The Bear Case for Mars

What if colonisation is much harder than advocates hope for? Can it still be done, and should it be? And are there other options if Mars is out?

Today SpaceX conducted its first flight test of the full Starship rocket, which after a number of engine and control problems on ascent, failed near the point of stage separation. It has taken a long time to get to this point; the last test flight was almost 2 years ago and it is over a year since the first Starship/Super Heavy stack when Elon Musk clai…