We describe preliminary results from the first 100 sols of ground temperature measurements along the Mars Science Laboratory's traverse from Bradbury Landing to Rocknest in Gale. The ground ...temperature data show long‐term increases in mean temperature that are consistent with seasonal evolution. Deviations from expected temperature trends within the diurnal cycle are observed and may be attributed to rover and environmental effects. Fits to measured diurnal temperature amplitudes using a thermal model suggest that the observed surfaces have thermal inertias in the range of 265–375 J m−2 K−1 s−1/2, which are within the range of values determined from orbital measurements and are consistent with the inertias predicted from the observed particle sizes on the uppermost surface near the rover. Ground temperatures at Gale Crater appear to warm earlier and cool later than predicted by the model, suggesting that there are multiple unaccounted for physical conditions or processes in our models. Where the Mars Science Laboratory (MSL) descent engines removed a mobile layer of dust and fine sediments from over rockier material, the diurnal temperature profile is closer to that expected for a homogeneous surface, suggesting that the mobile materials on the uppermost surface may be partially responsible for the mismatch between observed temperatures and those predicted for materials having a single thermal inertia. Models of local stratigraphy also implicate thermophysical heterogeneity at the uppermost surface as a potential contributor to the observed diurnal temperature cycle.
Key Points
Diurnal ground temperatures vary with location
Diurnal temperature curves are not well matched by a homogeneous thermal model
GTS data are consistent with a varied stratigraphy and thermophysical properties
In the first 100 Martian solar days (sols) of the Mars Science Laboratory mission, the Rover Environmental Monitoring Station (REMS) measured the seasonally evolving diurnal cycles of ultraviolet ...radiation, atmospheric pressure, air temperature, ground temperature, relative humidity, and wind within Gale Crater on Mars. As an introduction to several REMS‐based articles in this issue, we provide an overview of the design and performance of the REMS sensors and discuss our approach to mitigating some of the difficulties we encountered following landing, including the loss of one of the two wind sensors. We discuss the REMS data set in the context of other Mars Science Laboratory instruments and observations and describe how an enhanced observing strategy greatly increased the amount of REMS data returned in the first 100 sols, providing complete coverage of the diurnal cycle every 4 to 6 sols. Finally, we provide a brief overview of key science results from the first 100 sols. We found Gale to be very dry, never reaching saturation relative humidities, subject to larger diurnal surface pressure variations than seen by any previous lander on Mars, air temperatures consistent with model predictions and abundant short timescale variability, and surface temperatures responsive to changes in surface properties and suggestive of subsurface layering.
Key Points
Introduction to the REMS results on MSL missionOveriview of the sensor informationOverview of operational constraints
Scheduled to land in August of 2012, the Mars Science Laboratory (MSL) Mission was initiated to explore the habitability of Mars. This includes both modern environments as well as ancient ...environments recorded by the stratigraphic rock record preserved at the Gale crater landing site. The
Curiosity
rover has a designed lifetime of at least one Mars year (∼23 months), and drive capability of at least 20 km.
Curiosity
’s science payload was specifically assembled to assess habitability and includes a gas chromatograph-mass spectrometer and gas analyzer that will search for organic carbon in rocks, regolith fines, and the atmosphere (SAM instrument); an x-ray diffractometer that will determine mineralogical diversity (CheMin instrument); focusable cameras that can image landscapes and rock/regolith textures in natural color (MAHLI, MARDI, and Mastcam instruments); an alpha-particle x-ray spectrometer for
in situ
determination of rock and soil chemistry (APXS instrument); a laser-induced breakdown spectrometer to remotely sense the chemical composition of rocks and minerals (ChemCam instrument); an active neutron spectrometer designed to search for water in rocks/regolith (DAN instrument); a weather station to measure modern-day environmental variables (REMS instrument); and a sensor designed for continuous monitoring of background solar and cosmic radiation (RAD instrument). The various payload elements will work together to detect and study potential sampling targets with remote and
in situ
measurements; to acquire samples of rock, soil, and atmosphere and analyze them in onboard analytical instruments; and to observe the environment around the rover.
