nasa decadal survey mission hyspiri

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?



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


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


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?



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