Lynn Carter

Ice can go a really long way, or radar can go a really long way through ice.

So these ice caps at the poles of Mars seem like a great target for the radar.

And these ice caps, so they look really different.

So this is the north polar ice cap.

This is the south polar ice cap.

This north polar ice cap, when people try and age date it using cratering and relative stratigraphy techniques, it looks like it's only a few million years old, so it's very young.

which is kind of interesting.

And then the south polar cap, when people try and date it, it's pretty old, like tens of millions of years.

But remember that the obliquity swings back and forth a lot just on that less than a million year time scale.

So these polar caps could record that obliquity swinging back and forth in them.

And I don't know if some of you have seen this, but we actually use Antarctic sounding to understand Earth's climate.

So we go and we take core samples of Antarctica and you can look and see volcanic eruptions layered in that ash.

You can look at the isotope ratios that are there and find how the climate's changed through time.

And so we kind of thought this was like an analogy that we could do on Mars, looking at the polar caps and trying to get climate information out.

So this is the north polar cap, and it's really kind of striking that you see all these really fine layers in the polar cap.

So the charade team has been able to go and actually tie these layerings into the obliquity cycle of Mars.

So if you go and look at some of these layers and sort of form them into packets, like you can see there's this top layer here and then there's a gap and then there's other packet layers.

Some of these can be correlated to that climate record where when you watch the obliquity swings and you go back at the age that you expect this polar cap to be,

it looks like that layering is caused by the seasonal changes on Mars, basically.

And so this preserves a record of those obliquity changes.