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Celebrating Women's History Month: Yanping Guo

Yangping Guo

Even though the Space Department's Yanping Guo has a long list of interplanetary mission design accomplishments, perhaps no accolade speaks more to her contributions than the fact that she has an asteroid named after her. In 2004, the International Astronomical Union named asteroid 28513 "Guo" to honor her achievements—and that was almost a decade ago. Since then, she's remained busy calculating the complex routes and trajectories that space missions need to make to accomplish the most science objectives at the least cost, both in dollars and in "delta V" (ΔV), or change in velocity.

Her first mentoring experience at APL was working with a high school student several years ago (a student who is now working on her Ph.D. at MIT), an experience that left Guo with many fond memories." In the beginning, I had no idea where to start given she was only in high school," says Guo, "but it turned out to be quite easy because she was very bright and hard working."

"She was very motivated and capable. I remember I had her calculate the miles traveled by the New Horizons spacecraft each year on its way to Pluto, and she also looked at the Jupiter flyby scenario and computed the trajectory maneuvers."

Guo says that the experience was quite positive for her as well. "She reminded me of myself when I was young," she explains. "I was fortunate to get exposure and experience in different areas, and it helped me learn and grow quickly. It's important to get young people exposed to science and engineering early. I really enjoyed the opportunity to share my experience with her."

For Guo, working with a young mentee meant extra planning. "It definitely helped me to be more organized," she says. "You have to think about a detailed plan, and pay attention to the person's own capabilities and style, so they can see the positive results quickly." Today, she says, she recommends that her staff serve as mentors whenever they can, schedules permitting.

In a way, Guo's career at APL began thanks to the advice of a mentor; her Ph.D. advisor at The Catholic University of America (in Washington, DC) suggested she might find the Laboratory a good fit for her skills and interests—which at the time did not involve space travel and mission planning but rather radar cross-section and scattering analysis. She came to APL as a postdoctoral fellow in the early 1990s and divided her time between two areas of the Laboratory: In what is now the Research and Exploratory Development Department, she studied electromagnetic wave scattering; for the Undersea Warfare Mission Area, she worked on buried object detection systems.

As the Near Earth Asteroid Rendezvous (NEAR) mission neared its 1996 launch date, Guo became interested in the mission's goal to study asteroid 433 Eros. She began to do part-time analysis on NEAR laser rangefinder measurements of the asteroid's shape for navigation purposes, and she soon became science sequence planning lead for the mission. Guo then migrated into the broader field of mission design.

Over the past 17 years, she has produced a number of mission designs, including those for New Horizons (scheduled for a 2015 encounter with Pluto) and for Solar Probe Plus (slated for a 2018 launch to study the Sun). She has also worked on many mission proposals, such as the Aladdin mission (designed to return samples to Earth from the Martian moons Phobos and Deimos), the Mars-Moon Exploration, Reconnaissance and Landed Investigation mission (MERLIN), and The Great Escape Mars Scout mission.

For 2018's Solar Probe Plus, she is particularly proud of the problems she helped solved with the mission, which she describes as very challenging. "There was a lot of pressure to find a new way to approach the Sun under more stringent constraints," she says. "No more nuclear power systems were allowed, and it's very hard to get to the Sun because you need a lot of launch energy to slow down a spacecraft so it can fall to the Sun. We found a very good new trajectory: Instead of going way out to Jupiter for a gravity assist to decelerate, we can use repeated Venus flybys—up to seven of them—to reduce the speed of the spacecraft. The new trajectory allows a close solar encounter every three months, with a total of 24 solar encounters in seven years, instead of just two total solar encounters in the original solar probe mission design. In fact, that's why they added the 'Plus' to the mission's name."

Outside of APL, Guo is currently chair of the American Institute of Aeronautics and Astronautics' Astrodynamics Technical Committee, and she also serves on the International Symposium on Space Flight Dynamics Committee.