AAE Colloquium: Adrian Jaggi

Event Date: October 28, 2019
Hosted By: AAE
Time: 10:30 a.m.
Location: ARMS B071
Priority: Yes
School or Program: Aeronautics and Astronautics
College Calendar: Hide

Precise Orbit Determination and Global Gravity Field Recovery at AIUB

Adrian Jaggi
Astronomical Institute of the University of Bern

Abstract:

Precise Orbit Determination (POD) is an integral part for analyzing measurements from space geodetic techniques such as Satellite Laser Ranging (SLR) and Global Navigation Satellite Systems (GNSS), e.g. the Global Positioning System (GPS). In the last two decades POD based on GPS data has furthermore been established as one of the standard techniques to derive trajectories of satellites in the low Earth orbit (LEO) with highest accuracy. Since the launch of the dedicated gravity mission GRACE, POD based on GPS and ultra-precise K-Band inter-satellite ranging data may be exploited to recover the Earth’s gravity field on a monthly basis. With the GRAIL mission the GRACE concept has also been successfully realized around the Moon to recover its gravity field with unprecedented resolution.

The first part of the seminar introduces SLR and GNSS measurements collected by the terrestrial networks of the International Laser Ranging Service (ILRS) and the International GNSS Service (IGS) as the metrological basis for the establishment of a terrestrial reference frame within a generalized orbit determination problem. Relying on this foundation the basic mathematical methods of LEO orbit determination as implemented at the Astronomical Institute of the University of Bern (AIUB) are briefly explained.
The second part of the seminar is devoted to discuss a few selected results when applying the presented methods to GPS LEO data, SLR data of spherical satellites, and GRACE or GRAIL inter-satellite K-band data. Orbit determination will be presented in the context of generalized orbit determination problems, where satellite trajectories are simultaneously solved together with other parameters covering (at maximum) all three pillars of geodesy, i.e., the shape, rotation, and gravity field of the planet.

Bio:

Adrian Jäggi studied Astronomy at the University of Bern in Switzerland where he received his PhD in 2006. Between 2007 and 2009 he held a fellowship at the Institute for Advanced Study (IAS) of the Technical University of Munich (TUM), Germany. In 2009 he returned to the Astronomical Institute of the University of Bern as a Senior Scientist and was leading the scientific activities at the Zimmerwald SLR observatory. In 2012 he was eventually appointed Professor and Director of the Astronomical Institute of the University of Bern. Adrian Jäggi is active in the International Association of Geodesy (IAG) as a member of the Editorial Board of the Journal of Geodesy, Chair of the Combination Service of Time-variable Gravity Fields (COST-G), and was elected President of IAG’s Commission 2 – Gravity Field – in 2019. His main research interest is Precise Orbit Determination and its role as a discipline of Space Geodesy to enable the determination of planetary geophysical parameters.