Martian Surface Pressure Research Articles

The research of thermal environment test methodology for the Mars probe product

Abstract In order to ensure the success of the Mars exploration mission, it is necessary to accurately simulate the unique environment on the surface of Mars in a ground test and verify the effectiveness of the thermal control measures of the Mars rover. This paper proposes a thermal balance test method that can simultaneously simulate environmental factors such as Martian surface gas atmosphere, wind speed, pressure, solar radiation, and atmospheric temperature. This proposed test method meets the thermal design verification requirements of component-level products. Compared with similar large-scale facilities, the test cost is low, and the implementation efficiency is high. Furthermore, the influence of the Martian wind field on the surface temperature distribution of the product under both the Martian day and night environment was investigated using the proposed test method. The research results show that although the atmospheric pressure on the surface of Mars is much lower than the surface of the Earth, the Martian wind will still form forced convection heat transfer on the surface of the probe and its auxiliary products, which will affect the heat distribution of the products. In the thermal control design of the products, it is necessary to consider the impact of all the above environmental factors and carry out corresponding comprehensive environmental test verification.

Martian column CO2 and pressure measurement with spaceborne differential absorption lidar at 1.96 µm

Abstract. By utilizing progress in millijoule-level pulsed fiber lasers operating in the 1.96 µm spectral range, we introduce a concept utilizing a spaceborne differential absorption barometric lidar designed to operate within the 1.96 µm CO2 absorption band for remote sensing of Martian atmospheric properties. Our focus is on the online wavelength situated in the trough region of two absorption lines, selected due to its insensitivity to laser frequency variations, thus mitigating the necessity for stringent laser frequency stability. Our investigation revolves around a compact lidar configuration, featuring reduced telescope dimensions and lower laser pulse energies. These adjustments are geared towards minimizing costs for potential forthcoming Mars missions. The core measurement objectives encompass the determination of column CO2 absorption optical depth, columnar CO2 abundance, surface atmospheric pressure, and vertical distributions of dust and cloud layers. Through the amalgamation of surface pressure data with atmospheric temperature insights garnered from sounders and utilizing the barometric formula, the prospect of deducing atmospheric pressure profiles becomes feasible. Simulation studies validate the viability of our approach. Notably, the precision of Martian surface pressure measurements is projected to surpass 1 Pa when the aerial dust optical depth is projected to be under 0.7, a typical airborne dust scenario on Mars, considering a horizontal averaging span of 10 km.

Perseverance MEDA Atmospheric Pressure Observations—Initial Results

AbstractThe Mars2020 Perseverance Rover landed successfully on the Martian surface on the Jezero Crater floor (18.44°N, 77.45°E) at Martian solar longitude, Ls, ∼5° in February 2021. Since then, it has produced highly valuable environmental measurements with a versatile scientific payload including the MEDA (Mars Environmental Dynamics Analyzer) suite of environmental sensors. One of the MEDA systems is the PS pressure sensor system, which weighs 40 g and has an estimated absolute accuracy of better than 3.5 Pa and a resolution of 0.13 Pa. We present initial results from the first 414 sols of Martian atmospheric surface pressure observations by the PS, whose performance was found to meet its specifications. Observed sol‐averaged atmospheric pressures follow an anticipated pattern of pressure variation in the course of the advancing season and are consistent with data from other landing missions. The observed daily pressure amplitude varies by ∼2%–5 % of the sol‐averaged pressure, with absolute amplitude 10–35 Pa in an approximately direct relationship with airborne dust. During a regional dust storm, which began at Ls ∼ 135°, the daily pressure amplitude roughly doubled. The daily pressure variations were found to be remarkably sensitive to the seasonal evolution of the atmosphere. In particular, analysis of the daily pressure signature revealed diagnostic information likely related to the regional scale structure of the atmosphere. Comparison of Perseverance pressure observations with data from other landers reveals the global scale seasonal behavior of Mars' atmosphere.

