Future SAR mission concepts

Transcription

1 Future SAR mission concepts PREMIER M. Arcioni, M. Aguirre, P. Bensi, S. D Addio, K. Engel, F. Fois, F. Hélière, M. Kern, A. Lecuyot, C.C. Lin, M. Ludwig, K. Scipal, P. Silvestrin ESTEC, Keplerlaan 1, PO Box 299, 2201AZ Noordwijk, the Netherlands Tel: ; Marco.Arcioni@esa.int

2 Future SAR mission concepts The following 4 mission concepts based on SAR for Earth observation are under study at ESA: 1.BIOMASS phase 0 - Candidate Earth Exporer 7 mission 2.CoReH 2 O phase 0 - Candidate Earth Exporer 7 mission 3.C-band bistatic InSAR concept for coastal current estimation 4.Ka-band bistatic InSAR concept for topography determination

3 BIOMASS Candidate Earth Explorer 7 mission for a better understanding and quantification of land contribution to global carbon cycle

4 BIOMASS Mission Objectives Scientific Objective: To improve the quantification of the global terrestrial carbon cycle through the linking of BIOMASS mission products with global vegetation models. Primary Objective: Provide global forest biomass observations for monitoring forests extent and forest disturbance. Secondary Objective: Secondary Objective: Mapping surface and subsurface structures in polar regions and in arid zones

5 BIOMASS Mission requirements

6 Satellite concepts Concept 1 Concept 3 Concept 2 Mass kg Power W Data storage Gb Data Downlink Mb/s

7 Instrument Concept 1 Planar array on Snapdragon platform Four passive antenna panels folded around three hinges (77.6 m 2 aperture) 10 sub-arrays per panel Operated in stripmap mode 320 W total peak RF-power 102 km polarimetric swath 2.82m 27.5m

8 Instrument Concept 2 Planar array on conventional platform Central panel attached to the platform with two wings of four deployable, selfsupporting panels (65.9 m 2 aperture) Operated in stripmap mode 300 W total peak RF-power 70 km polarimetric swath Upper metallisation (CFRP) Annular slot Feed-lines Dielectric honeycomb Adhesive layers Dielectric honeycomb Ground plane (CFRP) m 3.36 m

9 Instrument Concept 3 Deployable reflector on conventional platform (14.7 m x 9.6 m aperture) 4 x 2 elements array-feed with beam-switching Supports stripmap, interleaved and scansar modes 300 W total peak RF-power 2 x 60 km polarimetric swaths (dual-beam) Array-feed with 4 pairs of patch radiators in elevation Engineering Qualification Model of 12 m diameter reflector

10 CoRe-H2O Cold Regions Hydrology High-resolution Observatory IGARSS, July 2007, Barcelona

11 CoReH2O Mission Objectives Scientific Objectives: Provide snow and ice observations to develop and improve: hydrological, climate and NWP modelling modelling of glacier/climate interactions in the global context understanding of permafrost response to climate change knowledge of sea ice thermo-dynamics in marginal ice zones and polynyas Mission Objective: Mission Objective: Observation of physical parameters of snow, surface water and glacier ice and their temporal variations with a SAR system at 2 frequencies (X and Ku-bands)

12 CoReH2O Mission Requirements

13 Satellite concepts Concept 1 Single antenna concept (4.5 m 2 m) Concept 2 Dual-antenna concept (3.3 m 2.1 m, 3.3 m 1.2 m) Flight Direction Deployed Reflector X-band Reflector Flight Direction Solar Array Feed Cluster Feed Arrays Solar Array Ku-band Reflector Mass kg Power W Data storage Gb Data Downlink 460 Mb/s

14 Future milestones Way ahead for BIOMASS and CoreH2O: Phase A studies to be kicked-off in Jan/Feb 2010 timeframe Phase A duration 15 months Selection of Earth Explorer 7 in 2011/2012 Launch in 2016/17

15 C-band Bistatic InSAR Concept to measure coastal currents

16 Mission Objectives The main purpose of this work is a feasibility study for a future bistatic mission, which exploits the Sentinel-1b SAR as source of illumination. The primary application of the mission will be the coastal current measurements. Information on costal currents is very useful for a huge number of applications such as monitoring of bathymetric changes, pollution and river outflows, as well as ship routing and regional circulation modelling. Along-Track Interferometry (ATI) from satellites can provide repeated current measurements over thousands of square kilometres with a spatial resolution in the order of m, as well as the coverage of Earth s coastlines within few days.

17 Along Track Interferometry (ATI) Principle When the two antennas operate in bistatic mode (i.e. one receiving and transmitting antenna plus one pure receiving antenna) it results that the interferometric phase is function of the radial velocity.

18 Instrument Requirements Orbit Altitude Sensor Polarization Incidence angle Range Noise equivalent sigma0 Total ambiguity ratio Spatial resolution Accuracy of current measurements Baseline Same semi-major axis and inclination of Sentinel-1b 698 Km 726 Km C-band (5.4 GHz) Receive-Only SAR Dual-linear in Rx 20 o -46 o -20 db; -17 db; 30 m x 30 m ( 36 looks) 20 % 300 m 1000 m

19 Satellite concept VEGA fairing Mass kg Power 300 W Data Downlink Mb/s (single polarization)

20 In summary A spatial resolution on the order of m and an accuracy of current estimation better than 0.1 m/s are realistic performance goals of this space-borne ATI system. Synchronization: an inter-satellite link appears as a feasible solution but not the best one, being unacceptable any modification of Sentinel- 1b SAR architecture. Formation fly: the short baseline is close enough to be challenging. Proximity operation of Sentinel-1b and the passive SAR satellite shall be conducted to minimize the collision risk.

21 Ka-Band SAR Interferometer for Spaceborne Applications Based on SCan-On On-REceive Techniques

22 High resolution interferometric Ka-Band SAR - Use of Ka-Band allows single pass cross-track interferometry with a baseline that can be accommodated on one platform - High bandwidth available in Ka-Band allows high spatial resolution - Product: High resolution images (1m) and generation of accurate digital elevation models (Target: HRTI-3, absolute height accuracy <10 m with 12mx12m post spacing) - Imagery with height information is applicable to civil security (e.g. object recognition), crisis management (e.g. risk assessment, operations planning), cartography (DEM) and science applications (e.g. height of snow and ice surface, tree canopies)

23 Ka-band InSAR concept - Snapdragon-derived bus with two foldable main and sub-reflectors for RX system - Design provides good shape stability of 12 m baseline, large internal volume and surface area, and allows accommodation in VEGA fairing - Rigidity of S/C allows for some platform agility which improves responsiveness - Scan-on-receive technique is used to improve signal-to-noise and reduce clutter from rain, which are challenges at Ka-Band - Height error within 3 m can be achieved for moderate rain of 2 mm/h, which is preliminary compatible with HRTI-3 DEM specification. Parameter Orbit Approx. dry mass Lifetime Centre Frequency TX bandwidth Value 500 km SSO 1000 kg 5 years GHz 300MHz Nadir (z) y Flight (x) RX subreflectors 12 m interferometric baseline TX power peak 3500 W Incidence angle Baseline length Swath width 34 deg 12 m 16 km TX antenna RX reflectors (d=2.25 m) Max. Res az x el 1 x 1m

24 Ka-band InSAR concept Thank you