This document discusses the use of Interferometric Synthetic Aperture Radar (InSAR) for measuring surface deformation over time. It summarizes Kiyo Tomiyasu's pioneering work on using InSAR from a geosynchronous orbit. It also presents a new method called MInTS that uses wavelet decomposition and physical parameterization to generate continuous deformation time series from large numbers of InSAR images. MInTS is demonstrated on data from Iceland's Northern Volcanic Zone, showing instantaneous velocities and asymmetries in deformation patterns. Finally, the document proposes a concept for a geosynchronous InSAR constellation that could provide near-continuous coverage of the Earth's surface.

1. Kiyo Tomiyasu, Co-Seismic Slip, and the Krafla Volcano: Reflections on InSAR and Earth Science Paul A. Rosen Jet Propulsion Laboratory California Institute of Technology Special Session Honoring the Achievements of KiyoTomiyasu IGARSS 2010 Honolulu, Hawaii

2. Background

3. Outline Trends in Interferometric SAR (InSAR) for Earth Science Geosynchronous InSAR Concept Presentation of 90th Birthday Celebratory Plaque of Appreciation to Kiyo Tomiyasu from JPL

4. Interferometric SAR for Measuring Earth Surface Change

5. Trends in Observational Techniques for Earth Science Frequent sampling in time Fine spatial resolution Time series / PS analysis Extraction of geophysical parameters automatically Exploitation of data for rapid response to events Anticipated mean access times for upcoming systems Interferogram stack U Mean Access Time (Day) ∞ 4 2 1.3 1 time

6. A multi-scale approach to InSAR time series analysis M. Simons, E. Hetland, P. Muse, Y. N. Lin & C. DiCaprio Interferogram stack U A geophysical perspective on deformation tomography Example: Northern Volcanic Zone, Iceland time

8. Good orbits with small baselines

11. MInTS Methodology Interpolate unwrapping holes in each interferogram where needed (temporary) Wavelet decomposition of each interferogram For later weighting purposes, track relative extent to which each wavelet coefficient is associated with actual data versus interpolated data Time series analysis on wavelet coefficients Physical parameterization + splines for unknown signals - all constrained by weighted wavelet coefficients of observed interferograms Recombine to get total deformation history

12. Example: Iceland Northern Volcanic Zone – Instantaneous Velocity

13. Example: Iceland Northern Volcanic Zone – Instantaneous Velocity (nonlinear)

14. Summary: Iceland Northern Volcanic Zone – Instantaneous Velocity

15. MInTS gives us continuous time, but does not yet combine multiple LOS to get 3D displacements. For the moment, we adopt a simple 2D reconstruction approach on a profile and neglect any rift parallel motion along the profile. Note asymmetries.

16. Rift zone models compared to data

17. Geosynchronous SARAn approach to observing the evolution of Earth’s surface

18. A Geosynchronous Synthetic Aperture Radar;for Tectonic Mapping, Disaster Management and Measurements of Vegetation and Soil MoistureIGARSS, Sydney, July 9–13, 2001 Søren N. Madsen, Wendy Edelstein, Leo D. DiDomenico Jet Propulsion Laboratory, California Institute of TechnologyJohn LaBrecqueNASA Headquarters

19. 16 Previous Work Tomiyasu K.:“Synthetic Aperture Radar in Geosynchronous Orbit,” Dig. Int. IEEE Antennas and Propagation Symp., U. Maryland, 42–45, May 1978“Synthetic Aperture Radar Imaging from an Inclined Geosynchronous Orbit,” IEEE Trans. Geosci. Remote Sens. GE-21(3), 324–328 (1983) Holt, B. & Hilland, J.“Rapid-Repeat SAR Imaging of the Ocean Surface: Are Daily Observations Possible?” Johns Hopkins APL Technical Dig., 21(1), 162–169, 2000

20. 17 GeoSync SAR Orbit and Measurement Description Orbit 35789 km altitude (geosynchronous) 60˚ inclination (not geostationary) 1 day repeat Instrument L-band SAR Continuous strip mapping, interferometricScanSAR, or spotlight operation 30 m diameter antenna aperture (electronically scanned array) Distributed T/R modules on membrane Nadir pointed, all steering electronic (only ±8º required side to side) Radar and spacecraft bus integrated on inflatable/rigidizable structure 5500 km accessible ground swath on either side of nadir 100% instrument duty cycle (always in view of land)

21. 18 Operational Modes Highly Flexible Operational modes Stripmap SAR with 400 km swath width: 10 m resolution @ 4–5 looks Suited for high-resolution mapping ScanSAR over 5500 km swaths on either side of nadir track: 50 m @ 4–5 looks Daily continental coverage Squint-scanned SAR (beam hops to +45˚, broadside, –45˚): 3–D displacement mapping of extended areas in a single day Useful for tectonic studies Spotlight SAR (beam dwells on single target area for long time): High resolution in azimuth, semi-continuous coverage Suitable for disaster management High resolution stepped frequency SAR (step frequency within 80 MHz band on successive passes then combine coherently to get high resolution without losing SNR or increasing data rate): 2 m ground range resolution, 2m azimuth resolution at far range 6-10 m resolution at near range Data rates and volumes Data rate 220 Mbits/sec per 20 MHz channel 2.4 TB/day with nearly 100% instrument duty cycle

23. 30m diameter antenna aperture

24. 65 KW peak transmit power

25. 724 kg total instrument mass

26. 28 KW DC instrument powerPropulsion Modules (x2) Thin-film Solar Arrays Horizontal booms (x12) L-band RF membrane antenna aperture Spacecraft Bus Telescoping booms (x2)

27. 20 GeoSync Constellations & Coverage Constellation of 10 satellites in 5 groups (2 satellites per “figure-8” ground track) Most of populated parts of Earth visible nearly continuously Max duration of gaps in coverage less than 2 hours for 90 % of surface 3-D displacement accuracy for select target areas < 1 cm with 24 hours of observations Maximum coverage gap Maximum 3D displacement error Relative Accuracy Minutes

28. Innovation New concepts for geosynchronous deformation observations New ideas in enabling technologies Seismology from Space Improving Earthquake Forecasting

29. Celebratory Plaque To Kiyo Tomiyasu With greatest appreciation on your ninetieth birthday for a lifetime of innovation in remote sensing Signed by Charles Elachi, Director Jet Propulsion Laboratory