...why we keep going back to the moon?

Ever Wonder? / February 3, 2021

...why we keep going back to the moon?

Headshot Dr. Kelsey Young out in the field.
Image attribution
Courtesy of Kelsey Young

We are kicking off a new series on space exploration, which is particularly relevant this month because a new Mars rover named Perseverance is hurtling towards the red planet for its landing on February 18. And joining me along for the ride as co-host for this series is my Science Center colleague and planetary geologist Devin Waller. There is a lot of science to unpack here, so we’ll be talking to people who explore all different corners of our solar system.

While we have sent quite a few rovers and other robots to Mars, we haven’t sent any humans there yet—it’s just too far away and dangerous right now. In the 1960s and 70s, NASA’s Apollo missions famously landed astronauts on the moon. And last December, NASA announced a new class of astronauts for the Artemis Team, which plans to send the first woman and the next man to explore the moon a few years from now. But if we’ve already been there before…

Do you ever wonder why we keep going back to the moon?

Kelsey Young (@RockDocYoung) is a planetary space scientist at NASA Goddard Space Flight Center. She explains that there is still quite a lot of science we can learn on the moon to better understand our own planet. Kelsey also has the enviable job of training astronauts how to be geologists here on Earth, so they can do science when they get to the moon.

Have a question you've been wondering about? Send an email to the podcast team to tell us what you'd like to hear in future episodes.

Subscribe to our show on Apple Podcasts, Spotify, or Google Podcasts. To see a full list of episodes, visit our show’s webpage.


Perry Roth-Johnson (00:06):

Hello! This is Ever Wonder? from the California Science Center. I'm Perry Roth-Johnson. Welcome to Season 2! We are kicking off a new series on space exploration, which is particularly relevant this month. A new Mars rover named Perseverance is hurtling towards the red planet for its landing on February 18. And joining me along for this ride, as co-host for this series is my Science Center colleague and planetary geologist, Devin Waller. There's a lot of science to unpack here, so we'll be talking to people who explore all different corners of our solar system. While we've sent quite a few rovers and other robots to Mars, we haven't sent any humans there yet--it's just too far away and dangerous right now. In the 1960s and 70s, NASA's Apollo missions famously landed astronauts on the moon. And last December, NASA announced a new class of astronauts for the Artemis Team, which plans to send the first woman and the next man to explore the moon a few years from now. But if we've already been there before... Do you ever wonder why we keep going back to the moon? Kelsey Young is a planetary space scientist at NASA Goddard Space Flight Center. She explains that there's still quite a lot of science we can learn on the moon to better understand our own planet. Kelsey also has the enviable job of training astronauts how to be geologists here on Earth, so they can do science when they get to the moon. We had a lot of fun talking to Kelsey--I think you'll find her enthusiasm for space is pretty infectious! Check it out.

Perry Roth-Johnson (01:40):

Kelsey Young, you are a planetary space scientist at NASA Goddard Space Flight Center. Welcome to the show!

Kelsey Young (01:45):

Thanks for having me.

Perry Roth-Johnson (01:47):

Yeah. And Devin Waller my co-host at the California Science Center. You're also here today. Hi Devin.

Devin Waller (01:52):

Hey Perry. Thanks for having me on and hi Kelsey. Thanks for joining us. So Kelsey, you're a planetary scientist and you focus on the integration of science priorities into human exploration. So tell us what does that mean and why is that important?

Kelsey Young (02:09):

