During the first two orbits, it proved difficult to reliably track Sputnik 2's flight path, but ground controllers were able to intercept theodolite data from an American tracking station in Perth, Australia. Data showed that Laika's heart rate and breathing spiked rapidly during ascent, but she otherwise reached orbit largely unscathed. Official Soviet press releases stated that Laika survived a week in orbit, but information released in the post-Soviet era indicated that she died only a few hours into the mission. Other sources suggested it had been four days before the dog succumbed to overheating and carbon dioxide buildup.