Atmosphere of Triton asymmetry was actually observed during star occultations by Triton in 1990s. Before Voyager 2 arrived, a nitrogen and methane atmosphere with a density as much as 30% that of Earth had been suggested. This proved to be a great overestimate, similar to the predictions of the atmospheric density of Mars, but like on Mars, a denser early atmosphere is postulated. Voyager 2 flew past Triton five hours after closest approach to Neptune in mid-late August 1989. During the flyby, Voyager 2 took measurements of the atmosphere, finding methane and nitrogen in the atmosphere. In the 1990s, observations from Earth were
S-80-class submarine weapons and sensors, which their government decided not to fund. DCNI then proposed a cheaper option called the S-90B, an S-70 "Agosta"-class submarine with limited improvements which was again rejected by the French but which was exported to Pakistan. Meanwhile, Spain faced the same problem in replacing their "Daphné"s, known as the "Delfín" class in Spanish service, as part of Plan ALTAMAR. Bazán (later Izar, and then Navantia) started on a new design but when it started to look like the S-80, it was agreed to collaborate in a joint venture based on the French S-80. This joint design was