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ESA supports calibration and validation of space data for New Space

27 Sep 2023

Cal-Val park logo

As New Space providers expand the global offering of remote sensing data, there is an elevated need for harmonisation in calibration and validation (Cal/Val) approaches. ESA is taking steps to bolster best practices in Cal/Val, while also fostering innovation, as set out in a workshop this October.

The ramping up of New Space has boosted the availability of commercial, high resolution (HR) and very high resolution (VHR) Earth observation data. ESA’s Earthnet programme continues to provide the framework to access Earth Observation (EO) data from non-ESA missions, for research and applications development purposes, via ESA’s Third Party mission (TPM) programme.

Spatial resolution categories of Earth observation data
Spatial resolution categories of Earth observation data

As New Space increases the data offering, there is even more focus on the role of Cal/Val to maintain data interoperability and ensure confidence in data quality. Cal/Val of mission data is achieved through sensor calibration, data validation and quantifying uncertainties with inter-comparison of data from other missions or ground-based measurements.

New Space must navigate Cal/Val landscape

However, for many New Space providers, navigating the Cal/Val landscape is challenging. Understanding best practices, or the pros and cons of specific reference data is not straightforward. The offering of instruments and sensors from New Space is also diverse, creating varying Cal/Val needs.

Furthermore, harmonisation in Cal/Val activity is lacking. While there are many Cal/Val reference sites and networks, each providing dedicated measurements needed for Cal/Val, synergies across such sites are rarely exploited. Each site is dedicated to a specific task with little flexibility for scalability, or adaptation to accommodate new requirements from the remote sensing data user community.

ESA’s support of the open and pioneering Cal/Val Park concept aims to bridge these shortcomings by providing a common platform for Cal/Val. The ESA Cal/Val Park project is led by a team at ESRIN and essentially aims to be a site to pool current Cal/Val data for many target missions in one large measurement observatory.

The concept aims to ensure adherence to best practices, such as Fiducial Reference Measurements (FRM), while also providing an open and flexible infrastructure to test new and innovative Cal/Val solutions.

Providing guidelines for best practice

Hyperspectral imagery from EnMAP
Hyperspectral imagery from EnMAP

“Many providers of data from new, small satellites do not have much experience of Cal/Val, nor have the means to install on-board Cal/Val instrumentation, and so they rely more on ground-site infrastructure than other missions. Through Cal/Val Park, ESA aims to support New Space by providing guidelines for Cal/Val, as well as creating standards for Cal/Val best practice. The target missions and instruments included in the park will also be expandable, allowing adaptability to different sensors as new technology in the domain emerges,” explains Noelle Cremer, Cal/Val Park project support at ESA.

The ground based targets can also be deployed at specific times and angles to suit specific missions. Cal/Val Park is dedicated to HR and VHR optical missions. It supports the Cal/Val needs of any optical mission in the VNIR/SWIR range - both multi- and hyperspectral - with a strong focus on HR/VHR sensors.

“Playground” to stimulate innovative new solutions

Operational reference networks – such as RadCalNet and Hypernets – are based on mature devices and do not facilitate novel technological solutions. While building on existing Cal/Val technologies, Cal/Val Park aims to develop new methods by testing concepts in temporary trials – promising a so-called “playground” to test and validate new solutions. Its goal is to ensure a cost effective and synergistic approach to Cal/Val, with the possibility to accommodate the needs of future sensors (such as high resolution thermal) and other instrument types (such as synthetic aperture radar).

RadCalNet processing chain ensures reliable reference measurements
RadCalNet processing chain ensures reliable reference measurements

The project is a multi-agency effort, currently supported by both ESA and the Italian Space Agency (ASI) while looking for further interested partners and is open for use by both institutional and commercial EO providers.
Within the design phase for the project, which started in March 2023, commercial and institutional providers of target missions have already been asked to provide their requirements for the platform. This exchange of information will continue in a planned workshop this October.

VH-RODA workshop in November

The first Cal/Val Park User Consultation workshop will take place as a virtual event on 2 and 3 October 2023. The workshop will bring together Space Agencies, institutional and commercial EO providers to share information about current status of Cal/Val activities and provide a forum for open discussion on topics such as, approaches and needs for Cal/Val of sensors devoted to atmospheric composition and the optical, SAR, hyperspectral and thermal domains, and how diverse requirements could be addressed by the new Cal/Val Park site.

The workshop shall provide an update on the status of the preliminary design of Cal/Val Park and through open dialogue, aims to consolidate its design requirements.

Further community discussion on Cal/Val reference networks and recent changes in the VHR data landscape will also be addressed at the next Very High-resolution Radar & Optical Data Assessment (VH-RODA) workshop scheduled for November 2023. This 4th edition of VH-RODA will be held in ESRIN from 27-30 November, with registration closing 13 November.