From Earth orbit to the Moon and Mars, explore the world of human spaceflight with NASA each week on the official podcast of the Johnson Space Center in Houston, Texas. Listen to in-depth conversations with the astronauts, scientists and engineers who make it possible.
On Episode 228, Sergio Santa Maria shares the details of a research investigation on the Artemis I mission around the Moon that will send microorganisms into deep space. This episode was recorded on December 14, 2021.
Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 228, “Deep Space Biology.” I’m Gary Jordan, and I’ll be your host today. On this podcast we bring in the experts, scientists, engineers and astronauts, all to let you know what’s going on in the world of human spaceflight. We’re continuing episodes about the Artemis I mission. This will send Orion on an uncrewed mission around the Moon, and will launch on top of the Space Launch System, or the SLS, the first launch of this rocket. We’ve talked a lot so far about the main objectives of this mission, both for Orion and for SLS, but there are a number of secondary missions. For the SLS, in addition to delivering the Orion into the lunar vicinity, the monster rocket will also deploy a number of nanosatellites with their own missions and objectives. One of those shoebox-sized satellites will carry life, or biological samples to be precise; specifically, yeast. This is to study the effects of deep space radiation on biology. And this investigation will be NASA’s first set of biology experiments to take place in deep space since the Apollo era. To discuss this investigation called BioSentinel, we’re bringing in the project scientist, Sergio Santa Maria from Ames Research Center in California. Originally from Lima, Peru, Sergio has a Ph.D. in biochemistry and molecular biology. He studied radiation and the effects in astronauts at the Johnson Space Center, and he also studied how cells repair radiation damage at the American Cancer Society in New York City. He’s been with the BioSentinel team since 2014, first as a scientist and then taking on the role of science lead and project scientist in 2019. So let’s learn more about this experiment, looking at life in deep space. Enjoy.
Host: Hey, Sergio, thanks for coming on Houston We Have a Podcast today.
Sergio Santa Maria: Thank you, Gary, I’m glad to be here.
Host: Very good. You are the project scientist for a super-cool experiment called BioSentinel, and that’s what we’re going to be talking about today. First, though, I want to understand what a project scientist does. If you were looking at this particular project, BioSentinel, what is your role specifically?
Sergio Santa Maria: BioSentinel is a particular project in that both the engineering and science is run at NASA Ames Research Center. So my role as a project scientist: to interact with both the science and the engineers, to help the engineers, support engineers, as well as conduct all the scientific experiments to support the mission.
Host: OK, and this, this mission that we’re going to be talking about today is called BioSentinel. So, high level, what exactly is this experiment all about?
Sergio Santa Maria: From a biology perspective, BioSentinel is trying to understand what’s going on with biology in space, what’s happening to terrestrial biology, to help contribute to how we can deal with this in future crew missions with astronauts.
Host: OK, so it is going to deep space, right? That’s, that’s the unique part about this experiment?
Sergio Santa Maria: That is correct. Out of the multiple secondary payloads on the Artemis I mission, BioSentinel happens to be the only biology mission and the only biology from NASA going outside of the Van Allen belts, outside of the magnetic fields, since the Apollo missions.
Host: And what exactly is, so, so you mentioned Artemis I, right; what exactly is that mission that’s playing into — how BioSentinel is going to actually get to deep space?
Sergio Santa Maria: So as probably your audience knows, Artemis I is part of the Artemis program from NASA. It’s going to be the first, the first mission part of the program. It’s not going to be crewed, so no astronauts here. It’s, the primary objective is to test the Orion multi-crew spacecraft. And as part of this, this launch, years ago NASA realized that there was enough mass and volume to carry secondary payloads; originally 13. Now, we’re going with ten secondary payloads. They’re all called CubeSats, which are small satellites. And once Orion gets released from the, the rocket, the remaining part of the rocket, each CubeSat is going to be deployed one at a time, and with that momentum, at least in the case of BioSentinel, gets into cislunar orbit, and it continues into its own heliocentric orbit.
