25 min read

Gravity Assist: Science & Science Fiction with Andy Weir

weir and green in sound booth
NASA's Planetary Science Division Director, Jim Green (right), interviews "The Martian" author Andy Weir during a taping of the podcast "Gravity Assist" Nov. 16, 2017 at NASA Headquarters in Washington.
NASA/Aubrey Gemignani

Does art imitate life or does life imitate art? In the season one finale of Gravity Assist, NASA’s Jim Green and bestselling author Andy Weir explore the fascinating intersection of science and science fiction. Green and Weir delve into biggest surprises about Mars and the Moon, what every aspiring writer needs to know, and how “The Martian” provided a powerful gravity assist for young readers.


Jim Green: Our solar system is a wondrous place with a single star, our Sun, and everything that orbits around it - planets, moons, asteroids and comets. What do we know about this beautiful solar system we call home? It's part of an even larger cosmos with billions of other solar systems.

Hi, I'm Jim Green, Director of Planetary Science at NASA, and this is Gravity Assist.

With me is Andy Weir, author of the bestseller The Martian and now Artemis, a thriller set on the Moon, and we're talking about the fascinating intersection of science fiction and science.

Andy Weir: Thanks for having me.

Jim Green: I usually ask this question at the end of an interview, but it seems more appropriate to begin with: and that is, how science inspired you to get into writing science fiction? What was your gravity assist, Andy?

Andy Weir: Well, probably my father - he's a scientist himself. He's a linear accelerator physicist. He's retired now, but he spent his whole career, you know, shooting electrons down a tube. And so, he's always been a science dork and a science fiction fan, and he had an inexhaustible supply of sci-fi books in the house for me to read. So, I guess you could say I was indoctrinated from birth.

Jim Green: I see. So, you had an opportunity to read the library. So, what were some of your favorite authors?

Andy Weir: Well, my “holy trinity,” so to speak, are (Robert) Heinlein, (Isaac) Asimov and (Arthur C.) Clarke, so--I'm 45 years old, but I grew up reading my father's science fiction collection. So, I grew up reading juvenile (novels) from the 50s and 60s and early 70s.

Jim Green: But, you know, that still holds up really well.

Andy Weir: Some of them, yeah. Parts of them don't. Parts of them didn't age well, but other parts of them still hold up really well, especially when they decided to stick with real physics.

Jim Green: What really surprised you about Mars when you were doing the research for your first book?

Andy Weir: Well, I mean, I had a lot of fun doing the research, and that's always the part of writing that I enjoy the most. I guess the--I already knew a lot about it to start with because I've spent my life doing a space dork. I feel like I'm in a building where that's very much accepted here at NASA Headquarters in D.C.

But, I've always been into it. So, I started with more than a layman's knowledge of this stuff, but a few things I discovered while researching Mars that I didn't know before was I didn't realize how fast Phobos' orbit really was, how ludicrously close to the planet it is. It's within the geo--well, Mars, whatever Mars' geosynchronous orbit is called.

Jim Green: Well within it, actually.

Andy Weir: Well, within it, and in fact, it's nearing the Roche limit, and it's probably gonna be a ring in a few hundred thousand years. But--so, that means that even though Phobos and Deimos both go the same direction around Mars, if you're on the surface of Mars, they appear to be going opposite directions, because Phobos is going around Mars faster than Mars can rotate. That's one thing I found really interesting.

I was also fascinated by Olympus Mons on Mars, the tallest mountain in the solar system, but it also has an incredibly wide base, almost the size of the state of Texas. And so, the grade is so gradual that the curvature of the planet actually has more of an effect on the horizon than the grade. So, you could be standing on, you know, on the slopes, for lack of a better word, of Olympus Mons, and you would think you're in a flat plain.

Jim Green: Yeah, it's really spectacular, and this is one of the features that a lot of our scientists point to that say--that says Mars doesn't have plate tectonics.

Andy Weir: Right.

Jim Green: And so, as magma just pokes through the surface, it just sits there and accumulates.

Andy Weir: Uh-huh.

Jim Green: But then--.

Andy Weir: --Well, I--I'm gonna interrupt you there because--I have very exciting, for me, news to share in that, you know, so recently, within the past year, they were able to prove that Mars had an active volcano that lasted over a billion--over 2 billion years maybe. How long was it that--?

Jim Green: --On that order, yes.

Andy Weir: On that order, okay. And the way they were able to prove that is by examining a specific shergottite, a meteorite that had fallen to Earth but originated on Mars. And they were able to analyze that and prove that it came from basically the same lava source that these other shergottites came from, and that proved, oh, wow, that same lava source has been active for like 2 billion years. Well, that shergottite that they did the proof with is my--I have a shergottite at home, a Mars rock at home--.

