Chief Lucan is a scientist who traveled aboard the Nexus to Andromeda. He specializes in planetary geology and oceanography.
On Pathfinder Ryder's first visit to the Nexus Chief Lucan can be found in Nexus Operations along with fellow scientists Professor Herik and Dr. Leynomi Aridana. He asks the Pathfinder to hit some rocks for science in exchange for monetary reward.
Once he and his fellow scientists move to the Tech Lab, the Chief can be overheard talking to Dr. Suvi Anwar about underground Remnant vaults. Suvi thinks it's more practical to build them on the surface, but Lucan disagrees: the rachni mastered underground construction over a thousand years ago, and the Remnant may have the same idea. He wouldn't mind taking seismometer readings, though, and requests SAM's assistance for it.
If the Pathfinder confronts Dr. Aridana about a virus that almost brings down SAM Node, the doctor defends herself and Chief Lucan later notes that the VI kiosk is currently busted. If Ryder downplays the threat of the anti-AI activists, the Chief snarks that entire races have been driven to exile by their AI creations, justifying the mindset.