Smith plays The Doctor, who hops about the universe in a time machine called a TARDIS shaped like an old-style British police phone box. The show ran on the BBC as a serialized daytime series for kids from 1963 to 1989 and achieved worldwide cult status with science-fiction fans.
The BBC revived the series as a nighttime drama in 2005. It became an instant hit, spawning two spin-off series.
Smith is entering his second season as The Doctor. He is the 11th actor, and, at 28, the youngest to play the role. (When the first Doctor, William Hartnell, became too ill to work in 1966, the show's writers came up with a clever plot device: The Doctor regenerates into a new body when near death, thus allowing new actors to take over the role.)
The current series usually films in and around Cardiff, Wales, but for the new season (which will begin airing next spring), producer Steven Moffat and his crew are filming two episodes in the United States.
"It says a lot for the scope and ambition of this particular [season] that we're doing," Smith said. "It lays down our mark about how epic we want this particular [season] to feel."
Moffat's crew started scouting locations in September, said Marshall Moore, director of the Utah Film Commission. After considering shooting at landmarks such as Mount Rushmore, "they settled on the look of the American West," Moore said.
Smith wouldn't divulge why The Doctor travels to Monument Valley, beyond saying "he's there for a very important reason, and the universe depends on him making the right choice."
Along with Smith, co-stars Karen Gillan and Arthur Darvill who play The Doctor's traveling companion, the feisty Scotswoman Amy Pond, and her sometimes clueless new husband, Rory are in Utah for the shoot. So is "ER" star Alex Kingston, who has a recurring role as interstellar bandit Dr. River Song.
About 30 local crew members are working on the shoot, Moore said. The crew is small compared with some Utah productions, but "it's a high-profile show," Moore said. "This is one of those cases where you like having that kind of exposure."
Just who is "Doctor Who"?
"Doctor Who" premiered on the BBC in 1963 and ran as a serialized daytime show for kids until 1989. The BBC revived the show in 2005 as a nighttime drama, which has become a worldwide success.
Reruns of "Doctor Who" air Saturday nights at 11 on KUED, Channel 7. BBC America will air new episodes this spring, as well as the annual Christmas episode with guest star Michael Gambon on Christmas, at 7 p.m. Mountain time.
Season Five of "Doctor Who" was just released on DVD.