GPS-derived orbits for the GOCE satellite

The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) was launched on 17 March 2009 into a sun-synchronous dusk-dawn orbit with an exceptionally low initial altitude of about 280km. The onboard 12-channel dual-frequency GPS (Global Positioning System) receiver delivers 1Hz data, which provides the basis for precise orbit determination (POD) for such a very low orbiting satellite. As part of the European GOCE Gravity Consortium the Astronomical Institute of the University of Bern and the Department of Earth Observation and Space Systems are responsible for the orbit determination of the GOCE satellite within the GOCE High-level Processing Facility. Both quick-look (rapid) and very precise orbit solutions are produced with typical latencies of 1day and 2 weeks, respectively. This article summarizes the special characteristics of the GOCE GPS data, presents POD results for about 2months of data, and shows that both latency and accuracy requirements are met. Satellite Laser Ranging validation shows that an accuracy of 4 and 7cm is achieved for the reduced-dynamic and kinematic Rapid Science Orbit solutions, respectively. The validation of the reduced-dynamic and kinematic Precise Science Orbit solutions is at a level of about 2c

and Navigation Group at DLR’s German Space Operations

member of the Executive and Governing Board of th

The importance of highly-accurate and consistent geodetic products for reliable Earth system monitoring

The Bureau of Products and Standards (BPS) supports IAG’s Global Geodetic Observing System (GGOS) in its goal to provide highly-accurate, consistent and long-term stable geodetic products needed to monitor, map, and understand changes in the Earth’s shape, rotation and gravity field. A key objective of the BPS is to keep track and to foster homogenization of adopted geodetic standards and conventions across all IAG components for the generation of geodetic products. This involves the interaction with IAG and other entities involved in standards and conventions, such as the IERS Conventions Center, the IAU Commission A3 "Fundamental Standards", ISO/TC 211 and the Working Group "Data Sharing and Development of Geodetic Standards" of the UN-GGIM Subcommittee on Geodesy. This contribution presents the role of the BPS, and it highlights some of the recent activities, which are focused on the updating of the BPS inventory of standards and conventions used for the generation of IAG products, the revision of the IERS Conventions, mainly related to Chapter 1 "General definitions and numerical standards" and the compilation of user-friendly product descriptions published at the GGOS website. The BPS also contributes to the generation of GGOS films to make other disciplines and society aware of Geodesy and its beneficial products

GGOS Bureau of Products and Standards: Description and Promotion of Geodetic Products

The Bureau of Products and Standards (BPS) is a key component of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG). It supports GGOS in its goal to provide consistent geodetic products needed to monitor, map, and understand changes in the Earth’s shape, rotation, and gravity field. In its present structure, the two Committees "Earth System Modeling" and "Essential Geodetic Variables" as well as the Working Group "Towards a consistent set of parameters for the definition of a new Geodetic Reference System (GRS)" are associated to the BPS. This paper presents the structure and role of the BPS and it highlights some of the recent activities. A major focus is on the classification and description of geodetic products and their representation at the renewed GGOS website (www.ggos.org). This website serves as an "entrance door" to geodetic products to satisfy different user needs and communities (e.g., geodesists, geophysicists, other geosciences and further customers) in order to make geodesy more visible to other disciplines and to society