The Explorers are a club of like-minded individuals who ride the shuttles to newly discovered planets and conduct scientific research into their contents. Usually some of this data is known in advance (breathable atmosphere, temperature, etc), but things like what rare chemicals and minerals can be found or what previous cultures may have inhabited an area tend to be more the domain of the Explorers and their fellows in planetbound expeditions, the Miners, Xenoarchaeologists, and the like. Typically a lead explorer brings one of the Overwatch Cameras so that the bridge can monitor their activities from a safe distance, the better to confirm whether to send in the miners or the Marines.