Europa Clipper Project System Engineer Jennifer Dooley discusses NASA’s outer planets flagship mission.
NASA’s Europa Clipper mission could answer a fundamental question: Are we alone? The expedition will conduct in-depth exploration to find out if conditions are right for life on Jupiter’s icy moon. Planned for launch in the 2020s, the Europa Clipper spacecraft — in orbit around Jupiter — will make about 45 close passes over Europa in an effort to eventually scan the entire moon.
In this episode of Small Steps, Giant Leaps, you’ll learn about:
- Systems engineering challenges of the Europa Clipper mission
- How diversity benefits the Europa Clipper team
- Best practices and communication within the team
Jennifer Dooley is the Project System Engineer for Europa Clipper, NASA’s outer planets flagship mission. Dooley leads the Project System Engineering Team and is responsible for the technical design and performance across the entire scope of the project. She has had a diverse career since joining NASA’s Jet Propulsion Laboratory as an academic part-time student. Dooley was previously the Project System Engineer for the Europa Lander Study and the Technical Group Supervisor for Observatory System Engineering, where she was responsible for project and flight system engineering of Earth-observing and astrophysical space missions. She has a bachelor’s in applied physics from Caltech and a master’s and doctorate in materials science from Carnegie Mellon University.
Jennifer Dooley: NASA is trying to answer one of the key objectives. Are we alone in the universe?
I think our whole view of ourselves and the universe will change after a discovery of life beyond our planet.
It’s going to be really exciting science.
Deana Nunley (Host): NASA’s Europa Clipper mission is preparing to conduct the first dedicated, detailed study of an ocean world beyond Earth. And that’s our topic today on Small Steps, Giant Leaps.
Welcome back to the NASA APPEL Knowledge Services podcast where we share novel ideas, best practices and lessons learned from project experiences. I’m Deana Nunley.
Our guest today is Jennifer Dooley, the Project System Engineer for NASA’s Europa Clipper mission.
Jennifer, thank you for joining us on the podcast.
Dooley: It’s a pleasure to be here.
Host: Could you give us an overview of the Europa Clipper mission?
Dooley: The Europa Clipper mission is going to go out to Europa, one of the moons of Jupiter. The reason that we’re interested in this body is that there’s an icy surface, and evidence suggests there’s a global ocean with actually twice the amount of water of all of Earth’s oceans combined. So, the goal of the Clipper mission is to investigate whether that ocean could support life.
Clipper is a solar-powered spacecraft. We carry state-of-the-art tools for characterizing the ice shell and the ocean. We look at composition, geology, and also collect reconnaissance of Europa.
During our science tour, we’ll be in a big orbit around Jupiter and we’re going to do fly-bys of Europa every couple of weeks. The spacecraft and the suite of instruments all together is really pretty large. For reference, all of the hardware we build has a mass of about 2,900 kilograms. Then we add about the same amount of propellant. That fueled spacecraft with the payload all together weighs about as much as an African elephant.
We have 100 square meters of solar array, but because Jupiter is so much further from the sun and actually, also, because the radiation environment is so harsh, it degrades the array and the amount of energy it’s able to produce. So, at the end of life, it’s going to produce 700 watts. That’s about half of what my hair dryer uses, just for context.
The Clipper mission is going to look at Europa in more detail than ever before. We are going to look at the surface. We’re going to probe the subsurface. We’re going to study composition and materials ejected off of the surface into space using cameras and ice-penetrating radar. We have a thermal imager, a plasma sensor, and we look in the ultraviolet and infrared spectrum. We also have a dust analyzer and a magnetometer and, finally, a mass spectrometer. So, it’s an incredibly capable, incredibly sensitive payload that’s going to just tell us more about this body than we’ve ever seen before. It’s going to be really exciting science.
On the solar arrays, we have these large, deployable booms. We also have a large boom for the magnetic field instrument, which gets it away from the spacecraft. Our spacecraft is also – in addition to being our ride out there and all of our infrastructure, it also can interfere with the instruments sensing themselves, so we have to kind of balance all of those needs. Our direct sampling instruments are going to be scooping up dust, molecules and charged particles, and our large antenna lets us send all that data back to Earth.
