page 1 igarss, denver, july 31-aug 4, 2006 sentinel-1 mission concept malcolm davidson, evert...

IGARSS, Denver, July 31-Aug 4, 2006

Sentinel-1 Mission ConceptSentinel-1 Mission Concept

Malcolm Davidson, Evert Attema, Malcolm Davidson, Evert Attema, Bjorn Rommen, Nicolas Floury,Bjorn Rommen, Nicolas Floury,

Laura Moreno Patricio, Guido LevriniLaura Moreno Patricio, Guido LevriniESAESA


Origin of Sentinel-1 Mission Sentinel satellite family represent new development by ESA for Global Monitoring for Environment and Security (GMES) space component

Sentinel-1 imaging SAR mission aimed at providing continuity of data for user services

Initial mission definition through ESA GSE services with additional inputs from EU GMES activities

Main application areas covered: Monitoring sea ice zones and the arctic environment Surveillance of marine environment (wind speed, oil spills, ship detection)

Monitoring land surface motion risks Mapping of land surfaces: forest, water and soil, agriculture

Support to humanitarian aid in crisis situations


ESA EO Programme Overview

Application

sServices

Science

ENVISAT

Earth Explorers

Earth Watch

ERS-1, 2

CryoSat1

GOCE

ADM-Aeolus

SMOS

GMES

SwarmEarthcare

95 00 05 10 15

Sentinels

EE7

1 CryoSat-2 in 2009


Key programmatic guidelines for mission requirements

Continuity of data for user services Data availability – no data gaps w.r.t. ENVISAT ASAR/ERS-2

Long term commitment to data provision Data quality e.g resolution, radiometry compatible with existing SARs – deviations in system parameters require careful analysis of impact

User driven mission Respond directly and demonstrably to user requirements Traceability between user, mission and system requirements

On-going dialogue with user service community => some users only recently exposed to GMES services through ESA GSE and EU projects

Conflict-free satellite operation for reliable access to data and exploitation of archive


Derivation of Mission Requirements

User Service Requirements

User Service Requirements

Mission RequirementsMission Requirements System RequirementsSystem Requirements

• Description of service/application

• Description of radar information product

• Geographical Coverage requirements

• Access to data (e.g. timeliness)

• Data availability (Continuity, quality, Operations, Processing and archiving, Distribution)• Coverage and revisit• Timeliness • Characteristics of data products (e.g. spatial & radiometric resolution, swath width, polarisation

• Detailed payload, system and ground segment specification of mission (e.g. Noise-equivalent Sigma0, Ambiguity ratio, antenna size)


Monitoring the European marine environment

Include the detection of oil spill pollution and ships

Key observation requirements

Daily coverage of marine transport corridors

Near-real time information delivery (< 3 hours with 1 hour as a goal)

Intensity product Co-polar (VV or HH + cross

polar) desirable


Monitoring and Assessing Land Surface-Motion Risk

Driving application: provide pan-European ground motion hazard information service

Key Mission Requirements Interferometry Twice-weekly measurements of

subsidence over all major urban areas

Regular surveillance over all major urban areas (every two weeks for gas pipelines)

Archive for building up time series


Forest Fire and Flood Management

Driving application: support operational service of prevention, anticipation and response to natural hazards

Key Mission Requirements Seasonal high-resolution

imaging of areas burnt by forest fires

On-demand rapid delivery of data over hazard

Multi-polarisation for best classification results

Archive for comparison with past


Based on analysis and distillation of user requirements from ESA GMES service element program (GSE)

Total of 18 mission requirements are formulated and discussed in the MRD (http://esamultimedia.esa.int/docs/GMES)

Three mission design elements appear as keys to meeting user requirements Revisit Coverage Timeliness

Additional mission requirements cover data availability, data product characteristics incl. resolution, radiometric characteristics

Mission Requirements Document (MRD)


Coverage and Revisit For interferometry, global exact repeat coverage shall be achieved within interval of less than 14 days (MR9) Automatically satisfies applications requiring monthly or annual global coverage

Fast global access on-demand shall be provided (MR10) Required for humanitarian aid - assumes that revisit time through systematic acquisitions not sufficient

Daily full coverage shall be achieved north and south of +-45 degree latitude (MR11) Requirement traceable to ice monitoring and marine environment (ship detection, oil spills) services

Two satellite baseline not sufficient to meet requirement => collaboration and interoperability with non-ESA SAR system required


Avg. revisit time vs. No of Satellites – 250km swath Average Revisit of a Satellite Constellation

with 250 km Swath in 12-175 Orbit

0

1

2

3

4

5

6

7

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0

Latitude (deg.)

Days

1 sat 2 sat 3 sat 4 sat


Observation Requirements – Swath Width

The swath width shall be at least 240km (MR15) Swath width user requirements often a proxy for revisit/coverage

Services mapping fast changing phenomena (sea ice, ship detection) do require a minimum instantaneous swath width

Compromise on spatial resolution and radiometric data quality possible for some services (sea ice) but impact others (ship detection, interferometry)

A wave mode shall be provided with 20 x 20km every 100km along track (MR16) Follows from continuity of service requirement


Observation requirements - polarisation The choice of polarisation depends service => continuity with ENVISAT ASAR implies consideration of HH, VV & cross-pol. Sea ice: currently based on HH or VV, cross-polar shows improved capacity for iceberg detection

Wind speed, oil spill detection: require VV Ship detection: HH best for incidence > 45 degrees, cross-pol for steeper incidence angles

Services based on land cover classification: require more than one polarisation for enhanced classification

The main mode of observation shall be VV+VH (MR17)

Optional additional modes shall be provided incl. HH+HV (MR18)


Cross-pol. mode for ship detection

For VV+VH mode over water, cross-pol. channel to provide ship information

0

5

10

15

20

25

S/N

29 37 42 57

Incidence

HH

VH

VV

Vachon and Geeling (2005)


Illustration of dual-polarisation mode over land


Baseline Technical Concept Orbit: 12 day repeat Operational Modes: IW (5x20m, 240km), EW (25x80m 3L, 400km), SM (4x5m, 80km), WM (20mx5m, 20kmx20km)

Polarisation: Dual pol all modes VV+VH or HH+HV NESZ: -22 dB Radiometric accuracy: 1.0 dB Launch date: mid 2011 Operations:

Consistent, reliable conflict free mission operations NRT delivery within 3h (worst case) with 1h goal Data from archive within 24 hours Expected to work in pre-programmed fashion, imaging of global land masses, costal zones, shipping routes (IW) and covering the ocean with imagettes (WV mode)


ConclusionsConclusions Sentinel-1 mission aims to satisfy its user requirements in terms of data availability, coverage & revisit, timeliness and the quality of its data products. IW forseen as major mode with wide swath, high resolution, multipolarisation, interferometric capability

Instrument trade-off studies under way supporting the assessment of radar system parameter impacts

Future work: International cooperation required to achieve revisit time requirements (interoperability with Canadian radar constellation desirable)

Continued verification of mission concept with GMES programmatic requirements and evolution of service community

page 1 igarss, denver, july 31-aug 4, 2006 sentinel-1 mission concept malcolm davidson, evert...

Documents