COMET Webinar: Dr Vicki Smith "2022: A Space Geodesy"

Dr Vicki Smith (British Geological Survey / NERC Space Geodesy Facility) presented this webinar on Wednesday 27th March titled:

"2022: A Space Geodesy"

Abstract:
Satellites observe the Earth on a global level and take measurements to help improve our understanding of the dynamic processes at work. Natural disasters, mass transport, ice sheet melting, ocean currents, climate change, the Earth's orientation in space and its varying gravity field are all studied using data gained from satellite technology. Many of these scientific missions require very precise satellite orbits to be determined using geodetic observation data. One of the tracking techniques employed for precise orbit determination (POD) of scientific satellites, as well as for calibration and validation of their products is Satellite Laser Ranging (SLR): the measurement of the two-way time of flight of short laser pulses as they travel between ground tracking stations and retro-reflectors onboard satellites.

The UK’s Space Geodesy Facility, run as a National Capability facility by the British Geological Survey, operates multiple geodetic techniques including a Satellite Laser Ranging system, global navigation satellite systems receivers (GNSS) and absolute gravimetry (highly accurate measurements of the local acceleration due to gravity). The SLR system is used to provide precise orbit information to targets in space at heights ranging from 300 to 42 000 kilometres to an accuracy of around 1 centimetre as part of the International Laser Ranging Service (ILRS). The SGF runs an ILRS analysis centre that contributes to the realisation of the International Terrestrial Reference Frame by performing orbital solutions using global range measurements to the LAGEOS and Etalon geodetic spheres.

The SGF operates the UK’s absolute gravimetry (AG) resource with two operational FG5 absolute gravimeters, one of which is permanently located and the other available for project work. The SGF AG data will form the UK’s contribution to the international gravity reference frame, currently in development. The AG resource also provides a key testing facility for new gravity sensors in development in the UK.
The aim of this talk is to introduce the geodetic techniques of satellite laser ranging and absolute gravimetry to the audience, explaining the technical aspects and their complexities, and showing some of the fundamental products derived from the measurements. An overview of the potentially exciting, and versatile, new gravity sensor technologies will be given.

More details on the Space Geodesy Facility can be found here:
http://sgf.rgo.ac.uk/index.html