Tonight's TV schedule contains a lot of space -- in more ways than one.
* "Day One" (8-9 p.m., WJZ, Channel 13) -- Unless ABC jettisons the prepared pieces of this final "Day One" and goes with the latest on the O. J. Simpson case instead, this hour will contain a report by Robert Krulwich -- who always makes even arcane subjects seem interesting -- on what we don't know about the 1969 moon landing. ABC.
* "The Nanny" (8-8:30 p.m., WBAL, Channel 11) -- Great stunt casting: Renee Taylor guest stars as Fran's mom (Fran Drescher). What accents: Talk about Queens for a day . . . CBS repeat.
* "The Babe" (8-10 p.m., WBFF, Channel 45) -- Hey, Babe, take a walk on the wild side. John Goodman plays Babe Ruth, and embodies him a lot more successfully than he does Fred Flintstone. Yet if you want to see the real Ruth, or learn the most about him, wait until September, when Ken Burns' "Baseball" documentary series more than does him justice. Fox.
* "Northern Exposure" (10-11 p.m., WBAL, Channel 11) -- The best "Northern Exposure" of last season is repeated tonight. It's the one involving the aurora borealis, which somehow causes some Cicely residents to "receive" one another's dreams. Best dream: The one of Maurice (Barry Corbin), in which he plays a shoe salesman waiting on Delia Sheppard, the sexy star of "Mirror Images" and tons of other straight-to-video erotic thrillers. Like the "St. Elsewhere" "Dreams" episode of years ago, it's a classic. CBS repeat.
* "Biography: Christa McAuliffe" (8-9 p.m., Arts and Entertainment) -- To the generation coming of age in the '80s, the Challenger disaster was to them what the Kennedy assassinations were to the previous generation: an unforgettable, horrible trauma, delivered via television. This "Biography" remembers, and salutes, the "teacher in space" member of that mission.
* "Moon Shot" (8:05-10:05 p.m., TBS) -- First of two parts. Barry Corbin, who plays a former astronaut on "Northern Exposure," gives voice to the viewpoint of the late astronaut Deke Slayton, who recounts the space race from his often funny point of view. I'd prefer a straightforward documentary, or docudrama, to this awkward hybrid, but the vintage film clips are often priceless.