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ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer. Terra Launch from VAFB. Terra Orbit Parameters. Orbit Sun Synchronous Descending Node Time of Day 10:30 am Altitude 705 km Inclination 98.2 o Repeat Cycle 16 days. ASTER Instrument Overview.

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ASTER

Advanced Spaceborne Thermal Emission and Reflection Radiometer



Terra Orbit Parameters

Orbit Sun Synchronous

Descending Node

Time of Day 10:30 am

Altitude 705 km

Inclination 98.2o

Repeat Cycle 16 days


ASTER Instrument Overview

  • ASTER is an international effort:

    • Japanese government is providing the instrument under METI (Ministry of Economy, Trade and Industry) and is responsible for Level 1 data processing

    • Flies on NASA’s Terra platform

    • Science team consists of Japanese, American and Australian scientists


ASTER Characteristics

  • Wide Spectral Coverage

  • 3 bands in VNIR (0.52 – 0.86 μm)

  • 6 bands in SWIR (1.6 – 2.43 μm)

  • 5 bands in TIR (8.125 – 11.65 μm)

  • High Spatial Resolution

  • 15m for VNIR bands

  • 30m for SWIR bands

  • 90m for TIR bands

  • Along-Track Stereo Capability

  • B/H 0.6

  • DEM Elevation accuracy: 15m (3σ)

  • DEM Geolocation accuracy: 50m (3σ)

Terra

ASTER


ASTER Bands




Item

VNIR

SWIR

TIR

Scan

Pushbroom

Pushbroom

Whiskbroom

Reflective (Schmidt)

Refractive

Reflective (Newtonian)

D=82.25 mm (Nadir)

D=190 mm

D=240 mm

Telescope optics

D=94.28 mm (Backward)

Dichroic and

Spectrum separation

Band pass filter

Band pass filter

band pass filter

Si-CCD

PtSi-CCD

HgCdTe (PC)

Focal plane (Detector)

5000 x 4

2048 x 6

10 x 5

Cryocooler (Temperature)

not cooled

Stirling cycle, 77 K

Stirling cycle, 80 K

Telescope rotation

Pointing mirror rotation

Scan mirror rotation

Cross-track pointing

+ 24 deg.

+ 8.55 deg.

+ 8.55 deg.

Cold plate

Cold plate

Thermal control

Radiator

and

and

Radiator

Radiator

2 sets of Halogen lamps

2 sets of Halogen lamps

Blackbody

Calibration method

and monitor diodes

and monitor diodes

270 - 340 K

ASTER Characteristic Functions



Aster cross track pointing
ASTER Cross-Track Pointing

  • EOS AM-1 Orbit Interval : 172 km on the equator

  • ASTER Imaging Swath : 60 km

  • Fixed 7 Pointing Positions

  • + Arbitrary Pointing (rare cases)

  • Total Coverage in Cross-Track Direction by Pointing

  • Full Mode : 232 km (+116 km / +8.55 degrees)

  • Recurrent Period : 16 days (48 days for average)

  • VNIR : 636 km (+ 318 km / +24 degrees)

  • Recurrent Pattern : 2-5-2-7 days (4 days average)


Comparison between ASTER

and the other imagers


i : the wavelength

TBB : the brightness temperature

C1= 3.7415 x 104 (W cm-2 µm4)

C2= 1.4388 x 104 (µmK)

(Fujisada, 2001)

Conversion of DN to Radiance

(Level-1A)

DN values can be converted to radiance as follows.

L = A V /G + D (VNIR and SWIR bands)

L = AV + CV2 + D(TIR bands)

Where L: radiance (W/m2/sr/µm)

A: linear coefficient

C: nonlinear coefficient

D: offset

V: DN value

G: gain

For TIR, radiance can be converted into brightness temperature using Plank’s Law as shown below.


Level-1B Data Product

• The Level-1B data product can be generated by applying the Level1A coefficients for radiometric calibration and geometric resampling.

Map projection : UTM, LCC, SOM, PS, Lat/Long

Resampling : NN, BL, CC

• The geolocation field data are included in the Level-1B data to know the pixel position (latitude/longitude) on the ground.

(Fujisada, 2001)


Conversion of DN to Radiance (Level-1B)

• Radiance value can be obtained from DN values as follows;

Radiance = (DN value -1) x

Unit conversion coefficient

• Unit conversion coefficients, which is defined as radiance per 1DN, are used to convert from DN to radiance.

• The unit conversion coefficient will be kept in the same values throughout mission life.

(Fujisada, 2001)



Subsystem

Band #

Specified

Value

Measured

Value

Remarks

VNIR

1

> 140

224

Onboard lamp data

(slightly lower than the specified input radiance)

2

> 140

200

3N

> 140

136

218

SWIR

4

> 140

Onboard lamp data

(the minimum values for Lamp-A, higher than the specified input radiance)

5

> 54

177

6

> 54

181

7

> 54

177

8

> 70

213

9

> 54

212

SNRs Measured in Actual Data


Aster gain settings
ASTER Gain Settings

Detection of

High Temperature

Targets


ASTER Science Team

Selects algorithms for higher level standard products

Produces software for standard products

Conducts joint calibration and validation exercises

Conducts mission operations, scheduling, and mission

analysis


ASTER Calibration Activities

1. Onboard Calibration Devices

VNIR: Halogen lamp + photodiode monitor (dual units)

SWIR: Halogen lamp + photodiode monitor (dual units)

TIR : Variable temperature blackbody (BB)

2. Onboard Calibration (OBC)

(1) Long-term calibration: Every 17 days ( Every 33 days)

VNIR, SWIR: Halogen lamp + earth night side observation

TIR: BB temperature changed from 270 K to 340 K

(2) Short-term calibration: Before each TIR observation

TIR: BB temperature fixed at 270 K

3. Vicarious Calibration (VC)

VNIR, SWIR: Ivanpah Playa, Railroad Valley Playa, Tsukuba, etc.