Jim Green: --Wow--.

Andy Weir: --That was one of my--that was a little gift from me to me with my Martian money.

Jim Green: Okay, got it.

Andy Weir: I have it at home.

Jim Green: Wow.

Andy Weir: And it is that same one. It's the same--.

Jim Green: --Really?

Andy Weir: It's--mine is a different piece from the same fall, but it's the same meteorite. And so, it was funny when I was reading that news, because of course, I, you know, read space news. I was like, and it's from this NWA7635--I don't know if that's the correct number, but--and I was like, wait, that sounds familiar, and I go into my living room and look at the little plaque I have, because of course, I have it in a little display case and stuff like that--.

Jim Green: --Right, right--.

Andy Weir: --And I'm like, oh, that's my meteorite.

Jim Green: All right.

Andy Weir: Shergottite.

Jim Green: Hang onto it. You know--.

Andy Weir: --Well, no, I'm not gonna be giving it away. It cost a lot.

Jim Green: That's true. (It) may have other secrets to behold. But, you know, this is really important why we need to do that next Mars mission, the sample return mission.

Andy Weir: Oh, absolutely.

Jim Green: We're gonna core rock, and we're gonna bring that back, and that's gonna tell us how fast the climate on Mars changed.

Andy Weir: That sounds fantastic. When are you gonna watch that?

Jim Green: Mars 2020 is what it’s called.

Andy Weir: --That'll collect--I'm still catching up on some of the details. That'll collect the samples and leave them behind for a future return mission?

Jim Green: Right.

Andy Weir: Yeah.

Jim Green: So, what it's gonna do, once we land it in a geologically diverse area, probably where the water has modified the minerals, you know, where the ancient shoreline on Mars has been, we'll start coring rock--it cores about a three-inch-long chalk-like cylindrical--.

Andy Weir: --Core sample--.

Jim Green: --Core sample, yeah, thank you. And then we put them in a sleeve, a metal sleeve, and then we lay--after we do several of those, we lay them in a pile, and then we move on.

Andy Weir: Right.

Jim Green: And then later on, we're gonna come pick them up, take them back to a Mars ascent vehicle.

Andy Weir: Yeah, that sounds great.

Jim Green: And then we'll bring it all back because we really want to interrogate those in the laboratory.

Andy Weir: Oh, yeah.

Jim Green: That's where the gold is, you know, to bring back those samples and really study them.

Andy Weir: Yeah, I mean, you guys are sending entire laboratories to Mars to look at the samples, but, boy, they're nothing compared to what we can do on Earth with their facilities here.

Jim Green: Yeah, that's the whole point.

Now, right now, we call it Mars 2020, but, you know, next year, we're thinking about having some sort of contest where we're have kids from across the country name it.

Andy Weir: Sure. That's how you named Curiosity.

Jim Green: And Spirit and Opportunity and Sojourner.

Andy Weir: Okay.

Jim Green: So, that's an important next step that we'll do, and that’s really--.

Andy Weir: --You know they're just gonna call it like “Marsy McMarsFace.” I mean, that's gonna be like the top voted one. That's the thing now.

Jim Green: Well, we hope not, but that's--I'm sure we'll get that as an entry, and it'll be from Andy Weir, at least.

Andy Weir: Oh, no, I'll be much nicer than that.

Jim Green: Okay, all right, all right.

You know, the concepts that came out in your book The Martian that I really enjoyed is that concept of what happens when humans first get to Mars. Why did you pick that era that's just around the corner to write about?

Andy Weir: Well, I wanted it to take place as close to the modern day as possible, but I needed to give enough time in the fictional future to actually develop the technologies that would be necessary. And the main kind of tech that's in The Martian that we don't have in reality yet is the strength of the ion drive that Hermes uses. Like, the technology's all proven. It works, but we don't have the--we don't have anything like the scale that would be necessary for it. So, I gave us about 20 years to work that out.

Jim Green: Well, you know, the way the movie was portrayed and the art direction and, you know, the things that (production director) Art Max did was--.

Andy Weir: --Oh, yeah--.

Jim Green: --Was really spectacular.

Andy Weir: Absolutely beautiful.

Jim Green: I mean, they really made it a beautiful movie.

Andy Weir: Oh, yeah.

Jim Green: What was it like to see The Martian in the theater for the very first time?

