ESA Intended Invitation To Tender

18.1ET.16


Title: STUDY INTO FRACTIONATED GEOSYNCHRONOUS RADAR SYSTEMS FOR CONTINUOUS MONITORING - EXPRO+
Program ref.: Technology Developme
Tender Type: C
Tender Status: INTENDED
Price Range: 200-500 KEURO
Budget Ref.: E/0901-01 - Technology Developme
Proc. Prop.: NO
Special Prov.: BE+DK+FR+DE+IT+NL+ES+SE+CH+GB+IE+AT+NO+FI+PT+GR+LU+CZ+RO+PL+EE+HU
Establishment: ESTEC
Directorate: Directorate of Tech, Eng. & Quality
Department: Electrical Engineering Department
Division: Radio Frequency Systems & Payloads Offic
Responsible: Coromina Pi, Francesc
Products: Satellites & Probes / Payloads / Instruments / RF and microwave Instruments / Imaging Radars
Techology Domains: RF Systems, Payloads and Technologies / RF Payloads / Payload Tools
RF Systems, Payloads and Technologies / RF Payloads / EO Instruments
Industrial Policy Measure: N/A - Not apply
Publication Date: 27-JUL-18

The opportunity of flying Synthetic Aperture Radars (SARs) in geosynchronous orbits dates back from early 80's. The motivation mainly derived from the interest in monitoring a delimited area with very short revisit time (24 hours), opening the door to security and environmental applications requiring almost continuous monitoring. At that time geosynchronous orbits with significant orbit inclination and eccentricity were proposed in order to achieve 24 hours revisit time over continental coverages. In order to achieve a proper Signal to Noise Ratio (SNR), high power amplifiers able to transmit significant amount of RF power as well as very large antenna dimensions were required, posing severe technological challenges to be solved for the concept implementation. In the late 90's, analternative concept, referred as quasi-geostationary SAR, was proposed, in which a low orbit eccentricity and a (quasi) zero inclination were selected, offering continuous monitoring of regional coverages. The SNR issues are resolved, in this case, by exploiting the long integration time of the synthetic aperture (i.e., in the order of hours), leading to much less demanding high power amplification and antenna size. This concept has been developing over time and targeting applications such as atmospheric phase screen measurement, snow-mass retrieval, earthquakes, landslides, volcanoes etc... Currently, the idea of embarking a quasi-geostationary SAR as hosted payload on a SATCOM is under investigation in the frame of an ESA EOPA Activity. Recently, a further enhancement of quasi-stationary SAR concept, has been introduced. The idea consists in the deployment of a fractionated geosynchronous SAR systems made upof a constellation of mini-satellites in geostationary orbit, achieving high resolution images (in the order of few meters) in lessthan one hour aperture time. The activity shall start from a comprehensive review of geostationary SARs concepts, identifying advantages and drawbacks of each solution in terms of both targetable applications and mission/instrument complexity and expected technical challenges. After that, a detailed definition, analysis, trade-off and performance assessment of candidate fractionated SAR systems made up of mini-satellites placed in the geosynchronous orbit shall be carried out. This task shall include a mission study including formation flying definition, instrument definition and sizing, identification and specification of satellite platform requirements, identification of potential launchers and launching strategy. Based on the outcome of this Task the most promising concept willbe selected for performance refinement as well as detailed instrument and data processing definition. A technology roadmap shall befinally derived at the end of the activity.