TIR: Lake Tahoe, Salton Sea, Lake Kasumigaura, etc.




ASTER Instrument Operations

  • ASTER has a limited duty cycle which implies decisions regarding usage must be made

  • Observation choices include targets, telescopes, pointing angles, gains, day or night observations

  • Telescopes capable of independent observations and maximum observation time in any given orbit is 16 minutes

  • Maximum acquisitions per day

    Acquired ~750

    Processed ~330


Science Prioritization ofASTER data acquisition

  • NASA HQ, GSFC, and METI have charged the Science Team with developing the strategy for prioritization of ASTER data acquisition

  • Must be consistent with EOS goals, the Long Term Science Plan, and the NASA-METI MOU

  • Must be approved by EOS Project Scientist


Global Data Set

  • A one-time acquisition

    • All land surfaces, including stereo

    • Maximize high sun

    • “Optimal” gain

  • Consists of pointers to processed and archived granules which:

    • Meet the minimum requirements for data quality

    • Are the “best” acquired satisfying global data set criteria

  • Science Team has prioritized areas for acquisition (high, medium and low)


Regional Data Sets

  • Focus on specific physiographic regions of Earth, usually requiring multi-temporal coverage

  • Acquisitions are intended to satisfy multiple users, as opposed to specific requirements of individual investigator or small team

  • Defined by the ASTER Science Team in consultation with other users (e.g., EOS interdisciplinary scientists)

  • Science team provides prioritization (relative to other regional data sets) on a case-by-case basis


Targeted Observations

  • Targeted observations are made in response to Data Acquisition Requests (DARs) from individual investigators or small groups for specific research purposes

  • Japanese Instrument Control Center (ICC) does prioritization of DAR based on guidelines provided by Science Team

  • Targeted observation may also be used to satisfy the global data set or regional data set acquisition goals, where appropriate


ASTER Operation Complexity

Data Acquisition Based Upon User’s Requests

Instrument Operation Constraints

(1) Data Rate

・Maximum average data rate : 8.3 Mbps

・Peak data rate : 89.2 Mbps

(2) Power Consumption

(3) Pointing Change

3. Selection of Operation Mode / Gain Settings

4. Utilization of Cloud Prediction Data

Duty Cycle : 8%

Automatic Generation of Data Acquisition Schedule


Aster us japan relation

Terra

ASTER US-JAPAN Relation

TDRS

ASTER Sensor

Downlink

ATLASⅡ

Uplink

Science data

Engineering data

Telemetry data

Command

Direct Downlink

TDRSS

US

Japan

data

Level-0 data

DRS

Expedited Data Set

ASTER GDS

EOSDIS

Telemetry data

Activity

Product

Product

DAR, DPR

DAR, DPR

Product

・Data Processing/Analysis

 (Level 0→Level 1)

(High Level Product)

・Mission Operation

 (Observation Scheduling)

・Data Archive/Delivery

User

User

Pacific Link



ASTER Primary Objectives

To improve understanding of the local- and regional-scale processes occurring on or near the earth’s surface.

Obtain high spatial resolution image data in the visible through the thermal infrared regions.

ASTER is the zoom lens of Terra!


ASTER Web Site:

http://asterweb.jpl.nasa.gov


APPLICATIONS

  • Surface Energy Balance

  • Geology

  • Wild Fires

  • Urban Monitoring

  • Glacial Monitoring

  • Volcano Monitoring

  • Wetland Studies

  • Land Use



Surface Energy Balance from ASTER data

El Reno OK, 4-Sep-2000, Kustas & Norman 2-source model



Geology Temperature


3 Temperature21

321 DST

468 DST

131210 DST


Wild Fires Temperature


Hayman Fire, Colorado Temperature

June 16, 2002

ASTER bands 8-3-2 as RGB


Urban Monitoring Temperature


Eiffel Tower Temperature

Arc de Triomphe

Louvre

La Defense


Glacial Monitoring Temperature


Global Land Ice Measurements from Space Temperature

View from top of Llewellyn Glacier, British Columbia

  • Goal is to determine the extent of world’s glaciers and the rate at which they are changing.

  • Acquire global set of ASTER images

  • Map global extent of land ice

  • Analyze interannual changes in length, area, surface flow fields


Volcano Monitoring Temperature


January 2002 Eruption of Nyiragongo Volcano, Congo Temperature

Nyiragongo erupted January 17, 2002 sending streams of lave through the town of Goma. More than 100 people were killed. This perspective view combines ASTER thermal data (red) showing the active lava flows and lava in the crater; Landsat Thematic Mapper image, and Shuttle Radar Topography Mission digital elevation data.


Wetland Studies Temperature



Land Use Image



How Do I Get ASTER Data? Image

  • Browse the archive: use the EOS Data Gateway (EDG) to find what data have already been acquired. Order data products desired:http://harp.gsfc.nasa.gov/~imswww/pub/imswelcome/

  • Submit a Data Acquisition Request: First become an authorized user; then request satellite obtain your particular data


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