Establishing a climate and calibration observatory in space

We need accurate and detailed satellite data to improve our understanding of how the Earth's climate is changing and make the best decisions to mitigate global warming. Satellites need to be able to detect changes such as the total solar energy and sea surface temperature, to a few tenths of a per cent per decade. However, the majority of current satellite measurements are not accurate enough to achieve this, and their performance is further exacerbated by the harshness of the launch and environmental conditions in space.

TRUTHS (Traceable Radiometry Underpinning Terrestrial and Helio Studies) is a proposed satellite mission able to record data on the Earth's climate to accuracies a factor of 10 better than current sensors. It will monitor key climate indicators such as the amount of cloud, albedo or solar radiation at a level that allows trends to be detected in a third of the time required compared with current instruments.

In addition to providing highly-accurate climate data itself, TRUTHS will act as an in-orbit measurement lab, able to upgrade the performance of much of the world's Earth Observation systems. By using an on-board primary standard – an instrument called a 'CSAR' (Cryogenic Solar Absolute Radiometer) – and performing reference calibrations of other in-flight sensors through near simultaneous observations of the same target, it can transfer its calibration accuracy to them.

TRUTHS represents the best climate monitoring we can ever achieve, and will provide invaluable benchmark data on the status of the Earth's climate, allowing scientists to identify trends in the shortest time possible. It will also improve our understanding of carbon and water cycles, crucial in providing the robust evidence needed to enable concerted international action on climate change.