Astrodynamics tools and techniques for Astrodynamics tools and techniques for Observation of the EarthObservation of the Earth

Berthyl Duesmann (ESA/ESTEC)Berthyl Duesmann (ESA/ESTEC)Montse Pinol (GMV @ ESA/ESTEC)Montse Pinol (GMV @ ESA/ESTEC)

3rd International Workshop on Astrodynamics tools and Techniques3rd International Workshop on Astrodynamics tools and Techniques2 - 5 October 20062 - 5 October 2006

ESTEC, Noordwijk, The NetherlandsESTEC, Noordwijk, The Netherlands

PurposePurpose To provide all partners

within ESA Earth-observation with identical Orbit model, Attitude model, Time model, (orbit number, time since ANX)

with identical geometry models (Earth, Sun, Moon).

The purpose is to eliminate the effect of differences in the orbit, attitude or geometrical models in the input / output for all project partners.

HistoryHistory The first version of the Mission Software was

conceived and implemented for ERS-1 in the late ‘80s of the last century by ESA / ESTEC. This version was re-used for ERS-2.

Later the mission software was industrialised, For METOP by GMV For ENVISAT by Deimos For Earth-Explorer’s by Deimos

ApplicationsApplications Geolocation of the Level 1 productsGeolocation of the Level 1 products Calculation of other geometric parameters Calculation of other geometric parameters Mission analysis, Mission analysis, Mission planningMission planning

Time segment calculation when sensor sees an Time segment calculation when sensor sees an areaarea

Time segment calculation when a station sees the Time segment calculation when a station sees the s/cs/c

Visualisation tools Visualisation tools

Direction to SunDirection to Sun ENVISAT / MERIS Observation / Calibration ENVISAT / MERIS Observation / Calibration

scenarioscenario Direction to Sun for Sentinel-1 (MLST ANX @ Direction to Sun for Sentinel-1 (MLST ANX @

18:00)18:00)

ApplicationsApplications

ApplicationsApplications Geolocation of the Level 1 products, Geolocation of the Level 1 products,

calculation of other geometric parameters calculation of other geometric parameters Mission analysis, Mission analysis, Mission planningMission planning

Time segment calculation when sensor sees an Time segment calculation when sensor sees an areaarea

Time segment calculation when a station sees the Time segment calculation when a station sees the s/cs/c

Visualisation tools Visualisation tools

ApplicationsApplications METOP / Windscat Swath over AtlanticMETOP / Windscat Swath over Atlantic

ApplicationsApplications SMOS (Asc.) Visibility over VILSPA stationSMOS (Asc.) Visibility over VILSPA station

Including the X-band Tilt Angle constraint (red)Including the X-band Tilt Angle constraint (red)

ApplicationsApplications Geolocation of the Level 1 products, Geolocation of the Level 1 products,

calculation of other geometric parameters calculation of other geometric parameters Mission analysis, Mission analysis, Mission planningMission planning

Time segment calculation when sensor sees an Time segment calculation when sensor sees an areaarea

Time segment calculation when a station sees the Time segment calculation when a station sees the s/cs/c

Visualisation tools Visualisation tools

ConsistencyConsistency Identical input (time) gives identical results, Identical input (time) gives identical results,

independent of calling sequence historyindependent of calling sequence history Avoid integratorsAvoid integrators

X,Y,Z X,Y,Z hh X,Y,Z X,Y,Z X,Y,ZX,Y,Zj2000 j2000 X,Y,ZX,Y,Zearth-fixed earth-fixed X,Y,ZX,Y,Zj2000j2000

ContinuityContinuity All resulting parameters and their rates are All resulting parameters and their rates are

continuouscontinuous PrecisionPrecision

Important for product processing Important for product processing

Model PhilosophyModel Philosophy

ABA InverseFunction

Function ABA InverseFunction

Function ABA InverseFunction

Function

ABA InverseFunction

Function ABA InverseFunction

Function ABA InverseFunction

Function

Model PhilosophyModel Philosophy Continuity exampleContinuity example

ENVISAT / MIPAS scientific community discovered a real ENVISAT / MIPAS scientific community discovered a real ENVISAT attitude discontinuity, whenever the onboard orbit ENVISAT attitude discontinuity, whenever the onboard orbit model was updated (2x per day)model was updated (2x per day)

