Future SAR mission concepts

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 NetherlandsTel: +31-71-5655681; E-mail: Marco.Arcioni@esa.int

PREMIER

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.CoReH2 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

Future SAR mission concepts

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

BIOMASSBIOMASS

BIOMASS Mission Objectives

Scientific Objective: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: 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

BIOMASS Mission requirements

Satellite concepts

Mass 1200-2600 kg Power 800-1200 WData storage 400-700 Gb Data Downlink 260-290 Mb/s

Concept 1

Concept 2

Concept 3

Instrument – Concept 1

• Planar array on Snapdragon platform• Four passive antenna panels folded

around three hinges (77.6 m2 aperture)• 10 sub-arrays per panel• Operated in stripmap mode• 320 W total peak RF-power• 102 km polarimetric swath

27.5m

2.82m

Instrument – Concept 2

• Planar array on conventional platform• Central panel attached to the platform

with two wings of four deployable, self- supporting panels (65.9 m2 aperture)

• Operated in stripmap mode• 300 W total peak RF-power• 70 km polarimetric swath

Upper metallisation (CFRP) Annular slot

Ground plane (CFRP)

Feed-lines

Dielectric honeycomb

Dielectric honeycombAdhesive layers

20.16 m

3.36 m

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)

Engineering Qualification Model of 12 m diameter reflector

Array-feed with 4 pairs of

patch radiators in elevation

IGARSS, 23-27 July 2007, Barcelona

CoReCoRe--H2OH2O

Cold Regions Hydrology High-resolution Observatory

CoReH2O Mission Objectives

Scientific 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)

CoReH2O Mission Requirements

Satellite concepts

Concept 1

Flight Direction

Feed Arrays

X-band Reflector

Ku-band Reflector

Solar Array

Flight Direction Deployed Reflector

Solar Array

Feed Cluster

Mass 960-1200 kg Power 1500-1700 WData storage 1200-1400 Gb Data Downlink 460 Mb/s

Concept 2Dual-antenna concept

(3.3 m

2.1 m, 3.3 m

1.2 m)Single antenna concept

(4.5 m

2 m)

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

C-band Bistatic InSAR Conceptto measure coastal currents

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 30-50 m, as well as the coverage of Earth’s coastlines within few days.

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.

Instrument Requirements

Orbit Same semi-major axis and inclination of Sentinel-1b

Altitude 698 Km ÷

726 Km

Sensor C-band (5.4 GHz) Receive-Only SAR

Polarization Dual-linear in Rx

Incidence angle Range 20o- 46o

Noise equivalent sigma0 ≤

-20 dB;

Total ambiguity ratio

-17 dB;

Spatial resolution

30 m x 30 m (

36 looks)

Accuracy of current measurements

20 %

Baseline 300 m – 1000 m

Satellite concept

VEGA fairing

Mass 1200-1300 kg Power 300 WData Downlink 250-360 Mb/s (single polarization)

In summary

• A spatial resolution on the order of 30-50 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.

KaKa--Band SAR Interferometer for Band SAR Interferometer for SpaceborneSpaceborne Applications Applications

Based on Based on SCanSCan--OnOn--REceiveREceive TechniquesTechniques

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)

Ka-band InSAR concept

Parameter Value

Orbit 500 km SSO

Approx. dry mass 1000 kg

Lifetime 5 years

Centre Frequency 35.75 GHz

TX bandwidth 300MHz

TX power peak 3500 W

Incidence angle 34 deg

Baseline length 12 m

Swath width 16 km

Max. Res az x el 1 x 1m

12 m interferometric baseline

RX reflectors (d=2.25 m)

TX antenna

RX subreflectors

Nadir (z)y

Flight (x)

- 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.

Ka-band InSAR concept

Thank you