Describe in-flight calibration for the Thermal Infrared Sensor (TIRS) (1) Overview of TIRS (2) On-orbit radiometric calibration (2a) Onboard calibrator (2b) Terrestrial sites (3) On-orbit geometric and spatial calibratio

Hook, S.

Markham, B.

Montanaro, M.

Reuter, D.

Thome, K.

NASA Technical Reports Server

GODDARD SPACE FLIGHT CENTER
In-flight calibration of the Thermal Infrared 
Sensor (TIRS) on the Landsat Data 
Continuity Mission 
K. Thome1, D. Reuter1, M. Montanaro2, S. 
Hook3, B. Markham1  
 
1NASA/GSFC , 2SigmaSpace, 4JPL 
https://ntrs.nasa.gov/search.jsp?R=20120003856 2019-08-30T19:34:06+00:00Z
Describe in-flight calibration for the Thermal 
Infrared Sensor (TIRS) 
 Overview of TIRS  
 On-orbit radiometric calibration 
 Onboard calibrator 
 Terrestrial sites 
 On-orbit geometric and spatial 
calibration 
Outline 
Landsat Data Continuity 
Mission continues 
Landsat data history 
  TIRS operates in concert with but 
independent of Operational Land 
Imager 
 Will produce radiometrically-
calibrated, geo-located data 
 United States Geological Survey/ 
Earth Resources Observation and 
Science (EROS) facility developing 
operational algorithms  
 On orbit calibration plays key role 
in merging OLI and TIRS data  into 
single data stream 
 
LDCM overview 
TIRS 
OLI 
X 
Y 
Z 
Scene Select
Mirror Scene Select
Mechanism
Incoming Light Path
Lenses
Focal 
Plane 
Assembly
Filter 
Assemblies
Telescope
Assembly
Cryocooler
Radiator
Telescope
Radiator
Scene 
Select
Mechanism
Nadir 
(Earth) 
View
Blackbody 
Calibrator
Radiator
Dual band, pushbroom system with 185-km 
swath width and 100-m spatial resolution 
 Quantum well infrared photodetector (QWIP) 
 10.8 µm and 12 µm 
 Scene-select mirror allows for nadir views of earth as well 
as views of deep space and onboard blackbody 
TIRS Overview 
On-orbit testing will follow past efforts for similar 
sensors 
  Verify sensor calibration and performance on orbit 
 Evaluate onboard calibrator performance 
 On-board blackbody is primary path to derive on-
orbit radiometric calibration 
 Intercomparison with ETM+ and other sensors 
 Geometric approaches 
 Cold deserts for OLI to TIRS registration 
 Hot spots for band-to-band registration 
 OLI comparison 
 Lunar views (recovery time, ghosting) 
On orbit calibration 
An important goal of TIRS is to place this sensor 
in context with past, present, & future sensors 
 Radiometric calibration allows TIRS to continue a 
long history of Landsat sensors 
 Consistency with Landat-7 ETM+ and Landsat-5 
TM 
 Putting TIRS on the same radiometric scale as 
other earth resources sensors 
 NIST traceability will allow TIRS data to be on the 
same scale as follow-on Landsat missions 
On-orbit calibration of TIRS 
OBB has similar design to that used for Moderate 
Resolution Imaging Spectroradiometer (MODIS) 
  V-groove, “flat” plate 
 OBB surface property: 92% absorption and 8% 
reflection 
 Reflection is specular 
 Variable temperature 
 
Onboard Blackbody (OBB) 
BBC 
Scene select mirror 
Aperture 
Detection sphere 
Optical modeling used 
to predict emissivity 
performance 
 
Incident light in blue 
Reflected light in purple 
Scene-select mirror provides views to nadir 
(earth), space, and an on-board blackbody 
 Nominal operation approach is 
 View deep space and OBB as 
sensor comes out of eclipse 
 Nadir view of earth for imaging 
 Repeat deep space and OBB 
as sensor goes into eclipse 
 Frequency of OBB views can be 
increased if needed 
 Temperature of OBB can be 
varied between collects 
 
