I’m not a craterologist but my understanding is an impact like this is going to chemically change the asteroid and the ground. So partly disentigrates and kinda becomes part of the ground (idk if that counts as under)
Comment on A close call
Paradachshund@lemmy.today 2 weeks ago
So does the rock itself disintegrate on impact or is it under the crater?
ArmoredThirteen@lemmy.zip 2 weeks ago
gandalf_der_13te@feddit.org 2 weeks ago
the impact velocity is so high that the kinetic energy is large enough that it instantly vaporizes the whole asteroid on impact.
Agent641@lemmy.world 2 weeks ago
Fun fact a rich guy once bought the mining rights to a meteorite impact crater believing that it would be an easy source of pure iron to mine since most meteorites are primarily iron, but after digging for hundreds of feet and finding no iron the project ran out of money and went bust, because meteorites disintegrate into first a liquid iron, which then oxidised very rapidly and becomes dust and small chunks which settle in an ejecta pattern around the impact zone, so.etimes many miles wide, and this thing layer is fairly quickly eroded away, so there’s no usable iron nor a meaningful amount of oxide remaining.
Smaller meteorites often land intact, as their surface area allows for meaningful atmospheric friction to slow them down, and these are chunks of iron, but larger than about the size of a large van, the meteorite is usually obliterated.
Entry angle can allow for exceptions, IE I’d a meteorite just grazes the atmosphere but still slows down enough to suborbital speeds,it can land as big chunks, but eve.ln these get scattered over hundreds of kilometres. Any impact steeper than about 20 degrees and larger than a large van is usually carrying so much momentum at ground level that it hits at several, and possibly tend if kilometres per second, which liquifies and scatters it widely.
PancakesCantKillMe@lemmy.world 2 weeks ago
Subscribe.
jaybone@lemmy.zip 2 weeks ago
That was a fun a fact.
SpecialSetOfSieves@lemmy.world 2 weeks ago
I have to note that this is not correct. Chondrites make up the vast majority of meteorites, and even the most iron-rich chondrites contain much less than 50% iron by weight.
I haven’t been to Barringer Crater and I don’t know all the sweet, gory details of the big bolide that made it, but LPI seems to have a nice summary. The estimated 30 tons of meteoritic iron retrieved from the site certainly isn’t very much, and I have heard a variant of Agent641’s story before, so I’ll refrain on commenting there.
I’m a little sad thinking about all that oxidized iron, though. On Luna that stuff gets reduced instead, so that the regolith is peppered with little spheres of iron. Of course, here, we don’t get the little balls of iron, or much in the way of intact craters at all… damn it, we could use a few more.
Sighs Earth. For all the predators and the continent-busting rifts here, this place just isn’t very hardcore sometimes.
bdonvr@thelemmy.club 2 weeks ago
I wonder what would happen if a large one came in directly perpendicular to the ground at high speed (for a meteor). Like the atmosphere is really pretty thin and that trajectory would have the least exposure to it.
Agent641@lemmy.world 2 weeks ago
It probably wouldn’t change the outcome much. Meteorites usually have a relative velocity to earth of 8-50 kilometres per second. At those speeds, it moves much faster than a ballistic missile, and those things haul ass. Whether entering at 25 degrees or 90, it would instantly turn the air to plasma and pass through the troposphere and hit the ground in just a few seconds.