Host: Jennifer, space advocates have long been intrigued by Europa. What do you think stimulates so much interest in this moon of Jupiter?
Dooley: Galileo Galilei discovered Callista, Io, Ganymede, and Europa – these are the four largest moons – in 1610. Really, that was an incredible moment in science. It changed our understanding of the solar system. It was also, actually, instructive in techniques for determining longitude, trying to use the understanding of the motion of those moons.
Then, after that, there wasn’t as much discovery in that area. But in more recent times, we’ve discovered that there’s a very thin atmosphere that’s mostly oxygen. There’s a rocky core and a layer of smooth ice, meaning that we don’t see a lot of crater marks. So, it’s a relatively young surface.
Based on magnetometer measurements, we were able to discern that it’s got an ocean. Essentially, this is looking at the induced magnetic field in that ocean. It’s a global ocean, so it can move under that ice shell. So, one of the really interesting things about it is that it looks like it’s got all of these different ingredients that could allow the evolution of life there. So that’s just become one of the real targets for astrobiology in the solar system.
Host: From a science perspective, this is a compelling mission. What is NASA trying to discover?
Dooley: NASA is trying to answer one of the key objectives. Are we alone in the universe? Beyond Earth, Europa is considered one of the most promising places to search for signs of life, and it could have all of the ingredients. The surface is mostly made of water ice with some salts. It’s got kind of a “reddy” color. In fact, recent experiments in the laboratory have shown that if you take sodium chloride – table salt – and irradiate it, it has that similar “reddy” color. So, we see evidence that it’s really a saltwater ocean like our own.
You know, we’ve got the water. We see evidence that the chemistry is there also. So, we have sulfur sputtered from Io that ends up on the surface. We have a rocky mantle, and contact between a liquid water ocean and that mantle, you can get chemical leaching out. So, you get a lot of interesting potential chemistry there.
We have irradiation on the surface, which we think of as being very harsh to life, but that also creates oxidants and those could provide important chemical energy, along with the reductants that can come out of mantle rock water reactions. So that, together with the – there’s actually heating, we think, in the core, related to tidal forces from Jupiter, and that seems to be the energy that allows that water to stay liquid. So, all of those ingredients together seem to really pique interest that this could be a very interesting target for that search for habitability and, ultimately, the search for life beyond our planet.
Host: Will you be scouting locations for possible future landings?
Dooley: Clipper collects a lot of local scale measurements. So that includes high-resolution imagery, stereo images that let us look at the surface topology, and a number of other coordinated datasets from other instruments. All of those measurements together primarily support Clipper’s main science objectives to understand the habitability, but that improved knowledge would also provide us important context for any potential future landed mission, and that’s what we see in the past with the exploration of the Moon and Mars.
Host: What are some of the engineering challenges of this mission, especially from a systems engineering perspective?
Dooley: Some of the biggest engineering challenges come from the environment of Jupiter. As a combined problem, this is a great example of kind of big architectural trade space that system engineers have to grapple with. We have to worry about the radiation environment, which is quite harsh, the data return, large amounts of data from this payload. How can we get global coverage? How do we provide power to the spacecraft?
One of the biggest challenges, really, is the huge magnetic field that Jupiter has, and that accelerates electrons. This results in a really large radiation belt and it stretches out for quite an extent. Europa is in that radiation belt. So, we have to make sure that we can survive all of that radiation.
To do that, we buy electric components that are less sensitive, but there are a lot of parts that have never really been used in that kind of environment. So, nobody has really done the testing. We have to do a lot of our own testing. We actually have a particle accelerator underneath them all, and we use metal for shielding, like the apron you wear at the dentist. Clipper has about a nine-millimeter thick vault. So, we take these really tough parts and we put them inside that vault to protect it.
