A rescue team is a special away team comprised of Federation Starfleet personnel in an event that an away mission is required to rescue potential survivors from a previous away mission. Occasionally, multiple rescue teams are deployed for the same rescue mission.
A rescue team was sent from the USS Voyager in to an irradiated M-class moon in 2374, but the primary mission was the recovery of Omega molecules from a research facility. (VOY: "The Omega Directive")
After the Delta Flyer ran into multiple ion storms and crash-landed on the surface of a M-class planetoid, Voyager deployed rescue teams to find the Delta Flyer crew. Rescue team alpha led by Chakotay asked Seven of Nine for data on the caverns near the crash site. (VOY: "Once Upon a Time")