Abigail Fraeman, deputy project scientist on the Mars Exploration Rover mission, discusses the Opportunity rover mission.

Abigail Fraeman: Opportunity landed in this sea of really dark sand with this bright sedimentary bedrock just right in front of the rover. That was so exciting and that really felt like it was a true mission of exploration, in the sense that we were seeing something that had never been seen before.

People signed up for this mission expecting it to last their summer vacation, and it went on for 15 years.

Everybody on the team, all the scientists and the engineers are just completely amazed at how long the mission actually lasted. It’s really a testament, I think, to how well designed this mission was and how carefully operated it was.

Deana Nunley (Host): You’re listening to Small Steps, Giant Leaps – a NASA APPEL Knowledge Services podcast featuring interviews and stories, tapping into project experiences in order to unravel lessons learned, identify best practices and discover novel ideas. I’m Deana Nunley.

NASA’s Mars Opportunity Rover mission was designed to last 90 Martian days and travel 1,100 yards. When the mission ended earlier this year, it had lasted 15 years and Opportunity had traveled more than 28 miles.

Considered one of the most successful and enduring feats of interplanetary exploration, Opportunity transformed our understanding of the Red Planet.

Mars Exploration Rover Deputy Project Scientist Abigail Fraeman joins us now to discuss this remarkable story and the massive change in the scope of the mission.

Thank you for taking time to talk with us.

Fraeman: Thank you. I’m thrilled to have the opportunity to talk to you guys.

Host: Let’s track back to the beginning. Where were you at the start of the Opportunity Mission?

Fraeman: Yeah, so Opportunity launched back in 2003 and landed in 2004. At the time, I was actually a student in high school. So, I was not involved at all in the development of this mission, but I certainly was inspired by this mission. So, the night that Opportunity landed on Mars, I actually myself had the opportunity to be at the Jet Propulsion Laboratory out in Pasadena, in the room with the crew when Opportunity landed. It was such a thrilling experience and it really inspired me to pursue a career in planetary science, and how exciting for me to be involved in the mission many, many year later.

Host: Wow, that is exciting. How long was the development time to determine the requirements and scope of the original mission?

Fraeman: Yeah. Like I said, I myself wasn’t around for the development, but for folks who are really interested in it, there’s a great explanation in the book written by the mission’s PI, Steve Squyres. It’s called Roving Mars, and in it he talks about the whole process. If you go way back to the beginning, when there’s this first idea that we want to send a mission to Mars to do geology and drive around and look at the rock, that concept started in the late ’80s and went through several iterations, including a proposal that was selected in the late ’90s to send a lander. But I think Opportunity and the twin sister rover, Spirit, in the form that we know it, really didn’t get started until about summer of 2000. So, the whole development phase, once funds were put down and this mission was really happening, was only about 26 months.

Host: So how long were you involved with the Opportunity Mission?

Fraeman: I’ve been kind of involved in and out through the course of the 15 years since landing. As I mentioned, I was in the room at the Jet Propulsion Lab with the science and the engineering team on landing night. I did a little bit of some outreach activities with the mission at the time. Then, as an undergraduate, I got to spend the summer working with Professor Jim Bell, who is the lead for Opportunity’s camera system, and in that role, I helped analyze some of the camera and the spectral data that came down from that instrument for the summer.

Then I really became involved in the mission in 2010, when I was a graduate student at Washington University in St. Louis, working with Professor Ray Arvidson, and he’s the deputy PI for the mission. He is fabulous at making sure students can be involved, both in the scientific data analysis part, but also in the tactical operations of the mission. So as a graduate student, I started to take on tactical roles to help on sort of a day-to-day basis, collect the data. Then as my research, I got to look at the data that came back and think about what it all meant.

Fast-forward a few years, I was hired to work at Jet Propulsion Laboratory, and in 2016 I was hired on as the Deputy Project Scientist for the mission. So, I’ve been in that role ever since.

What were some of the challenges associated with launch, travel to Mars, and landing Opportunity as far as what the team has told you over the years?

Fraeman: Yeah. One of the biggest challenges was just getting everything done in the very compressed timeline that they had. It’s a miracle that Spirit and Opportunity ever made it to the launch pad on time, but they did. There are stories. One of the biggest challenges was the parachute, getting a parachute to work, to land a mass that was as heavy as these rovers were, was something that had never been done before. So that was an engineering challenge. Thinking about what the operational constraints were going to be and manufacturing this mission, which had never been done before, was all entirely new and done at a very rapid pace.

