space mission is launched without human passengers or crew. When a vehicle is unmanned, it's controlled from far away or by a robotic or autopilot system. Compared to manned missions, unmanned missions are less expensive, as their missions are able to gather data for an extended period of time. Messenger: sent on a mission to Mercury; about $446 million (including spacecraft and instrument development, launch vehicle, mission operations and data analysis).