[ Music ] I'm Jan McGarry, I'm a mathematician and I work in the Laser Remote Sensing branch at the Goddard Space Flight Center. Satellite Laser Ranging is a technique of measuring the distance to the satellites. The light goes up to the spacecraft, bounces off, comes back, and that's the round-trip time of flight. And it's used both for very precise orbit determination, as well as once you've got the orbit nailed down then you can very precisely determine the location of where the center of mass of the Earth is and how it's moving. And then from the standpoint of the station location, the position of the stations in reference to one another give you indications of how the tectonic plates are moving with respect to each other. Goddard is actually the birthplace of Satellite Laser Ranging, it was developed by Henry Plotkin in the early 1960's when lasers were just first starting. He also developed the Satellite Laser Ranging ground station, which was the Goddard Laser Ranging Station, or GODLAS for short. And in fact we're coming up on the fiftieth anniversary of Satellite Laser Ranging here because that was done October 31, Halloween, 1964. During a typical day I spend a lot of my time at meetings. But at night I'm often at the optical site operating the system, doing software development or working on the automation of the Next Generation Satellite Laser Ranging system. When you do R and D development you run into a lot of dead ends sometimes and you run into a lot of problems that seem very difficult to solve. That's one of the reasons why Goddard is such a great place to work. People don't take no for an answer, when they find a problem they work very hard to solve it and get past it. [ Music fades ] [ Sound effect ]