Commercial Space-based Synthetic Aperture Radar (SAR) Application to Maritime Domain Awareness John Stastny SPAWAR Systems Center Pacific Phone: NIPR: SIPR: JWICS:

2 ▼ Introduction to Synthetic Aperture Radar (SAR)  Terminology and Characteristics ▼ Benefits of SAR as applied to MDA ▼ Steps involved in utilizing space-based SAR for routine MDA  Identifying region of interest  Defining relevant performance requirements  Tasking acquisitions  Processing raw data to obtain relevant information.  Visualizing information in context Overview

3 Introduction to space-based SAR ▼ Large radar antenna is synthesized by a moving radar antenna plus signal processing.  Practical implication: RADAR imaging from space at high resolutions over very large areas RADARSAT- 2 Image

4 ▼ Active sensor (i.e. transmits and receives signals)  Practical implication – Does not require sun to illuminate target, works day or night. ▼ Operates at microwave frequencies  Practical implication – Works in all weather (not effected by clouds) Benefits of SAR for MDA ▼ Allows detection of non-cooperative targets (i.e. those without AIS) ▼ Can be used for ship detection and oil spill detection (multiple uses) ▼ Can be collected over remote areas.

5 Benefits of SAR for MDA – Very Large Footprint

6 Atmospheric Transmission of Electromagnetic Waves in Spectral Areas of Visible Light and Different Radar Bands. (NASA 1989) SAR is an active source, all weather, day or night imaging system. Operating Frequencies of SAR

7 SAR Mode Examples - SAR sensors use different modes to obtain different viewing areas and resolutions. Spotlight Mode ScanSAR Mode Stripmap Mode SAR Modes

8 TerraSAR-X /Tandem-X DLR/Infoterra X-band Dual Polarization Radarsat-2 MDA/DRDC C-band Quad Polarization Radarsat-1 MDA/DRDC C-band Single Polarization Cosmo skymed E-geos X-band 4 satellites Dual Polarization ERS-2 ESA C-band Single Polarization ENVISAT ASAR ESA C-band Dual Polarization Current Comercial SAR Sensors

9 ▼ Coverage area - how large is my region of interest?  SAR swath widths range from 10km to 500km. ▼ Resolution – how small are the vessels I’m interested in?  SAR resolutions vary inversely with swath width from less than 1m to 50m. Even in very high resolution SAR, it is not typically possible to detect small wooden vessels. ▼ Polarization – what phenomena am I looking for?  Ships, oil spills, etc. Different polarizations are best for each (HH for ships, VV for oil) ▼ Revisit rate – how often do I want my ROI covered?  One or more sensors may be utilized to achieve the desired revisit rate. ▼ Delivery speed – how timely must my data be?  Within 12 hours, within 2 hours, within 20 minutes? ▼ Cost – how much am I willing to pay?  Costs vary by sensor, mode, scene size. 9 Routine SAR use – Defining Performance Requirements

10 ▼ Example technical proposal for RADARSAT-2 based on input parameters (ROI, dates, swath width, resolution, polarization). 10 Routine SAR use – Tasking SAR

11 Routine SAR use – Raw SAR Imagery

12 Routine SAR use – Process Data to Derive Relevant Information (Vessels Locations)

13 Routine SAR use – Visualize Information in Context SAR-based contacts AIS-based contacts

14 SAR MDA Exercise

15 ▼ Satellite-based SAR provides valuable information to complete the MDA picture.  Detection of vessels with and without AIS over large area.  Day/night, all weather.  Ship detection, oil spill detection, other MDA applications.  Highly cost effective when compared with MPA or patrol vessels. ▼ However, SAR does have limitations which are important to understand.  Only provides a snapshot in time – cannot collect SAR continuously.  Some time delay between acquisitions and information delivery– not real time like AIS  Can not task on demand – must have some idea of ROI prior to data collection. 15 Conclusions