Research vessels are terran large ships designed to ferry researchers to field sites.
During the End War, Cartwright's researchers used these vessels to bring researchers to the xel'naga ruins on the planet. Cartwright requested the allied commanders help protect them from Amon's Forces.
Research vessels are the bonus objective of the Co-op Missions map "Void Launch." At preset times they will launch to the three shrines on the map, first to the middle, then to the east, finally to the west. After the vessels land, a smaller enemy attack wave will spawn to attack the vessel.