Lynn Carter

previously studied habitability.

And so studying Mars and Venus are sort of two end cases that we can then take forward when we study extrasolar planets to try and understand whether what we find out elsewhere in the galaxy is a place that could be habitable or that could have been habitable for a while.

So that's kind of the picture of why we're interested in Mars climate.

And then from the standpoint of radar, there's a couple of reasons why I'm really interested in radars.

So for geology, stratigraphy is really key to understanding things.

I mean, that's how we understand the history of the Earth.

So you can go to the Grand Canyon and you can see all those beautiful layers and look back through Earth's history and understand how the climate's changed, how organisms changed over time.

And what we want to do on Mars is the same thing.

So if you just use optical images, and these are some of the images from the HiRISE camera, you can see evidence for layering, like in crater walls.

This is one of the polar ice caps of Mars, and you can see layering there.

But the advantage of radar is that it's long wavelengths that can penetrate into the surface and you can reveal buried structures.

So you're not limited to just what you see on the surface.

You can actually see into the subsurface.

And then also radar is sensitive to the density and composition of materials, but in a different way than spectroscopy.

And so sometimes with the radar, we can understand something about the composition of those materials that it's going through.

So stratigraphy is really, I think, the main reason that we're interested in radars at Mars.

So what is radar, especially compared to optical systems like the HiRISE camera that everyone's probably familiar with?

Radar is light too, but it's at very long wavelengths.

So it's radio wavelengths.

So on the electromagnetic spectrum, we're talking about things that are down here.