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// Workers AI · dad joke modeWhat did Traceable Radiometry say? You can count on me.

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(Redirected from TRUTHS)
TRUTHS
NamesTraceable Radiometry Underpinning Terrestrial- and Helio-Studies
Mission typeSolar radiation measurement, traceability
Mission duration5-8+ years (planned)
Start of mission
Launch date~2030 (proposed)
RocketVega-C (planned)
Launch siteCentre Spatial Guyanais
Orbital parameters
Reference systemGeocentric
RegimePolar
Altitude610 km
Inclination90°
Period96.9 minutes[1]
Repeat interval61 days
Instruments
CSAR - cryogenic solar absolute radiometer
HIS - hyperspectral imaging spectrometer

ESA insignia

TRUTHS (Traceable Radiometry Underpinning Terrestrial- and Helio-Studies) was a planned European Space Agency (ESA) satellite. It was meant to improve the accuracy, reliability, and integrity of Earth observation data,[2] and to be the first of a new class of "SI-traceable satellites" (SITSats) that would have enabled other Earth observation missions to calibrate measurements with reference to them.[3] The mission was led by the UK National Physical Laboratory (NPL) and its lead scientist for Earth observation, Nigel Fox.[4] The UK Space Agency withdrew its funding for the project at the end of 2025, ending the satellite's development.[5]

Science goals

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TRUTHS had two primary objectives:[6]

  • "To establish a gold-standard reference dataset against which to cross-calibrate other sensors, facilitating an upgrade to the performance of the global Earth observing system to ensure interoperability and robust anchoring to an SI reference in space."

A secondary objective of the mission was to collect global hyperspectral data to "constrain and improve retrieval algorithms".[7]

TRUTHS was projected to be ready for launch around 2030, aboard a Vega-C from the Guiana Space Centre.[8] The mission had a targeted duration of five years, with consumables for up to eight years.[5]

Science instruments

[edit]

Alongside communications and navigation equipment, the scientific payload of the satellite would have included three instruments: the cryogenic solar absolute radiometer (CSAR), the onboard calibration system (OBCS), and the hyperspectral imaging spectrometer (HIS).

The instruments would have produced global hyperspectral (320 nm to 2400 nm) measurements of "top-of-atmosphere earth spectral radiance (0.3% k=2); solar irradiance (both total and spectrally resolved, 0.02% and 0.3% respectively); and lunar spectral irradiance (0.3%)".[3]

The cryogenic radiometer is the primary standard used by national metrology institutes for radiometric measurements and "recommended as the means to achieve SI traceability".[7] The CSAR, which would be cooled to < 60 K, was therefore considered "the heart of the calibration system".[7]

The mission would have been the first to host a primary standard cryogenic radiometer aboard a satellite.[3] The OBCS would "...transfer calibration traceability from the SI defining power measurement... to a full spectrally resolved radiance calibration of an instrument" – in the case of TRUTHS from the CSAR to the HIS – in a simplified manner to the steps used by terrestrial metrology institutes.[7] The HIS could then be used to image the Earth, the Moon, and also to "measure incident solar spectral irradiance."[7]

Timeline

[edit]
  • In order to obtain both scientific and financial support for the mission, many reports and academic publications were produced by Fox and collaborators over several decades.[9][10][11][12][13][14]
  • Early 2000s – Mission proposed by the UK National Physical Laboratory (NPL)[8]
  • 2019 – Adopted at the ESA ministerial conference, with 85% funding from the UK. The remainder from Switzerland, Greece, Czechia, and Romania.[15][16]
  • 2020 – Airbus UK selected as lead contractor,[17] Teledyne e2v selected to provide the infrared detectors.[18]
  • 2021 – At COP26: Began early design phase.[19]
  • 2022 – Passed preliminary design, technical, and scientific reviews.[20] Received further funding at the ESA ministerial conference.[21]
  • 2023 – Further funding awarded during COP28, to Airbus UK for design and development; and to Teledyne e2v to construct the hyperspectral imaging spectrometer detection system.[22]
  • 2025 – The UK Space Agency withdrew its funding, ending the satellite's development.[5]

See also

[edit]

