I enjoyed Jake Tapper’s guide to The X-Files’ past presence both inside and outside the Beltway (“Local Aliens,” 4/17). Being only a casual X-Files viewer, I hadn’t realized the show had been quite that pervasive over its five-season run. The one local reference that was omitted, however, was the one that stuck the most in my mind. In its “Tunguska/Terma” episode (1996), we visit the NASA Goddard Space Flight Center’s “Department of Exobiology” (if this department truly exists) in Greenbelt, Md., where a sample is taken from a Mars rock. (No, I am not a fan who has each episode committed to memory—in fact, I researched this fact, just to be certain I hadn’t dreamt it up—or had the memory purposefully implanted by some shadowy government agency…)

Greenbelt, Md.