These electrons also result in electrostatic discharge, like you would get if you rubbed your sock-covered feet in a thick carpet and then touch your friend. You get a shock, but out at Jupiter, the ESD is significant enough that it could destroy the electronics. So, we have to do a lot of careful protection of those materials as well. We have special gaskets. We have to be really careful about dielectrics, so things that could charge up like plastics or other insulators, and let that charge build up until it’s enough to cause damage.
We also have a really harsh thermal environment. The spacecraft, in different parts of its lifetime, has to be able to survive very hot temperatures and really cold temperatures, and the design has to tolerate both. Especially during the science phase, we have to really understand all the behavior. So material properties change with temperature and they also change under radiation exposure.
So that, again, takes us back to extensive testing. So, we find that we have lots of different outgassing from materials at cold temperature under radiation exposure, and we see dielectric properties vary, too, at those cold temperatures.
That can be a big challenge because it just extends the range that you have to protect for and plan for. For example, the contamination control issues. Our payload is exquisitely sensitive. So, every time we have additional material coming off of the spacecraft, that’s a contamination source to the science. So, we have a delicate balance trying to manage all of those things.
Ideally, we want to have global coverage of a body like Europa. We want to go and understand its geology, and global coverage is a really important tool for doing that and understanding what’s really happening there.
But the radiation environment is so harsh the exposure collects very quickly. It turns out that even with all of the things that we do to try to make ourselves robust to that environment, we still can’t just go into orbit and stay within that radiation environment for the life of the mission. The mission would be used up very, very quickly, and we’d have a lot of challenge getting all the data back given how far away we are from Earth.
So, we use a fly-by approach that lets us be in a large orbit around Jupiter and kind of dip our toe down into the region right next to Europa, getting very close. We have all the science instruments on. We collect all of the data very quickly, within a couple of days of being right near Europa. Then we pop back out, so we can collect energy on the solar array, return the science data, and bleed off some of that static charge we built up. And we’re getting ready for the next encounter then.
During a fly-by, the spacecraft turns to point all of the remote sensing instruments toward the surface. The magnetometer and the plasma instrument are on. Then we start to scan in the ultraviolet and take pictures. We also start taking some measurements looking away from Europa, and that lets us do some dark sky calibrations and some other science that gives us more context.
Then at about 40,000 kilometers, we reorient the solar arrays and we put the radar antennas toward Europa, and we point the apertures in the direction we’re heading, so they can scoop up the dust, molecules, charged particles.
Then we get all of the instruments going. So now we’re collecting a lot of data very fast. The imagers are going. The radar collects all of its data very close to the surface. Spectrometers are going. Things are getting a little frantic. We also have the radio on and that supports the gravity science, which is looking at small perturbations in the orbit and lets them probe the interior structure.
From that point on, all the instruments that are taking data are poised to do so. On the departure leg, it’s largely mirroring the approach leg with few differences, mostly associated with data return and, typically, we have a cleanup trajectory maneuver that happens, too, on the outbound path.
We also then get another solar array reorientation because every watt is precious. So, we want to get that array back on sun point as soon as we can and maximize our power generation. Then we just kind of take a minute and say, “Whew. It’s time to go back to planning for the next encounter.”
One of the challenges actually is that very fast cadence for operations. So, we’re trying to do all of the science, instrument, and data collection coordination. Really, it’s on a two-week cadence, to be able to do all of that coordination and planning. So, one of the strategies has been to try to standardize that fly-by behavior, so we can be ready in time for the next encounter.
System engineering is focused on making sure that the entire mission holds together. We fill in the gaps and we make sure that all of the parts of the spacecraft play well together. As you think about the radiation and ESD and the thermal challenges and the operational challenges, you can imagine there are thousands of different parts that might be affected, and scores of different things you need to do to protect the entire system.
So, we have tests, analysis, hardware changes and mechanical power, computers, the instrument cabling, software changes to double-check the data or to be ready to protect the spacecraft in case the radiation causes an error. The system engineering has to look across this entire story and say, “Yes. We all hold together with the same design.”
In a mission this big, just trying to keep track of the baseline, what is it that we think we’re building, is a challenge all in itself.