Andy Weir: Oh, man, it was great. So, Fox brought me in to--you know, onto their lot, and we watched it in one of those little, you know, test theater rooms where they watch it internally. And the first cut I saw, it was missing most of its special effects, so they're a bunch of, you know, just people walking around in front of green screens or big obvious--.

Jim Green: --Or no visors.

Andy Weir: No visors, right--or big obvious black wires holding them up in the zero G scenes. And--but still, I'll tell you, like right at the beginning, when it started that intro and it put like The Martian up on screen, I cried.

Jim Green: Oh, wow.

Andy Weir: I mean, of course.

Jim Green: I can understand that. Yeah, of course, there's your baby.

Andy Weir: There's my baby.

Jim Green: There's your baby.

Well, I'm here with Andy Weir, and we're having a great time talking about science and science fiction. And tell me about your new book, Artemis.

Andy Weir: Well, Artemis takes place in a city on the Moon, humanity's first off-Earth city. And the main character is a woman who's a small-time criminal, and she gets in way over her head.

Jim Green: Way over her head, I might add.

Andy Weir: And it's less about national space exploration and more about the colonization of space, so the stuff that happens a little bit later on. And I--so, I had to come up with an economic reason why the city of Artemis exists and so on.

Jim Green: Yeah, and I thought you did it really well. I mean, it's very exciting to see how, you know, as a science fiction writer you can think about the future. You know, I always say, if we don't spend time thinking about our future, we don't have a future.

Andy Weir: Yeah.

Jim Green: And I think science fiction plays a very important role in that.

Andy Weir: Yeah, everybody's got--every reality starts with a dream, right?

Jim Green: Every reality starts with a dream, exactly.

What kind of lunar science research did you do to help write that book?

Andy Weir: Well, quite a lot. And, actually, you know, the vast majority of that information came from the Apollo missions. Mainly, I needed to know the mineral breakdown of the ores that are available on the surface. And what I learned was just amazing. I had no idea that the Moon was being so cooperative in us colonizing it. 85 percent of the rocks in the lunar highlands are anorthite, which is aluminum, silicon, calcium and oxygen all put together into a very, very stable molecule.

If you can break that apart, you end up with aluminum to build your Moon city and oxygen to fill it. I mean, the Moon is made of moon bases, just some assembly required. And that was just the most awesome part. From there, I'm like, okay, how do I smelt anorthite. And I'm like, well, it takes a ludicrous amount of energy. Okay, fine, we're gonna need a ludicrous amount of energy, we're gonna need some reactors.

You know, it would be cheaper to ship the entire city to the Moon than it would be to ship the solar panels necessary to smelt anorthite, so it's gonna have to be a reactor. And I just kind of built out from there how the city got built and how it grew and how to make maximum use of the resources on the Moon.

In fact, they would generate so much oxygen that the people in the city can't breathe it fast enough. They'd still be venting it out into space. And oxygen is really handy. So, you know, for every kilogram of hydrogen you want to bring to the Moon, you can make nine kilograms of water.

Jim Green: This is really thinking ahead in the sense that just in the last few years, there's been quite a bit of thinking about how to go out into our solar system, go to asteroids, potentially go to the Moon and be able to mine and get those resources. And I think your book goes right at that very important point. That's in our future.

Andy Weir: Well, possibly, although to be fair, all of their mining and resource collection is to build out the city itself. So, that works out to be economically neutral for them. It's like they get the resources from the Moon, they use the resources on the Moon. They don't really export it to Earth. It's still cheaper even within the setting of Artemis to just mine whatever you want on the planet you're on.

Jim Green: Well, indeed. Typically, the concept is we would want to mine material and then use it in that framework, use it in space. And so, having space helps sustain us as we move out, you know, go well beyond low-Earth orbit is just a critical new way of thinking, and I think your book really hits that.

Andy Weir: Thanks. Yeah, it's building out infrastructure, right? It's no different than the like westward expansion. You don't go straight to California. You build railroad stations along the way.

Jim Green: Absolutely. You know, some people say, well, why go back to the Moon, and I think as you point out in the book, there's all kinds of different reasons.

Andy Weir: Yeah, absolutely. Well, my--the whole conceit of Artemis is based on it takes place in the 2080s timeframe and where the price to low-Earth orbit has been driven down, and it's been driven down far enough that middle class people can afford to go to space. Once you have that, you have economics in space. You have a tourist destination. Artemis is 40 kilometers away from the Apollo 11 landing site, aka Tranquility Base, and there's a visitor center built there. So, you stay in pressure and look through windows at it. And the historical site is, of course, very well-protected and they don't let anybody mess with it.