Plasma-based conversion of martian atmosphere into life-sustaining chemicals: The benefits of utilizing martian ambient pressure

We explored the potential of plasma-based In-Situ Resource Utilization (ISRU) for Mars through the conversion of Martian atmosphere (∼96% CO2, 2% N2, and 2% Ar) into life-sustaining chemicals. As the Martian surface pressure is about 1% of the Earth’s surface pressure, it is an ideal environment for plasma-based gas conversion using microwave reactors. At 1000 W and 10 Ln/min (normal liters per minute), we produced ∼76 g/h of O2 and ∼3 g/h of NOx using a 2.45 GHz waveguided reactor at 25 mbar, which is ∼3.5 times Mars ambient pressure. The energy cost required to produce O2 was ∼0.013 kWh/g, which is very promising compared to recently concluded MOXIE experiments on the Mars surface. This marks a crucial step towards realizing the extension of human exploration.

Warming early Mars with climate cycling: The effect of [formula omitted]-[formula omitted] collision-induced absorption

Explaining the evidence for surface liquid water on early Mars has been a challenge for climate modelers, as the sun was ∼30% less luminous during the late-Noachian. We propose that the additional greenhouse forcing of CO2-H2 collision-induced absorption is capable of bringing the surface temperature above freezing and can put early Mars into a limit-cycling regime. Limit cycles occur when insolation is low and CO2 outgassing rates are unable to balance with the rapid drawdown of CO2 during warm weathering periods. Planets in this regime will alternate between global glaciation and transient warm climate phases. This mechanism is capable of explaining the geomorphological evidence for transient warm periods in the martian record. Previous work has shown that collision-induced absorption of CO2-H2 was capable of deglaciating early Mars, but only with high H2 outgassing rates (greater than ∼600 Tmol/yr) and at high surface pressures (between 3 to 4 bars). We used new theoretically derived collision-induced absorption coefficients for CO2-H2 to reevaluate the climate limit cycling hypothesis for early Mars. Using the new and stronger absorption coefficients in our 1-dimensional radiative convective model as well as our energy balance model, we find that limit cycling can occur with an H2 outgassing rate as low as ∼300 Tmol/yr at surface pressures below 3 bars. Our results agree more closely with paleoparameters for early martian surface pressure and hydrogen abundance.

Potential for Aerobic Methanotrophic Metabolism on Mars.

Observational evidence supports the presence of methane (CH4) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether aerobic methanotrophy is a potentially viable metabolism in the martian upper regolith, by calculating metabolic energy gain rates under assumed conditions of martian surface temperature, pressure, and atmospheric composition. Using kinetic parameters for 19 terrestrial aerobic methanotrophic strains, we show that even under the imposed low temperature and pressure extremes (180–280 K and 6–11 hPa), methane oxidation by oxygen (O2) should in principle be able to generate the minimum energy production rate required to support endogenous metabolism (i.e., cellular maintenance). Our results further indicate that the corresponding metabolic activity would be extremely low, with cell doubling times in excess of 4000 Earth years at the present-day ppbv-level CH4 mixing ratios in the atmosphere of Mars. Thus, while aerobic methanotrophic microorganisms similar to those found on Earth could theoretically maintain their vital functions, they are unlikely to constitute prolific members of hypothetical martian soil communities.

Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (⋅OH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ⋅OH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ⋅OH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars.

The low pressure at the surface of Mars (average: 6mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25mbar. The study reported here tested the survivability of four methanogen species (Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6mbar - 143mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3days - 21days) at pressures down to 6mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.

Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate.

Pressure observations by the Curiosity rover: Initial results

REMS‐P, the pressure measurement subsystem of the Mars Science Laboratory (MSL) Rover Environmental Measurement Station (REMS), is performing accurate observations of the Martian atmospheric surface pressure. It has demonstrated high data quality and good temporal coverage, carrying out the first in situ pressure observations in the Martian equatorial regions. We describe the REMS‐P initial results by MSL mission sol 100 including the instrument performance and data quality and illustrate some initial interpretations of the observed features. The observations show both expected and new phenomena at various spatial and temporal scales, e.g., the gradually increasing pressure due to the advancing Martian season signals from the diurnal tides as well as various local atmospheric phenomena and thermal vortices. Among the unexpected new phenomena discovered in the pressure data are a small regular pressure drop at every sol and pressure oscillations occurring in the early evening. We look forward to continued high‐quality observations by REMS‐P, extending the data set to reveal characteristics of seasonal variations and improved insights into regional and local phenomena.

