The Earthnet Data Assessment Pilot (EDAP) is a project that is responsible for assessing the quality and suitability of candidate missions being considered for the Earthnet Third Party Missions (TPM). For over 40 years ESA's Earthnet Programme has played a significant role as part of ESA's mandatory activities, providing the framework for integrating non-ESA missions, i.e. Third Party Missions, into the overall ESA Earth Observation (EO) strategy. Complementary to ESA-owned EO missions, the programme allows European users access to a large portfolio of TPM and is particularly important for promoting the international use of EO data.
The key objective of ESA's EDAP is to take full advantage of the increased range of available data from non-ESA operated missions and to perform an early data assessment for various missions. that fall into one of the following instrument domains:
• VHR, HR and MR Optical Missions
• LR Optical Missions
• SAR missions
• Atmospheric Missions
The present contribution focuses on the assessment of the data quality of third-party SAR missions. The early data assessment is intended to provide some indication of the potential of each existing mission to remain as a TPM. The mission quality assessment is based on specific guidelines and cover the following aspects:
• Data Provider Documentation Review: the assessment covers the products information, metrology and products generation topics. The goal of this assessment is to evaluate the quality of the documentation provided to the users in terms of products formats, generation and calibration; and of the availability and accessibility of the SAR products.
• Independent validation of the data quality by analyzing ad hoc datasets of the third-party missions over calibration sites (e.g., point target calibration sites or Rain Forest) in order to verify the overall data quality in terms of Impulse Response Function characteristics, resolution, radiometric calibration, geolocation accuracy and noise level.
The results of the performed validation are documented in dedicated Technical Notes that are published on the EDAP website (https://earth.esa.int/eogateway/activities/edap/sar-missions). The published TNs include the so-called Mission Quality Assessment Matrix, summarizing in a compact form the results of the performed validation activities.
The following third-party SAR missions have been evaluated so far in the framework of the EDAP project:
• SAOCOM: an L-band SAR constellation made of two satellites operated by the Argentinian space agency (CONAE). The first of two satellites, SAOCOM 1A, was launched on 7 October 2018 into a Sun-synchronous orbit polar orbit, with a 16 day repeat cycle. The same orbit was used for the second satellite, SAOCOM 1B, which was successfully launched on 30 August 2020. The constellation allows a revisit time of 8 days. SAOCOM is the first L-band mission implementing the TopSAR acquisition mode.
• ICEYE: as of the beginning of 2021, the ICEYE constellation consisted of 10 X-band Synthetic Aperture Radar (SAR) satellites. Over the next years, ICEYE will continue to grow its constellation capacity in specialized orbital planes designed to provide persistent monitoring capabilities and high-resolution view of the Earth's surface. Currently, the satellites operate in three modes called 'Strip Mode', 'Spot Mode' and 'Scan Mode'.
• Capella: Capella Space is a U.S. based company, founded in 2016. The company is focused on design and operation of small Synthetic Aperture Radar (SAR) satellites, to monitor the Earth. The Capella satellites operate in the X-band, and can acquire in Spotlight, Sliding Spotlight and Stripmap modes. The constellation provides SAR images with very fine spatial resolution, ranging from 0.5 m up to 1.2 m. The scene coverage goes from 5 x 5 km up to 5 x 20 km.
• PAZ: the PAZ satellite, launched on 22 February 2018, is owned and operated by Hisdesat, and is based on the use of a high-resolution X-band Synthetic Aperture Radar (SAR). The satellite operates in the same orbit of its twin satellites TerraSAR-X and TanDEM-X. The three satellites work together as a constellation. The satellite can operate in Stripmap, ScanSAR, Spotlight and high-resolution Spotlight modes.
The contribution will present the activities performed within the EDAP project and the results of the assessment of the missions reported above.