If the Mission Software would have contained discontinuities If the Mission Software would have contained discontinuities then detection would have been impossible / more difficultthen detection would have been impossible / more difficult

ABA InverseFunction

Function ABA InverseFunction

Function ABA InverseFunction

Function

ABA InverseFunction

Function ABA InverseFunction

Function ABA InverseFunction

Function

• Orbit Model Update procedure updated (December 2003) discontinuity drastically reduced• Attitude File introduced in Mission Software (2004)• Attitude File introduced in processing

Attitude noise down to 4 mdeg (rms)

AchitectureAchitecture Software is delivered as object library, Software is delivered as object library,

to guarantee an identical model to guarantee an identical model

File Driven(Orbit Event File, Predicted Orbit File, all XML)

Epoch Driven(UTC, Orbit Number + ANX time)

Period Driven(Orbit Range, Time Range)

Supported Computer PlatformsSupported Computer Platforms EnvisatEnvisat

Sun Solaris: 7 or higher, 32 Sun Solaris: 7 or higher, 32 bits bits

8 or higher, 64 bits 8 or higher, 64 bits MacOSX: 10.2 or higher, 32 MacOSX: 10.2 or higher, 32

bits bits Windows: 95 or higher Windows: 95 or higher Linux: Linux: Suse 9.2 Suse 9.2 SGI: SGI: IRIX 6.5 IRIX 6.5 IBM: IBM: AIX 4.3 AIX 4.3

Earth Explorer Sun Solaris: 7 or higher, 32

bits 9 or higher, 64 bits

MacOSX: 10.2 or higher, 32 bits

10.4 or higher, 64 bits

Windows: 95 or higher Linux: RedHat 8 32 bits

RedHat Linux Enterprise 4.0 64 bits

Download from:

EOP System Support Division Web Server: http://eop-cfi.esa.int/

Helpdesk:

Montse Pinol cfi@jw.estec.esa.nl

Mission AnalysisMission Analysis Zero DopplerZero Doppler

For the coming Sentinel-1 & EarthCare For the coming Sentinel-1 & EarthCare mission, mission, a specific attitude model has been proposed:a specific attitude model has been proposed:

Mission AnalysisMission AnalysisAttitude model has already been built into the Attitude model has already been built into the

softwaresoftwareThe proposed attitude has been analysed The proposed attitude has been analysed with respect to the classical local normal pointingwith respect to the classical local normal pointing

Range Rate (with respect to target rotating with earth) Range Rate (with respect to target rotating with earth) DopplerDoppler

Elevation with respect to Local Nadir Elevation with respect to Local Nadir

Please note that the final Zero-Doppler Attitude is identical Please note that the final Zero-Doppler Attitude is identical to the Attitudes for Terrasar-X and Aeolus. to the Attitudes for Terrasar-X and Aeolus. However the proposed algorithm to achieve this attitude is However the proposed algorithm to achieve this attitude is substantially more simple. substantially more simple.

Earth Fixed Range Rate Earth Fixed Range Rate

Earth Fixed Range RateEarth Fixed Range RateZero-Doppler Attitude Zero-Doppler Attitude

Elevation to NadirElevation to NadirZero-Doppler Attitude Zero-Doppler Attitude

ConclusionsConclusions ESA Earth Observation Missions are ESA Earth Observation Missions are

supported by dedicated mission software, supported by dedicated mission software, since ERS-1since ERS-1 Software Philosophy:Software Philosophy:

Consistency of transformationsConsistency of transformations Continuity in results Continuity in results Precision for processingPrecision for processing Identical results across platforms / projectsIdentical results across platforms / projects

Proven Concept:Proven Concept: Analysis, Planning & ProcessingAnalysis, Planning & Processing ERS-1, ERS-2, EnviSat ERS-1, ERS-2, EnviSat Coming soon: Earth-Explorer, Metop Coming soon: Earth-Explorer, Metop