I have an undergraduate degree in archaeology and worked for about 10 years as a field archaeologist in the United Kingdom, the last 5 of which were with the Museum of London Archaeology Service. I then decided to change careers and received a PhD in satellite navigation from University College London, during which time I got the opportunity to travel to NASA's Jet Propulsion Laboratory (JPL) with my supervisor to implement the models we had developed in JPL’s highly regarded GPS processing software. I am now a Senior Research Technologist at JPL, where I specialize in satellite geodesy. In this field, we study the continuously changing size and shape of the Earth and its oceans from space. My research is focused mainly on accurate tracking of Earth-orbiting satellites, and on the scientific applications related to this. The satellites involved in my studies include the United States Global Positioning System (GPS) constellation of satellites, and numerous NASA satellites that are directly observing the Earth from space. I am an international expert in the investigation of very small forces that affect the motion of GPS satellites. These forces include, for example, pressure generated by photons (particles of sunlight) striking the satellite. In the space environment, a photon force equivalent to thirty grains of salt pressing down on the palm of your hand is enough to alter the orbit of a satellite weighing 1000 kg by hundreds of meters over the course of one day.

• University College London - Satellite Geodesy and Astrodynamics PhD - 2006
• University College London - Surveying MSc - 2002
• University of Reading - Archaeology and Philosophy BA (Hons) – 1996

My main research interest focuses upon small forces that, if unaccounted for, can cause the position of a GPS satellite to differ from our predictions by several hundred meters over the course of just one day. These forces include pressure from photons (particles of sunlight) striking the satellite, coming either directly from the Sun, or reflected from the Earth as light and heat. Understanding these effects is critical for precise positioning of almost all human-made satellites. I am also deeply involved in two significant software development projects: the first will replace the software that controls the GPS constellation, while the second will unify processing of observations from all available space geodetic techniques, including GPS, satellite laser ranging and very long baseline interferometry (http://space-geodesy.nasa.gov/).

• 2010-present Reviewer for Journal of Geodesy and Advances in Space Research.
• 2008-present Senior Technologist, NASA Jet Propulsion Laboratory.
  • Member of the OCX team, developing, testing and validating software; cognizant engineer for the orbit integrator library.
  • Member of the Space Geodesy Project team, developing, testing and validating software.
  • Responsible for weekly delivery of final GPS orbits to the International GNSS service.
  • Co-developer of new GSPM10 solar radiation pressure model for GPS and GLONASS constellations.
  • Primary engineer for new high rate GPS clock determination system.
• 2007-2011 Appointed to the International Association of Geodesy's reference frames commission 1 (IC-SG2).
• 2007-2008 Researcher: European Space Agency project to design & test new timing, positioning and communication architecture for manned/unmanned exploration of Moon & Mars.
• 2007-2008 GPS fieldwork on La Palma (Canary Islands), investigating possible tsunamigenic collapse of a volcanic ridge network. Collaboration with Benfield Hazard Research Centre.
• 2005-2008 Post-Doctoral Work - University College London - "Reducing the Impact of Orbit Error on the Measurement of Polar Ice Thickness and Sea Level Variations". 2006-2007 GPS fieldwork for Vertical Offshore Reference Frame project, University College London & UK Hydrographic Office.
• 2006-2007 GNSS consultant to NAVCOM (USA).

• Professional Society and External Organization Awards | Group Achievement Award - Precise Orbit Determination Team for OSTM. (2010)
• Professional Society and External Organization Awards | Tech Brief Initial Award - Geodetic Strain Analysis Tool. (2010)