What if Earth had a truly habitable sister planet?

How long did it take humans to go from the cart wheel and the steam engine to cars? Quite literally 2 millennia of refinement. There is a reason we've been able to land probes on mars for decades but never a human. The scale of the challenge is at least an order of magnitude more difficult. We haven't even managed a Mars sample return and there's a very good reason for that.

Another keyword, atmosphere. Getting out of atmosphere is again far more difficult than just going to mars and back, again something we haven't yet accomplished.

The reason they stayed concepts is because the people who payed for the prior feats decided it wasn’t worth it to pay to do it again on body further away and with higher gravity than the Moon.

Lastly, do you have a shred of evidence for this? For such a claim you must have the reports from the 50s saying it's feasible but too expensive? This flies in the face of what a concept is by any definition. As I said, it would be a historic undertaking to build something remotely similar to this today. It could probably be done, but only if we devoted a substantial portion of global GDP to research and engineering. Regardless, the concepts in the 50s were made before any human had even made it to space. The field was in its infancy and the concepts are more adjacent to pipe dreams than concepts, because again, they were made years before we even seriously considered going to the moon.

/r/HistoryWhatIf Thread Parent