Well, as many people are familiar, we've actually done geology on another planetary surface factoring the Apollo program. So during Apollo, we had, you know, six missions of two crew, each two crew members each exploring the lunar surface. Uh, and what are you, what are they doing there? What were they doing on a lunar surface while I'm sure a lot of you have seen pictures of people in spacesuits bouncing around the surface of the moon. Um, what they were actually doing on the lunar surface was doing geology. They were collecting samples that geologists here on Earth, you know, 50 years later are still using to answer science questions. They were making observations, exploring ground that no person had ever traveled over before. They were deploying science payloads that tell us something about lunar geology in situ or in place on, uh, on the lunar surface. And now we're preparing for the Artemis program, which is going to put the woman and the next man on the lunar surface, uh, we're targeting the South Pole for the Artemis program. Uh, and the same will be true, you know, during Artemis, what will the astronauts be doing? Well, there'll be doing science, they'll be collecting samples, making observations, taking photos and videos, communicating with scientists back on Earth, deploying instruments that tell you something about you know the world around you when you're using them. And so my job at NASA is to facilitate the integration of science into that human space flight program. So, uh, you know, how will the astronauts do geology? What kind of tools do they need? What kind of, you know, in situ instruments do they want use, um, what environments can they go to here on Earth to prepare them for that lunar exploration? Uh, it's about kind of integrating two communities that, you know, while they talk a little bit, it's about, you know, forming this really cohesive community that, you know, to ensure a really successful, you know, Artemis program from a science perspective.

Perry Roth-Johnson (03:54):

Can you talk a little bit about more specifically how your work supports the Artemis mission to return humans to the moon and like, what's interesting about the South Pole and what is a geologists like you excited to, to look at when we send astronauts there eventually?

Kelsey Young (04:10):

Yeah. For those not familiar with the Apollo program and where they landed on the moon, um, it, it would be like if you extrapolated the sort of geography and size of the moon to the Earth and dropped the Apollo landing sites on the Earth, it would be like, if you were an alien who visited the Earth and only visited the United States and never went anywhere else. Um, and so as a, you know, first of all, that that's a gut reaction of like, Oh my gosh, like, you wouldn't understand nearly enough about our planet by visiting only one continent. And as a geologist, we would miss so much about the geologic history of our planet. If we only visited, you know, that small of a space. Uh, and so we have a lot left to learn about the moon. Uh, all the Apollo landings were in the equatorial region.

Kelsey Young (04:54):

So near the equator of the moon, um, we never went to the far side with, with humans. Um, the same side of the moon always faces our planet and all six Apollo missions were on the near side of the moon. We have not yet sent people to the far side. Um, and the pole, especially, you know, has a lot of interesting science objectives and, and, and geology that we can't get anywhere else on the moon. Uh, one of the reasons that makes the south pole so exciting is volatiles, um, which, you know, have the ability to provide, you know, when, when processed and extracted from the lunar surface have the ability to be turned into rocket fuel. Um, so if you want to not have to bring in a fuel with you from Earth to get there and back, um, you could think about, you know, just putting enough fuel on the rocket to get to the moon.

Kelsey Young (05:35):

And then once you're at the moon, being able to do what we call in situ resource utilization to extract these really interesting volatiles from the subsurface of the moon and, and turn them into things like drinking water and rocket fuel. Um, but another science question at the south pole that is near and dear to my heart, I did my PhD on impact cratering. So impact craters are something that are all across the solar system. When you look up at the moon at night, you see lots of little circles, those are all impact craters on the lunar surface. And there's a really big one at the south pole of the moon called the South Pole - Aitken basin. And we think it's, you know, the oldest impact crater in our solar system and getting a sample from that SPA (South Pole - Aitken) basin crater is one of the highest priorities right now in solar system science. And the reason for that is because if we can get a sample that we know is from SPA, we know is really old. One of the first things that happened in our solar system evolution in history, it can provide a timing constraint for the rest of solar system exploration. Um, yeah, so South Pole - Aitken basin is, you know, where it's at and we're hoping to be able to, you know, one of, one of the many wonderful science objectives that we're targeting with the Artemis program,

Perry Roth-Johnson (06:43):

It's like, you're, uh, you're Rosetta Stone, you're dead sea scrolls, but like on a cosmic scale.

