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CURRENT Results of the Decadal Survey HyspIRI Imaging Spectrometer Concept Study: A High Signal-to-Noise Ratio and High Uniformity Global Mission to Measure Plant Physiology and Functional Type . Measuring the composition, function and health of global land and coastal ocean ecosystems - PowerPoint PPT Presentation
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CURRENT RESULTS OF THE DECADAL SURVEY HYSPIRI IMAGING SPECTROMETER CONCEPT STUDY: A HIGH SIGNAL-TO-NOISE RATIO
AND HIGH UNIFORMITY GLOBAL MISSION TO MEASURE PLANT PHYSIOLOGY AND FUNCTIONAL TYPE.
Measuring the composition, function and health of global land and coastal ocean ecosystems
Robert O. Green*, Greg P. Asner**, Stephen G. Ungar***, Robert G. Knox*** and PPFT Science Working Group
*Jet Propulsion Laboratory, California Institute of Technology
** Carnegie Institute of Washington, Stanford, California***Goddard Space Flight Center
NASA Decadal Survey Mission
HyspIRI Visible ShortWave InfraRed (VSWIR) Imaging Spectrometer
+
Multispectral Thermal InfraRed (TIR) Scanner
VSWIR: Plant Physiology and Function Types (PPFT)
Multispectral TIR Scanner
Red tide algal bloom in Monterey Bay, CA
Map of dominant tree species, Bartlett Forest, NH
Plant Physiology and Functional Types NASA Mission Concept Study
Science Questions:
• What is the composition, function, and health of land and water ecosystems?
• How are these ecosystems being altered by human activities and natural causes?
• How do these changes affect fundamental ecosystem processes upon which life on Earth depends?
Red tide algal bloom in Monterey Bay, CA
Map of dominant tree species, Bartlett Forest, NH
Imaging spectrometer: 100kg / 67W
Schedule: 4 year phase A-D, 3 years operations
All components have flown in space
Measurement:
• 380 to 2500 nm in 10nm bands
• Accurate 60 m, 145 km swath
• 19 days revisit at equator
• Global land and shallow water
Aquatic Terrestrial
Building on NASA Hyperion Technology Demonstration
Global Coverage >> 10XSoil C:N RatioWhite Mountain
National Forest, NH
Swath > 10X
SNR > 10XW
avelength
Cross Track Sample
Uniformity > 10X
Overview
• Science and Context
• Science and Measurement
• Mission Concept
• Summary
The US National Academy of Sciences Decadal Survey (2007) placed “critical priority” on a:
“Mission to observe distribution and changes in ecosystem function: An optical sensor with spectral discrimination greatly enhanced beyond the LANDSAT and MODIS class is required to detect and diagnose changes to ecosystem function such as water and nutrient cycling and species composition. Such observations include nutrient and water status, presence and responses to invasive species, health of coral reefs, and biodiversity. We propose a hyperspectral sensor with pointability for observing disturbance events such as fire and droughts when and where they occur at higher temporal frequency.”
Scientific and Societal Context
Science Questions
• Ecosystem Function and Diversity: – What are the spatial distributions of different plant functional groups, diagnostic species, and
ecosystems? – How do their locations and function change seasonally and from year to year?– What are the trends?
• Biogeochemical Cycles: – How do changes in the physical, chemical, and biotic environment affect the productivity,
carbon storage and biogeochemical cycling processes of ecosystems? – How do changes in biogeochemical processes feed back to other components of the Earth
system?
• Ecosystem Response to Disturbance:– How do human-caused and natural disturbances affect the distribution, biodiversity and
functioning of ecosystems?
• Ecosystems and Human Well-being: – How do changes in ecosystem composition and function affect human health, resource use,
and resource management?
Science Questions
Topic Areas
Vegetation Functional Type Analysis, Santa Barbara, CAMESMA Species Type 90% accurate
Species Fractional Cover
Dar Roberts, et al, UCSB
Science Questions
Ecosystem Function and Diversity
Dierssen et al. 2006
Phytoplankton groups have different pigment suites that give them unique spectral “fingerprints” that can be used to measure their presence and to understand their roles in
aquatic ecosystems.
