unmanned exploration; unmanned probing
Refers to exploration or investigation conducted by unmanned vehicles, probes, or robots, especially in space or hazardous environments.
NASA is planning unmanned exploration of Mars.
Robots are used for unmanned exploration of the deep sea.
有人探査 means manned exploration, contrasting with 無人探査 which is unmanned.
Compound of 無人 (むじん, 'unmanned') and 探査 (たんさ, 'exploration/probing').