Jim Green: Well, you know, all those I think were really critical aspects of your book in terms of how the whole plot evolves and what happens to the--what happens to Jazz (the character Jasmine “Jazz” Bashira) and her friends.

Andy Weir: Yeah. (laughs)

Jim Green: What kind of advice do you have to those budding science fiction writers that would follow your footsteps?

Andy Weir: Well, I guess for not just science fiction but any writers, the first step is you have to actually write. You can get stuck in world building and day dreaming and planning it out forever, but you're not actually writing until you're putting words into your word processor. And so, you have to actually sit down and do it, and that's when you start to notice the problems. That's why it’s not fun. It's fun to sit there and go like, oh, this will be my five book series. But, when you start writing it, you're like, oh, I see all the problems now. So, that's step one.

Step two, and this is difficult but more important, resist the urge to tell your story to your friends and family, especially if it's good. It's even worse if it's good because they'll be, wait, and then what happens, oh, tell me more, tell me more. You have to not do that.

The reason is most writers are driven by a desire to have an audience. We're driven--not all, but most of us--I certainly am. We want other people to experience the stories that we've created. And by telling the story to people verbally, it satisfies that need and saps your will to actually write the thing.

So, if you make yourself a rule that says, okay, no one can find out anything about my story except by reading it, then that motivates you, at the very least to motivate you, okay, I'll finish this chapter, and then I'll give it to my buddy to get his feedback and so on.

Jim Green: Well, you know, that must be the case because I think while we had chit-chatted in a couple of events about The Martian at various stages along the way, I had asked you about your next book, and you were--.

Andy Weir: --I was cagey--.

Jim Green: --Well, you were pretty darned cagey. I couldn't get any information out of you on that.

Andy Weir: Yeah, I have to--yeah, I'm, you know, following my own advice there. I have to--.

Jim Green: --So, I assume you're working on another project?

Andy Weir: I am, I am. My next project--well, this is my plan is that my next project would be a follow up book to Artemis that also takes place in Artemis, but Jazz is not the main character. It's a different person, and it's a different story. I would love to write a bunch of stories that all take place in Artemis as it goes forward--as it moves forward through its own history. And I just love that.

Like with Terry Pratchett's Discworld and other authors that have a consistent setting, the setting seems incredibly solid and tangible after you're a few books in.

Jim Green: Uh-huh. Well, you know, now there's quite a bit of thinking about how the Moon or at least being near the Moon in a, what's called a (Deep Space) Gateway could help us move them to Mars. And I think what we'll see over the next several years is a lot more thinking about going back to the Moon and doing a variety of science.

Andy Weir: Well, I think the Moon would be fantastic for a stepping stone on the way to Mars, because if Artemis really existed, a manned Mars mission would be monumentally easier because you have this entire infrastructure, including fuel generation and metal working and everything like that in a gravity well that's considerably lower than Earth. It would be real nice.

Jim Green: It would be. I understand completely. I don't know if I can wait to 2070, though, but--.

Andy Weir: --Yeah, I don't think we're gonna get to enjoy the benefits of that. I'm not gonna live to be 112, which is how old I'd be when Artemis takes place. Well, I might. I guess there's a chance, slim.

Jim Green: Are there any plans (in your future writing) to go back to Mars?

Andy Weir: Well, I don't know. I mean, not as a sequel to The Martian. I may have things take place on Mars in the future, but The Martian is sort of a “one-and-done” story. It's--I have never been able to come up with an idea for a sequel to it that wasn't stupid. It's like if Mark Watney gets in trouble again, well, NASA starts to look really incompetent, right? And if somebody else is in trouble and Mark is helping, then Mark isn't really the main character any more. And it was really people liked Mark, and so I just don't see any way to make a sequel on that. But, Mars, Mars itself is a setting where lots of fun stuff could happen.

Jim Green: Okay. So, here's Jim Green being a science fiction writer or at least a science fiction thinker. One of the things that I really liked about The Martian in the opening of it is that, you know, the scientists were out, they were deploying instruments, the astronauts were doing a variety of things, and Mark was picking up samples.

Andy Weir: Uh-huh.

Jim Green: And he would say, okay, the samples here are--.

Andy Weir: --Course and--yeah--.

Jim Green: --Yeah, and a little dirt in there he was throwing in the little box. And I would have loved as he goes back and gets his helmet for the last time to leave the station, Ares 3, that he picks up that file and takes it with him.

Andy Weir: Well, actually, in the book, he still remained an astronaut and a scientist through the whole ordeal during his long trip from Acidalia (Planitia) to Schiaparelli (Crater). He deliberately would still like take samples of the area, label them, tag them, put them in a box and leave them out in the surface for possible future sample returns. And I did have an idea of something like, ooh, we found something interesting, now we have to go back to where Mark was at this one point.

