No. of Recommendations: 11
1. Plenty
What, exactly?
2. Aerogels are cool. And very versatile. Ask yourself what problem radiation shielding represents to a space vehicle. One must balance protection effectiveness with weight (because every gram matters when launching things).
I have no doubt that they are cool and versatile. But cosmic rays have different physics than other types of radiation.
The problem that radiation shielding for cosmic rays presents to a spaceship is that they can't be blocked with shielding. They are so high-energy that they blast through everything - and when they do interact with something, that interaction creates a secondary radiation emission that is also very dangerous. Ironically, if you provide more shielding it becomes more dangerous for the occupants inside, because the damage from the secondary radiation increases faster than the reduced exposure from the cosmic rays. We can't shield against cosmic rays with any currently-existing technology, nor are there any real prospects for developing a material that can do so over the next few decades.
3. And finally, we can definitely tell who’s a problem solver vs. somebody who points them out, then jumps up and down.
Solving problems isn't always just a matter of optimism vs. pessimism. Some problems simply can't be solved with then-existing technology. You couldn't have launched a space mission in 1880, no matter how much you might have wanted to. You couldn't develop self-driving cars in 1968, no matter what. The general level of human knowledge wasn't far enough along.
We're almost certainly at a similar position when it comes to long-term settlements outside the magnetosphere. We do not have any technology that can possibly provide both: i) earth-level gravity; and ii) protection against cosmic rays. You can get gravity by spinning in a spaceship, but we don't know how to protect a spaceship from cosmic rays. You can get protection from cosmic rays by being deep underground, but we don't know how to generate gravity under those conditions. These are not "we don't know how" like we didn't know how to develop velcro before we did it - these are "we don't know how" in the sense that nothing we know about the physics of the material world suggests a possible solution at current levels of knowledge about the universe.
