SoSWEET solar activity and space weather mission for extreme events prediction, solar flares and CMEs, and solar ultraviolet variability influence on climate
Résumé
SoSWEET (Solar ultraviolet variability & Space Weather Extreme EvenTs Microsatellite Mission) is an innovative small satellite mission proposed in response to the ESA Call for an F mission that aims to address, on one part, Space Weather extreme events prediction, solar flares and coronal mass ejections (CMEs) onset and, on the other, the solar ultraviolet variability influence on climate. Space Weather extreme events early detection/prediction is better observed in Lyman Alpha with 3 orders more sensitivity than in H Alpha and a resolution and contrast on eruptions largely superior to the commonly used He II line at 30.4 nm. Previsions are possible hours in advance by following flux ropes rising and deforming in the solar atmosphere. However, Lyman Alpha is a delicate spectral line to observe due to contamination and degradation of the transmission of instruments, as observed in the past. A disruptive telescope is developed to address this issue. Concerning climate and solar variability, it is worth recalling that UV is the only wavelength band with energy absorbed in the high atmosphere (stratosphere), creating ozone (Herzberg continuum, 200-242 nm), and that high variability is most probably at the origin of a climate influence. A simultaneous observation of the incoming UV and of the ozone production, would bring an invaluable information on this process of solar-climate forcing (we recommend the simultaneous observation, by a constellation of cubesats, of ozone and of the Earth radiation budget: the GAIA-y78 constellation mission). To address these objectives and flares and CMEs observations, a small satellite of less than 150 kg on a PROBA or similar platform (OneWeb Arrow, etc.), and on a polar orbit for an almost continuous solar following, is chosen (a polar orbit is also essential to understand the relation between solar UV variability and stratospheric ozone on arctic and Antarctic regions); alternately, having the satellite at L1 Lagrange point would be a definitive advantage. The SoSWEET polar satellite model payload definition includes the disruptive SUAVE telescope (Solar Ultraviolet Advanced Variability Experiment), an optimized heavy-duty thermally stable off-axis SiC telescope for FUV (Lyman-Alpha) and MUV (200-242 nm Herzberg continuum) imaging (sources of variability, extreme events detection), and the SOLSIM spectrometer (SOLar Spectral Irradiance Monitor), a newly designed double-monochromator instrument covering the 170-340 nm ultraviolet spectral range (absolute measurements) and providing 0.65 nm resolution still in within a limited mass-power budget. The payload is completed by a small but performing coronagraph, new UVC detectors (optimized for Herzberg continuum), Electron-Proton detectors and a vector magnetometer. Science objectives, mission profile and model payload will be presented.