Host: OK, so it means that at some point that, you said, you mentioned the primary mission is really to test the SLS, the Space Launch System, the Orion. But it sounds like these, these payloads are being deployed at some part of the mission, and then it’s going to orbit the Moon and then eventually the Sun, which is spectacular. Exactly at what point is BioSentinel going to be deployed, at what point where Orion and SLS are relative to maybe the Earth and Moon?
Sergio Santa Maria: Oh, that’s a pretty good question. So there are a few spots, I believe, where the payloads will be released. BioSentinel, to the best of my understanding, is either the first or second payload coming out of the ICPS (Interim Cryogenic Propulsion Stage), which is the stage underneath Orion, and then we continue into our own orbit. It’s pretty early on. I would like to, if I tell you that I know the exact time.
Host: [Laughter] OK, all right, very good. And it is deployed, how exactly is it deployed? Is it deployed by some contraption on the Space Launch System itself? On one of the rocket stages that’s actually going to be, quote-unquote, launching these CubeSats?
Sergio Santa Maria: Right. So right underneath Orion, it is what is called the OSA, is the Orion Stage Adapter. It’s like a, like a ring. And all ten secondary payloads, all ten CubeSats, are inserted currently into a dispenser. And what it pretty much happens, it’s like a spring release. It pretty much pushes out each CubeSat at a time with a couple seconds between each other. They will never touch each other, will never see each other again.
Host:[Laughter] Now, now when you say they — it’s very interesting because, when it’s deployed it goes into, you said a lunar orbit and then in heliocentric orbit around the Sun; is there any propulsion that’s on the CubeSat to guide it, or is the trajectory such that it will naturally fall into these trajectories?
Sergio Santa Maria: So the BioSentinel does have a propulsion system. However, it’s not going to be used for the, you know, your typical understanding of propulsion. It’s pretty much going to be continued with its own momentum. It continues into its own trajectory. The propulsion system with the BioSentinel is a cold-gas system, but that’s more to stabilize the little space capable satellite, because it is going to come probably rotating once it gets into space by its own. So it does have the propulsion, it just doesn’t use it to, to move around in space.
Host: OK. Now we’ve been talking a lot about the where, you know, exactly where and exactly how this experiment is getting to space. But let’s get into the experiment itself. You talked about this being a deep space biological experiment. So let’s get into, what exactly makes up BioSentinel? What exactly is being tested? What is the biology on this experiment?
Sergio Santa Maria: Right, perfect. So there are actually two main, let’s call them compartments within BioSentinel. BioSentinel is what is called a 6U CubeSat. 6U stands for six units, one unit being a small cube of 10 by 10 by 10 centimeters. This 6U CubeSat is, again, divided into two different sections. One is the biology section, which we call the biosensor. It’s a small box of 4U in volume. And the other remaining volume is part of what is called the bus for all the spacecraft components. We talk about the avionics, the solar panels, the batteries, all that is part of the bus. Inside the other 4U box is where we’re carrying the biology. And this particular case, biology is what we call budding yeast. These are organisms that are used in the pharmaceutical industry, in breweries, to produce food. It’s just your standard laboratory variation of, of yeast.
Host: OK, and what, and what exactly is interesting about yeast that, that is the, what’s been chosen? What is yeast going to help you to understand about what’s happening in deep space?
Sergio Santa Maria: So I told you that, that yeast is being used, has been used for many, many, many years around the globe for multiple reasons. One of those is in academic laboratories, because many of the, the processes, what happens inside a human cell are also present in these yeast cells. So overall, their response, for example, to radiation, in this case space radiation, is similar in yeast than in humans. So we can capture that information using these small microbiology organisms to understand what could happen in human cells later. So it’s what is called a model biological organism.
Host: OK, and so, so really, the goals here, you’re sending, you’re sending yeast in a little shoebox around space. And the goal here is, the reason that you’re doing that, is the unique radiation environment of deep space. Now, it sounds like that’s something you want to study. You want to study radiation in yeast. Just exactly what are you looking at in the yeast to, to study radiation?
