Doctor Hammond is Trace's colleague at the New Mexico laboratory where Trace's accident occurs in the game's opening cutscene. Hammond and Trace are also somewhat close friends, as Hammond is the only one who sticks by Trace's side when he is outcast by other scientists.
Doctor Hammond is depicted as a fairly young white man, probably in his 20s, with brown hair shaped into a bowl-cut. He is most often seen wearing a white labcoat and black pants.
Given that Dr. Hammond is the only associate close to Trace that we know of, it is highly likely that he accompanied Trace Prime on the first journey to Sudra. This is evidenced by the fact that Hammond worked closely with Trace on the theories needed to make Breach travel possible, and since Trace was still blind and crippled when he first arrived on Sudra, Trace would not have been able to make the trip alone, nor would he have been able to discover and utilize the Rebirth Chamber alone.
Unfortunately, it is unclear what happens to Doctor Hammond after their arrival on Sudra. It can be logically assumed that Hammond and Trace comprise the "we" written in Faded Note (Note), but from there, Hammond's fate remains a mystery.