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Learn about the Shuttle Radar Topography Mission (SRTM) and how it acquires topographic data using synthetic aperture radar (SAR) and interferometric SAR (InSAR). Explore the applications of SRTM elevation maps and their insights into land formation history.
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Shuttle Radar Topography Mission: Objectives and Application Bridget R. Smith Scripps Institution of Oceanography Institute of Geophysics and Planetary Physics 2002 STARS Workshop
Introduction • What is SRTM? • How is global topography obtained? • What does the data look like? • How will the SRTM elevation map be applied?
What is SRTM? SRTM = Shuttle Radar Topography Mission Mission Objectives: 1.) acquire topographic data over 80% of the Earth (60º N and 56° S ) 2.) use C-band interferometric synthetic aperture radar technique 3.) complete during 11-day Shuttle mission 4.) produce global elevation map with 30 x 30 m spatial sampling Space shuttle facts:Speed = 7.5 km/s Altitude = 233km Earth orbits = 16 times/day Mission duration:February 11th - 22nd, 2000 Total Mission Cost:$ 142 M
How is global topography obtained? Synthetic Aperture Radar (SAR): • Radar antenna emits and receives microwave signals reflected by surface • Antenna measures back-scatter strength and travel time (radar phase) • Calculate distance of reflection (range) Interferometric SAR (InSAR):combine 2 radar images • Requires radar phase difference dr = range change l = wavelength
What does SRTM data look like? x 2 + IR color Radar phase image 3-D elevation map Radar image San Francisco Bay Area, California SRTM - MRPS95918,JSC2000-E-02778 2000-02-21
How will the SRTM elevation map be applied? • High resolution topography can tells us about formation history of major geologic features: San Andreas Fault • Major questions: Did topography form the San Andreas, or did the San Andreas form topography? Can we recover information about earthquake history from present day topography? What extra forces do large mountains add deep within the Earth?
Conclusions • SRTM mission has successfully mapped 80% of land mass on Earth. • InSAR technique of combining two radar phase amplitude images is the key element to swift global topography mapping. • The high resolution elevation data of SRTM will assist in the study of land formation history. • Tectonic stress models of topographic “weight” can be used to determine crustal structure deep within the Earth.
Acknowledgements David T. Sandwell (Ph.D advisor) NASA/JPL (SRTM Project Investigator) Julia Adame & Victor Chavez ( STARS )