Scientific Applications

Applications
Title	Scientific Applications
Author(s)	ESA
Edited by	GMV
Level	Basic
Year of Publication	2013

GNSS systems offer important contributions in a variety of scientific research domains. As a matter of fact, a good part of the progress achieved in recent years is due to new or improved data analysis techniques, jointly with a growing variety of available measurements (use of all GNSS signals, GPS and GLONASS). In addition the already implemented GNSS systems are evolving and new systems are being developed, such as Galileo and BeiDou, which will contribute to further improvements in the current available applications as well to promote new applications.

Earth Sciences

Earth Science covers sciences related to understanding the planet Earth, being the use of GNSS signals most relevant on the aspects of Earth physics (as opposed to chemistry or biology). The main fields of this science that are studied using GNSS as tools are:

• Geodesy and Geodynamics;
• Remote Sensing Using GNSS-R;
• Physics of the Ionosphere and Troposphere.

Detailed information about Earth Sciences can be found here.

Space-Time Metrology

Space and time metrology is the science of making measurements that covers three main activities:

• The definition of internationally accepted units of measurement; e.g., the metre and the second;
• The realisation of units of measurement by scientific methods; e.g., the realisation of the second through the operation of atomic clocks;
• The establishment of traceability chains by determining and documenting the value and accuracy of a measurement and disseminating that knowledge, e.g. the relationship between time scales realised in different scientific establishments.

Sciences are completely dependent on measurements. As an example Geologists measure shock waves when the gigantic forces behind earthquakes make themselves felt, and atomic physicists use local frequency references (lasers, microwave sources) to do spectroscopy on atoms, molecules and ions, just to give a couple of examples. Thus, accurate time and frequency measurements form the backbone of a variety of studies in the fields of geodesy, astronomy, space exploration, etc., either by measuring the time of arrival of propagation of a radio or light signal, or by measuring the change in frequency incurred by a propagating signal. This is also the case regarding the operation of a GNSS. On one hand, the successful operation of such systems relies on time and frequency metrology and, on the other hand, the availability of such systems supports several scientific activities.

Detailed information about Space-Time Metrology can be found here.

Fundamental Physics

GNSS may be considered as one of the first practical applications where relativistic effects are taken into account, not just from the theoretical point of view, but as a regular engineering constraint on the overall design requirements.

Credits

The information provided in this article has been compiled by GMV. In some cases, figures, tables and paragraphs have been extracted from the indicated references, in particular from the Galileo Science Opportunity Document.

References

Detailed information about Fundamental Physics can be found here.