By the late 2360s, Dalen had risen to become commanding officer of the USS Darwin, a starship manned entirely by Horta and had been adapted to be a suitable environment for Horta. In 2369, Dalen commanded the Darwin on a scientific and archaeological expedition into the Sarpeidon Nebula and performed extensive research on the extinct Sarpeidan species.
The following year, Dalen and the Darwin were ordered to assist the USS Enterprise-D in exploring a Dyson Sphere. Enroute, Dalen studied the current research available on the Dyson Sphere and began to see certain similarities between the builders of the Sphere and the Sarpeidans. (TNG novel: Dyson Sphere)