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1. We have absolutely no certainty that no planet-killers are there. All we know is that none mapper are. 2. China has an Arecibo-class device. Actually bigger

by ncmncm 4y ago

1. We have absolutely no certainty that no planet-killers are there. All we know is that none mapper are. 2. China has an Arecibo-class device. Actually bigger than Arecibo. Do we need two? Considering that the whole Free World could not scratch together enough money just to maintain Arecibo, building it again seems beyond possibility.

hotpotamus 4y ago
The astronomers I've seen lecture say that they have a pretty good mapping of the asteroid belt and they know that there are no planet killers in there anytime soon which seems to intuitively make sense since we only get planet killers on the order of every 100 million years or so. Of course there are tons of smaller asteroids out there that can be problematic as well. I wouldn't want to be around when Berringer Crater was created, but that was still a few 10's of thousands of years ago if I'm remembering right. (I'd recommend stopping by if you're ever in the American Southwest). I'm not all that familiar with any of the big radio telescopes, but I thought that China's didn't have the active radar capabilities that Arecibo did. That said, I find it sad that something like Arecibo was possible to build and maintain in the 60's but not now. I suppose that has to do with the perception of it moving from defense project to science project.
- jamiek88 4y ago
  When the risk is extermination of the species ‘pretty good mapping’ doesn’t cut it.
  - hotpotamus 4y ago
    There's a fair amount of chaos/uncertainty in orbital mechanics, so perfection may be impossible. Also, the smaller "city killers" can be very hard to spot, especially if they're in the wrong position relative to the sun, but those aren't extinction level. That said, I would think runaway climate change or nuclear war are much greater threats to civilization (though humanity would probably survive in some form), so those are probably where the effort should go if survival of human civilization is your thing.
- ncmncm 4y ago
  We have orbital predictions for all the asteroids above a certain size, but only a fraction of tens of thousands of smaller bodies entirely sufficient to end civilization and very possibly drive us to extinction. One struck the ice sheet in Canada only 12,800 years ago that wiped out 30+ genera in North America including camels, horses, cheetahs, mammoths, mastodons, giant ground sloths, dire wolves, sabertooth cats, a giant beaver, and a giant bear. Their bones, and Clovis spear points, appear only below a thin stratum with massively elevated platinum concentration. Radar is just a matter of putting the right antenna horn on the focal carriage, wired to appropriate gadgetry.

by ncmncm 4y ago

hotpotamus 4y ago

The astronomers I've seen lecture say that they have a pretty good mapping of the asteroid belt and they know that there are no planet killers in there anytime soon which seems to intuitively make sense since we only get planet killers on the order of every 100 million years or so. Of course there are tons of smaller asteroids out there that can be problematic as well. I wouldn't want to be around when Berringer Crater was created, but that was still a few 10's of thousands of years ago if I'm remembering right. (I'd recommend stopping by if you're ever in the American Southwest). I'm not all that familiar with any of the big radio telescopes, but I thought that China's didn't have the active radar capabilities that Arecibo did. That said, I find it sad that something like Arecibo was possible to build and maintain in the 60's but not now. I suppose that has to do with the perception of it moving from defense project to science project.

jamiek88 4y ago
When the risk is extermination of the species ‘pretty good mapping’ doesn’t cut it.
- hotpotamus 4y ago
  There's a fair amount of chaos/uncertainty in orbital mechanics, so perfection may be impossible. Also, the smaller "city killers" can be very hard to spot, especially if they're in the wrong position relative to the sun, but those aren't extinction level. That said, I would think runaway climate change or nuclear war are much greater threats to civilization (though humanity would probably survive in some form), so those are probably where the effort should go if survival of human civilization is your thing.
ncmncm 4y ago
We have orbital predictions for all the asteroids above a certain size, but only a fraction of tens of thousands of smaller bodies entirely sufficient to end civilization and very possibly drive us to extinction. One struck the ice sheet in Canada only 12,800 years ago that wiped out 30+ genera in North America including camels, horses, cheetahs, mammoths, mastodons, giant ground sloths, dire wolves, sabertooth cats, a giant beaver, and a giant bear. Their bones, and Clovis spear points, appear only below a thin stratum with massively elevated platinum concentration. Radar is just a matter of putting the right antenna horn on the focal carriage, wired to appropriate gadgetry.