Kelsey Young (06:49):

Yeah. And, and another, that's actually a wonderful analogy. And another kind of comparable analogy that we like to say about the moon is the moon is a witness plate for the entire inner solar system. So whatever the moon experienced Earth experienced Mars experienced Venus experienced. And so we can actually learn a lot about our own planet by exploring the moon while it's, that was not really an intuitive concept to me when I first heard about it. But think about all the things we have here on Earth that make it a pleasant and wonderful place to live, like drinking water, vegetation, people, um, to use another example, plate tectonics and atmosphere. Um, these are all things that are really important for us, um, but actually obscure the geologic record. Um, so take plate tectonics for an example, um, we have all the time, you know, cross to being destroyed, new cross being created. And, you know, while that drives a lot of the processes that we see at our planet and makes Earth what it is, it also destroys rocks and describes the geologic record where we don't have plate tectonics or oceans or vegetation is the moon. And so the moon actually captures four plus billion years of solar system history that we do not have access to on our planet because it's long been destroyed. Um, so we can actually learn a lot about the evolution of our own planet by exploring the moon. And a lot of the science objectives that we're hoping to target with the Artemis program are seeking to again, use the moon as a, as a witness plate for the rest of the solar system.

Perry Roth-Johnson (08:11):

Okay. That, that that's cool. That helps motivate, you know, we're not just going back to the moon to relive the Apollo glory days, although those were awesome, but we're like learning new things about not only the moon, but how our Earth and the rest of the planets and their solar system got to where they are today.

Kelsey Young (08:28):

We have a lot of science left to do at the moon. So looking forward to getting going.

Devin Waller (08:33):

So along with the research that you do, you are in the process of training these astronauts to go back to the moon and understand the geology of the lunar surface that they're going to see.

Kelsey Young (08:45):

Yeah, absolutely and you know, taking it back once again, and there's a lot of lessons learned from the Apollo program and, and, you know, back during Apollo, uh, the astronauts that flew to the moon, you know, we say they basically had the equivalent of a master's degree in geology because they had hundreds and hundreds of hours of geology training. And that training took place in the classroom and in the field. So they went out to these analog environments as we call them that looked like, you know, the areas on the lunar surface, where their missions were targeted to land, uh, and they were in the classroom just like, you know, all students are, you know, here on Earth. They, they learned about principles of geology, uh, in, in the classroom at the Johnson Space Center. So, you know, again, flash forward 50 years to today and, and we're still training astronauts in geology. Um, but it doesn't just start when they're assigned to a mission. Uh, it starts when they're selected as an astronaut candidate. Um, so during that initial two years of candidacy training that they undergo at the Johnson Space Center, you know, they received training and just, you know, a whole host of topics, including, you know, the international space station, robotics, how to fly a T-38 jet. Um, they learn, you know, Russian as of now to, you know, given our partnerships with the International Space Station. Um, but they're also trained in geology. Um, so myself and my colleagues from both inside NASA and across the academic community, provide them with that, you know, geology and intro to science training. So again, just like Apollo, we trained them in the classroom. We train them in the field, we train them about, you know, fundamentals of geology. We train them about the solar system and you know, why NASA is interested in exploring it.

Kelsey Young (10:12):

Uh, we teach them how to geologic map. We teach them about the features that they observe on Earth from the international space station, because of course they spend some of their time on ISS taking pictures of the Earth. So we help them understand what they're looking at and the processes that shape our own planet. Um, so we provide them with this, you know, few weeks of fundamental science training, both in the classroom and in the field during their astronaut candidacy. Um, and then, you know, flash forward to now we're planning for the Artemis program. Uh, and we're, you know, with that, again, there'll be trained in a whole variety of topics, like landing on the moon, how to operate in a space suit on the lunar surface, how to launch in the rocket that will take them to the moon. Um, but we will also treat, train them in geology. So right now we're planning out the classroom and the field, um, curriculum that, you know, these Artemis astronauts will take after they're assigned to a mission.

Perry Roth-Johnson (11:02):

Man, I'm so jealous. Cause I think like a lot of people, uh, you know, I wanted to be an astronaut when I was a kid and I wish I was your student right now. I just want it. I want you to unpack a little bit of what you said in the beginning. You, you briefly explain, uh, about analog sites and how they're places here on Earth that kind of look like the places we want to explore and other worlds. Um, can you give a few more examples of that? Like I've heard of these, these fake Mars sites on Hawaii, like, are there others that you've been to, that you train your astronauts at and like, why are they so important for training?

