...than expected. That's my point.

Interestingly John Campbell predicted it would be even less like Earth than we found it to be - he predicted 0.001 bar of ozone for an atmosphere, back in 1937. But he still imagined plant-life and great big gasping critters... the seasonal colour changes couldn't be explained any other way, could they?

Except now we know better. Mars fooled us all.

But then space itself has proven somewhat deadlier than imagined. By 1950 everyone knew meteoroids weren't the disaster waiting to happen they were imagined to be in the 1930s. Cosmic rays were a big unknown. But no one expected the Sun to pump out so much high-energy nastiness during flares. And no one expected the Van Allen Belts of Earth or Jupiter would be so inconveniently placed or so full of charged death.

Space-travel, for real, killed the old romances of Earth-like life everywhere. No "Captain Future" or "Dan Dare" scenario with humanoids on every planet (fun old stories those.)

Micro-electronics and the Van Allen Belts killed all the intermediate altitude manned Space Stations everyone expected.

A bone-dry Moon killed the idea of a refuelling port built there.

An unbearably hot Venus killed so many tales dead.

Nuclear propulsion proved harder than anyone imagined.

Chemical rockets proved more expensive than anyone imagined.

I could go on.

Von Braun's old 1969 presentation on what to do with and after "Apollo" wasn't much different to what he imagined in 1948 or published in "Colliers" in 1952. I grew up imagining how the world would be with a "Space Base" and the Nuclear Shuttle supporting a Moon base infra-structure and then NERVA propelled Mars missions... but then discovered - 20 years after the fact - that it had all been strangled in its crib by Nixon.

Having lived with that disillusionment for the next 20 years has been difficult at times. Discovering that the Shuttle was oversold and many, many worthwhile planetary missions never leave the study stage, has only matured my cynicism.

However Zubrin's Mars plan kept the 'fire' alight for me, even if the technical details continually mutate. And I agree that colonisation is the only worthwhile goal - at present. It's too soon to imagine how money might be made off-world. First we have to get off-world for real!

Enough rant. That's off my chest.