Finding SEIS North on Mars: Comparisons Between SEIS Sundial, Inertial and Imaging Measurements and Consequences for Seismic Analysis. Issue 3 (15th March 2021)

• Record Type: Journal Article
• Authors: Savoie, D.; Richard, A.; Goutaudier, M.; Lognonné, P.; Hurst, K. J.; Maki, J. N.; Golombek, M. P.; van Driel, M.; Clinton, J.; Stutzmann, E.; Mimoun, D.; Banerdt, W. B.; Williams, N. R.
• Is Part Of: Earth and space science. Volume 8:Issue 3(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-15
• Subjects: InSight -- Mars -- Seismology -- Sundial; Space sciences -- Periodicals; Geophysics -- Periodicals; 500.5
• DOI: 10.1029/2020EA001286
• Languages: English
• ISSNs: 2333-5084

Abstract

Abstract: In this paper, we present the results obtained in the determination of the true north direction on Mars by using a gnomon on the InSight mission and compare the measurements with either the North determination from the Inertial Measurement Unit and imaging analysis. The obtained measurement has been used to populate the SEIS orientation information in the archived SEIS data. Images taken during December 2018 and January 2019 allow to determine the gnomon shadow position and length over a target. By calculating the Sun local coordinates using planetary ephemeris VSOP87, the images are used to estimate the true North direction on the landing site. By using eight different images selected, we obtain the true North direction with an accuracy up to 2.5°, which is confirmed by the IMU and imaging analysis. The true North direction is also confirmed by an image taken near local noon, when the sun crosses the meridian. The North determination precision is then discussed in view of the seismic determination of the back azimuth. Key Points: True North on Mars has been found using a sundial during the InSight mission This reference direction is used for Marsquakes location