He works in JPL's Solar System Dynamics group, focusing on asteroid and comet statistical orbit determination, developing the On-Site Orbit Determination (OSOD) software used to update asteroid solutions and tracking predictions for planetary radar at Goldstone, Arecibo, and elsewhere. He created JPL's public Horizons facility, which makes the latest navigation and solar system solutions and ephemerides available to ground and spacebased platforms for the 1.3 million objects currently known.