# NASA - National Aeronautics and Space Administration

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Jan McGarry - Medal-Winning Mathematician Is All About the Lasers

## In between winning medals at the National Senior Games in women’s volleyball, mathematician Jan McGarry leads development of the next generation of the satellite laser ranging system.

Name: Jan McGarry
Title: Mathematician, Laser Remote Sensing Lab, Solar System Exploration Division, Sciences and Exploration Directorate
Formal Job Classification: Mathematician
Organization:Code 694, Laser Remote Sensing Lab

### What do you do and what is most interesting about your role here at Goddard? How do you help support Goddard’s mission?

My typical day is full of meetings, so I do my technical work at night at home. I am responsible for developing the next generation of Satellite Laser Ranging (SLR) systems as part of NASA’s Space Geodesy Project. SLR systems use laser to track Earth-orbiting satellites in order to very precisely determine their orbit, which is important in order to command the satellites so as to obtain and understand the data.

We use a relatively high power, high repetition rate, short pulse width laser. In other words, the laser pulses have to travel a long distance through the atmosphere, bounce off mirrored reflectors on the spacecraft and return to earth. For Earth-orbiting satellites, we measure the round-trip time from when the pulse leaves the station to when it returns and, using the speed of light, we determine the distance. Once we know the distances at various times, we can calculate the orbit.
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Photo of Jan McGarry at the Laser Ranging Facility at Goddard. Credit: NASA/W. Hrybyk

We also send laser pulses to the Lunar Reconnaissance Orbiter, which is a satellite going around the moon. For this satellite, we use one-way ranging, which is a slightly different technique for measuring the distance to a satellite.

### How important is teamwork or collaboration with others to your being able to do your job?

NASA is part of the International Laser Ranging Service, a service organization of about 30 countries that coordinates international tracking of the laser ranging stations around the world. NASA has eight operational stations including one at Goddard.

### What is the coolest thing you’ve ever done as part of your job at Goddard?

In my 38 years here, there are many cool things that I’ve done but two stand out. I got to develop the real-time software for the Microaltimeter Experiment, which involved firing a laser at the ground from an airplane to measure the topography. I got to fly on the plane and operate the system during the data-taking runs, which was cool in itself. In the data we collected, you could actually see trees and buildings in great detail, which was also very neat.

The second cool thing is my work on laser ranging to the Laser Reconnaissance Orbiter. I started on this work when it was just a concept, led the team that developed the ground station and I’m still working on it now. The fact that I can stay with the same project from the start is very cool.

 Mathematician Jan McGarry discusses the science and history of Satellite Laser Ranging (SLR), her role in developing the Next Generation Satellite Laser Ranging system, and her career at NASA's Goddard Space Flight Center. Credit: NASA/Goddard Space Flight Center

### What makes Goddard a great place to work?

For me, Goddard has been a very inclusive place. I started at Goddard in 1974. I was one of only a few women here at that time. Some of the facilities did not even have any women’s bathrooms. Even at that, Goddard was and remains a great place for women to work.

### What lessons or words of wisdom would you pass along to somebody just starting their career at Goddard?

Find out what you love to do and do it. I have been very fortunate to be able to do that throughout my career at Goddard.

### Is there something surprising about you, your hobbies, interests, activities outside of work that people do not generally know?

I started playing volleyball when I came to Goddard and joined the Goddard Volleyball Club. I play volleyball in the National Senior Games, commonly referred to as the Senior Olympics, which take place every other year but in a different city each time. My senior women’s team has won the bronze medal. My team also plays in the Huntsman’s World Senior Games, which is an international event held every fall in St. George, Utah, and we have won several medals there as well.