All you know anxious, of course, about the landing and i just can’t wait to see those first images of the surface of mars at our new landing site. Absolutely now the rover is set to land february 18th in jezreel crater. I know there were a few other contenders for the landing site. What is so exciting about this specific region on mars jezreel is: is such a fantastic landing site, um it’s, first of all, it’s situated uh in a very interesting area of mars that that uh scientists have had their eyes on for quite a number of years. Now, uh and it’s, actually just just now with mars 2020, that we have the capabilities with the landing system uh to get into a site like jezreel um. A couple of things that led us there were that the region around jezreel, crater um, is it’s actually on the edge of a much larger crater, uh called iscidus, and so an isidis is a very, very old impact. Crater that would have formed in the very earliest part of mars history, and so the crust the rocks around isidius are some of the oldest exposed on the surface of mars and and jezreel itself was formed sometime after that isidus impact, but still very early in mars’s History, we think um and so jezrow is this crater and into which um on the the northwestern edge flows in an ancient river channel. So we very clearly see from from satellite images an ancient river channel flowing into the northwest corner of jezreel and out of the northeast corner, is an exit channel so there’s another river channel flowing out and then just at the end of that first inlet channel.

Just inside the crater is a beautiful delta exposed there and delta’s form. We know on earth where a moving body of water, like a river with a lot of energy to carry a lot of sediment along in the water, meets a standing body of water and all of a sudden that energy drops out and the sediment drops out in A big pile like a delta, and so the fact that those river channels are there flowing into and out of the crater and the delta is there. Uh gives us very good evidence that there was a lake once in jezreel and it was an open system. Late dynamically, you know bringing water in filling up the the crater and flowing out, so we think it was a great place uh for for life to have have thrived if life existed on mars at that time, absolutely so speaking of life, it is no secret that Perseverance, one of its main mission objectives is to search for evidence of life on mars, whether that’s ancient microscopic life or something slightly more recent i’m curious. Why do we think that life could have existed on mars, and why do we think we’re going to find it with perseverance at jezreel, with this mission right well, there’s, a long history of exploration of mars, starting in the 60s, with the mariner missions actually starting well Before that, you know using telescopes from earth to look at mars and even going back to those early maps made by scaparelli um showing canals, you know what he interpreted as canals on the surface of mars.

From from his early telescopes um. You know scientists started to to imagine the possibility of life beyond earth and on mars and as we got closer and closer and our images of the surface of mars got better and better. We started to see more and more geologic evidence of what looked like flowing. You know ancient flowing water on the surface of mars and before we had um the mars exploration, rover spirit and opportunity, scientists would debate whether those those flow features were from water or or maybe from lava. But in the in this modern era of rover exploration of the surface, we’ve got more and more great evidence that very early in mars’s history, liquid water, was abundant on mars surface and the most recent mars rover that’s still active today. Curiosity has shown beautifully that that mars was once very habitable, uh and and could have supported life as we know it on earth there were bodies, standing bodies of water, floating water. There were all the energy sources needed for metabolism for life to to fuel itself, uh and grow. But what we do not know is whether life ever emerged on mars or or whether mars was ever inhabited and so that’s. The step that that we’re, taking with mars 2020 that natural next step from following the water to looking for habitable environments to to next looking directly for signs of ancient life and so really mars, 2020 and mars, sample return of which mars 2020 is, is a first Part uh are our best opportunities to to find evidence of life beyond earth if it ever existed.

Absolutely now i know that one of the first things that perseverance or percy is set out to do on mars is do exactly that cash samples um for what is hopefully going to be the first successful sample return mission to and from the red planet. Could you speak a bit about why it was decided that perseverance would not just collect and study but collect and return samples to earth and what that really means for our growing understanding of mars in general right well, there’s a lot there in that question, and – and First of all, i will say that that mars, 20 20 is the first part of what would be a multi mission sample return campaign. So so our job uh is to select and collect the best possible samples in our exploration area and then place them safely. On the surface of mars, and then some follow on missions that that could launch as early as 2026 would be required to go and pick up our samples, get them into mars orbit and then grab them out of mars orbit and fly them back to earth. Uh. For study in earth based laboratories, and why would we want to go to all that trouble to do? You know all that incredibly difficult, uh stuff to go and get uh some rocks from from mars? Well, a great way to think about it, i think is, is the closest uh comparison to the search for ancient life on mars? Is the search for the most ancient record of life on earth and we have a great fossil record of life on earth.

