[P-CG24] [EJ] 惑星大気圏･電磁圏

[PCG24-05] Search of CH4 on Mars by SOFIA/EXES

青木 翔平²、*中川 広務¹、笠羽 康正¹、佐川 英夫³、Richter Matthew⁴、DeWitt Curtis⁴ (1.東北大学　大学院理学研究科　地球物理学専攻太陽惑星空間物理学講座　惑星大気物理学分野、2.Institut d'Aéronomie Spatiale de Belgique、3.京都産業大学、4.Physics Department, UC Davis)

キーワード：火星、メタン、SOFIA

Discovery of CH4 in the Martian atmosphere has led to much discussion since it could be a signature of biological/geological activities on Mars. However, the presence of CH4 and its temporal and spatial variations are still under discussion. We performed sensitive measurements of Martian CH4 by using the Echelon-Cross-Echelle Spectrograph (EXES) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) on 16 March 2016, which corresponds to summer (Ls = 123.2°) in the northern hemisphere on Mars. The high altitude of SOFIA telescope (~13.7 km) enables us to significantly reduce the effects of terrestrial atmosphere, and the high spectral resolution of EXES (R~90,000) enables us to detect the intrinsically narrow lines of Martian CH4 at the 7.5 μm band. . Mars disk was spatially resolved into 3 x 3 areas, none of the observed region showed the unambiguous detections of CH4. The upper limits on the CH4 volume mixing ratio ranges from 1 to 6 ppb.