Space Exploration By Tonksiboi 2000 BCE First solar-lunar calendar was created 280 BCE Aristarchus suggests the Earth revolves around the sun and estimates Earth-Sun distance 1916 Einstein introduces the Theory of Relativity 1957 Russians launch first official satellite, Sputnik 1 1961 NASA launches a chimpanzee named Ham into space aboard a Mercury Rocket 1966 First moon landing (by Soviet spacecraft Luna 9) 1969 US astronaut Neil Armstrong becomes the first person to walk on the moon 1986 Space shuttle Challenger explodes during launch, killing all 7 crew members 2004 Twin Mars Exploration Rover missions Spirit and Opportunity land on Mars 2015 Astronauts took their first bites of space lettuce 2016 Ice was discovered on Mars in large quantities 2017 Scientists found several planets the same size as Earth, all of which may be capable of supporting life