Host: Were you able to incorporate any lessons learned from Sojourner and Spirit?

Fraeman: Yeah, absolutely. Sojourner was the first rover that we sent to Mars in the mid-’90s. That really opened the parameter space, that we could have mobility on another planet. As a geologist, having mobility is so important because you need to be able to reach these rocks, to get close to them to look at their textures, to look at their chemistry. So, having that ability for this mission was huge and it’s really what enabled the entire mission to happen.

Spirit and Opportunity were built at the same time, so there weren’t a whole lot of lessons learned we could use for Opportunity, based on what was happening with Spirit. In fact, Opportunity, even though it landed second, was actually built first. But because Opportunity landed second, we did have a few days operating Spirit before we had to start with Opportunity. Something happened kind of early in the mission, on actually the 18th day. A Mars day is called a sol, so we called it sol 18.

Spirit experienced this huge anomaly, where the rover went silent and then just started rebooting and rebooting and rebooting. It turns out what happened is the memory had been completely filled up. So once that was figured out, they were able to delete the products on the memory and restore the rover and everything functioned normally. But because of this, we learned that we need to keep very good track of how much data we have stored onboard the rover, and we were able to solve all of this before Opportunity landed on Mars. So, certainly, we were able to avoid a similar situation with Opportunity at that point in the mission.

Host: Very interesting. When you consider the science performed on Sojourner and Spirit missions, how was it different to science performed on the Opportunity mission?

Fraeman: Sojourner, again, was really this demonstration to prove that we had mobility. So that mission lasted for about 88 days. It just had a very simple science payload that it drove around. We did learn a lot about the chemistry of the rocks and the soils and the landing site. But with Spirit and Opportunity, this was really the first mission where we had a payload that approximated what a field geologist would have. So not only were we able to look at the chemistry and the makeup of the rocks, we were also able to look at their textures. We were able to look at how the mineral – how the elements inside the rocks were arranged, what minerals they formed. We even had what is essentially analogous to a geologist’s rock hammer. It’s a tool on the end of the rover that can drill into the rocks and expose the fresh rock faces. So, the science with Spirit and with Opportunity really enabled us to act we would if we were field geologists, boots on the ground investigating these outcrops.

Even though Spirit and Opportunity had identical payloads, the science they did was very different. That’s because they landed in two very different places on Mars. When Spirit first landed, we were in a field of lava flows. It was all this what we call basaltic rock, kind of the sort of rocks you find in Hawaii. When Opportunity landed, in the very first images that the rover sent back, we found sedimentary rock. We found that this was rock that was laid down, probably by wind, but which had been cemented by water, and we found evidence that had been cemented by water in the textures of the rocks and in the minerals that were in these rocks. So, for Opportunity, it was kind of right off the get-go, as soon as we landed, evidence for liquid water in the past on the surface of Mars.

Back in the early 2000s, this was completely new. We thought we’d had liquid water on Mars in the past, but we had never actually proven it on the ground until Opportunity landed.

Host: At what point did the team realize that the scope of the original mission could be expanded, and what steps were taken to operationalize the scope expansion?

Fraeman: Yeah. So, both Spirit and Opportunity, the requirement for the mission success was 90 days and something like, I think, 600 meters or a kilometer of driving. We kind of hoped maybe they’d last a little bit longer, but we assumed what would eventually end the mission would be dust settling on the solar panels, and we wouldn’t have enough energy to recharge the battery. What actually ended up happening was we saw the dust accumulating on the panels. We saw the power levels dropping. But then Mars blessed us with the most amazing event, which ended up being a wind-cleaning event.

What we found was these big gusts of wind came by and cleaned the solar panels off of dust, and we saw these huge spikes in power that we weren’t expecting. It was kind of around the time that we started to see these events that we realized, “Ah-ha. This mission might last slightly longer than the 90 days we thought.” But every day we operated the mission as if that day would be the last day of the mission, because we kept going so far after warranty.

Operating in that way meant a couple of things. We tried to be expeditious, to be as aggressive in doing science as we could, without missing anything and without risking safety to the vehicle. We also tried to keep very good track of the assets we had onboard, so things like actuator usage, how often we used the motors. If you’re investigating targets, do it in such a way to minimize our actuator usage.

