Geodesy is the science of measuring and representing the Earth, including its gravity field. It has applications in monitoring climate change, natural hazards, volcanoes, water resources, soil moisture, glaciers, and landslides using space-based technologies like GNSS, altimetry, and gravity missions. Some key technologies are GPS, GLONASS, altimetry missions like TOPEX and JASON-1, and gravity missions like GRACE and CHAMP. Geodesy has its origins in ancient Greece and has evolved into a modern discipline using satellites to study Earth systems and processes.

1. Satellite
Geodesy
Shahbaz Ali Khidri

2. OUTLINE
• Geodesy and Space-Geodesy
• What is Geodesy ?
• Historical perspective
• Space-based technologies
• Applications
• Selected books on Geodesy
• References

3. GEODESY ?
• One of the oldest profession of the world.
• It comes from the words:
Geo = Earth
Daisia = I divide
• Geo Daisia = Dividing the Earth

4. DEFINITION OF GEODESY
• The classical definition:
Geodesy is the science of measuring, and portraying the
earth’s surface.
[Helmert, 1880].
• The modern definition:
Robert
Helmert
(1843 - 1917)
Geodesy is discipline that deals with the measurement and
representation of the earth, including it’s gravity field, in a
3D time varying space.
(International Association of Geodesy)

5. HISTORICAL PERSPECTIVE
• Eratostethens (276 BC – 194 BC) measured the angle of
sun rays between Alexandria and Syene (Egypt).
• Measured the Earth’s circumference accurately with
15% deviation as compared to the current estimate.

6. SUB-DISCIPLINES OF GEODESY
• Geometrical Geodesy
• Dynamical Geodesy
• Mathematical Geodesy
• Space or Satellite Geodesy
• Marine Geodesy
• Etc.

7. SATELLITE GEODESY
• Geodesy with the help of Satellites.
• It is used to study the climate change, water
resources, natural hazards, disasters, etc.

8. SPACE GEODETIC
TECHNOLOGIES
• Positioning techniques
• Global Navigation Satellite Systems (GNSS)
• Altimetry
• Gravity Missions
• Etc.

9. POSITIONING
TECHNIQUES
• Satellite Laser Ranging
• Lunar Laser Ranging
• Etc.

10. POSITIONING
TECHNIQUES
Satellite Laser Ranging
Lunar Laser Ranging

11. GNSS
• GPS
• GLONASS
• Galileo
• Compass

12. ALTIMETRY
• SeaSAT
• GeoSAT
• TOPEX
• JASON-1
• ENVISAT
• Etc.

13. GRAVITY MISSIONS
• GRACE
• CHAMP
• LAGEOS-1
• Etc.
GRACE
LAGEOS-1
Measurements of small changes in
the Earth’s gravitational field

14. APPLICATIONS
• The Deformation of the Earth from Earthquakes.

15. APPLICATIONS
• Volcano Monitoring.
Studies of hazardous
volcanoes in Mexico, Central
America and the Caribbean

16. APPLICATIONS
• Monitoring of water resources.
Monitoring of water resources
(Everglades, south Florida)

17. APPLICATIONS
• Monitoring of soil moisture.
• Soil moisture is critical for vegetation growth and
survival.

18. APPLICATIONS
• Glacier flow.

19. APPLICATIONS
• Landslides.
Ground movements in Berkley Hill, near San Francisco

20. APPLICATIONS

21. SELECTED BOOKS ON
GEODESY
GEODESY: THE
CONCEPTS
by Peter Vanicek, E.J.
Krakiwsky,
Elsevier Science, 1996 Edition
GEODESY
by Wolfgang Torge, Alter de
Gruyter, Berlin, 2000
INTRODUCTION TO GEODESY:
The History and Concepts of
Modern Geodesy
by James R. Smith - 1997
SATELLITE GEODESY,
FOUNDATIONS,
METHODS, AND
APPLICATIONS,
by Gunter Seeber, Walter de
Gruyter, Berlin, 2003

22. REFERENCES
 http://oceanservice.noaa.gov/education/kits/geodesy/welcome.html
 http://gge.unb.ca/Research/GRL/GeodesyGroup/tutorial/tutorial.htm
 http://www.geod.nrcan.gc.ca/geodesy/index_e.php
 http://en.wikipedia.org/wiki/Geodesy
 http://www.ngs.noaa.gov/PUBS_LIB/Geodesy4Layman/TR80003A.HTM
 http://www.colorado.edu/geography/gcraft/notes/datum/datum.html
 http://www3.sympatico.ca/craymer/geodesy/geodesy.html