Tardigrades have a reputation as the toughest animals on the planet. Some of these microscopic invertebrates shrug off temperatures of minus 272 Celsius, one degree warmer than absolute zero. Other species can endure powerful radiation and the vacuum of space. In 2007, the European Space Agency sent 3,000 animals into low Earth orbit, where the tardigrades survived for 12 days on the outside of the capsule. To a group of theoretical physicists, tardigrades were the perfect specimens to test life's tenacity. “Life is pretty fragile if all your estimates are based on humans or dinosaurs,” said David Sloan, a theoretical cosmologist at Oxford University in Britain. The tardigrade lineage is ancient. “Tardigrade microfossils are reported from the Early Cambrian to the Early Cretaceous, 520 million to 100 million years ago,” said Ralph O. Schill, an expert on tardigrades at the University of Stuttgart in Germany who was not involved with this research. “They have seen the dinosaurs come and go.” Read more: https://www.washingtonpost.com/news...h-astrophysicists-say/?utm_term=.be7b6a873869