That extends all the way back to about three and a half billion years ago, where we have these stromatolites, and these are fossil. Microbial mats. I’Ve got one here: there are these wrinkly layered structures, uh that that are preserved in the rock. So this originally would have been like this and there would have been domes layered domes, so this has been weathered away and you’re, seeing it from the top down now and these concentric circles. These are actually layers of microbes, so the the individual organisms are single, celled and microscopic, but this is like pond scum at the edge of a lake or or a pond or a puddle, where little microscopic organisms collect in groups and exude this sort of sticky substance That traps sediment um and eventually can fossilize in a form like this, so our earliest evidence for life on earth that that pretty much all the scientists who who are interested in this sort of thing can agree on. Are these rocks that are about three and a half billion years old? There are examples of potential fossil evidence of life in rocks older than that, but we just can’t, really get good agreement and they’re very controversial and they take you know, year after year of different analytical techniques focused on the same rocks. To really try to understand were these features that are observed in these rocks actually produced by living organisms, or are they the products simply of geologic and chemical processes that don’t require life, so the case would would even be more extreme for the extraordinary claim of ancient Life on mars right, so we would require particularly extraordinary evidence, uh and and we’re quite confident that, although it’s possible, we could observe something like this, which would would really absolutely have us jumping up and down with excitement.

Even this would not be enough, i think, to to get real scientific consensus about you know whether mars was once inhabited. We’D have to get those samples back to study with our most powerful instruments on earth and – and so these, these most powerful scientific instruments on earth. Often tend to be very large, you know to send a scientific instrument to mars. You have to miniaturize it and harden it against the the harsh conditions of the mars environment. Inevitably, you have to make some compromises in terms of the the capability of those instruments you don’t have to do that on earth, so you can use instruments like a synchrotron that’s as big as a city block you know, and so so we want to get those Samples back so we can bring all of our powerful capabilities to bear on these samples and have generations of scientists working on them to to address that question of whether life existed beyond earth, but also other big questions. How did how did mars form? How did it evolve as a system? How did the solar system form, how do terrestrial planets form all kinds of big uh, wonderful science questions can be addressed with these samples absolutely well. I, for one cannot wait till until those samples are back on earth and and all of that wonderful research can really kick into high gear um. Now that kind of leads me into my next question. I think that, as you know, agencies like nasa have continued to send more and more advanced probes and landers to mars.

People continue to ask the questions of kind of the larger, more existential questions of why. Why are we so excited about mars? But more importantly, why do we even want to find life off of earth? Why are we trying to answer these big questions and i’m curious as a scientist so close to this project? How you would answer something like that yeah? Well, i am where i am today in my career, just because of early motivations. You know going back to when i was a kid and fascinated with dinosaurs uh. You know as a young kid and then starting in about high school. I would say i just started to get personally interested in understanding life in its in its most basic essence. So beyond really what we do with biology – and you know understanding the ribosome and the cell membrane and the golgi apparatus and all these lists of terms. What is life on earth um more, you know what is life in the most fundamental sense and has it ever existed beyond earth and what you know, what crazy forms might it take on other planets and what are different ways that life could have emerged and evolved? What is it that makes life distinct from non living things? In some sense, it seems obvious, but but if you really take a moment to think about it, what is it you know? What is that that uh, you know life force that that uh has matter organize itself together and and form such wonderful shapes and do such wild things, and so what is that stuff? And so so? Starting to you know finding another example: uh is a great step along that way to to answering the question, which i think is probably very basic and and humans have been wondering about in one form or another uh.

I imagine you know as long as there have been humans as long as people have been able to look up at the stars, you know and wonder what are these things and and are there planets out there and what’s out there and are we alone? You know uh, these are very basic human questions, but it really is, you know these things are really just a matter of curiosity, uh and uh, and the the basic science of it is less about. You know practical application, but about just addressing these very basic uh human questions and curiosity, of course, along the way. There are inevitably these technological advances that that allow us to do new things and and apply those technologies uh to to other interesting problems on earth um. But uh, you know another interesting thing: i’ll say is um, you know going beyond just you know, evidence of life and looking at at the fate and history of planets. So we have these these three terrestrial planets close to one another venus earth and mars, and there are three planets that are in many ways very similar. You know they’re rocky rocky bodies, but they they took very different paths right earth. As we know, it obviously remained very habitable and supports. You know a very diverse biosphere uh today, but venus and mars. Not so much and venus had this runaway greenhouse effect and and warmed up and it you know, melts lead on its surface it’s that hot, whereas mars kind of took the opposite path.

It it almost died as a planet. Its magnetic field collapsed, its atmosphere collapsed. The water dried up, you know and it’s now a very desolate and inhospitable place, at least on its surface it’s possible that you know there are habitable environments deep in mars’s subsurface, but the surface of the planet is, is not a very nice place for for living Organisms, so why did that happen? How did that happen? When did that happen? These are all you know, basic questions and and uh in terms of working to understand the future of of life on this planet potentially important for us all to understand absolutely well. Thank you.

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