"The frontier" is an arbitrary concept that we choose. We can choose another one.
We have limited time and limited resources, whatever we use for one thing we stop using for another. When the public mind is focusing on a big thing like space, it is not focusing (and reallocating enough resources) to another big thing like reaching the Earth's core.
I don't think it can be handwaved away, I think it's impossible outside of fanciful science fiction.
I'm sure that with enough time and effort we can figure out how to reach the Earth's core. Of course it will take a lot of creativity and lots of people and resources to figure it out, but we can definitely do it.
Also the Earth is right here, we are on it right now. Mars is very, very far away. We can iterate a lot faster here on Earth than anything we want to do on Mars.
What do we gain by colonizing Mars?
We can probably gain the same, or more, and faster, trying to reach the Earth's core first than trying to colonize Mars. In fact, reaching the Earth's core might even make it easier/faster to colonize Mars by applying all the knowledge and tech we would develop.
The deepest hole ever dug is not even to the mantle and is less than a foot wide. We could all live in a (modestly) deep cave no problem, but navigating lava is beyond the properties of any known material.
It's literally impossible to reach the core. No nanomaterials, no carbon nanotubules, no fusion reactors, no superalloys. I am 100% confident saying that human kind will never reach the center of the Earth.
The only reason why the Earth's core might seem out of reach to you is because of how little focus and resources have been put into it (compared to colonizing Mars).
> I am 100% confident saying that human kind will never reach the center of the Earth
Well, that is your own personal opinion. And in my personal opinion, it sounds very pessimistic.
We can definitely do it, and we might not even need to drill any holes. We just need to get excited about it and go for it.
On the topic of surviving extinction level events, it may very well be that researching how to live deep down indefinitely is a much better way to spend resources than researching how to survive Mars.
But for some reason you are arguing about going to the core -- which is so far beyond our current technology level that we may as well consider it scientifically impossible for now.
> -- which is so far beyond our current technology level that we may as well consider it scientifically impossible for now.
That's exactly it. Going to space or Mars, were impossible dreams for hundreds or thousands of years, now we have robots and satellites over there.
If we don't dream about going to the core, we will never get there. Big challenges make us dream big and work hard to accomplish them.
Also, despite now seeming so hard, I bet there's tons of low hanging fruit discoveries just waiting to happen. Have you seen a diagram of the inside of Earth? It's just laughable, especially if you compare that to the level of detail that we have of Earth's surface, or even the Martian surface.
I completely disagree with you here. Neither economies or governments (or "the public mind") are so completely focused and one dimensional as to only direct resources towards one endeavor.
The Apollo program didn't prevent the Soviets from drilling the borehole in the early 70's or Jacque Cousteau from exploring the oceans in the 60's.