MoMo’s prediction of Mars’ ionosphere contribution to InSight RISE Doppler data. S. Le Maistre, N. Bergeot, O. Witasse, P.-L. Blelly, W. Kofman, K. Peter, V. Dehant, J.-M. Chevalier and O. Karatekin Motivation Doppler observables vs Free Core Nutation (FCN) Yseboodt et al. 2017 The impact of a liquid core on Martian Orientation Parameters is of the order of 10-3mm.s-1. Motivation Centimeter level on the signal delay (or 10-3 mm.s-1 in Doppler observables) accuracy is required on X-band radio link between an antenna on Earth and a lander on Mars. → Needs for correction of Earth and Mars atmospheres ? Here: effect of Mars and Earth Ionospheres on RISE X-band radio waves down link (8.4 GHz) since InSight Landing. Instant Doppler shift (mHz) Delay (m) Change in velocity (mm.s-1) Total Electron Content in TECu (1 TECu = 1016 e-.m-2) RISE InSight data set Data from RISE : 266 days, (2018-11-27 to 2019-12-31) 13 482 data. Mars data emission Insight landed in western Elysium Planitia on Mars on November 26, 2018. Localization: 4.502°N, 135.623°E. Earth data reception Three stations from NASA Deep Space Network (DSN). Localization: DSS 43 (Australia), DSS 63 (Spain),DSS 14 (Goldstone, California) Variation of the elevation and azimuth of the data set at Mars and Earth Estimation of Ionospheric vertical TEC (vTEC) Mars vTEC Earth vTEC Model of Mars’ ionosphere (MoMo, Bergeot et GNSS-data based IONEX maps (Hernández-Pajares. al., 2019) based on Mars Advanced Radar for et al. 2009). Based on 330 ground stations. Global Subsurface and Ionospheric Sounding (MARSIS). maps 2.5° lat. X 5° long. every 2h. The vertical TEC is projected to estimate the slant TEC (sTEC) in direction of the emitted and received signal. Then the signal delay, the instant doppler shift and the change in velocity are estimated using the 8.4 GHz down link frequency Contribution of Mars’ and Earth’ ionospheres on InSight RISE X-band signal. Mars’ ionosphere impact Earth’ ionosphere impact The effect of the Mars’ ionosphere is one order of magnitude lower than the Earth. The maximum range delays are : 10 mm for Mars / 25 cm for Earth The maximum doppler shifts are : 2. 10-2 mHz for Mars / 4. 10-1 mHz for Earth The maximum velocity changes are : 5.10-3 mm.s-1 for Mars / 5.10-2 mm.s-1 for Earth Summary ▪ We estimated the Mars’ and Earth’ ionospheres contributions on InSight RISE X-band signal for the period end-2018 to end-2019. ▪ The effect on X-Band signal Doppler can reach 2.10-2 mHz (5.10-3 mm.s-1) for Mars and 4.10-1 mHz (5.10-2 mm.s-1 for Earth. ▪ The Mars’ ionosphere contribution is about one order of magnitude below the estimated noise of the RISE instrument but is of same order of magnitude as the contribution of the liquid core in the Doppler. ▪ The MoMo software for the prediction of the Mars’ ionospheric Total electron content is available at https://lara.oma.be/marsatmo/iono/momo.html.