Kelsey Young (11:36):

Uh, analog sites are my favorite topics to talk about so I can talk your ear off for hours about those. Um, absolutely. So an analog environment is, you know, a site on Earth that resembles something about another planetary surface. Um, so for example, we can go to volcanoes on Earth that looked like on Mars, or we can go to an impact crater on Earth that looks like the impact crater on the moon, which was actually what I did my PhD on. Um, so really, I mean, I think the main takeaway is that there is no perfect analog. There's no place that you can go to on Earth that looks exactly like the moon, because of course we need to go to the moon and explore it. And it's just by looking up at the moon at night, you can see that it's very different from our own planet. So we can't go to a place here on Earth that, you know, 100% mimics the conditions we'll see on the moon, but by combining work in multiple analog environments, it gets you really close to understanding the conditions that await us on the lunar surface. So, um, a few examples of analog sites that, you know, I personally work at... Well, uh, you mentioned Hawaii, um, definitely have spent a lot of time on the Big Island of Hawaii. The style of volcanism that you see on the Big Island and, and, you know, in Hawaii in general really mimics a lot of the volcanic processes we see, especially on the moon and Mars. Um, so a lot of field work that, um, myself and the team that I work with do is on, you know, the Kīlauea volcano. Um, for example, on the big Island, which has made press lately, cause there's been some small, um, you know, eruptions that have, you know, come close to where humans live on the big Island. Um, we spend a lot of time in Iceland. Um, the Apollo astronauts actually trained, um, quite near where we work in Iceland. And again, we see comparable processes that shape the whole solar system in Iceland. So by visiting there, um, we can really learn about, you know, volcanic processes on Mars, for example, um, a little bit closer to home, uh, Arizona, the state of Arizona, uh, we're actually did my masters and PhD is actually incredibly wonderful to provide lessons learned about other planetary surfaces. Um, the, uh, Flagstaff, Arizona area is an area where, you know, going all the way back to Apollo, um, was really heavily used for Apollo astronaut training. And we use it now for astronaut candidacy training as well as just, you know, understanding planetary surface processes. Um, so I could, you know, wax poetic for hours about the geology sites of interest on Earth that tell us about other planets, but, um, that's not the only type of analog environment that we can work in, right? That's those are, those are, um, really logical places to go to study, you know, planetary surface processes that shape, you know, not only the Earth, but the moon and Mars, but to learn how to operate in space. Uh, we want to combine that with operations, for example, underwater. Um, if you've seen, you know, a variety of space movies that came out of Hollywood, you've seen, you know, astronauts training in a big pool in a spacesuit. Well, um, that pool actually exists. It's called the Neutral Buoyancy facility, the Neutral Buoyancy Lab, and it's at the Johnson Space Center. And it actually has, you know, a full scale replica of the areas, um, on the International Space Station where the astronauts, you know, conduct their extra vehicular activities, what we call EVAor spacewalks, uh, and by operating underwater, you can simulate what it's like to work in gravity conditions that are different from the gravity conditions we have here at the surface of the Earth. Um, so, you know, by combining, you know, the science work and these terrestrial analog environments like, Arizona, Hawaii, Iceland with operating in environments like the MBL, the Neutral Buoyancy Lab, you know, to, to simulate lower gravity conditions, we're able to help the crew members prepare for space flight by showing them what geology to expect. Um, but also helping them train in what it's gonna feel like to be in a space suit on the surface of another planet.

Perry Roth-Johnson (15:10):

I want to stick with this underwater training that for a second, um, because there's like a long history, uh, of, of training underwater. And then there's like a cool mashup word, uh, aquastronauts where you have aquanauts and astronauts all mashed up into one word, um, from the early, uh, mercury seven astronauts in the 1960s, uh, Scott Carpenter was the first aquastronaut right? Can, can you explain like what aquastronaut means and like why we've been doing it for so long? Absolutely. So I love that word. Um, astronaut is somebody who's flown in space, of course. Um, aquanaut is someone who has, you know, explored and lived under water. Um, so you mentioned Scott Carpenter, who, as you said, was the OG aquastronaut. Um, and he, you know, of course after his experience working with NASA, um, he was able to partner with, you know, a group that did saturation diving or, you know, when you actually, rather than scuba diving, which, you know, you might be familiar with, you actually can, um, let your body adjust to living at the pressures, found underneath the surface of the ocean. Um, and you can actually, you know, stay for, you know, days and weeks at a time living under water. Um, and so the, you know, the, the term that was coined was, you know, once you've, you know, you've saturated and spend a day under water, you're an aquanaut. Um, so if you've done both, you've been to space and you've lived under water, you are an aquastronaut of which, you know, Scott Carpenter was the first and there have been many since then.

