is the solar UV radiometer on board Proba-2
PROBA2 is the second satellite in the European Space Agency's series of PROBA low-cost satellites that are being used to validate new spacecraft technologies while also carrying scientific instruments. PROBA2 is a small satellite developed under an ESA General Support Technology Program contract...
, a European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
technology demonstration satellite that was launched on November 2, 2009.
LYRA has been designed and manufactured by a Belgian-Swiss-German consortium (ROB-SIDC
, 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:
- the 115-125 nm Lyman-α
In physics and chemistry, the Lyman series is the series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1...
- the 200-220 nm Herzberg
Gerhard Heinrich Friedrich Otto Julius Herzberg, was a pioneering physicist and physical chemist, who won the Nobel Prize for Chemistry in 1971, "for his contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals". Herzberg's main work concerned...
- the Aluminium filter channel (17-50 nm) including He II at 30.4 nm, and
- the Zirconium filter channel (1-20 nm).
The radiometric calibration of the instrument is traceable to synchrotron source standards (PTB). Its stability will be monitored by onboard calibration light sources (light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s), 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 Marchywka Effect refers to electrochemical cleaning of diamond using an electric field induced with remote electrodes.-Discovery and development:...
). The SWAP
The "Sun Watcher using Active Pixel System Detector and Image Processing" telescope is a compact EUV imager on board the PROBA2 mission that will observe the Sun in extreme ultraviolet ....
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
Solar Orbiter is a planned Sun-observing satellite, under development by the European Space Agency . The main mission scenario is a launch by an Atlas V from the Kennedy Space Center in Florida in January 2017...