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I'm Jan McGarry, I'm a mathematician and I work in the Laser Remote Sensing branch at the Goddard Space Flight Center.

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Satellite Laser Ranging is a technique of measuring the distance to the satellites.

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The light goes up to the spacecraft, bounces off, comes back, and that's the round-trip time of flight.

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And it's used both for very precise orbit determination, as well as once you've got the orbit nailed down

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then you can very precisely determine the location of where the center of mass of the Earth is and how it's moving.

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And then from the standpoint of the station location, the position of the stations in reference to one another

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give you indications of how the tectonic plates are moving with respect to each other.

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Goddard is actually the birthplace of Satellite Laser Ranging.

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It was developed by Henry Plotkin in the early 1960's when lasers were just first starting. 

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He also developed the Satellite Laser Ranging ground station, which was the Goddard Laser Ranging Station, or GODLAS for short.

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And in fact we're coming up on the fiftieth anniversary of Satellite Laser Ranging here,

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because that was done October 31, Halloween, 1964.

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During a typical day I spend a lot of my time at meetings.

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But at night I'm often at the optical site operating the system, doing software development,

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or working on the automation of the Next Generation Satellite Laser Ranging system.

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When you do R&D development you run into a lot of dead ends sometimes

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and you run into a lot of problems that seem very difficult to solve.

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That's one of the reasons why Goddard is such a great place to work.

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People don't take no for an answer, when they find a problem they work very hard to solve it and get past it.

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[ Satellite beeping ]