The 155-km diameter Gale crater was chosen as
Curiosity’s
field site based on several attributes: an interior mountain of ancient flat-lying strata extending almost 5 km above the elevation of the landing site; the lower few hundred meters of the mountain show a progression with relative age from clay-bearing to sulfate-bearing strata, separated by an unconformity from overlying likely anhydrous strata; the landing ellipse is characterized by a mixture of alluvial fan and high thermal inertia/high albedo stratified deposits; and a number of stratigraphically/geomorphically distinct fluvial features. Samples of the crater wall and rim rock, and more recent to currently active surface materials also may be studied. Gale has a well-defined regional context and strong evidence for a progression through multiple potentially habitable environments. These environments are represented by a stratigraphic record of extraordinary extent, and insure preservation of a rich record of the environmental history of early Mars. The interior mountain of Gale Crater has been informally designated at Mount Sharp, in honor of the pioneering planetary scientist Robert Sharp.
The major subsystems of the MSL Project consist of a single rover (with science payload), a Multi-Mission Radioisotope Thermoelectric Generator, an Earth-Mars cruise stage, an entry, descent, and landing system, a launch vehicle, and the mission operations and ground data systems. The primary communication path for downlink is relay through the Mars Reconnaissance Orbiter. The primary path for uplink to the rover is Direct-from-Earth. The secondary paths for downlink are Direct-to-Earth and relay through the Mars Odyssey orbiter.
Curiosity
is a scaled version of the 6-wheel drive, 4-wheel steering, rocker bogie system from the Mars Exploration Rovers (MER)
Spirit
and
Opportunity
and the Mars Pathfinder
Sojourner
. Like
Spirit
and
Opportunity
,
Curiosity
offers three primary modes of navigation: blind-drive, visual odometry, and visual odometry with hazard avoidance. Creation of terrain maps based on HiRISE (High Resolution Imaging Science Experiment) and other remote sensing data were used to conduct simulated driving with
Curiosity
in these various modes, and allowed selection of the Gale crater landing site which requires climbing the base of a mountain to achieve its primary science goals.
The Sample Acquisition, Processing, and Handling (SA/SPaH) subsystem is responsible for the acquisition of rock and soil samples from the Martian surface and the processing of these samples into fine particles that are then distributed to the analytical science instruments. The SA/SPaH subsystem is also responsible for the placement of the two contact instruments (APXS, MAHLI) on rock and soil targets. SA/SPaH consists of a robotic arm and turret-mounted devices on the end of the arm, which include a drill, brush, soil scoop, sample processing device, and the mechanical and electrical interfaces to the two contact science instruments. SA/SPaH also includes drill bit boxes, the organic check material, and an observation tray, which are all mounted on the front of the rover, and inlet cover mechanisms that are placed over the SAM and CheMin solid sample inlet tubes on the rover top deck.
•This paper presents the first wind measurements in an active dune field on Mars.•Daytime upslope/nighttime downslope flows dominate in winter on the slopes of Aeolis Mons.•The mid-morning and ...evening wind rotates rapidly and generally clockwise between these directions.•Wind blocking and wind speed distribution broadening occurs in the lee of a dune.•Mesoscale modeling captures the general pattern of wind speed and direction.