Chlorophyll (mg m-3)
Chlorophyceae
Prochlorococcus
Cryptophyceae
Dinophyceae
Raphidophyceae
Haptophyceae
Bacillariophyceae
Synechococcus
Rhodophyceae
A
2 5 10 15 20 30 40 50
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
400470
480
490
500
510
520530
540
550
560
570
580
590600
610620
700
x
y
BChlorophyceae
Bacillariophyceae
Rhodophyceae0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 10
0.2
0.4
0.6
0.8
1
400 500 600 7000
0.02
0.04
0.06 B
Wavelength (nm)
a* ph(
) (m
2 mg-1
)
Chlorophyceae
Proclorococcus
CryptophyceaeDinophyceae
Raphidophyceae
HaptophyceaeBacillariophyceae
Synechococcus
Rhodophyceae
400 500 600 7000
0.02
0.04
0.06
0.08
0.1
b bp (m
-1)
A
400 500 600 7000
0.005
0.01R
rs (
sr-1
)
BCeratium sp.Ceratium furcaGymnodinium brevaLingulodinium polyedra
400 500 600 7000
0.005
0.01
L w(
) (W
m-2
nm
-1 s
r-1)
Wavelength (nm)
C
400 500 600 7000
0.005
0.01
D
Rrs
(sr
-1)
Chlorophyll a (mg m-3)
Spe
ctra
l ref
lect
ance
(sr
-1)
Wavelength (nm)
Phytoplankton Groups Perceived water color
11
Science Questions Response to Disturbance
James Goodman, UPRM
Imaging spectroscopy is used to measure the functional types and fractions in a coastal coral ecosystem in order to ascertain the impacts of nutrients on habitat composition.
Airborne imaging spectroscopy measurements of coral reef ecosystem, Hawaii.
Sand
AlgaeCoral
Natural Color Image Habitat Composition
12
Science Questions
Ecosystems and Human Well-Being
Airborne imaging spectrometer measurements of a red tide algal bloom in Monterey Bay, CA
A complete spectral measurement is required to determine the species type including species that cause potentially harmful algal blooms.
October 2002
Ceratium spp. bloom
Paul Bissett, Florida Environmental Research Institute. Spectral Signatures
Post-fire response to three different fires, two in 1993 and one in 1996. Canopy moisture is the most sensitive measure of change, as shown by overlap between the 1996 and 1993 Calabasas and Topanga fires. High fire return intervals in Southern California are impacting ecosystems, eliminating some shrub species.
Science Questions Response to Disturbance
0
100
200
300
400
500
600
700
800
0 10 20 30 40 50 60
Stand Age (97)
DL
iqu
id W
ater
DS98-S97
DS95-S97
Interannual changes in canopy moisture show significant stand age differences up to 30 years (shown as the difference in canopy moisture between spring98 and spring 97 –blue, and spring97 and spring 95 - green). These results indicate that seasonal drought response is age dependent in shrublands, with older stands less impacted by drought. These results require seasonal imaging spectroscopy observations.
Non photosynthetic Vegetation
Green vegetation
Canopy Liquid Water
14
Cerro Grande Fire Severity, Los Alamos, NM, Ray Kokaly
GreenGreenVegetationVegetation
Mineral/AshMineral/Ash
Mineral-1Mineral-1mm
Mineral-2Mineral-2mm
Dry ConiferDry Conifer
Dry & GreenDry & GreenConiferConifer
Straw mattingStraw matting
Ash/CharcoalAsh/Charcoal
Straw mattingStraw matting & Green grass& Green grass
AVIRISAVIRIS
Spectral Fitting MapSpectral Fitting Map
Lignin-Cellulose LabLignin-Cellulose Lab Lignin-Cellulose Lignin-Cellulose AVIRISAVIRIS
PhotoPhoto
Ray Kokaly, USGS
Science Response to Distrubance
15
Canopy water content
Leaf nitrogen concentration
Invasive species and nitrogen-fixing PFT
Soil nitrogen trace gas emissions
RadiativeTransfer
Bio
ch
em
ica
l
Fin
ge
rpri
nti
ng
BiogeochemicalAnalysis
Invasive Species in the Hawaiian Rainforest Invasive Species in the Hawaiian Rainforest from Airborne Imaging Spectrometer data: from Airborne Imaging Spectrometer data: Patterns of Invasion and Biogeochemical Patterns of Invasion and Biogeochemical ConsequencesConsequences
Asner and Vitousek, PNASHall and Asner, GCB
Fractional material cover
CanopyModeling
The Complete PPFT Data Stream for Ecosystem Composition, Function and Health
Myrica infestations
• A set of overarching science question have been defined– What is the composition, function, and health of terrestrial and aquatic ecosystems?
– How are these ecosystems being altered by human activities and natural causes?
– How do these changes affect fundamental ecosystem processes upon which life on Earth depends?
• These overarching questions are best addressed with detailed science question defined for each of the following topic areas
– Ecosystem Function and Diversity
– Biogeochemical Cycles
– Ecosystem Response to Disturbance
– Ecosystems and Human Well-Being
• Antecedent measurements and derived products have been shown as pathfinder examples to address the PPFT overarching and topic area science questions.