Chemical evolution of organic molecules under Mars-like UV radiation conditions simulated in the laboratory with the “Mars organic molecule irradiation and evolution” (MOMIE) setup

Understanding the evolution of organic matter on Mars is a major goal to drive and discuss past, present and future in situ analyses. Here we demonstrate the ability of the MOMIE (for Mars organic molecules irradiation and evolution) laboratory device in giving both in situ qualitative and quantitative data on the evolution of organic molecules under simulated Martian surface ultraviolet light (190–400nm), mean temperature (218±2K) and pressure (6±1mbar). We describe the chemical evolution of glycine, an amino acid, which is very rapidly processed when exposed to direct ultraviolet radiations, with a molecular half-life of 231±110h on Mars consistent with existing results. Moreover we report the first tentative detection of peptide bond formation activated by UV radiation reaching the Mars surface. We show that organics as simple as glycine could experience multiple chemical pathways at Mars, both in the solid and gaseous phase. Finally, we derive the quantum efficiency for the photodestruction of glycine of 2.18±1.45×10−3 molecule photon−1 in the 200–250nm wavelength range. This value is significantly higher than previous estimates done by methane evolved measurements. Current and future studies performed with this simulation setup could produce kinetic and chemical insights into the evolution of organics on Mars.

Development of a fast, accurate radiative transfer model for the Martian atmosphere, past and present

We present details of an approach to creating ak‐distribution radiative transfer model (KDM) for use in the Martian atmosphere. Such models preserve the accuracy of more rigorous line‐by‐line models, but are orders of magnitude faster, and can be effectively implemented in 3‐D general circulation models. The approach taken here is sufficiently generalized that it can be employed for atmospheres of any arbitrary composition and mass, and demonstrations are provided for simulated atmospheres with a present‐day Martian surface pressure (∼6 mb) and a putative thick early Mars atmosphere (∼500 mb), both with and without atmospheric water vapor. KDM‐derived absorption coefficients are placed into a look‐up table at a set of gridded points in pressure, temperature and atmospheric composition, and a tri‐linear interpolation scheme is used to obtain the coefficients appropriate for the local atmospheric conditions. These coefficients may then be used within any of a variety of commonly used flux solvers to obtain atmospheric heating rates. A series of validation tests are performed with the KDM for both present‐day and early Mars atmospheric conditions, and the model is compared against several other widely used radiative transfer schemes, including several used in contemporary general circulation models. These validation results identify weaknesses in some other approaches and demonstrate the efficacy of the KDM, providing a rigorous test of these types of models for use in the Martian atmosphere. A demonstration of results obtained by implementing the KDM in a Mars general circulation model is provided.

Empirical Estimates of Martian Surface Pressure in Support of the Landing of Mars Science Laboratory

The aim of this work is to develop an empirical expression for diurnal mean martian surface pressure in support of the landing of Mars Science Laboratory. We eval- uate the consistency of surface pressure measurements from four landers, Viking Lander 1, Viking Lander 2, Mars Pathfinder, and Phoenix, and one radio occultation experiment, Mars Global Surveyor. With the exception of Mars Pathfinder, whose measurements are 0.1 mbar smaller than expected, all are consistent. We assume that the diurnal mean surface pres- sure is a separable function of altitude and season, neglecting dependences on time of day, latitude, and longitude, and use the Viking Lander 1 dataset to characterize the sea- sonal dependence as a harmonic function of season with annual and semi-annual periods. We characterize the exponential dependence of surface pressure on altitude using Mars Global Surveyor radio occultation measurements widely-distributed below +1 km altitude and within 45 degrees of the equator. These measurements have local times of 3-5 hours, which may introduce biases into our estimates for diurnal mean surface pressure. Our em- pirical expression for diurnal mean surface pressure, pdm ,i sp0,V L1 exp(−(z − z0,V L1)/H0)

