A typical day for Carol pondering the plasma physics of the solar system while canoeing in Wyoming.
Carol Paty, a professor at Georgia Institute of Technology, spends her days figuring out how plasmas in space interact with the atmospheres around various planets and their moons. “I really like taking physics and applying it to big problems that you can observe with spacecraft,” she says.
Paty has been interested in science since she was a child growing up in rural New York. She spent a lot of time playing in the woods and learning to love nature. The family had a backyard telescope and a great view of the stars, far from the light pollution in the cities. Like many children, she dreamed of being an astronaut. Her first research project in fifth grade described the twin Voyager spacecraft’s missions to all of the planets.
So it was natural that by the time she was in middle school she knew she planned to go to college and study physics. Paty majored in physics at Bryn Mawr College. During that time, she spent a semester abroad in Scotland, where she happened to take a class in solar magnetohydrodynamics, and she was in love with the subject. “I thought wow, this is a really exciting field, this whole study of space plasma physics,” she recalls.
Paty went to graduate school at the University of Washington in Seattle. After receiving her PhD, she worked as a postdoctoral researcher at Southwest Research Institute in San Antonio, Texas, where her research involved looking at data from NASA’s Cassini spacecraft. Paty has recently started as an assistant professor at Georgia Tech in Atlanta.
Paty studies the near space environment of planets and their moons. Using computer simulations as well as data from spacecraft, she looks at how space plasmas interact with planets’ magnetospheres (the magnetized area surrounding a planet).
“At Earth we see that interaction expressed as the aurora. And it turns out all of the magnetized planets also have their own aurora,” she explains. “For example, Ganymede is a moon of Jupiter and it has its own mini-magnetosphere embedded in Jupiter’s much larger magnetosphere. And their interaction is both expressed as aurora at Ganymede, and also expressed as an aurora footprint of Ganymede that maps all the way down to the ionosphere of Jupiter hundreds of thousands of kilometers away.”
Paty runs 3-dimensional plasma dynamic computer models called multi-fluid simulations. These simulations simultaneously track the various components of a space plasma, including electrons and different ion species, which make up the environment around a planet or its moon. The model tracks differential motions of these charged particles as coupled to the electric and magnetic fields. These are determined by the four laws of electricity and magnetism known as Maxwell's equations. The models can become quite complex. There are magnetic fields intrinsic to the planet or moon. In addition, there are also dynamic fields created by the motion of electrons and ions.
To begin to understand what’s going on around other planets, Paty starts by looking at models that have worked well for Earth. “All of space physics starts out with Earth as a template because we have the most data and the best understanding of how the system works,” she says. Then she has to figure out which approximations don’t apply to the new planet, which might be dominated by a different process that wasn’t present at Earth. So for instance, “Jupiter has a much stronger magnetic field and is rotating very rapidly. Suddenly things that weren’t important at Earth become important at Jupiter,” she explains. “The rules of physics don’t change when you look at one system to the next, but what does change is the relative importance of the components.”
On the left is Saturn. The middle image zooms in on Saturn's rings to show Enceladus, one of Saturn's moons. The right image zooms in on Enceladus to show a large plume or geyser on its surface. This plume is feeding gas and dust into one of Saturn's rings. Carol's research involves modeling the interaction of Enceladus and the neutral gas in its plume with Saturn's magnetosphere.
She finds all these differences among the planets fascinating. Each has interesting features that on each that we don’t yet fully understand. For instance, NASA’s Cassini mission recently found that Saturn’s moon Enceladus has a large plume or geyser that feeds neutral gas and dust into one of Saturn’s giant rings. Scientists don’t completely understand this plume on Enceladus, but clearly “It’s really neat,” Paty says. “You have this tiny tiny moon. The system is gigantic and this little moon is no more than a pebble by comparison, and yet this tiny little pebble has a plume on the end that’s creating an entire ring around Saturn.” Her current research involves modeling the interaction of Enceladus and the neutral gas in its plume with Saturn's magnetosphere, a topic that inherently requires a reworking of existing magnetospheric model paradigms to include collisions and chemistry between the ions, electrons and neutrals.
Paty hasn’t begun teaching yet, but she enjoys talking about her work with students who drop by her office, and is looking forward to teaching a class next spring on the science and history of space instrumentation.
On her way to Saturn, Carol stopped to visit a few remarkable places on Earth. In the picture above, we see Carol on an adventure in Turkey.
She also enjoys talking about science with kids and students of all ages. She likes to tell kids, “One of the great things about being a scientist is you kind of get to break the rules.” Scientists work with a set of frameworks or paradigms that describe our understanding, she points out. “What’s exciting about science is when you see something or understand something that lies outside the paradigm and then you get to reformat the paradigm that people have been operating under to include the new information.”
While some scientists get to travel to cool places for their work, most of her time is spent at a desk. “Simulation work involves a lot of me and the computer,” she says. “Unfortunately I don’t have a field location that I get to go out to and study volcanoes or anything like that. We haven’t quite worked out how I can go to Enceladus and collect samples.” Paty does enjoy traveling to conferences and for vacations--she’s been to the Czech Republic, Turkey, Austria, Hawaii, Greece, Wales, Wyoming, Scotland, and most recently Germany.
Paty’s life has been a bit hectic lately, with moving to a new city (she has found she loves Atlanta, somewhat to her surprise after growing up with the snowy winters of the northeast) and setting up her new research program. When she finds time outside of work, Paty enjoys yoga, as well as all sorts of outdoor activities, including hiking, running, kayaking, and swimming. Her husband is also a professor of geosciences at Georgia Tech.