A number of news sites says hacker community Anonymous has hacked the European Space Agency. Anonymous has previously targeted organisations like the Church of Scientology, the Westboro Baptist Church and ISIS. To add ESA to that list seem a bit odd. Not sure everyone takes Anonymous seriously but for those who do their new hack may need a better explanation than doing it just for fun. IBTimes is one of few sources saying this is hack is not verified independently.
Computer World: Attackers hack European Space Agency
Tech Times: Anonymous hacks European Space Agency