Sergio Santa Maria: So, right, and the scientific objective of BioSentinel is to understand the response to space radiation, which outside of the magnetic field, which is once you go outside of the Earth-Moon system, it’s composed primarily of two radiation types. One is the, what is called the solar protons, that come from the Sun, and of course, the galactic cosmic radiation that comes from the, the universe in general. So what we’re trying to understand is, how do these different radiation particles affect the biology, affect the yeast, and how the yeast is able to perhaps repair that damage caused by radiation over the course of the 6-to-12-month mission.
Host: OK, that’s pretty important, the duration of the experiment as well. OK, so you’re measuring radiation. And exactly what, what sensors, what equipment is on the CubeSat to allow you to understand the radiation environment and understand the DNA repair sequences that are happening inside the yeast? What’s the technology you’re using to measure that?
Sergio Santa Maria: So I told you that yeast is a very important organism because it’s used all around the globe. It can replicate some of the conditions in human cells. A second very, very important aspect of why we use this particular budding yeast, this organism, is because we can dry it. I mean, you can find your, your food yeast in the market to make bread or whatever you want to make. So we can dry these guys inside what we call microfluidic cards, microfluidic cassettes. So we have the yeast dry inside these little compartments, inside these microfluidic cards. And then we actually inject, inside these cards, nutrients and also what we call a dye, a so-called viability or metabolic dye. So what happens is, the more radiation the biology experiences, the more damage the biology, the yeast cells, experience, the longer they will take to grow, obviously, just based on the amount of damage, but also this dye changes color when the cells become active. So we can do a pretty precise follow-up of how the cells respond to radiation over the course of the mission. So we can try to estimate the amount of damage and how long they take to fix that, that damage. Something else very important about this mission besides the biology per se, is that right next to the 4U biosensor box we have what is called an LET (linear energy transfer) spectrometer, which is pretty much dosimeter, which was designed and developed at Johnson Space Center by the Radworks team. It’s a Timepix-based chip that allows to characterize the type of radiation hitting the payload, but also the amount of radiation. So now we have biology responding to radiation and a pontification of the amount and type of radiation hitting the biology. So it’s a pretty, I would say pretty cool complete system there.
Host: Yeah, yeah, that’s pretty important to, to understand, right? If you’re, if you want to understand what’s happening to the biology and how radiation is affecting the biology, you also want to understand the radiation itself and help to characterize that. That makes, that makes certainly a lot of sense. I want to go back to the, how, how the yeast is on the CubeSat though. You mentioned cassettes, and you mentioned these fluids, and this is a biological experiment so I wonder, beyond, beyond that — you called it a cassette, the way that the yeast is carried inside the, the CubeSat, is that really all, all you need to help to understand what’s happening to the yeast, or is there maybe some, we’ll call it a life-support system, right, some, some way that the organism can live and breathe to allow the DNA repair sequence, or, or does it really, does yeast in this case really not need that and it’s really just the fluid and the cassettes that’s really all that’s needed for the yeast to, to do what it needs to do?
Sergio Santa Maria: So you just got into the most complicated part of both biological missions, which is the temperature control. We need to keep the biology, when the cells are dry, the biology stays pretty much at your refrigerator type of temperature, which is approximately 4 Celsius degrees. However, when we grow them, when we inject the nutrients into these fluidic cassettes or cards, we increase the temperature to approximately ambient temperature, which is around 23 Celsius degrees. So the whole system carries multiple heaters to maintain either at 4 degrees or at 23 degrees, because we cannot afford having the, the cold temperature of space because it would freeze absolutely everything, including the electronics. So we depend on these active heaters throughout the whole, the whole little spacecraft actually, either to keep the fluids in liquid form, not frozen, to keep the biology happy and allow it to grow. And everything that we’re trying to do, it actually allows us to monitor how the cells are doing. Are they maintaining them at the right temperature? Or how we read the biology: what that means is, after we inject the liquid, these nutrients carrying this, this color dye, we have to monitor that. And the way we do that is with LED lights. So we have different LED lights that allow us to check growth. So just looking at what is called the turbidity, or how many cells are blocking the light path — so that allows you to calculate how many cells are growing and how fast — and then we also have a couple of LED lights that are specific to measure this, this metabolic dye and the different colors. So now we can actually use all that data to estimate how long it’s taking for the cells to grow, how long it’s taking for the cells to potential repair that damage, and how long it’s taking for the cells to change the color of that dye, again, across the entire mission. So we’re expecting different growth rates or different changes of color rates at the beginning of the mission and at the end of the mission. And, of course, we’ll follow this with our ground control units.
