I'm John Batch with my colleague David Livingston.

This is Hotel Mars, and it's a pleasure to speak with Miroslav Broche of Charles

University and the Czech Republic about the work he and his colleagues have published in Nature

magazine about origins of meteorites that are in abundance on Earth.

70% of the meteorites right now coming from three recent breakups of asteroids in the asteroid belt.

But we now go to a similar family that is dated 466 million years ago.

That's a while, but it also may be suggestive of connection to Earth's climate.

Miroslav, what is the difference between the 466 and the others?

Is it all the same or is this a much bigger breakup?

It should be bigger, and it's very important to stress that we actually do have meteorites

from this event falling on Earth today. It was very difficult to understand why such an old breakup is able to deliver something

on Earth today. Approximately one half of el-condrite meteorites exhibit this radiometric spike.

It's called shock age, 466 million years.

Our discovery is actually that 466 million years ago, there was a breakup in the asteroid belt,

but a substantial part of these fragments are accumulated back onto the body.

So it was not a complete disruption and complete ejection.

A part of the material was reaccumulated back.

And it was essentially preserved in the asteroid belt.

And then the second collision occurred, which ejected fragments which we still observe and find on Earth today.

So that's explanation why we are able to measure something which is that old, 466.

I see.

And then, okay, then the next question is whether we see meteorites from this old event, and we do.

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