Perry Roth-Johnson (16:37):

Classic overachiever. All right. I want to transition from under the sea to back up above, uh, on land.

Devin Waller (16:42):

Yeah. So you've lead a team that explores lava tubes and that I think is super cool. It's a, it's a project called ?Tube X and you're using LIDAR sensors and other instruments to produce like a 3-D map of the tubes themselves. What's the connection between lava tube work that you do here on Earth and your planetary exploration?

Kelsey Young (17:05):

Yeah. So lava tubes are just a really exciting concept. And I think it's, it's just fun to visualize how we might be able to use them to support exploration someday in the future. So what a lava tube is, um, is it's a sort of void space underground, um, that basically formed during the, in placement of a lava flow. So during a volcanic eruption, there are a couple of different processes that can form these lava tubes. It's typically just the in placement of that lava flow. So the outside of a lava flow becomes hardened because it's exposed to the cool air, relatively cool air at the surface. Um, so the outside hardens, but the inside, because it's protected from that cooler air is able to stay molten and continues to flow. Um, so what you actually get is when all, when the, basically when the faucet turns off and the volcano stops erupting that molten lava just drains out the bottom of the tube and leaves this void space behind. Uh, and so they can be small, like on the order of a few feet in diameter, or they can be, you know, really quite large. Um, so missions to the moon have highlighted the potential for some of these lava tubes to be big enough to, you know, really be able to, if we're able to ingress them safely, you know, provide really robust support for human explorers on the surface of the moon.

Perry Roth-Johnson (18:15):

So they're basically like natural tunnels, right?

Kelsey Young (18:17):

There exactly like natural tunnels. And how do we know they're there, if it's a tunnel? Um, well that's because, um, you can often get what are called skylights where, you know, the roof in just one area or a couple areas collapses into the bottom of the tube, which means that you kind of get this window into the tunnel, so to speak, um, that is basically your entrance, your, your, your door into that rest of that, you know, tunnel system. So the TubeX project, um, is a NASA funded project that combines, uh, you know, I'm on the team with some NASA colleagues, uh, as well as we have some academic colleagues from the University of South Florida and the University of Maryland. Uh, and we're actually able to, you know, develop an exploration strategy for these tubes. So it sounds great, right. Um, you know, there's dangerous radiation at the surface of the moon and Mars, there is meteorite meteor impacts that can come and impact the lunar surface and being able to ingress one of these tubes and, you know, spend some time in there means that you're shielded from all of these potentially dangerous situations at the surface. However, um, picture being in basically your own personal spacecraft--in a spacesuit, which is essentially what that is right--and having, you know, drop down a hole into a tunnel that you're not exactly sure how big this tunnel is, how deep does it go? Does it go, you know, just 10 meters past the edge of the hole, or does it go, you know, potentially miles and miles? Um, so the TubeX project is really designed to not only just learn scientifically about how these tubes form and evolve over time, but also to say, okay, what instruments can an astronaut or a robotic explorer use at the surface without, you know, dropping down into the tube to map these tubes so that we can say, "Hey, this tube might be a good one to actually go ahead and try to ingress." And what data, what instruments can help us map that too? Without, you know, putting, putting the crew member actually down into the tunnel.

Perry Roth-Johnson (20:02):

Got it. And like, was LIDAR one of the tools that you used that you gave to the astronauts or, or was it used for some other purpose?

