Tensions between the Russian space agency and those of western nations due to Vladimir Putin’s invasion of Ukraine became more personal over the weekend, as Russia’s space chief attacked a Nasa astronaut on Twitter and likened the Ukrainian president to Adolph Hitler. In the wake of Russia’s invasion of Ukraine on 24 February, the European Space Agency and Nasa issued carefully worded statements about the value of international cooperation in space, particularly on the International Space Station, which currently hosts five Nasa and European astronauts and two Russian cosmonauts . But Dmitry Rogozin, director general of Russia’s space agency, Roscosmos,...