5 Humans in Space Between 1968 and 1972 seven spacecraft and 24 astronauts made the nearly 250,000-mile 400,000-km journey to the Moon Since then astronauts have been confined to orbiting Earth At present the only habitat for humans in Space is the International Space Station ISS which orbits about 220 miles 354 km above Earth Exploring Space Scientists study Space to try to understand how the Universe began and how it works They are searching for traces of life on other planets and for minerals that could be useful to humans on Earth Scientists also use satellites in Space to study events on Earth such as floods and forest fires rising sea levels and air pollution In this book we will look at how space scientists carry out their research what they do with the results and some of the discoveries they have made This close-up of Saturn and its rings was taken by an unmanned spacecraft called Cassini DANGER Lack of air to breathe is not the only hazard facing astronauts in Space The temperature changes from 212 F 100 C in the sunlight to extremely cold 148 F 100 C in the shadows In addition lethal amounts of radiation from solar particles and cosmic rays can strike with little or no warning
