The selection of the Discovery Program InSight landing site took over four years from initial identification of possible areas that met engineering constraints, to downselection via targeted data from orbiters (especially Mars Reconnaissance SPAC 11214 layout: Small Condensed v.2.1 file: spac321.tex (ELE) class: spr-small-v1.2 v.2016/06/09 Prn:2016/12/02; 14:37 p. 1/91» « d o c to p i c : R e v i e w P a p e rn u m b e r i n g s t y l e : C o n t e n t O n l yr e f e r e n c e s t y l e : a p s » latitude (initially 15°S-5°N and later 3°N-5°N for solar power and thermal management of the spacecraft), ellipse size (130 km by 27 km from ballistic entry and descent), and a load bearing surface without thick deposits of dust, severely limited acceptable areas to western Elysium Planitia. Within this area, 16 prospective ellipses were identified, which lie ∼600 km north of the Mars Science Laboratory (MSL) rover. Mapping of terrains in rapidly acquired CTX images identified especially benign smooth terrain and led to the downselection to four northern ellipses. Acquisition of nearly continuous HiRISE, additional Thermal Emission Imaging System (THEMIS), and High Resolution Stereo Camera (HRSC) images, along with radar data confirmed that ellipse E9 met all landing site constraints: with slopes <15°at 84 m and 2 m length scales for radar tracking and touchdown stability, low rock abundance (<10 %) to avoid impact and spacecraft tip over, instrument deployment constraints, which included identical slope and rock abundance constraints, a radar reflective and load bearing surface, and a fragmented regolith ∼5 m thick for full penetration of the heat flow probe. Unlike other Mars landers, science objectives did not directly influence landing site selection. AUTHOR'S PROOF
<p>NASA&#8217;s InSight mission deployed the Seismic Experiment for Interior Structure (SEIS) instrument on Mars, with the goal of detecting, discriminating, characterizing and locating the seismicity of Mars and study its internal structure, composition and dynamics. 44 years since the first attempt by the Viking missions, SEIS has revealed that Mars is seismically active. So far, the Marsquake Service (MQS) has identified 365 events that cannot be explained by local atmospheric or lander-induced vibrations, and are interpreted as marsquakes. We identify two families of marsquakes: (i) 35 events of magnitude MW=3-4, dominantly long period in nature, located below the crust and with waves traveling inside the mantle, and (ii) 330 high-frequency events of smaller magnitude and of closer distance, with waves trapped in the crust, exciting an ambient resonance at 2.4Hz. Two long period events with larger SNR and excellent P and S waves occurred on Sol 173 and 235, visible both on the VBB and the SP channels; the location of these events has been determined at distances of 26&#176;-30&#176; towards the East, close to the Cerberus Fossae tectonic system. Over ten additional long period events show consistent body-wave phases interpreted as P and S phases and can be aligned with distance using models of P and S propagation. Marsquakes have spectral characteristics similar to seismicity observed on the Earth and Moon. From the spectral characteristics of the recorded seismicity and the event distance, we constrain attenuation in the crust and mantle, and find indications of a potential low S-wave-velocity layer in the upper mantle. In contrast, the high-frequency events provide important constraints on the elastic and anelastic properties of the crust. The first seismic observations on Mars deliver key new knowledge on the internal structure, composition and dynamics of the red planet, opening a new era for planetary seismology. Here we review the seismicity detected so far on Mars, including location, distance, magnitude, magnitude-frequency distribution, tectonic context and possible seismic sources.</p>
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The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission began collecting high quality seismic data on Mars from February 2019. This manuscript documents the seismicity observed by SEIS, InSight’s seismometer, since this time until the end of March, 2020. Within the InSight project, the Marsquake Service (MQS) is responsible for prompt review of all seismic data collected by InSight, detection of events that are likely to be of seismic origin, and curation and release of seismic catalogues. In the first year of data collection, MQS have identified 465 seismic events that we interpret to be from regional and teleseismic marsquakes. Seismic events are grouped into 2 different event families: the low frequency family are dominated by energy at long period below 1 second, and the high frequency family primarily include energy at and above 2.4~Hz. Event magnitudes, from Mars-specific scales, range from 1.3 to 3.7. A third class of events with very short duration but high frequency bursts have been observed 712 times. These are likely associated with a local source driven by thermal stresses. This paper describes the data collected so far in the mission and the procedures under which MQS operates; summarises the content of the current MQS seismic catalogue; and presents the key features of the events we have observed so far, using the largest events as examples.
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