2. Introduction Goddard Space Flight Center
•EcoSAR is a new radar development at NASA/Goddard Space Flight
Center for the measurements of terrestrial ecosystem structure and
biomass.
•The EcoSAR measurements will directly support science
requirements for the study of the carbon cycle and its relationship to
climate change.
•EcoSAR will use Electronic Beam Steering and Digital Beamforming
to implement Polarimetric and Interferometric Synthetic Aperture
Radar (SAR) .
2
ESTO-IIP 2011-2014
3. Science Driver Goddard Space Flight Center
The CARBON CYCLE. Carbon in the atmosphere is a controlling factor
on climate and hence on ecological productivity and the
sustainability of life.
Science Question
How are the Earth's carbon cycle and ecosystems changing, and
what are the consequences for the Earth's carbon budget,
ecosystem sustainability, and biodiversity?
EcoSAR will acquire unique measurements that will help
us quantify carbon in vegetation, and how it is changing.
3
4. Instrument Science Rationale
Goddard Space Flight Center
P-band SAR penetrates vegetation structure allowing the sensing of the entire canopy
volume and woody density. Such measurements can be directly related to
aboveground biomass.
SAR measurements can be performed in most weather conditions and provide the
capability of mapping the vegetation cover and changes due to natural and human-
induced disturbances frequently.
Polarimetric radar is
sensitive to the shape,
orientation and
dielectric properties of
scatterers and allows
the identification and
separation of the
scattering mechanisms.
4
5. Pol-InSAR height measurements:
- InSAR is highly sensitive to the spatial variability of
Goddard Space Flight Center
vertical structure parameters and enables accurate 3D
localization of the scattering center.
- EcoSAR will implement Pol-InSAR techniques to provide
measurements that will allow us to separate ground
from canopy and derive canopy height and to investigate
the 3-D structure of volume scatterers .
HV
HH
HV scattering
phase center
HH scattering
phase center
6. EcoSAR Main Science objectives Goddard Space Flight Center
• EcoSAR instrument will quantify:
– Biomass
– Canopy and Surface Height
– Ecosystem structure and extent
– Disturbance and recovery
• Science Goals
– Height with 1 m accuracy from single-Pass
Polarimetric Interferometry
– Biomass up to 200 Mg/ha from PolSAR
measurements alone
– Resolution of 0.75 m in range
• Additional Science :
– Solid Earth: deformation and subsidence
– Cryo: ice sheet and permafrost depth
– Hydro: surface water extent, salinity, soil
moisture
– Applications: soil/canopy penetration for
archaeological studies
7. EcoSAR Architecture
Goddard Space Flight Center
• 18 transceivers support polarimetric and
interferometric measurements.
• Each antenna consists of 9 dual polarization, high
bandwidth subarrays.
Radar Transceivers, Antenna Subarrays, and
Synthesizer/Acquisition and Processor (SAP) Unit
• 18 Waveform generators directly synthesize P-band
signals with up to 200 MHz bandwidth.
•18 Receivers will sample the radar returns directly.
•Synthesizer/Acquisition and Processor system will be
designed around the Xilinx Virtex 5 FPGA. Antennas
• Digital I&Q demodulation, decimation and filtering will
be performed on board.
• Processor supports subsequent onboard radar
processing (e.g., digital beamforming, SAR image
formation, multi-look, etc…)
SAP SBIR Prototype by IAI
8. EcoSAR System description Goddard Space Flight Center
Center Frequency 435 MHz Pulse Length 1 usec – 50 usec
Maximum Bandwidth 200 MHz Array Peak Power 40 Watts
Polarization HH, VV, VH,HV PRF 100 Hz – 10 KHz
Polarization Isolation < 25 dB Swath 4 km – 8 km
Noise Equivalent σo - 41 dB * Finest Range Resolution 0.75 m
Total Number Channels 36 Single Look Azimuth 0.5 m
Resolution
Interferometric baseline 25 m Vertical Accuracy <5m
EcoSAR will fly on the NASA P3 airplane
based at Wallops Flight Facility
12. Example of SAR and InSAR
using DBSAR (L-band) measurements Goddard Space Flight Center
Height (m)
13. Example of multiple beam technique Goddard Space Flight Center
t Path
nna Fligh
Ante
θ1
θ2
ry
rx
Swath 1
ry
rx
Swath 2
F
L
I
G
H
T
T
R
A
C
K
14. EcoSAR Resolution
Goddard Space Flight Center
Azimuth (Cross Range) Resolution
0.5 m (single look)
Range Resolution
Slant Low Resolution
Ground
25 m 44 m
Medium Resolution
5m 8.7 m
High Resolution
0.75 m 1.3 m
15. EcoSAR Antennas
Goddard Space Flight Center
Antenna Parameters
Type Micro-Strip Patch
Center Frequency 435 MHz
Bandwidth 200 MHz
Gain 19 dB
Area 3 m2
Polarization Dual, linear
Each antenna array mounts the P3 aircraft wing
Cross Polarization Isolation < 25 dB
Number of Sub Arrays 9
Total Number of Elements 27
3m Three-element subarray
1.0 m
The EcoSAR antenna arrays will allow to steer the beam across track
Subarray S11 and S22 parameters
Cross coupling is below -80dB
16. Schedule and Milestone
Goddard Space Flight Center
Year 1
Definition of the EcoSAR science and system requirements
Antenna Arrays Design and fabrication
Radar Electronics Unit Design and fabrication
Year 2
Completion of Waveform generator/data system
Testing and programming of waveform generator/data system
Radar Electronics evaluation, testing and initial assembly.
Full system integration and testing in laboratory and in anechoic chamber.
Year 3
Installation and test flight operation of the system on the NASA P-3 aircraft
Validation of EcoSAR test flight data sets
Field Campaign 1 New Hampshire and Maine
Field Campaign 2 Costa Rica
Science Retrievals from EcoSAR campaigns
17. Concluding Remarks Goddard Space Flight Center
• Our team has successfully completed the design of prototype dual
polarized wideband P-band antenna element. A full array
simulation is underway.
• The aerodynamic analysis on antenna structure has been
performed.
• The radar transceiver schematic has been completed.
Components specifications and availability are currently being
investigated.
• The processor development is scheduled to begin in August 2011.
