I think the analogies to colonization of remote areas on Earth used to suggest that human colonization of Mars will be possible in the near future (i.e. within next century) are far-fetched & invalid.

You might as well analogize that Incredible Journey type submarine journeys of miniaturized humans into a person's blood vessels is also a near possibility because we have mastered aquatic submarines.

There is, literally, a world of difference between trying to set up humans living on Mars compared to doing the same on even the most inhospitable Earthly environment, such as Antarctica.

For that matter, consider how far we are now from setting up the sort of large-scale human colony on the ocean's bottom that Fraser & Pamela suggested might be set up on Mars. Yet even that would be orders of magnitude easier than the Martian scenario.

I think expending vast resources on such pipe dreams today or even within the next few decades would be like Elizabethan England deciding they are going to land people on the moon. Even if every human and physical resource on Earth had been expended in the effort, it could have not succeeded. The knowledge & technology required simply had not yet been acquired at that time, and no matter how hard they'd tried, could not have been whipped up in a few decades.

I think the same is true now for human travel to & habitation of other planets. It's just too soon, and even though technological and scientific progress does seem exponential in some aspects, the innovations needed are so vast it will still take, I think, many decades or even centuries.

The notion that Mars colonization could be a "back up" in case humans make Earth uninhabitable for our species is a particularly sad and deluded concept, and even one dollar spent on that pipe dream rather than on finding ways to keep our own planet healthy and livable on is a criminal waste.

That said, I do have an idea for a hybrid position between the two seemingly opposed ideas of robot vs. human exploration of Mars that I will post in a separate thread.

P.S. Don't take my rhetoric personally! When I say Mars as "back up" is a sad & deluded concept, I am referring specifically to the concept, and not to our beloved hosts, Fraser & Pamela, whom I admire & respect greatly. I love the Astronomy Cast podcast, & in an electronically platonic way, its creators as well. Being a Vancouverite, I also feel a certain geographical kinship with Fraser.

So, unlike those who say "no offense" just before saying something really offensive, I must stress: no offense intended!