Mars 2020 is the latest, and in important ways most ambitious, of the space missions of the United States and a growing number of other nations. On Feb. 18, the roving vehicle Perseverance landed on ...

It sounds like a pretty absurd premise: in a post-apocalyptic world, the city of London – or what’s left of it – has been hoisted onto huge tracks and hunts down other smaller cities for resources.

Mars 2020 is the latest, and in important ways most ambitious, of the space missions of the United States and a growing number of other nations. On February 18, the roving vehicle Perseverance landed ...