We kept very good track of the battery state of charge. Our battery engineer, Jennifer Herman, was just stupendous in how carefully she checked and made recommendations for how you should discharge the battery, how much we should charge it up. This really, I think, enabled the battery to last as long as it did. Even after 15 years on the surface, the battery was still at something like 85% capacity. So, imagine if your cell phone battery could last that long. It would be absolutely terrific.

Also, we were smart in how we tried to operate the vehicle. When it was wintertime and we had lower power, we tried to park on sun-facing slopes and only use the power we needed in order to stay alive. Then of course when it was summertime and power was abundant, we did as much science as we could and drove all over the place.

Host: 15 years is an incredible scope expansion. What original science did the mission expand upon?

Fraeman: Yeah. So, the original goal of the mission was really to search for evidence that Mars once had liquid water. From the orbital images, we see what looked like they could be streams and rivers and lakes, but you don’t really know if that’s true until you can get down onto the ground and prove it. As I mentioned, Opportunity kind of found that right away, when it landed.

But the questions then became more sophisticated. The watery environment that Opportunity found in the beginning was probably this really acidic, really low amount of water environment, kind of like battery acid almost. But about halfway into the mission, Opportunity reached the rim of this giant impact crater, and it turns out the rocks that were exposed in this rim were much older than any of the rocks we’d been investigating before.

So, driving up into the rim of this crater – it’s called Endeavour Crater – was essentially starting a brand new mission. What we found in those rocks was even more evidence for water, but what we found was that the chemistry of that water was probably very different. It was probably a lot more drinkable, water like you’d get out of your faucet. So, it showed us that not only was Mars once a place that had liquid water, it probably had liquid water over a very long period of time, and it had many different kinds of environments and chemistries that this water had where it persisted.

Host: So, were there many true enhancements to the original scope of the mission, or when Opportunity kept going and going, was it a matter of performing science similar to the original plan, but in a lot more locations on Mars?

Fraeman: Yeah. It was using our same payload to look at rocks that were put down in different times and in different geologic settings. So, as we drove along, we did the science looking at the rocks, finding the evidence for water, but we also did some great science looking at wind ripples across the surface of Mars, and that taught us about how wind acts as an agent on modern day Mars to move sediments around and to erode things.

We studied impact craters, which is really important because we have impacts all over the solar system. So, the physics of impact cratering is really this fundamental process in planetary science. Right before we lost contact with Opportunity, the rover was exploring a very interesting feature on the rim of this big crater that looked like it may have been carved by water. It looked almost like a gully or a valley. We named it Perseverance Valley.

As we drove down this valley, we were looking for evidence for the geologic forces that shaped it. Was it a river-carved valley? Was it formed by maybe a muddy debris flow rolling down? Or was it just wind that carved out a preexisting fracture? Again, it was kind of the study of these fundamental processes that shaped the Martian surface and formed it into what it is today.

So yeah, as the mission went on and we kept driving and exploring new places, we learned a lot about different times in Mars’ history, from modern Mars to Mars three and a half or four billion years ago. We learned a lot also kind of about fundamental planetary science topics.

Host: So, you’re learning as you go on a mission like this. I’m just curious. How was the additional science determined? How were the resources to perform science analysis maintained and secured?

Fraeman: Yeah, that’s a great question and it’s one of the remarkable things about this mission, the really amazing collaboration between the scientists and the engineers. So, when we talk about trying to do science, we also have to make sure that the resources permit the science goals to achieve. So, because we had this really close collaboration between the two teams, the scientists, we could work together ourselves and come up with what we thought were the big science priorities, and then present them to the engineering teams to see if it was possible.

Then in turn, the engineering teams, they really bent over backwards to try and achieve everything that science asked for because they understood how important it was. And because of this good communication, we were able to kind of iterate with each other. If something with engineering was not what we needed, we could work out a good solution using the approaches that both kinds of people working on this mission want in order to come up with a solution that was sometimes even better than what we had originally proposed.

On day-to-day basis, of course, we were always mindful of our list of priority of science observations we wanted to make, and fitting those within the data volume we had available to us, the time we had available to us during that day, the amount of power we had, and figuring out what those sets of activities were, again, this real dialog between all the scientists, amongst ourselves, and also dialog with the engineers.

Host: And, so, at some point the mission team must have realized that the resilience of Opportunity was exceptional. And I know you said that you were not on the project from the very early days, but do you recall how you felt when the scope expansion was deemed feasible?

