text:  And this was about not only spending time on Mars, but also travelling to Mars. I mean, that's a journey that's going to take, what, six, eight months? Yes, it can take anywhere between six, nine months or possibly even longer. And of course, then the same to get back again. So I think the estimate is that a whole duration of a crew trip to Mars would probably be about 21 months, which is a long time.