Onboard calibrator (OBB) 
Onboard blackbody (OBB) is 
calibrated using TIRS as a transfer 
Onboard blackbody characterization 
TIRS
OAP
Fold Mirror
Lab. BB
Radiance
Laboratory
blackbody
calibration
NIST Facility
Laboratory
Blackbody
Lab. BB DN
Low temp. 
DN
OBC BB
DN
Radiometric calibration of the OBB 
during preflight activities ensuresNIST 
traceability 
On-orbit testing will evaluate sensor calibration 
and noise performance on orbit 
  Evaluate onboard calibrator performance 
 Radiometric approaches 
 Intercomparison with ETM+ 
 Ground sites 
 Intersensor comparisons 
 Geometric approaches 
 Band-to-band registration 
 OLI comparison 
 Lunar approaches 
 Three-month commissioning and checkout phase 
 Schedule is still under development 
 Transfer to orbit of calibration is one component 
Transfer to orbit 
Transfer to orbit will take place during the first 
90 days of TIRS operation 
 Rely on combination of deep space views, OBB 
collections, and vicarious calibration data 
 Validate radiometric sensitivity model 
 Characterize variations in detector responsivity over 
2 instrument out gassing (decontamination) cycles 
 Identify dead, inoperable, and out-of-spec 
detectors for each band 
 Compare prelaunch to on orbit data 
 Deep space views 
 OBB 
 ETM+ comparisons with common targets and 
maximum 20 minute time delay  
Transfer to orbit 
Transfer to orbit 
Deep space
view differs
from preflight
OBC data
differ from
preflight
TIRS data
differ from
vicarious
No
No
No Calibration unchanged
Yes
Yes
Yes
OBC data
differ from
preflight
TIRS data
differ from
vicarious
TIRS data
differ from
vicarious Yes
No
Yes
No
OBC and offset changed
Yes
TIRS offset change
No
TIRS gain change
Systematic error between
vicarious and preflight
calibration
TIRS gain and offset changed
OBC changed
Well established vicarious approaches planned 
for TIRS evaluation 
 Well-understood ground scenes 
 Simultaneous nadir overpass (SNO) approach 
 Melt ponds 
 Sea-surface temperature retrievals 
 Characterized ground scenes 
 Lake Tahoe 
 Lake Ontario 
 Salton Sea 
 Cross comparisons with other sensors 
 MODIS/VIIRS 
 GOES 
 
Vicarious radiometric calibration 
Concentrate on instrumented sites 
accessible in N.H. winter 
 Lake Tahoe and Salton Sea shown 
to work well for ETM+ and TM 
 Measure water leaving radiance 
 Measure bulk temperature 
 Characterize the atmosphere 
 Predict at-sensor radiance 
Ground sites 
Characterize instrument to Attitude 
Determination System Reference alignment  
  Characterize detector arrays 
lines of sight 
 Relative band to band 
 Relative to reflective 
bands 
 Ground scenes 
 Cold deserts for OLI to 
TIRS registration 
 Hot spots for band-to-
band 
 Verify spatial characteristics 
via linear features 
On-orbit Geometric calibration 
OLI is scheduled to use the moon for 
radiometric calibration 
  Platform maneuver required to do so 
 Monthly basis but more frequently during check 
out 
 TIRS will also view the moon during the same 
maneuvers 
 Moon is high-temperature source 
 Examine data related to 
 Stray light 
 Ghosting 
 Validate recovery time to return to nominal 
image performance 
Lunar views 
On-orbit calibration of TIRS will place it in 
context with past, present, & future sensors 
  Effort builds on successful approaches developed 
for Landsat-5 TM and Landsat-7 ETM+ 
 Result of long-term partnership between NASA 
and USGS and university collaborations 
 Past effort demonstrates that the required 2% 
accuracy is readily achievable with TIRS 
 90-day commissioning phase will be the key to the 
transfer to orbit of prelaunch calibration 
 NIST traceable 
 Geometric and radiometric characterizations 
 Cross-calibration to currently flying sensors 
Summary 


In-Flight Calibration of the Thermal Infrared Sensor (TIRS) on the Landsat Data Continuity Mission

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