Fraeman: It was incredible. Again, I was in high school when it landed and it’s supposed to be 90 days. So, it was great to be involved for just a small amount as a high school student, and hoping as part of my career I could work on something similar. So, to be able to, as an undergrad, continue to work on this mission that’s still going two years later, oh my goodness, that’s crazy. But then pick it up again as a graduate student another five years down the line, it was just beyond my wildest dreams. Then of course to be involved in the project management as a full research scientist here at JPL has been incredible.

We were all hoping, again, that it would last longer than the 90 days that was proposed, but everybody on the team, all the scientists and the engineers are just completely amazed at how long the mission actually lasted. It’s really a testament, I think, to how well designed this mission was and how carefully operated it was. Again, just going back to the fact that that is was really this awesome collaboration between the scientists and engineers that I think enabled something so wonderful to be built and operated for so long.

Host: You’re talking about the collaboration between the scientists and the engineers. How were personnel changes within the team managed and what did it take to keep the operations team together?

Fraeman: Yeah. That’s a really interesting question. As you can imagine, there was quite a lot of turnover. People signed up for this mission expecting it to last their summer vacation, and it went on for 15 years. There are a few people who have been with the mission the whole time, but a lot of people have kind of rolled on and rolled off. It’s been a challenge kind of keeping that knowledge transfer from person to person, but of course doing the best we can.

I think Spirit and Opportunity both started to get a reputation within the Jet Propulsion Lab, the JPL, for being a really good training ground for engineers to go on and learn how to operate a mission like this, and move on to the next mission that we’re working on, either to Mars or elsewhere in the solar system. We grabbed engineers, trained them up, made them really good, and then they went on to do future things. So, in that sense, I think it’s been really successful in how well we’ve done, both in doing turnover of personnel, but then also using it as an opportunity to train personnel and keep our knowledge bases going, and keep our ability to operate missions like these and continue to build missions like these going.

Host: As you reflect on the amazing achievements of Opportunity and the mission team, what were some of the most challenging and some of the most exhilarating moments?

Fraeman: Certainly, an exhilarating moment for me was landing night for Opportunity. Just the pictures that came back to Earth were, at the time, so unlike anything any lander on Mars had seen. Instead of these sort of rocky volcanic plains, Opportunity landed in this sea of really dark sand with this bright sedimentary bedrock just right in front of the rover. That was so exciting and that really felt like it was a true mission of exploration, in the sense that we were seeing something that had never been seen before.

I think it was equally exciting for Opportunity when we drove up to the rim of Endeavour Crater, because it was like we started the mission all over again. Six years after landing, here we were at brand new rocks, all new things to investigate, a totally new story to piece together. So that was extremely exciting to see.

Certainly, there have been a fill of challenges, the challenge of keeping something operating for this long on Mars. There was a big dust storm that happened back in 2007. That wasn’t as bad as the dust storm that eventually ended Opportunity’s mission, but that was still challenging to weather that storm.

A recent challenge that I was around for a year or so ago, we were driving around and we were just doing a routine turn, and one of the wheels got stuck, turned outward 30 degrees. So, we weren’t able to steer with that wheel anymore. It was a bad situation because if you aren’t able to steer the wheel, it’s going to be locked in place and we don’t want something locked in place, kind of toed out like that.

We tried to send commands to straighten it. Nothing worked. We assembled the team here to figure out what might be broken, to decide if we could do anything on Earth that would make it worse. We decided no. We sent a bunch more commands to try and straighten it again, and the last command of the last planned attempt the wheel straightened. We still don’t really know what happened, but we were very happy that the wheel got straightened, and it certainly made driving from then on less challenging than it would have otherwise been. So that was kind of a fun challenge.

But, of course, the biggest challenge was the global dust storm that kicked up this past summer. It started in June of 2018. As I mentioned, we’d weathered a global dust storm back in 2007. Mars gets these global dust storms every couple of Mars years, so it’s not an unheard of or unknown phenomenon, but this year was particularly bad because the storm basically started right on top of Opportunity. So, there was a lot of dust that got lofted into the air and it got lofted very quickly. So, the skies, because of all the dust, got very dark very quickly. And when you have a solar paneled rover, that’s a problem. You need the sunlight to recharge the battery.