Host: You’re clearly having to address a lot of complexities with this mission. Are there best practices or lessons learned that you could share?
Dooley: People often think of a technical best practice, but I think one of the things I’ve learned in this role is the criticality of keeping our whole team on track with respect to communication. It’s complicated. We have nine instruments, seven subsystems, hundreds of people working across the overall project, and the communication is a huge challenge. It’s important that we’re all in sync, that we all understand that we’re building an internally consistent baseline.
It’s amazing how challenging it is to actually accomplish that. Sometimes the communication is through our work products, drawings, interface control documents, technical memos. We have a huge array of new communication tools for informal things like chat programs and things like that.
One of the things I tell my team is while the technical resources are incredibly precious, our power, our mass, energy, it’s also true that, to some extent, the most valuable resource we have on our project is the time of the technical team. They are the ones who are going to find the engineering solutions to the shared problem, and anything we can do to make that more effective has got to be a priority.
Host: How would you describe the diversity of the Europa Clipper team and benefits that are derived from a diverse team?
Dooley: A significant portion of our leadership team, project manager, business manager, payload manager, PSE, me, mission assurance manager and several PIs are women, which sort of struck me recently. It’s a difference from what we have often seen in the past. We have many people of color. We have people with doctorate degrees and people who have been to trade schools, technicians. We also have people with decades of experience, along with people who are coming directly from a university environment, bringing new perspectives, new tools and new thinking. So, it’s an incredibly exciting team to work with.
If you have a team that all has the same background, sometimes we all come up with the same solution or the same thinking about how to approach a problem. But it turns out that some of the benefits that diversity brings are different perspectives. We see more innovation, less sort of groupthink, which can be a risk. It’s sort of a blind spot. There’s more creativity, faster problem solving.
Some of the earlier career engineers on my team, one of the things I look for is not slowing them down by over-constraining them. So, I’m often surprised at how if I give an open-ended assignment, they find more efficient ways, more design solutions, and more ways of approaching the problem than I would have been able to think of myself, and they’re often excellent solutions. So that has been a real pleasure for me, to see how much a diverse group like that brings it together to help us solve these hard problems and make a successful mission, which is the goal.
Host: Is the team spread across the agency?
Dooley: Yes. Actually, we also have a lot of geographical diversity. The Jet Propulsion Lab is the lead center and we partner with the Applied Physics Lab, and together we’re responsible for the entire mission. But we couldn’t do it without help from centers across the agency. Our program management is centered at Marshall. Our propulsion system is being built by Goddard Space Flight Center, and of course we’ll be launching from Kennedy.
We have a number of other contributors, including instrument teams at both JPL and Applied Physics Laboratory. In addition, there is Southwest Research Institute, University of Texas at Austin, the University of Colorado at Boulder, and Arizona State University. These missions are so challenging and there is so much competition in the aerospace area right now, we are incredibly well served by being able to go out across the country and take advantage of the best and the brightest that we have.
Host: What is it like for you personally to be a member of the Europa Clipper team and part of such an ambitious mission?
Dooley: Exploring Europa is the most challenging and rewarding work I’ve ever had the privilege to do. The science is so personally compelling for me. The investigation of habitability is a key step toward the search for life beyond our planet. I think our whole view of ourselves and the universe will change after a discovery of life beyond our planet.
Before I joined the Clipper team, I spent a couple of years as the pre-project system engineer for the Europa Lander Study, and that would rely on Clipper science to inform the mission. But when the opportunity came to be a part of the Clipper team, I just couldn’t resist taking the first ride back out to Europa.
Host: Well, we wish you all the very best with this mission. Thank you so much for being on the show today.
Dooley: It’s been a great pleasure. Thank you so much for having me.
Host: You’ll find links to topics discussed on the show and related APPEL courses along with Jennifer’s bio and a transcript of today’s episode on our website at APPEL.NASA.gov/podcast.
If you have suggestions for interview topics, please let us know on Twitter at NASA APPEL, and use the hashtag SmallStepsGiantLeaps.
As always, thanks for listening.