5 June – Researchers at Case Western Reserve University School of Medicine synthesise the first artificial human prion.[183] 6 June Footprints in the Yangtze Gorges area of South China, dating back 546 million years, are reported to be the earliest known record of an animal with legs.[184] The spacecraft Dawn assumes a final (and much closer) orbit around the dwarf planet Ceres: as close as 35 km (22 mi) and as far away as 4,000 km (2,500 mi) (see images).[185][186] 7 June – NASA announces that the Curiosity rover has detected a cyclical seasonal variation in atmospheric methane (see image) on the planet Mars, as well as the presence of kerogen and other complex organic compounds.[187][188][189][190][191][192][193][194] 8 June – The U.S. Department of Energy’s Oak Ridge National Laboratory unveils Summit as the world’s most powerful supercomputer, with a peak performance of 200,000 trillion calculations per second, or 200 petaflops.[195][196] 11 June – KATRIN, an experiment designed to measure the absolute mass of neutrinos, starts data-taking.[197]