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Earth observation, climate and optical

Pre-flight satellite instrumentation calibration

Giving organisations confidence in their instrumentation

Understanding the end-to-end performance of a satellite instrument under operational conditions before it is launched is a critical task for any space mission. NPL has decades of experience in providing specialised transfer standards and developing novel methods and instrumentation to ensure that fit-for-purpose solutions can be optimally employed in clean rooms across the world.

NPL can provide standards or complete turnkey measurement facilities on both a full supply or lease basis, to ensure the customer has the most cost-effective solution for their project. Our expertise can not only help customers get best use from the facilities, but also help them evaluate the various sources of error and develop an uncertainty budget for their instruments. Our services include calibration checks on established facilities, supply of cryogenically cooled black body standards and calibration of equipment for new missions.


Spectroscopically Tuneable Absolute Radiometric, calibration and characterisation, Optical Ground Support Equipment (STAR-cc-OGSE) has been developed in partnership with the innovative company, M Squared.  The STAR facility provides a state-of-the-art solution to instrument calibration and characterisation, ensuring the required performance is achieved while also minimising the time and effort involved in the pre-launch vacuum test environment.

The STAR facility is designed to meet the demanding needs of climate and environmental monitoring, and its flexibility, comprehensiveness and ease of use makes it suitable for a wide range of applications.  It can enhance the performance of missions previously thought to be impossible due to cost and complexity, by providing end to end calibration and characterisation, and also be used by the cube-sats of new space providers. STAR-cc-OGSE is fully traceable to NPL’s primary radiometric standard, the cryogenic radiometer, and can provide unprecedented uncertainties well below 0.5% across a wide spectral range.


MicroCarb is the first mission that will utilise STAR-cc-OGSE. It is a joint mission between UKSA and CNES which will measure sources and sinks of carbon, the principal greenhouse gas driving global warming. Better knowledge of the flow of CO2 is needed to understand the annual cycle of vegetation and its response to meteorological anomalies. It is also important that terrestrial ecosystem carbon sinks and sources can be identified and quantified, as well as building an understanding of how they change because of climate variation. The mission will also measure the links between carbon emissions and fossil fuel use.  As the UK’s National Metrology Institute, NPL is underpinning the measurements provided by MicroCarb, providing traceability and confidence in the outputs of the mission.  

NPL assisted in the production of this Space4Climate film

BRDF calibrations

The bidirectional reflectance distribution function (BRDF) of reference white reflection plaques is of critical importance to the EO community. They are regularly used to convert solar irradiance into radiances for calibration of instrumentation pre- and in-flight. They also commonly provide the reference target for calibration of field instruments. We have two facilities for BRDF calibrations, one laser based and a second using conventional sources. Measurements are routinely made over the spectral range 300 to 2500 nm, with an uncertainty of <0.2 % in the visible. We are also carrying out work to develop improved (stable) reference white diffusers and have recently demonstrated the potential of a new standard material in an experiment for Committee on Earth Observation Satellites (CEOS).

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