They've been called the minutes of terror – the moments during which spacecraft perform a series of seemingly impossible maneuvers to get from the top of Mars' atmosphere down to its surface and mission controllers anxiously await the signal heralding a successful landing. This past summer, it was intern Samalis Santini De Leon's task to make sure that when NASA's next Mars rover lands in February 2021, those minutes are as terror-free as possible. That meant bringing her Ph.D. research on the process known as entry, descent and landing, or EDL, to NASA's Jet Propulsion Laboratory, where she could apply it to a real space mission. The Puerto Rico native says she never imagined she would one day play a key role in landing a spacecraft on the Red Planet – especially as an intern. But now that she's worked on the Mars 2020 mission, she'll be just as anxious as the rest of the team when those final minutes arrive. We caught up with the Texas A&M University student to find out how you test a Mars landing while on Earth and how she set herself on a trajectory to NASA.
What are you working on at JPL?
I'm working on Mars 2020 entry, descent and landing simulations. I'm evaluating different scenarios, such as a hardware failure, and I'm trying to assess whether the mission will still land safely on Mars. I'm making sure that the system is robust enough that even if something goes wrong, the mission is not in danger and can still land safely. After all that work, we want the rover to land in one piece and do the science we want to do.
What does entry, descent and landing entail?
It's a series of events and maneuvers required to land safely on a planet. So once you enter the atmosphere, there are things you have to do – steps to ensure that the vehicle lands safely.
What's different about this landing from the one used for NASA's Curiosity Mars rover?
One difference is that we have a new trigger for deploying the spacecraft's parachute. This trigger will help reduce the landing footprint size, meaning we can land closer to the intended landing spot. The mission will also be using Terrain Relative Navigation for the first time. The rover will take images of the surface as it's descending and compare them to its onboard reference maps so it can locate itself with respect to the landing site and avoid any hazards.
What's your average day like?
It's mostly gathering all the concerns from other people on the entry, descent and landing team. Then I run simulations, and I look at the overall behavior of the system and communicate with the teams about what's happening. For example, if there was a hardware concern, I would do simulations to analyze the system's performance and ensure there's no significant effect on the success of the mission.
On the side, I'm doing my Ph.D. work in entry, descent and landing, using artificial intelligence to help analyze very large simulations and communicate critical issues to the experts. As humans, there is only so much we can analyze manually. We hope that these tools can help engineers for future missions.
What lead you to focus on entry, descent and landing for your Ph.D.?
I have no idea. [Laughs.] I did my undergraduate work in mechanical engineering back in Puerto Rico, where I'm from. I volunteered on a project run by Space Grant, building experiments that involved launching sounding rockets from NASA's Wallops Flight Facility. I started to get into space at that time. After that, I tried to pursue aerospace engineering, which is not a possibility in Puerto Rico. So I left Puerto Rico, and I ended up initially working with satellites. Then my advisor said, "I have a friend in EDL, and he's talked about the challenges. Why don't we write a proposal on this?" I got a NASA Science and Technology Research Fellowship for that, and now I'm doing EDL. I was always secretly leaning towards space exploration and getting my hands on a mission.
What made you want to study mechanical engineering initially?
I think it was the closest I could get to aerospace engineering back home. Also, space is very interdisciplinary. I always liked robots. Building robots in high school for competitions got me very interested in that.
What brought you to JPL for this internship?
This is my first summer at JPL. With my fellowship, I do rotations at the NASA centers, so I work with people who do similar stuff.
How many different NASA centers have you interned at now?
I've interned at three. I did two summers at NASA's Ames Research Center, last summer at Langley Research Center, now here at JPL. And in my Space Grant project and undergrad, I did frequent visits to Wallops to put our experiments in the rockets, so that was very cool.
That was all part of the buildup to get here. Coming from an island, it seemed not even possible at the time [that I would ever be at NASA].
What were the challenges that you faced coming from Puerto Rico and trying to pursue aerospace engineering?
The options for aerospace engineering in Puerto Rico are limited. But getting into the Space Grant program was a very good thing to expose me to those fields. After that, the hard part was trying to find a place to do my graduate studies outside of Puerto Rico – where to go, how to get in. There's not a lot of orientation back in Puerto Rico about these things, so you're a little bit on your own. After that, the big problem is dealing with grad school. [Laughs.]
What's your ultimate career goal? Do you think you'd like to go back to Puerto Rico someday?
I would definitely like to continue working on space missions for a while. Whether it's here at JPL or other NASA centers. Just the exposure and the experience – nothing can compare to that. But at some point later on, I would like to go back and consider teaching at the University of Puerto Rico to bring back what I've learned. They're trying to make an aerospace department at the university, so I could bring new perspectives and maybe motivate more people to do what I'm doing.
Speaking of future careers: If you could play any role in NASA's plans to send humans back to the Moon and on to Mars, what would you want to do?
Maybe I'm biased now that I'm in EDL, but it's one of the biggest challenges. I think getting enough knowledge and expertise in it and playing a role in landing people on the Moon or on Mars would be incredible, because it's a problem we still haven't found a solution to. Being able to help achieve that by whatever means is probably the most amazing thing I could ever do.
What do you hope to accomplish in your role on the Mars 2020 mission?
I definitely want to demonstrate that they've built an amazing system – that it works. I guess the goals are more personal, like getting exposure to the testing side of things, more of the real-life aspects. I'm more locked on the computer simulations. So I'm hoping to get the whole picture of how EDL works and how it all comes together.
Your mentor is Allen Chen, who is the lead for Mars 2020 entry, descent and landing, so he'll be calling the shots on landing day. What is it like having him as a mentor?
It's amazing. I feel very lucky and very proud that I get to work directly with him. He's someone who has so much expertise. I am learning a lot from him. Just sitting in meetings and hearing what he and the team have to say is amazing. He's great, too – easy to talk to, knows way too much about EDL. [Laughs.]
What's been the most unique experience that you've had at JPL this summer?
What I've found the most shocking is seeing the actual rover that's going to Mars and seeing the rover getting built. That has definitely been quite cool. I think JPL is known for stuff like this. It's here that you can see it and you can see the progress. It also seems like a very collaborative environment. That's not common, so that's really cool.
The rover is scheduled to land in February 2021, after your internship has ended. Will you be able to come back to JPL for landing?
It is possible. My mentor [for my Ph.D.] will definitely be here when the rover arrives on Mars. He'll actually spend two months here doing shifts in mission control. He told me he will try to have me here for that to learn about how it all works. I will definitely try to make that happen. The excitement in that room and the fear will collide. It must be very interesting to be in there.
Are you already picturing what it will be like on landing day?
Yeah. Now that I've had some role in it, wherever I am – whether it's here or at home – I'm going to be freaking out. Regardless of how confident we are, it's a challenging process.
Explore JPL’s summer and year-round internship programs and apply at: jpl.nasa.gov/intern
Career opportunities in STEM and beyond can be found at: jpl.jobs
The laboratory’s STEM internship and fellowship programs are managed by the JPL Education Office. Extending the NASA Office of STEM Engagement’s reach, JPL Education seeks to create the next generation of scientists, engineers, technologists and space explorers by supporting educators and bringing the excitement of NASA missions and science to learners of all ages.