So, what happened was the skies got really dark. We just didn’t have enough photons hitting our solar cells to recharge the battery and we slipped into a low power fault. We were hoping once the dust storm settled, and the dust came out of the atmosphere and the skies cleared, the battery would charge back up on its own and we’d be able to regain control of the vehicle, but that didn’t happen. So, we think either there was just so much dust in the atmosphere, when it fell out it coated the solar panels and we just never really had a chance, or it could have something to do with the battery was just old and it wasn’t able to kick back up, or we weren’t able to manage power on the rover because it was in a low power fault.

In fact, there’s a heater that’s been stuck on the rover since landing, and we weren’t able to go into the rover to kind of tell it to shut everything down, including that heater. So, we’re not sure if that heater was just drawing a little too much power that we were never able to really kick ourselves out of this and call back to Earth.

Host: What is some of the more significant science gained from the mission that’s helping pave the way for future Moon and Mars missions?

Fraeman: Yeah, absolutely. In terms of the science, finding out that Mars not only once had liquid water on its surface, but had many episodes of liquid water over billions of years in very diverse environments, I think just is a hint at how complex and how interesting this planet is. Certainly, the science we found shows how important it is in order to send missions to the surface of the planet.

Spirit, the other rover, one of the most significant discoveries Spirit made was because the wheel was broken and we dragged it along, and we actually turned up some of the soil in the subsurface. What we found there was huge amounts of silica, and that allowed us to conclude that the area was probably once kind of a hot spring, which would have been a habitable environment. We never would have seen that if we hadn’t dug with the wheel, and we certainly never would have seen that from orbit. So, certainly, it showed us the value of the science we can do when you actually get down on the ground.

I think more broadly, kind of in terms of exploration for Mars and future new missions, Spirit and Opportunity really set the tone, and they set the tone for Mars exploration from the mid-2000s to today, in terms of what is possible and the value of having a mobile mission. So, following on from Spirit and Opportunity, at least on the Mars side, we had the Curiosity rover that launched in 2012. Then the upcoming sample return, kind of first step rover, the Mars 2020 rover, both of those would never have been possible without the success of Spirit and Opportunity. So, I hope these lessons we’ve learned about what it takes to drive on another planet, and the kind of science you can do and how you do that science continues to move forward to the future of the Mars program and, hopefully, to the future of the Moon program as well.

Host: After playing such a key role in a trailblazing mission that exceeded expectations or even imagination, what’s next for you? And what’s your mindset going forward?

Fraeman: Yeah, so I am fortunate to be also deeply involved with the Curiosity rover mission. So, I will continue working on that mission. I still get to come into work every morning and help drive rovers on Mars. So that’s such a thrill.

And yeah, the end of the mission also really had me thinking about the future. What’s next after Mars 2020 for Mars exploration? How can we think about what science we need to do and how that science needs to be achieved using missions we’ve learned from Spirit and Opportunity, and then also the more recent rovers in terms of where we want to go, what we want to do, what questions we want to ask. So, it’s fun to think about this blank page we have now for what can be done.

Host: Abigail, this is all so exciting and it’s just been such a pleasure talking with you. Thank you so much for joining us today.

Fraeman: It’s been my pleasure. Thanks so much for having me.

Host: Sure. Do you have any closing thoughts?

Fraeman: I think I’ve said most of the thoughts. These missions, Spirit and Opportunity, really were a remarkable mission, and I think really did set a standard for what is achievable when we explore. I think part of the reason the mission was so successful, again, was this really good collaboration between the science team and the engineering team.

I’ll also highlight, in addition to the science that this mission performed, another return on investment that we got was the inspirational return. So, there’s my story, where I myself was inspired to pursue a career in science because of the pictures that Opportunity sent back. But I have been talking to many people since we declared the mission over, and there are so many people who have stories that are so similar to mine, other engineers and scientists here at JPL, but also people in other careers, science journalists who want to tell the story of space exploration, camera leads. There are so many people who were inspired by these missions. I think that’s so important and really one of the major parts of these missions’ legacies.

Host: You’ll find links to videos and articles about the Mars rovers discussed on the show today on our website at APPEL.NASA.gov/podcast along with Abigail’s bio and a show transcript.

We invite you to subscribe to the podcast, and also to share your ideas for upcoming episodes. We’d like to hear your suggestions for topics and guests. Let us know via Twitter at NASA_APPEL, and use the hashtag SmallStepsGiantLeaps.

Thanks for listening.