It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet's surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander's seismometer, including over 20 events of moment magnitude M w = 3-4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indicate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately M w = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding M w = 4 have been observed. The lander's other instruments-two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer-have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander. Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The thermal and electrical conductivity probe (TECP), a component of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA), was included on the Phoenix Lander to conduct in situ measurements of the exchange of heat and water in the Martian polar terrain. TECP measured regolith thermal conductivity, heat capacity, temperature, electrical conductivity, and dielectric permittivity throughout the mission. A relative humidity sensor returned the first in situ humidity measurements from the Martian surface. The dry overburden above the ground ice is a good thermal insulator (average κ = 0.085 W m−1 K−1 and average Cρ = 1.05 × 106 J m−3 K−1). Surface thermal inertia (I) calculated from these values agrees well with daytime orbital determinations, but differences in the spatial and temporal scale of heat transport lead to very different measurements at night. Electrical conductivity was consistent with open circuit throughout the mission; an upper limit conductivity of 2 nS cm−1 is derived. Bulk dielectric permittivity (ɛb) shows several puzzling signals but also a systematic increase overnight in the latter half of the mission, contemporaneous with H2O adsorption. The magnitude of the increase is difficult to reconcile with expected changes in unfrozen water. Atmospheric H2O averages around 1.8 Pa during the day, corresponding to a RH < 5%. At night, much of the H2O disappears from the atmosphere, and RH increases to ∼100%. Temperature and H2O partial pressure data suggest that adsorption on mineral surfaces plays a major role in scrubbing H2O, with a possible contribution from perchlorate salts.

The Heat Flow and Physical Properties Package HP 3 for the InSight mission will attempt the first measurement of the planetary heat flow of Mars. The data will be taken at the InSight landing site in Elysium planitia (136 • E, 5 • N) and the uncertainty of the measurement aimed for shall be better than ±5 mW m −2. The package consists of a mechanical hammering device called the "Mole" for penetrating into the regolith, an instrumented tether which the Mole pulls into the ground, a fixed radiometer to determine the surface brightness temperature and an electronic box. The Mole and the tether are housed in a support structure before being deployed. The tether is equipped with 14 platinum resistance temperature sensors to measure temperature differences with a 1-σ uncertainty of 6.5 mK. Depth is determined by a tether length measurement device that monitors the amount of tether extracted from the support structure and a tiltmeter that measures the angle of the Mole axis to the local gravity vector. The Mole includes temperature sensors and heaters to measure the regolith thermal conductivity to better than 3.5% (1-σ) using the Mole as a modified line heat The InSight Mission to Mars II Edited by William B.

The diffusion coefficient of water vapor in unconsolidated porous media is measured for various soil simulants at Mars‐like pressures and subzero temperatures. An experimental chamber which simultaneously reproduces a low‐pressure, low‐temperature, and low‐humidity environment is used to monitor water flux from an ice source through a porous diffusion barrier. Experiments are performed on four types of simulants: 40–70 μm glass beads, sintered glass filter disks, 1–3 μm dust (both loose and packed), and JSC Mars–1. A theoretical framework is presented that applies to environments that are not necessarily isothermal or isobaric. For most of our samples, we find diffusion coefficients in the range of 2.8 to 5.4 cm2 s−1 at 600 Pascal and 260 K. This range becomes 1.9–4.7 cm2 s−1 when extrapolated to a Mars‐like temperature of 200 K. Our preferred value for JSC Mars–1 at 600 Pa and 200 K is 3.7 ± 0.5 cm2 s−1. The tortuosities of the glass beads is about 1.8. Packed dust displays a lower mean diffusion coefficient of 0.38 ± 0.26 cm2 s−1, which can be attributed to transition to the Knudsen regime where molecular collisions with the pore walls dominate. Values for the diffusion coefficient and the variation of the diffusion coefficient with pressure are well matched by existing models. The survival of shallow subsurface ice on Mars and the providence of diffusion barriers are considered in light of these measurements.

[1] The Phoenix and Mars Reconnaissance Orbiter (MRO) missions collaborated in an unprecedented campaign to observe the northern polar region summer atmosphere throughout the Phoenix mission (25 May to 2 November 2008; L s = 76°-150°) and slightly beyond (∼L s = 158°). Five atmospherically related campaigns were defined a priori and were executed on 37 separate Martian days (sols). Phoenix and MRO observed the atmosphere nearly simultaneously. We describe the observation strategy and history, the participating experiments, and some initial results. We find that there is general agreement between measurements from different instruments and platforms and that complementary measurements provide a consistent picture of the atmosphere. Seasonal water abundance behavior matches with historical measurements. Winds aloft, as measured by cloud motions, showed the same seasonally consistent, diurnal rotation as the winds measured at the lander, during the first part of the mission (L s = 76°-118°). A diurnal cycle recorded from L s ∼ 108.3°-109.1°, in which a dust front was approaching the Phoenix Lander, is examined in detail. Cloud heights measured on subsequent orbits showed that in areas of active lifting, dust can be lofted quite high in the atmosphere, doubling in height over 2 h. The combination of experiments also revealed that there were discrete vertical layers of water ice and dust. Water vapor column abundances compared to near-surface water vapor pressure indicate that water is not well mixed from the surface to a cloud condensation height and that the depth of the layer that exchanges diurnally with the surface is 0.5-1 km.