Asteroids are apparently a lot softer and fluffier than we thought. More like gravel and sand clumped together rather than being giant boulders.
Close up pictures showed that it is a lot less homogeneous than they expected, with huge boulders right on the surface as well. That doesn’t match with the measured mass and density since boulders are heavy and dense, but maybe there are more internal voids. But then when they touched it, the nitrogen gas that was supposed to blow some dust and sand into the collection chamber also threw a huge amount of material out and away from the probe. It may even have shattered some of the gravel, meaning that stuff is really more like styrofoam. It may still be silicates, but it is probably foamy. Think of pumice rather than sandstone or granite. Those giant boulders might be more like stage props than actual boulders. It will be very interesting to see what that stuff looks like when they get the samples back.
All those stories of hollowing out an asteroid and turning it into a habitat or generation ship for 50,000 people aren’t looking so prescient. :)
Of course on the other hand it could turn out to just be selection bias: sample return missions are obviously going to pick a low–density asteroid that they hope will at least have some dust they can scoop up, instead of picking a really dense one that might turn out to be too difficult to collect from.
Also, I’m ignoring the dwarf planets that happen to be in the asteroid belt, like Ceres. We can reasonably expect them to have some real rocks.
Even simpler then, insert giant balloon in the middle, pump it up, cover walls with concerete and you have habitat, no expensive drilling and hollowing out.
> Heating and melting foam is harder than solid rock or metal
You can grind it, then blow it with very hot gas onto your baloon, making a nice melted coat of rocks. This technique is already used to repair metal rotor shafts, it deposits machinable metal: https://www.youtube.com/watch?v=NAeBpF84Q9M
Hollowing out an asteroid is more about raw materials and micrometeorite/particle shielding, both of which a slushy will provide in abundance.
If it's as loose as that then you could just put an inner steel "pressure" hull (the actual pressure from the outside would be negligible but it'd have to be able handle a human compatible air pressure) inside the asteroid and use the asteroid material as a radiation shield instead I guess.
Would work for a base but not for a ship with any appreciable thrust would shed material.
It would be very interesting to figure out how far away we are from the technology to send a "Seed" probe to a large conglomerate asteroid, designed to replicate itself into thousands of builder-bots. Then the builders would slowly but surely turn the asteroid into millions of assembler-chunks consisting of layers of concrete and metal. Then those assemblers would connect to each other, turning into sections of habitat hull.
Basically do it like Mother Nature does it: tiny building blocks that self-assemble into bigger building blocks that self-assemble into bigger building blocks, over and over. In other words, proteins into DNA/lipids/etc, DNA/lipids/etc into organelles, organelles into cells, cells into muscles/organs/etc. Not saying it would be squelchy organic technology, just that the process would look similar from a high level. Maybe it would look like self-assembling Lego!
Seed probe -> Processing-bots -> raw material -> fibrous, metallic, and concrete-like Assemblers -> various types of building blocks.
Terrifying capabilities for such soft and fluffy, brittle things.
The live coverage just made it look slow and small.