which led to the "natural" idea that the Russians were experimenting separately from the Syndicate to create a vaccine for the black oil. Series writer John Shiban felt it was natural to create an arms race-like story between the United States and Russia, being that the Cold War had ended a few years earlier. The writers desired to expand the series' mythology globally, a concept that continued into the fifth season and the series' 1998 feature film adaptation. The idea of a conspiracy with a global reach was first broached in the series' second season, and it was felt that this two-part story was a good place to expand upon this, allowing the production crew to "stretch the limits" of their resources and imagination. The inspiration for the oil-containing rocks was NASA's announcement of possible evidence of extraterrestrial life in the Allan Hills 84001 meteorite; while the gulag scenes were based on Aleksandr Solzhenitsyn's books The Gulag Archipelago and One Day in the Life of Ivan Denisovich. The scenes featuring the SWAT raid on a terrorist cell found to be harbouring Alex Krycek were filmed in a single night, requiring sixty individual film setups split between three camera crews working simultaneously. By dawn, only four of the sixty required shots had not been filmed, and these were later completed on a sound stage. Additional scenes shot for the episode featuring The Smoking Man and the Well-Manicured Man were cut due to time constraints. A scene featuring Scully briefing Skinner on the events of the episode was also cut, as it was felt that it was "redundant" within the narrative, repeating information that had already been shown to the audience. David Duchovny's father was present during production of the episode, leaving the actor to enjoy the shoot, although the crew described production as expensive and "stubbornly trouble-plagued". "Tunguska" marked the fourth appearance in the series by Malcolm Stewart, who had previously appeared in "Pilot", "3" and "Avatar". Reception Ratings "Tunguska" premiered on the Fox network on , and was first broadcast in the United Kingdom on BBC Two on . The episode earned a Nielsen household rating of 12.2 with an 18 share, meaning that roughly of all television-equipped households, and of households watching television, were tuned in to the episode. A total of viewers watched this episode during its original airing. Reviews "Tunguska" received mostly positive reviews from critics. Based