Tanzina Vega: I'm Tanzina Vega. We're going to end our show today a bit far from home, more or less 34 million miles away. Unless you've been living under a Martian rock, it's likely, you've heard about NASA's latest expedition to the dusty red planet that's long fascinated us, earthlings. Last Thursday, the rover Perseverance, or Percy, made its harrowing journey to the surface of Mars.

Audio clip: Touch down confirmed. Perseverance safely [cheering] on the surface of Mars, ready to begin picking the sands of past life.

Tanzina: For decades, we've explored the tiny red dot in the night sky with each mission getting us a bit closer to understanding its mysteries, but our interest in Mars expands beyond space exploration itself. The planet is also part of our history and popular culture, from the early days of science fiction on the airwaves-

Audio clip: The bells you hear are ringing to warn the people to evacuate the city as Martians approach.

[music]

Tanzina: - to hit songs from artists like David Bowie-

Audio clip music: Is there life on Mars?

Tanzina: - to the Martians invading the big and small screen.

Audio clip: Range, 6783 and closing. 65 minutes until Mars orbital [unintelligible 00:01:32]

Audio clip: This is the plan. Get your [bleep] to Mars.

Audio clip: There's a Martian right behind me,

Audio clip: Or maybe we're on Mars because we have to be.

Tanzina: Nadia Drake is a contributing writer for National Geographic and she wrote recently about Mars for the magazine's March cover story. Nadia, welcome to the show.

Nadia Drake: Hi, thank you for having me.

Tanzina: Why are we so obsessed with Mars?

Nadia: I love this question. It's so interesting to me and it's actually the reason why we wrote the feature, because I'm not personally that obsessed with Mars and so I went into writing the story wondering what it was that's so captivating for so many people or what still is. I think there are a handful of reasons and some of them are more interesting than others, but overall I think our obsession with Mars has a lot to do with life.

Over the last century or so we've harbored some very different but very compelling ideas about what sorts of life forms might exist on Mars. First, that was intelligent aliens who were capable of building a planet-spanning network of canals. Then we moved on to thinking that maybe vegetation was seasonally darkening the planet surface. Then once we found out that was wrong, we thought, well, maybe there might be microbes in the soil, and so now we have this mission, the Perseverance mission, which is actually going there to look for signs of ancient life on Mars. Even though we keep finding out that what we think about life there tends to be wrong, we've never really been able to eliminate the possibility that Mars is, or at least was a living world. I think that's very compelling for a lot of people.

Tanzina: How far back does our obsession with this planet date? There are scientific reasons as you mentioned why Percy or Perseverance is now on Mars, but there are also cultural expectations. You said that the obsession that we have with the idea that life on Mars may have existed at one point is one reason, but it's also made its way into film, into music, into pop culture. Why is that?

Nadia: Absolutely. I think in many ways, Mars is captivating because we can imagine ourselves there. When I first started asking this question, why are people so fascinated with it? One of the most boring answers that came back is that we can see it. We can see the planet. This has been true for millennia. We've been able to watch Mars cross the night sky since we first started looking up. Even if you don't have a telescope, if you just walk outside on a dark night, perhaps last October when Mars was so close to earth, you see this beautiful red light and it takes kind of a capricious path through the heavens. That's just because as earth and Mars are orbiting the sun, earth laps Mars, and so it traces a slightly different pattern than Venus and Mercury, which are anterior to it.

For millennia, we've been seeing this object in the sky and attaching our deities to it. It's been a source of mythology. We've used it to portend the fates of battles or the deaths of kings or plan our crop harvests. Since the space age, when we've actually been able to see its surface through telescopes and up close with the orbiters and the landers that we now have on the planet, we've gotten to see this alien vista that looks somewhat so entirely earth-like.

You can look at these landscapes that come back from rovers and they look like you're in the American Southwest. It doesn't take a huge stretch of imagination to imagine walking across them. I think for a lot of people, that's a very compelling reason to continue looking at Mars because we can imagine ourselves on it.

Tanzina: There are people who would say we've got enough trouble, issues, problems, things that are happening here on planet earth. Why do we even bother with this obsession? Why are we still sending probes up to Mars for some fantasy that someone will have? There is a scientific takeaway, if I may use that word, in all this, right?

Nadia: Absolutely. We do get that question a lot. Why are we spending resources exploring space when there are so many problems on earth? It's a valid question to be asking because there are a lot of problems on earth right now, but the answers are many and as you said, there are some very good scientific reasons to be looking at Mars. One of them has a lot to do with how life evolves and whether we, the life on earth, is it.

If we can look at Mars, we see a planet that we know was once very different than the world that we see today. The Mars of today is arid. There isn't a lot of liquid on its surface, but the Mars of three and a half billion years ago had water flowing over its surface. It had lakes and rivers and seas. It had all of the ingredients that we think are necessary for life as we know it to evolve. We want to know, did life ever take hold there? Because if it did, that tells us something really profound about the ingredients and the conditions under which life evolves.

If we find out that life never took, hold on Mars, that also tells us something incredibly profound about the ingredients and conditions that life needs to evolve. By studying Mars, if we get to understand the planet enough, it actually teaches us something about what it means to be earthlings in the grandest cosmic sense.

Tanzina: Can we rule out that there are Martians out there? Have we been able to get to that point yet, Nadia?

Nadia: I don't think so. I would be surprised if there were surface lifeforms on Mars today, but I wouldn't rule out the possibility of a subsurface biosphere. It's really hard to prove a negative in general, which I think is why we keep looking.

Tanzina: On that note, I think that's all the science my brain is going to hold for today. Nadia Drake is a contributing writer at National Geographic and the author of its March issue cover story on Mars. Nadia, we'll see you here or we'll see you on Mars, who knows? Thanks for joining us.

Nadia: Thank you, Tanzina.

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