Host: OK, yeah. So, yeah, it sounds like there is a monitoring aspect to this. There is data. There is data flowing from your, when you were describing the CubeSat, all the avionics and communications and the power box, that is relaying the data that you need to the ground. So, you know, give me, give us an understanding of exactly what you are looking for. It sounds like, it sounds like you are — what sorts of things are you measuring? It sounds like there’s an aspect of light, so is there maybe spectroscopy that you’re looking at? Or I think there are dosimeters on board, right? There has to be if you’re measuring the radiation environment. Tell me, what’s some of the data that you have flowing from the CubeSat down to the scientists on the ground?
Sergio Santa Maria: Right. So, so you have everything that comes from the spacecraft, from the bus, and I won’t get into details because I’m not an expert whatsoever —
Host: You’re the scientist.
Sergio Santa Maria: — on engineering.
Sergio Santa Maria: So, but we do get a lot of data from the spacecraft, and that’s to check that all the subsystems within the spacecraft per se are actually working properly. Then from the scientific data, you’re absolutely right, we actually get two sets of data, primary sets of data. One of them is the spectroscopy data, you got absolutely right again. That’s the data that comes with these spectroscopy or absorbance or optical density. So these are just numbers that are trying to provide us with information of how the cell is responding to radiation using these, these LED lights. The other set of data comes from the dosimeters. It’s only one. The spectrometer —
Host: Oh, OK.
Sergio Santa Maria: — and this one, it’s actually a lot of data because it characterizes the whole, like a big spectrum of type of particles. So and everything gets downlink or sent back to Earth using the, the DSN, the Deep Space Network. And once the data is down at Ames, we get the data’s binary, binary data, binary code; that gets transformed into useable data for us. And then we go through entire process at our SOC or Science Operation Center that’s also located at NASA Ames.
Host: OK, all right. So that’s, and that is going to be, you know, from the time of Artemis launch, you said around 12 months, around a year. So really over the next year, over 2022 into 2023, you are going to be in data collection mode and looking at some of the things. Is that a fair characterization of what’s, what’s on your calendar for at least the next year?
Sergio Santa Maria: Well, I’ll tell you what’s in my calendar, in a couple weeks we are flying to ISS on the 21st [December 21, 2021], which is, I will talk probably about that a little bit later. The way it’s going to work is we actually get data at every single pass, every single time that we are able to communicate with the spacecraft, with the CubeSat, we’ll get data downlinked to Earth that gets processed and sent to the SOC, the Science Operation Center, and to the science team, which is pretty interconnected. And then we actually start processing the data pretty much as soon as we get it, because we need to understand what’s going on. Do we need to make any potential changes? For example, let’s say our biology is doing better or worse, depending on what we get from the data, so we might decide to activate different fluidic cards at different time points, and we have that capability within this particular CubeSat. And then we continue the mission. And the nominal mission is actually six months with a potential extension, if the data that we’re getting is successful. And then we, at the end of mission, we do the whole archiving.
Host: OK, all right, yeah. That makes a lot of sense. You got the command capabilities, you can make some subtle tweaks, but really, yeah, you’re, it’s a, your mission is to gather the science. And you were alluding, Sergio, to another key aspect of this, right, we’re talking about BioSentinel and that’s going to deep space; part of the investigation is to characterize the radiation environment of deep space and see what’s happening to the yeast. That is not the only location that you are measuring that. And that is for, I’m guessing, a very specific purpose. You alluded to the International Space Station as another place where yeast is going to be sent and you’re going to do some sort of similar things in a, in a different radiation environment, and that is on board the International Space Station. So what’s that experiment going up here, at least at the time of this recording, going up very shortly on CRS-24?
