Mars beckons
Mankind has never been closer to setting foot on Mars. NASA is completing construction of its new Mars rover, in readiness for launching next summer, while SpaceX is firing prototypes of its Mars rocket engines, getting ready for short test flights in late 2020. David Pogue reports on the prognosis for manned exploration of the Red Planet, and how human endurance is being tested in a habitat constructed on the slopes of a Hawaiian volcano.