Lyman Alpha Radiometer
Alternative namesLYRA Edit this at Wikidata
Part ofPROBA-2 Edit this on Wikidata
Telescope stylespace instrument Edit this on Wikidata

LYRA (Lyman Alpha Radiometer) is the solar UV radiometer on board Proba-2, a European Space Agency technology demonstration satellite that was launched on November 2, 2009.[1]

LYRA[2][3] has been designed and manufactured by a Belgian-Swiss-German consortium (ROB-SIDC, PMOD/WRC, IMOMEC, CSL, MPS and BISA) with additional international collaborations (Japan, USA, Russia, and France). Jean-François Hochedez (ROB) is Principal Investigator, Yves Stockman (CSL) is Project Manager, and Werner Schmutz (PMOD) is Lead co-Investigator.

LYRA will monitor the Solar irradiance in four UV passbands. They have been chosen for their relevance to solar physics, aeronomy and Space Weather:

  1. the 115-125 nm Lyman-α channel,
  2. the 200-220 nm Herzberg continuum channel,
  3. the Aluminium filter channel (17-50 nm) including He II at 30.4 nm, and
  4. the Zirconium filter channel (1-20 nm).

The Radiometric calibration of the instrument is traceable to Synchrotron source standards, Physikalisch-Technische Bundesanstalt (PTB) and National Institute of Standards and Technology (NIST).[4] Its stability will be monitored by onboard calibration light sources (light-emitting diodes), which allow distinguishing between potential degradations of the detectors and filters. Additionally, a redundancy strategy contributes to the accuracy and the stability of the measurements. LYRA will benefit from wide bandgap detectors based on diamond: it will be the first space assessment of a pioneering UV detectors program. Diamond sensors make the instruments radiation-hard and solar-blind: their high bandgap energy makes them quasi-insensitive to visible light (see also references in Marchywka Effect). The SWAP extreme ultraviolet (EUV) imaging telescope will operate next to LYRA on Proba-2. Together, they will establish a high performance solar monitor for operational space weather nowcasting and research. LYRA demonstrates technologies important for future missions such as the ESA Solar Orbiter mission.


  1. ^ Successful launch qualification test for Proba-2 Archived 2011-07-25 at the Wayback Machine
  2. ^ Hochedez, J; Schmutz, W; Stockman, Y; Schuhle, U; Benmoussa, A; Koller, S; Haenen, K; Berghmans, D; Defise, J; Halain, J.-P.; Theissen, A.; Delouille, V.; Slemzin, V.; Gillotay, D.; Fussen, D.; Dominique, M.; Vanhellemont, F.; McMullin, D.; Kretzschmar, M.; Mitrofanov, A.; Nicula, B.; Wauters, L.; Roth, H.; Rozanov, E.; Rüedi, I.; Wehrli, C.; Soltani, A.; Amano, H.; Van Der Linden, R.; et al. (2006), "LYRA, a solar UV radiometer on Proba2", Advances in Space Research, 37 (2): 303, Bibcode:2006AdSpR..37..303H, doi:10.1016/j.asr.2005.10.041
  3. ^ LYRA website Proba-2 Science Center