Remote sensing of surface pressure on Mars with the Mars Express/OMEGA spectrometer: 2. Meteorological maps

Surface pressure measurements help to achieve a better understanding of the main dynamical phenomena occurring in the atmosphere of a planet. The use of the Mars Express OMEGA visible and near‐IR imaging spectrometer allows us to tentatively perform an unprecedented remote sensing measurement of Martian surface pressure. OMEGA reflectances in the CO2 absorption band at 2 μm are used to retrieve a hydrostatic estimation of surface pressure (see companion paper by Forget et al. (2007)) with a precision sufficient to draw maps of this field and thus analyze meteorological events in the Martian atmosphere. Prior to any meteorological analysis, OMEGA observations have to pass quality controls on insolation and albedo conditions, atmosphere dust opacity, and occurrence of water ice clouds and frosts. For the selected observations, registration shifts with the MOLA reference are corrected. “Sea‐level” surface pressure reduction is then carried out in order to remove the topographical component of the surface pressure field. Three main phenomena are observed in the resulting OMEGA surface pressure maps: horizontal pressure gradients, atmospheric oscillations, and pressure perturbations in the vicinity of topographical obstacles. The observed pressure oscillations are identified as possible signatures of phenomena such as inertia‐gravity waves or convective rolls. The pressure perturbations detected around the Martian hills and craters may be the signatures of complex interactions between an incoming flow and topographical obstacles. Highly idealized mesoscale simulations using the WRF model enable a preliminary study of these complex interactions, but more realistic mesoscale simulations are necessary. The maps provide valuable insights for future synoptic and mesoscale modeling, which will in turn help in the interpretation of observations.

Principal modes of variability of Martian atmospheric surface pressure

An analysis of daily‐to‐interannual variability in the surface pressure field of the Martian nothern hemisphere as given by a Martian climate model is presented. In an empirical orthogonal function (EOF) decomposition, the dominant first two modes of variability comprise a zonal wavenumber 1 feature centered at 70 N latitude moving eastward with a period of 6 to 8 sols. This feature is a baroclinic wave and accounts for 53% of the northern hemisphere non‐stationary surface pressure variability, and, when active, has an amplitude of up to 2% of local surface pressure. The third mode of the EOF decomposition is annular about the Martian north pole, is null southward of 70 N, and accounts for 7% of the northern hemisphere non‐stationary surface pressure variability. The baroclinic wave (EOFs 1 & 2) is active during northern hemisphere winter and spring, consistent with models of the Martian atmospheric circulation, and the annular mode (EOF 3) is active only at the onset and demise of the baroclinic feature. When active, it is not uncommon for the annular mode to reside in either its positive or negative state stably for 20 to 30 sols. It is postulated that baroclinic waves with longitudinal wavenumber 2, 3, and 4 act as a pump for the annular mode. The annular mode should not be present in MGS TES data.

The sensitivity of the Martian surface pressure and atmospheric mass budget to various parameters: A comparison between numerical simulations and Viking observations

The sensitivity of the Martian atmospheric circulation to a number of poorly known or strongly varying parameters (surface roughness length, atmospheric optical depth, CO2 ice albedo, and thermal emissivity) is investigated through experiments performed with the Martian version of the atmospheric general circulation model of Laboratoire de Météorologie Dynamique, with a rather coarse horizontal resolution (a grid with 32 points in longitude and 24 points in latitude). The results are evaluated primarily on the basis of comparisons with the surface pressure records of the Viking mission. To that end, the records are decomposed into long‐period seasonal variations due to mass exchange with the polar caps and latitudinal redistribution of mass, and short‐period variations due to transient longitudinally propagating waves. The sensitivity experiments include a 5‐year control simulation and shorter simulations (a little longer than 1 year) performed with “perturbed” parameter values. The main conclusions are that (1) a change of horizontal resolution (twice as many points in each direction) mostly affects the transient waves, (2) surface roughness lengths have a significant impact on the near‐surface wind and, as a matter of consequence, on the latitudinal redistribution of mass, (3) atmospheric dust optical depth has a significant impact on radiative balance and dynamics, and (4) CO2 ice albedo and thermal emissivity strongly influence mass exchange between the atmosphere and the polar caps. In view of this last conclusion, an automatic procedure is implemented through which the albedo and emissivity of each of the two polar caps are determined, together with the total (i.e., including the caps) atmospheric CO2 content, in such a way as to get the closest fit of the model to the Viking pressure measurements.

