London. Four years ago, a European spacecraft has started observing from close range the asteroid that the American space agency NASA had hit during Earth's defense test. As announced by the European Space Agency (ESA) on Wednesday, the spacecraft named 'Hera' is currently studying the asteroid 'Didymos' and its small moon 'Dimorphos' from a distance of 25 to 30 kilometers. To test whether Earth can be protected from potentially fatal space rocks in the future, NASA had deliberately crashed its 'DART' spacecraft into Dimorphos in 2022. That collision had shortened the orbit of Dimorphos around Didymos and also caused a...