An exobiologist (also referred to as astrobiologist or xenobiologist) was a biologist who specialized in the field of exobiology. Doctor Phlox once noted to Elizabeth Cutler that he found her "assistance in the field invaluable" due to her training as an exobiologist. (ENT: "Dear Doctor") Rudolph Ransom was a Starfleet exobiologist who was promoted to captain after he made first contact with the Yridians. (VOY: "Equinox") In early 2368, two new exobiologists and three stellar cartographers transferred from the USS Zhukov to the USS Enterprise-D. (TNG: "The Game" )