Threshold windspeeds for sand on Mars: Wind tunnel simulations

Wind friction threshold speeds (u*t) for particle movement (saltation) were determined in a wind tunnel operating at martian surface pressure with a 95 percent CO2 and 5 percent air atmosphere. The relationship between friction speed (u*) and free‐stream velocity (u∞) is extended to the critical case for Mars of momentum thickness Reynolds numbers (Reθ) between 425 and 2000. It is determined that the dynamic pressure required to initiate saltation is nearly constant for pressures between 1 bar (Earth) and 4 mb (Mars) for atmospheres of both air and CO2; however, the threshold friction speed (u*t) is about 10 times higher at low pressures than on Earth. For example, the u*t (Earth) for particles 210 µm in diameter is 0.22 m s−1 and the u*t (Mars, 5 mb, 200 K) is 2.2 m s−1.

Mie scattering and the Martian atmosphere

It has been suggested that the discrepancy between radio occultation determinations of the Martian atmospheric surface pressure (3.8 to 7 mb) and those deduced from optical polarization measurements and a simple Rayleigh atmosphere model (about 10 mb) are the results of sub-micron sized aerosols in the Martian atmosphere. Based on observed viewing angle dependence of the polarization of the Martian disk in the visual range, a Mie scattering analysis has been made utilizing the measured complex index of refraction of limonite and bulk solid CO2. The results of this study indicate that limonite aerosols alone are unsatisfactory to explain the viewing angle observations, whereas solid CO2 (and H2O ice) aerosol spheres, having a dominant particle radius range between 0.28 and 0.35 μ, could bring planetary and laboratory observations into compatibility. It is suggested, further, that solid CO2 aerosols could explain limb brightening in the blue spectral range. Various distributions of solid CO2 and H2O Mie particles with radii up to 0.35 μ show an opposition effect. However, the role of these aerosols in explaining the Mars opposition observations is very dependent on the optical properties of the underlying Mars surface material.

Observations of the martian 1.2 μ CO2 bands

A method to determine independently the Martian surface pressure from measurements of individual lines in the 1.2030 and 1.2177 μ CO2 bands is presented. Observations obtained during the 1967 apparition and some preliminary results of the 1969 apparition observations yield CO2 abundances near 100 m-atm and surface pressures of 4–8 mb.

Elevation differences on Mars

Observations of apparent frost phenomena, occurring preferentially in the Martian bright areas, have in the past led to the conclusion that the bright areas are elevations. The argument hinges on the implicit assumption that, near midday, highlands should be at lower temperatures than lowlands. On the earth, this assumption is valid, because of adiabatic cooling of rising air, a diminished greenhouse effect, and a greater inclination of surfaces to the sun's rays for highlands than for lowlands. It is shown that these factors are unlikely to be important on Mars and that the polar cap recession data, in particular, suggests that the dark areas are highlands. From the radar Doppler spectra, it is found that the Martian dark areas tend to have higher elevations than the adjacent bright areas. Slopes of a few degrees are deduced, and peak elevation differences between 4 and 17 km are inferred. These results may bear on the discrepancies between ground-based spectrometric values and Mariner 4 occultation values of Martian surface pressure and on the discrepancies between the optical and the dynamical oblateness of Mars. They suggest that pressures ∼20 mb are typical of the centers of bright areas, and 6 mb is a typical dark area pressure.