But, still, it's hard to make a story out of that. These are things that it's really difficult because some of these things that you can imagine would be unbelievably exciting if they happened in real life but are not that interesting if you write it as a story. Like, if we found like--if we just found like a sample of like, “Oh, my God, there's actually like a little microbe that we found that lives on Mars, that would be the most amazing scientific discovery.”--.

Jim Green: --It would, it would--.

Andy Weir: --Of our lives.

Jim Green: Uh-huh.

Andy Weir: But, in a movie, that's like, okay, well, so what. Are they gonna invade? You know, so you have to really--I really have to temper my own like what would excite me compared to what would excite a mainstream audience of readers.

Jim Green: In your career, you kind of really fell -- and I mean really hard -- into the ability to write science fiction. What's changed in your life since then?

Andy Weir: Well, you know, I was writing The Martian just as sort of a labor of love. I was posting it to my website at the time. And I spent 25 years as a computer programmer, a software engineer, and I really liked that, too, by the way. I enjoyed that job.

And now, like every aspect of my life is different. I'm a pretty social guy, and I used to really like going into work in the morning, and there were all my coworkers and, “Hey, how ya doing, can I buy you some coffee?” Yeah, you know, whatever. And just that social interaction in the morning--now what I do is I go down to my home office, and I'm by myself, and I write, you know, and I kind of miss that--.

Jim Green: --Well, what happened to the cat?

Andy Weir: Oh, well, I've got cats.

Jim Green: Yeah, that's what I thought.

Andy Weir: I've got cats. The cats keep me--I live with my girlfriend, also. It's not like it's this, you know, sad, super lonely existence. But, I do miss having a large group of people that I work with as part of a team, and I miss that.

But, other things that are awesome is still probably the best week of my life was about two years ago when NASA brought me out to Johnson Space Center, and I got a week of VIP tours of everything, and it's still just so awesome. The access that I have gotten to various people and places as a result of The Martian--there's--you imagine this Venn diagram that's surrounded by like awesome scientists, awesome writers, movie stars and then I'm like right there in the middle. I get to play with all of them.

Jim Green: Yeah, that's pretty neat. You're writing at a level where all the kids in this generation just eat that up. What kind of letters from kids do you get?

Andy Weir: Well, it's really cool. I had no idea when I wrote The Martian that it would be such a useful educational tool, but it turns out that it is, of course, because it's basically a long series of algebra questions and with the answers later on. And I've learned that a lot of teachers are using it in the classroom. That's why we made a classroom edition with all the swearing toned down. And so, that's fantastic.

But, I would say that one of my--if I had to just pick--I do get a lot of information about that from people and parents. Like, I got an email just this morning from a woman whose son is like severely autistic and doesn't really engage well with things but loved The Martian and just like would read the book, and that was a method by which she could interact with him.

But, I think my favorite though was right around the time the film was out in theaters, a woman sent me a picture of like, hey, this is my little girl's Halloween costume, and the little girl, she was like, I don't know, seven, something like that, had dressed up as Commander Lewis from the book for--yeah, so she had her little astronaut outfit on, it said, you know, Lewis, Melissa Lewis on it, and she had a cardboard box that was labeled Hermes and stuff like that. And I just thought it was awesome that, you know, this little girl because of my book decided to be an astronaut for Halloween instead of a princess, you know?

Jim Green: Uh-huh.

Well, let me tell you, in my experience, it's gravity assists that propel our kids forward, and it's really quite a privilege to be involved in being that person that provides that gravity assist, and it's clear that you have.

Andy Weir: It was unintentional, but I'm happy about the result.

Jim Green: Yeah, I congratulate you for that, too, Andy. That's very important. Thank you.

Andy Weir: Oh, thank you.

Jim Green: Well, Andy, you know, it's just been an absolute privilege to sit and chit-chat with you and get caught up. We haven't talked in a little while.

Andy Weir: Yeah, it's been great being here. Thanks for having me again.

Jim Green: Join us next time as we continue our virtual tour of the solar system. I'm Jim Green.

Andy Weir: And I'm Andy Weir, and that's your Gravity Assist.

If you enjoyed this Gravity Assist podcast, listen to these previous episodes on Mars and the Moon.

More on NASA’s Mars Exploration Program

For more NASA science, follow NASA’s Science Chief Thomas Zurbuchen on Twitter using @Dr_ThomasZ and check out #ScienceInSeconds for short videos.