Sergio Santa Maria: That is correct. So we actually have four identical units from the perspective of the 4U biosensor box, the smaller enclosure. We have the one, the free-flyer, which is the deep space satellite; we have its ground control, which is going to be run at Ames; we have our ISS microgravity control that is at the low radiation environment, like you mentioned; and then we have also the ground control for the ISS. We are flying on the 24th [of December], and we’re activating the first set of fluidic cards early in January 2022.
Host: And why is it important to have all of these components in different places? How does that help you to understand and characterize the radiation environment, what’s happening to the yeast, versus just picking one location and sticking with that?
Sergio Santa Maria: One of the main issues that we have had for many years is we are not have the capability of measuring biological response to many factors in space. What has been done many times is we actually expose biology in space, and then we bring it back to the ground, and they conduct some experiments. And we do this by playing with temperatures, by freezing the samples, or by using what is called fixatives. We just fix them in time and then bring them back to Earth. This particular mission, BioSentinel, allows us to look at in situ in real-time, meaning we can see the actual response to radiation in, in space and get the data back. For the ISS, we, we know that we’ve used gravity, in this case microgravity, can have some effects on biology, potentially in the DNA repair pathways of yeast, how they repair this damage, how they responds to the microgravity environment. So having these microgravity control with a lower radiation environment compared to deep space allows us to look at that particular aspect of the mission, just separating high, high-energy or deep space radiation to lower orbit inside the ISS. And then, of course, you have the ground control units that have none of that radiation effect. And they are one gravity, although we actually mount the ground control units on what we call a rotisserie instrument — it’s pretty much a rotisserie that allows you to rotate back and forward, not a full rotation, just going one way and then the other. And that’s just to prevent the, the yeast cells to sediment. You know, these yeast cells are bigger than bacteria, so they tend to go down by gravity over time. So this instrument just rotates to prevent that and give us an idea of what the response on the ground to compare to both ISS and deep space.
Host: OK, all right, yeah. Having, that’s very, very important. Thank you, Sergio. Lots of exciting stuff coming up. We’re in the, it seems like the, really the home stretch here. We got experiments going on the International Space Station very shortly. And there’s — this experiment going on the first Artemis mission, Artemis mission around the Moon, Artemis I. And coming up very, very shortly. For that one specifically, for that CubeSat going up on Artemis I, we’re in the final home stretch, as I’m saying; what do you have left to do? What are some of the final steps you have before its integrated on this stage of, of the vehicle and ready to go?
Sergio Santa Maria: We delivered the spacecraft, the free-flyer CubeSat, in, I recall, early October, late September. It was integrated not that long ago. We’re really just waiting for the SLS folks to put Orion on top, and we are ready on our side. We know that we’re waiting for that launch in, hopefully in the next few months. For the most part, we are just, we continue our work at Ames preparing for the ISS mission, preparing our ground control operations center, mission operations. But most importantly from the science perspective, we are still going through the optical data, the spectrometry data, because many of the experiments that we do on the ground, if not most of the experiments we do on the ground with radiation, are using what is called acute radiation, meaning we deliver the dose pretty much very fast, and we do this using gamma radiation or X rays or even high-energy particles at, for example, Brookhaven National Laboratory; these are accelerated ionizing particles. However, in a space, in reality, everything is done in a chronic way. So we deliver that same dose over the course of a month or weeks or multiple months. So we’re still trying to understand what we’re going to see. So we’re trying to fine tune, really fine tune how we analyze that data, trying to get the optical data processing the different protocols and procedures so when we actually start getting data from flight, we’re kind of ready to respond if changes need to be made. So that’s, that’s what we are investing a lot of our time nowadays.
Host: OK, yeah. Just really gearing up to make sure that you are set to go for when this thing launches. I mean, overall, though, because of this timeline, how are you feeling? Do you feel, I mean, it seems like you’ve got a couple of things to wrap up, but do you feel good? Do you feel excited, nervous, about, you know, you have all this, your investigation, which you’ve been working for, for years on is about to launch?
Sergio Santa Maria: I mean, since the time, since the one time I heard deep space, I was in love with this mission – I’m talking about, when I was hired in early 2014; have been working for years on this mission, we believe we’re ready to go. Although you’re never ready until you actually start getting your data. And that’s the one advantage of flying, perhaps, the ISS mission first, because it’s a more benign environment and because of the system for checking the biology, for reading the, the response, it’s, is identical. We’ll get perhaps trained during that ISS experiment, and I believe that will help us a lot to fine tune, to get ready for the actual deep space mission a couple months later.