Science Questions
Summary
Science Rationale
18
• Plant and phytoplankton functional types and species have biochemical and biophysical properties that are expressed as reflectance and absorption features spanning the spectral region from 380 to 2500 nm.
• Individual bands do not capture the diversity of biochemical and biophysical signatures of plant functional types or species.
• Changes in the chemical and physical configuration of ecosystems are often expressed as changes in the contiguous spectral signatures that relate directly to plant functional types, vegetation health, and species distribution.
• Important atmospheric correction information and calibration feedback is contained within the spectral measurement.
Science Rationale The Need for Continuous Spectral Measurements
19
Science Rationale
STM Ecosystem Function and Diversity
Sum
mar
y S
TM
Science Rationale
STM Biogeochemical Cycles
Sum
mar
y S
TM
21
Science Rationale
Ecosystem Response to Disturbance
Sum
mar
y S
TM
Science Rationale
STM Ecosystems and Human Well-Being
Sum
mar
y S
TM
Science Measurements
Science Measurements
Approach
• Measure the global land and coastal/shallow water (> -50m).
• 19 day equatorial revisit to generate seasonal and annual products.
Spatial 1000 m
• Measure the molecular absorption and constituent scattering signatures in the spectral range from 380 to 2500 nm at 10 nm, and at 60 m spatial sampling.
PPFT at 60 m
SpectralRange 380 to 2500 nm in the solar reflected spectrumSampling <= 10 nm {uniform over range}Response <= 10 nm (full-width-at-half-maximum) {uniform over range}Accuracy <0.5 nm
RadiometricRange & Sampling 0 to 1.5 X max benchmark radiance, 14 bits measuredAccuracy >95% absolute radiometric, 98% on-orbit reflectance, 99.5% stabilityPrecision (SNR) See spectral plots at benchmark radiancesLinearity >99% characterized to 0.1 %Polarization <2% sensitivity, characterized to 0.5 %Scattered Light <1:200 characterized to 0.1%
SpatialRange >145 km (12 degrees at 700 km altitude)Cross-Track Samples >2400Sampling <=60 mResponse <=60 m sampling (FWHM)
UniformitySpectral Cross-Track >95% cross-track uniformity {<0.5 nm min-max over swath}Spectral-IFOV-Variation >95% spectral IFOV uniformity {<5% variation over spectral range}
Science MeasurementsSummary Measurement Characteristics
TemporalOrbit Crossing 11 am sun synchronous descendingGlobal Land Coast Repeat 19 days at equatorRapid Response Revisit 3 days (cross-track pointing)
Sunglint AvoidanceCross Track Pointing 4 degrees in backscatter direction
OnOrbit CalibrationLunar View 1 per month {radiometric}Solar Cover Views 1 per week {radiometric}Surface Cal Experiments 3 per year {spectral & radiometric}
Data CollectionLand Coverage Land surface above sea level excluding ice sheetsWater Coverage Coastal zone -50 m and shallowerSolar Elevation 20 degrees or greaterOpen Ocean Averaged to 1km spatial samplingIce Sheets Averaged to 1km spatial samplingCompression >=3.0 lossless
Science Measurements Characteristics Continued
27
Science Measurements
Key SNR and Uniformity Requirements
Wavelength
Cross Track Sample
Depiction-Grids are the detectors-dots are the IFOV centers-Colors are the wavelengths
RequirementSpectral Cross-Track >95% cross-track uniformity {<0.5 nm min-max over swath}
Spectral-IFOV-Variation >95% spectral IFOV uniformity {<5% variation over spectral range}
Benchmark Radiances
Uniformity Requirement
Required SNR
Mission Concept
29
Mission Concept
PPFT Overview
• Duration: 4 years implementation, 3 years science
• Coverage: Global land and coast/shallow water every 19 days
• 3 day event revisit capability
• Data are acquired over all reasonably illuminated areas (Sun elevation > 20 deg).
• Data download using dual-polarization X-band at high-latitude stations
• Instrument: 67W, 100kg, 1.6X1.6X1 m
• Spacecraft Example: LEO RSDO bus (SA-200HP)
• Launch: Taurus-class launch vehicle.
