Exactly a year from now, a capsule will come hurtling through the atmosphere of Mars with the Americans’ next big rover. If it survives the “seven minutes of terror” that describe its descent to the surface, the new robot promises a very different mission to all those that have gone before it. The rover will trundle across equatorial Jezero Crater seeking out rocks that look as though they might have been laid down in the presence of biology. The best examples will be drilled and sealed in small tubes the size of whiteboard markers. These canisters will then be placed on the surface for a later mission to pick up and take home.