Host: That’s right, and that’s, like you’re saying, the exciting part, right, is the deep space aspect. And that’s the era that we’re entering into now. We’ve got, you know, Artemis, the Artemis program is returning humans, but we also have this wonderful capability of continuing, or restarting, I guess, science out in deep space. You said this is the first biology experiment in deep space since the Apollo era; that’s a long, long time. I mean, what excites you just in general about the Artemis program and what it offers from a scientific perspective?
Sergio Santa Maria: Just the fact that a biology mission is part of the first Artemis I rocket is just fantastic. You know, kudos to all our folks at AES (Advanced Exploration Systems) and NASA, NASA Ames and NASA Headquarters, that pushed for this mission, because it’s just good to have biology in there. One out of ten, but I think the odds are much better for the next generation of missions going into Artemis. We are, as a separate project, we’re also working on trying to get us on the surface of the Moon, also as part of the Artemis program but in a future mission, and, and using this very similar hardware. So it’s just perhaps the continuity or the continuum that allows us to have not just missions in lower orbit but now start exploring into deep space. We are limited, of course, on what we can fly nowadays; you know, we’re talking about microorganisms, even though you would love to fly something even closer to humans, perhaps even like what is called tissue culture human cells. But we’re not ready yet just because the conditions of this particular flight, you have to, I told you we have had the CubeSat already installed for months now; you cannot do that yet with some other organisms. But we hope that the more and more missions, biological missions we fly using platforms like CubeSats, perhaps we’ll be ready to do like what is called late loads, being able to put your biology right before launch, which will open to many, many more investigations, not just yeast but many organisms, and getting closer to what future will be for us, you know, in 10, 20, 30 years, and we can actually go farther away than the Moon.
Host: Yeah, it sounds like you’re excited for the possibilities, right? That this is the beginning, and the continuity of this is really opening up something that we’re just at the beginning, and you’re already, it sounds like, Sergio, you’re already excited about what’s possible in the future. And that excites me, that this is kicking off a new era to get scientists excited about deep space research and, and science. It’s a fascinating time that we’re a part of. Sergio Santa Maria, thank you so much for coming on Houston We Have a Podcast. It has been a pleasure to get to know this experiment a little bit more, and I wish you and your team the best of luck on the International Space Station and Artemis experiments. Lots of great data that we’re going to learn about biology and DNA repair and all very critical for continuing human spaceflight, particularly in deep space. So appreciate the work that you’re doing and thank you so much for coming on.
Sergio Santa Maria: Thank you very much. I’m very happy to be with you, and we’ll be in touch, I’m pretty sure. Thanks a lot.
Host: Yeah, of course, take care.
Host: Hey, thanks for sticking around. I really enjoyed the conversation with Sergio today. It seemed like he was pretty excited about the possibilities that Artemis is offering us. So I hope you got excited too, and I hope you learned something about deep space biology. If you want to learn more about the Artemis program or what’s happening on that or the International Space Station as well, visit NASA.gov for the latest. You can also visit Ames Research Center page to learn more about the stuff they have going on there. We’re one of many NASA podcasts across the agency. Check us all out at NASA.gov/podcasts. That’s where you can find our full collection of episodes to listen to in no particular order. If you want to talk to us, we’re on social media. We’re on the Johnson Space Center pages, to be precise, of Facebook, Twitter and Instagram. Just use the hashtag #AskNASA on your favorite platform to submit an idea for the show or maybe ask a question. Just make sure to mention it’s for us at Houston We Have a Podcast. This episode was recorded on December 14th, 2021. Thanks to Alex Perryman, Pat Ryan, Heidi Lavelle, Belinda Pulido, Nicole Rose, Rachel Barry, and Gina Figliozzi. And, of course, thanks again to Sergio Santa Maria for taking the time to come on the show. Give us a rating and feedback on whatever platform you’re listening to us on and tell us what you think of our podcast. We’ll be back next week.