30
Mission Concept
Instrument: Offner SpectrometerLow Cost and High Fidelity
• The instrument design selected is an Offner imaging spectrometer with extensive relevant heritage
– Hyperion, CRISM, COMPASSair, TBair, ARTEMIS, M3
• At the core of the PPFT instrument is a pair of f/2.5, high signal-to-noise ratio, uniform, full-spectral-range Offner spectrometers
27 micron uniform e-beam slit
Multi-blazé e-beamlow scatter, low Plz.convex grating
One of twofull spectral rangeHgCdTe detector arrays 610 used cross-track213 used spectral
Order sorting filter
Spherical Mirror
Spherical Mirror
One of two Offner spectrometersin the PPFT instrument
• Each spectrometer has two full range detector arrays that cover the spectral range from 380 to 2500 nm @ 10 nm intervals with 610 cross-track spatial elements used– CRISM, TBair, ARTEMISfull_range,
M3full_range
Uniform air slit
Convex multi-blaze grating
Full rangeDetector array and filter
31
Mission Concept Instrument with Telescope with Spectrometers
• The light from the PPFT telescope is field split in order to feed the two spectrometers (A,B).
• In each spectrometer two detector arrays provide 610 cross-track by 213 spectral detector elements.
• Each spectrum is read out as a snap-shot, so that there is no time delay, yaw, or jitter impact to the spectral-IFOV-uniformity
• Total coverage 2400 cross-track by 213 spectral• Mirror coating for high reflectivity 380 to 2500 nm
• Mirror surface specified for extremely low scatter
• Mirror orientations and coatings specified to minimize polarization < 2%
• Detectors and spectrometer are passively cooled
Mission Concept Heritage: NASA Moon Mineralogy Mapper (M3)
24 Month Build-- Mouroulis Offner Design (PPFT)-- Convex e-beam grating (PPFT)-- 6604a MCT full range detector array, multiplexor & signal chain (PPFT)-- Uniform slit (PPFT)-- 0.5 micron adjustment mounts lockable for flight-- Aligned to 95% cross-track uniformity (PPFT)-- Aligned to 95% spectral IFOV uniformity (PPFT)-- Meets high SNR requirements (PPFT)-- Passive radiator (PPFT)
Mass 8 kg, Power 15 Watts
First spectrum 18 Months from funding start
M3 Spectrometer
Cross-track uniformity > 95%Spectral IFOV uniformity > 95%
Mission Concept
Instrument Calibration
• Every week at the end of the sunlit pass, once the surface illumination is below threshold. The instrument cover will be brought to 45 degrees of the closed position and be illuminated by the sun with the spacecraft holding an inertially fixed attitude.
• Once a month (fixed Moon phase), the spacecraft attitude will be adjusted during the eclipsed part of the orbit to make the Moon cross the instrument field-of-view.
• Three times a year, calibration data of chosen test sites will be acquired.
Solar Calibration Lunar Calibration Ground Calibration
Polar Ground StationX-band dual polarization 640 mbits/sec7 min/orbit average
Mission Concept Ground Data System
Science Data Processing and Distribution CenterLevel 1, 2 and selected
Level 3
Instrument Science Team
Multidisciplinary Science Team
640 Mb/s7 minutes/orb
1.6 Terabit memory0.6 Terabit Orbit average0.2 Terabits 3X compressed
Example approach (updated 16 July 2007)
35
1.1 m
1.6 m
Mission Concept Example Launch Vehicle
1.6 m
Taurus 3210
Capability to 694 km sun-sync (per KSC website): 765 kg
Example approach
Summary
Summary
Plant Physiology and Functional Types
Three fundamental components required for understanding ecosystems are: function, composition, and structure.
This mission for the first time provides global measurements of function with vastly improved measures of composition including biodiversity.
The science, measurements, and algorithms enabling this mission have been consistently demonstrated with antecedent airborne and ground measurements and experiments.
This PPFT mission addresses a set of compelling science questions that have beenrepeatedly identified as critical to science and society by independentassessments and scientific panels. Recent examples include: the NRCDecadal Survey, the 4th assessment of the IPCC and the Millennium EcosystemAssessment (2005).
The PPFT instrument (24 Month build) and mission have high relevant heritage, and correspondingly low risk, in conjunction with a modest cost.
Plant Physiology and Functional Types NASA Mission Concept Study
Science Questions:
• What is the composition, function, and health of land and water ecosystems?
• How are these ecosystems being altered by human activities and natural causes?
• How do these changes affect fundamental ecosystem processes upon which life on Earth depends?
Red tide algal bloom in Monterey Bay, CA
Map of dominant tree species, Bartlett Forest, NH
Imaging spectrometer: 100kg / 67W
Schedule: 4 year phase A-D, 3 years operations
All components have flown in space
Measurement:
• 380 to 2500 nm in 10nm bands
• Accurate 60 m, 145 km swath
• 19 days revisit at equator
• Global land and shallow water
Aquatic Terrestrial
Building on NASA Hyperion Technology Demonstration
Global Coverage >> 10XSoil C:N RatioWhite Mountain
National Forest, NH
Swath > 10X
SNR > 10XW
avelength
Cross Track Sample
Uniformity > 10X