References

[edit]
  1. ↑ "THE CEOS DATABASE : MISSION, INSTRUMENTS AND MEASUREMENTS - TRUTHS". database.eohandbook.com. Archived from the original on 2023-09-28. Retrieved 2023-12-05.
  2. ↑ "Mission objectives". NPLWebsite. Retrieved 2023-12-05.
  3. 1 2 3 "Learn more about TRUTHS". NPLWebsite. Retrieved 2023-12-05.
  4. ↑ "Nigel Fox". NPLWebsite. Archived from the original on 2024-01-12. Retrieved 2024-01-12.
  5. 1 2 3 "TRUTHS - Facts and figures". ESA. January 2026. Archived from the original on 16 June 2023. Retrieved 29 March 2026.
  6. ↑ "Mission objectives". National Physical Laboratory. Archived from the original on 2023-12-03. Retrieved 2023-12-03.
  7. 1 2 3 4 5 "TRUTHS (Traceable Radiometry Underpinning Terrestrial-and Helio-Studies) - eoPortal". www.eoportal.org. Archived from the original on 2023-11-29. Retrieved 2023-12-05.
  8. 1 2 "TRUTHS Mission Explainer" (PDF). space4climate.com. Space4Climate. July 2023. Archived (PDF) from the original on 2023-12-03. Retrieved 2023-12-03.
  9. ↑ Fox, Nigel P.; Aiken, James; et al. (2003-04-08). Fujisada, Hiroyuki; Lurie, Joan B.; Aten, Michelle L.; Weber, Konradin (eds.). "Traceable radiometry underpinning terrestrial- and helio-studies (TRUTHS)". Sensors, Systems, and Next-Generation Satellites VI. 4881. SPIE: 395–406. Bibcode:2003SPIE.4881..395F. doi:10.1117/12.462438. Archived from the original on 2025-11-21. Retrieved 2023-12-03.
  10. ↑ Fox, Nigel; Green, Paul; et al. (2016). "Traceable Radiometery Underpinning Terrestrial- and Helio- Studies (TRUTHS): Establishing a climate and calibration observatory in space". 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS). pp. 1939–1942. doi:10.1109/igarss.2016.7729499. ISBN 978-1-5090-3332-4.
  11. ↑ Boesch, H; Brindley, H; et al. (2022-01-25). SI-traceable space-based climate observation system: a CEOS and GSICS Workshop. National Physical Laboratory, UK, 9-11 Sept 2019 (Report). National Physical Laboratory. doi:10.47120/npl.9319.
  12. ↑ Fox, Nigel; Green, Paul (2020-07-27). "Traceable Radiometry Underpinning Terrestrial- and Helio-Studies (TRUTHS): An Element of a Space-Based Climate and Calibration Observatory". Remote Sensing. 12 (15): 2400. Bibcode:2020RemS...12.2400F. doi:10.3390/rs12152400. ISSN 2072-4292.
  13. ↑ Fox, Nigel; Kaiser-Weiss, Andrea; et al. (2011-10-28). "Accurate radiometry from space: an essential tool for climate studies". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1953): 4028–4063. Bibcode:2011RSPTA.369.4028F. doi:10.1098/rsta.2011.0246. ISSN 1364-503X. PMID 21930564.
  14. ↑ Fehr, Thorsten; Fox, Nigel; et al. (2023-02-22). Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS) – A 'gold standard' imaging spectrometer in space to support climate emergency reseaerch (Report). Copernicus Meetings. doi:10.5194/egusphere-egu23-12399. Archived from the original on 2023-12-03. Retrieved 2023-12-03.
  15. ↑ "Space mission to reveal 'Truths' about climate change". BBC News. 2020-01-22. Retrieved 2023-12-03.
  16. ↑ Norman, Helen (2020-02-03). "Europeans discuss TRUTHS climate change mission". Meteorological Technology International. Archived from the original on 2023-11-10. Retrieved 2023-12-03.
  17. ↑ "Airbus wins European Space Agency TRUTHS mission study for metrological traceability of Earth observation data". www.airbus.com. 28 October 2021. Archived from the original on 2023-11-10. Retrieved 2023-12-03.
  18. ↑ "Teledyne e2v to supply Infrared detector for TRUTHS Climate Change Satellite". UKspace. 2020-12-02. Archived from the original on 2023-11-10. Retrieved 2023-12-03.
  19. ↑ Jewett, Rachel (2021-11-05). "UK-Led TRUTH Mission to Fight Climate Change Moves to Early Design Phase". Via Satellite. Archived from the original on 2023-11-10. Retrieved 2023-12-03.
  20. ↑ "The TRUTHS climate satellite mission passes key test - Space4Climate". 2022-10-12. Archived from the original on 2023-11-10. Retrieved 2023-12-03.
  21. ↑ "NPL TRUTHS mission receives funding". NPLWebsite. Retrieved 2023-12-03.
  22. ↑ "COP28: UK climate satellite contracts". GOV.UK. Archived from the original on 2023-12-05. Retrieved 2023-12-05.
[edit]
External videos
video icon TRUTHS mission explanation - Space4Climate (2021)[1]
video icon Onboard Calibration System (OBCS) animation - National Physical Laboratory (2019)[2]
  1. ↑ "TRUTHS". Space4Climate. 2020-02-26. Archived from the original on 2023-11-10. Retrieved 2023-12-02.
  2. ↑ "SI traceability in-flight". National Physical Laboratory. Archived from the original on 2023-12-02. Retrieved 2023-12-02.
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