Monitoring space traffic

Monitoring space traffic
by Elizabeth Durant | Office of the Vice Chancellor
Boston MA (SPX) Jan 10, 2025

AeroAstro PhD student Sydney Dolan uses an interdisciplinary approach to develop collision-avoidance algorithms for satellites. If there's a through line in Sydney Dolan's pursuits, it's a fervent belief in being a good steward - both in space and on Earth.

As a doctoral student in the MIT Department of Aeronautics and Astronautics (AeroAstro), Dolan is developing a model that aims to mitigate satellite collisions. They see space as a public good, a resource for everyone. "There's a real concern that you could be potentially desecrating a whole orbit if enough collisions were to happen," they say. "We have to be very thoughtful about trying maintain people's access, to be able to use space for all the different applications that it has today."

Here on the Blue Planet, Dolan is passionate about building community and ensuring that students in the department have what they need to succeed. To that end, they have been deeply invested in mentoring other students; leading and participating in affinity groups for women and the LGBTQ+ community; and creating communications resources to help students navigate grad school.

Launching into new territories

Dolan's interest in aerospace began as a high school student in Centerville, Virginia. A close friend asked them to go to a model rocket club meeting because she didn't want to go alone. "I ended up going with her and really liking it, and it ended up becoming more of my thing than her kind of thing!" they say with a laugh. Building rockets and launching them in rural Virginia gave Dolan formative, hands-on experience in aerospace engineering and convinced them to pursue the field in college.

They attended Purdue University, lured by the beautiful aerospace building and the school's stature as a leading producer of astronauts. While they're grateful for the education they received at Purdue, the dearth of other women in the department was glaring.

That gender imbalance motivated Dolan to launch Purdue Women in Aerospace, to facilitate connections and work on changing the department's culture. The group worked to make study spaces more welcoming to women and planned the inaugural Amelia Earhart Summit to celebrate women's contributions to the field. Several hundred students, alumni, and others gathered for a full day of inspiring speakers, academic and industry panels, and networking opportunities.

During their junior year, Dolan was accepted into the Matthew Isakowitz Fellowship Program, which places students with a commercial space company and pairs them with a career mentor. They interned at Nanoracks over the summer, developing a small cubesat payload that went on the International Space Station. Through the internship they met an MIT AeroAstro PhD alumna, Natalya Bailey '14. Since Dolan was leaning toward going to graduate school, Bailey provided valuable advice about where to consider applying and what goes into an application package - as well as a plug for MIT.

Although they applied to other schools, MIT stood out. "At the time, I really wasn't sure if I wanted to be more in systems engineering or if I wanted to specialize more in guidance, navigation, controls, and autonomy. And I really like that the program at MIT has strength in both of those areas," Dolan explains, adding that few schools have both specialties. That way, they would always have the option to switch from one to the other if their interests changed.

Being a good space actor

That option would come in handy. For their master's degree, they conducted two research projects in systems engineering. In their first year, they joined the Engineering Systems Laboratory, comparing lunar and Martian mission architectures to identify which technologies could be successfully deployed both on the moon and Mars to, as Dolan says, "get our bang for the buck." Next, they worked on the Media Lab's TESSERAE project, which aims to create tiles that can autonomously self-assemble to form science labs, zero-gravity habitats, and other applications in space. Dolan worked on the controls for the tiles and the feasibility of using computer vision for them.

Ultimately, Dolan decided to switch their focus to autonomy for their PhD, with a focus on satellite traffic applications. They joined the DINaMo Research Group, working with Hamsa Balakrishnan, associate dean of the School of Engineering and the William Leonhard (1940) Professor of Aeronautics and Astronautics.

Managing space traffic has become increasingly complex. As the cost to get to space decreases and new launch providers like SpaceX have spun up, the number of satellites has grown over the last few decades - as well as the risk of collisions. Traveling at approximately 17,000 miles per hour, satellites can cause catastrophic damage and create debris that, in turn, poses an additional hazard. The European Space Agency has estimated that there are roughly 11,500 satellites in orbit (2,500 of which are not active) and over 35,000 pieces of debris larger than 10 centimeters. Last February, there was a near-collision - missing by only 33 feet - between a NASA satellite and a non-operational Russian spy satellite.

Despite these risks, there's no centralized governing body monitoring satellite maneuvers, and many operators are reluctant to share their satellite's exact location, although they will provide limited information, Dolan says. Their doctoral thesis aims to address these issues through a model that enables satellites to independently make decisions on maneuvers to avoid collisions, using information they glean from nearby satellites. Dolan's approach is interdisciplinary, using reinforcement learning, game theory, and optimal control to abstract a graph representation of the space environment.

Dolan sees the model as a potential tool that could provide decentralized oversight and inform policy: "I'm largely just all in favor of being a good space actor, thinking of space as a protected resource, just like the national parks. And here's a mathematical tool we can use to really validate that this sort of information would be helpful."

Finding a natural fit

Now wrapping up their fifth year, Dolan has been deeply involved in the MIT AeroAstro community since arriving in 2019. They have served as a peer mediator in the dREFS program (Department Resources for Easing Friction and Stress); mentored other women students; and served as co-president of the Graduate Women in Aerospace Engineering group. As a communication fellow in the AeroAstro Communications Lab, Dolan has created and offered workshops, coaching, and other resources to help students with journal articles, fellowship applications, posters, resumes, and other forms of science communications. "I just believe so firmly that all people should have the same resources to succeed in grad school," Dolan says. "MIT does a really great job providing a lot of resources, but sometimes it can be daunting to figure out what they are and who to ask."

In 2020, they helped found an LGBTQ+ affinity group called QuASAR (Queer Advocacy Space in AeroAstro). Unlike most MIT clubs, QuASAR is open to everyone in the department - undergraduate and graduate students, faculty, and staff. Members gather several times a year for social events, and QuASAR has hosted academic and industry panels to better reflect the variety of identities in the aerospace field.

In their spare time Dolan loves ultrarunning - that is, running distances greater than a marathon. To date, they've run 50-kilometer and 50-mile races, and recently, a whopping 120 miles in a backyard ultramarathon ("basically, run 'til you drop," Dolan says). It's a great antidote to stress, and, curiously, they've noticed there are a lot of PhD students in ultrarunning. "I was talking with my advisor about it one time and she's like, 'Sydney, you're crazy, why on Earth would you do anything like that?' She said this respectfully! And I'm like, 'Yeah, why would I ever want to do a task that has an ambiguous end date and that requires a lot of work and discipline?'" Dolan says, grinning.

Their hard work and discipline will pay off as they prepare to complete their MIT journey. After wrapping up their degree program, Dolan hopes to land a faculty position at a college or university. Being a professor feels like a natural fit, they say, combining their fascination with aerospace engineering with their passion for teaching and mentoring. As to where they will end up, Dolan waxes philosophical: "I'm throwing a lot of darts at the wall, and we'll see ... it's with the universe now."