Kelsey Young (20:10):

Yeah. Um, so we combine a series of instruments to develop this tube exploration strategy. Uh, we use, um, primarily surface deployable instruments. So a ground penetrating radar, which to oversimplify it is basically like a lawn mower that you can drag over the surface and an it images the subsurface as you push your lawn mower or pull your lawn mower. Um, and so we use ground-penetrating radar. We use seismic studies, we use GRUB imagery and magnetometry. These are all geo-physical techniques that from the surface can map what's underneath your shoes when you're walking around the surface. Um, and we use LIDAR, which is light detection and ranging inside the tubes to provide kind of that map or the answer key to provide that calibration for what those surface to play. All it deployable instruments are seeing versus what's actually there. So by getting into the tube with a LIDAR, it creates this really detailed, 3-D resolution, high resolution map of the interior of the tube. And then we take those data sets that we obtained from lawnmowing across the surface of the tube and say, how close did we get with these datasets? Uh, and to do that, you know, by doing that, we actually say, okay, well, these are the ideal instruments that we would take to the moon. If we wanted to actually do this with astronauts.

Devin Waller (21:16):

So you create this high resolution 3-D map using LIDAR inside the, the lava tube. And then you go onto the surface and you use all of the, you know, handheld instruments in order to see if you can match that 3-Dmap on the surface. So exactly that on another planet, what you're looking at from the surface or from orbital data, you'll be able to make good predictions or accurate predictions as to what's underneath the surface, based upon your research here, is that kind of like what you're doing?

Kelsey Young (21:47):

Exactly right. So imagine going to an area on the moon where you had, I'm making this up just for an example, but, you know, 10 skylights into a series of lava tubes and you're, you know, you're an astronaut, um, Devin and Perry, you're a crew on the lunar surface trying to figure out which of those 10 pits to choose to repel down into, uh, how do you pick, how do you down select from 10 to the best candidate for, for exploration. Uh, and so by using these instruments, let's say you took your ground penetrating radar and your magnetometer around all 10 of these skylights into these tubes. And by creating the maps that you've now know how to create by calibrating with the LIDAR data you can pick, okay, well, this is the best candidate for exploration, and this is where I want to try to explore.

Perry Roth-Johnson (22:25):

Where can people follow you online to find your work?

Kelsey Young (22:29):

Uh, yeah. So, uh, if you just Google my name and NASA, you'll see the, my like website on the, you know, NASA agency website pop-up, um, I'm on Twitter, but I'll be honest. I'm not, I'm not a super prolific poster. Um, but you can find me @RockDocYoung, if you want to see a post every once in a while. Um, but you can definitely learn a lot about, um, you know, NASA's missions and, and a lot of the work that I've mentioned today, like the astronaut training and the analog projects that we do on NASA, social media accounts, NASA and NASA moon, um, as well as if you just Google any of the projects that I mentioned today, they'll, you'll definitely see content on NASA's website. So, um, stay tuned and we do try hard to, um, put out content about the field campaigns that we do in the work that we're doing. And as we press toward the Artemis program, we will definitely be communicating with the public about it. You can be sure about that. So definitely stay tuned to kind of all those sources that I mentioned. And, and you'll definitely see some, some really exciting content about the work that we're doing.

Perry Roth-Johnson (23:25):

Well, Kelsey, thanks for joining us on the show and sharing with us how we do science and other worlds. And it's been a pleasure talking to you.

Kelsey Young (23:31):

Yeah. Thanks so much for having me. I honestly could talk about this all day. I've tried to rein myself in today, but really happy to have you guys have me here today and looking forward to more conversations in the future.

Devin Waller (23:41):

Thanks, Kelsey. It's been great.

Perry Roth-Johnson (23:43):

That's our show. And thanks for listening until next time keep wondering.

Perry Roth-Johnson (23:52):

Ever Wonder? From the California Science Center is produced by me, Perry Roth-Johnson, along with Jennifer Castillo, Liz Roth-Johnson is our editor. Theme music provided by Michael Nickolas and Pond5. Special thanks to Devin Waller for producing and hosting this series. We'll drop new episodes every other Wednesday. If you're a fan of the show, be sure to subscribe and leave us a rating or review or tell a friend about us. Now, our doors may be closed, but our mission to inspire science learning, and everyone continues. We're working hard to provide free educational resources online while maintaining essential operations like onsite animal care and preparing for our reopening to the public. Join our mission by making a gift at californiasciencecenter.org/support.