A high density of REMS wind measurements were collected in three science investigations during MSL's Bagnold Dunes Campaign, which took place over ∼80 sols around southern winter solstice (Ls∼90°) and constituted the first in situ analysis of the environmental conditions, morphology, structure, and composition of an active dune field on Mars. The Wind Characterization Investigation was designed to fully characterize the near-surface wind field just outside the dunes and confirmed the primarily upslope/downslope flow expected from theory and modeling of the circulation on the slopes of Aeolis Mons in this season. The basic pattern of winds is ‘upslope’ (from the northwest, heading up Aeolis Mons) during the daytime (∼09:00–17:00 or 18:00) and ‘downslope’ (from the southeast, heading down Aeolis Mons) at night (∼20:00 to some time before 08:00). Between these times the wind rotates largely clockwise, giving generally westerly winds mid-morning and easterly winds in the early evening. The timings of these direction changes are relatively consistent from sol to sol; however, the wind direction and speed at any given time shows considerable intersol variability. This pattern and timing is similar to predictions from the MarsWRF numerical model, run at a resolution of ∼490m in this region, although the model predicts the upslope winds to have a stronger component from the E than the W, misses a wind speed peak at ∼09:00, and under-predicts the strength of daytime wind speeds by ∼2–4m/s. The Namib Dune Lee Investigation reveals ‘blocking’ of northerly winds by the dune, leaving primarily a westerly component to the daytime winds, and also shows a broadening of the 1Hz wind speed distribution likely associated with lee turbulence. The Namib Dune Side Investigation measured primarily daytime winds at the side of the same dune, in support of aeolian change detection experiments designed to put limits on the saltation threshold, and also appears to show the influence of the dune body on the local flow, though less clearly than in the lee. Using a vertical grid with lower resolution near the surface reduces the relative strength of nighttime winds predicted by MarsWRF and produces a peak in wind speed at ∼09:00, improving the match to the observed diurnal variation of wind speed, albeit with an offset in magnitude. The annual wind field predicted using this grid also provides a far better match to observations of aeolian dune morphology and motion in the Bagnold Dunes. However, the lower overall wind speeds than observed and disagreement with the observed wind direction at ∼09:00 suggest that the problem has not been solved and that alternative boundary layer mixing schemes should be explored which may result in more mixing of momentum down to the near-surface from higher layers. These results demonstrate a strong need for in situ wind data to constrain the setup and assumptions used in numerical models, so that they may be used with more confidence to predict the circulation at other times and locations on Mars.
Display omitted
Dose rate measurements from Mars Science Laboratory‐radiation assessment detector (MSL‐RAD) for 300 sols on Mars are compared to simulation results using the Badhwar‐O'Neill 2011 galactic cosmic ray ...(GCR) environment model and the high‐charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation is used. Daily atmospheric pressure is measured at Gale Crater by the MSL Rover Environmental Monitoring Station. Particles impinging on top of the Martian atmosphere reach RAD after traversing varying depths of atmosphere that depend on the slant angles, and the model accounts for shielding of the RAD “E” detector (used for dosimetry) by the rest of the instrument. Simulation of average dose rate is in good agreement with RAD measurements for the first 200 sols and reproduces the observed variation of surface dose rate with changing heliospheric conditions and atmospheric pressure. Model results agree less well between sols 200 and 300 due to subtleties in the changing heliospheric conditions. It also suggests that the average contributions of albedo particles (charge number Z < 3) from Martian regolith comprise about 10% and 42% of the average daily point dose and dose equivalent, respectively. Neutron contributions to tissue‐averaged effective doses will be reduced compared to point dose equivalent estimates because a large portion of the neutron point dose is due to low‐energy neutrons with energies <1 MeV, which do not penetrate efficiently to deep‐seated tissues. However the exposures from neutrons to humans on Mars should become an important consideration in radiobiology research and risk assessment.
Key Points
Model simulation agrees with RAD measurements on Mars surface
Dose rate varies with heliospheric condition and atmospheric pressure
Neutron flux on Mars to be considered for radiobiology and risk assessments
Summary
The surge of SARS‐CoV‐2 has challenged health systems worldwide and efficient tests to detect viral particles, as well as antibodies generated against them, are needed. Specificity, ...sensitivity, promptness or scalability are the main parameters to estimate the final performance, but rarely all of them match in a single test. We have developed SCOVAM, a protein microarray with several viral antigens (spike, nucleocapsid, main protease Nsp5) as capturing probes in a fluorescence immunoassay for COVID‐19 serological testing. SCOVAM depicts IgG and IgM antibody responses against each of these proteins of 22 individuals in a single microscope slide. It detects specific IgM (0.094 μg ml‐1) and IgG (~0.017 μg ml‐1) and is scalable and cost‐effective. We validated SCOVAM by comparing with a widely used chemiluminescent commercial serological test (n = 742). SCOVAM showed twice the sensitivity and allowed following seroconversion in a single assay. By analysing the prevalence 4 months later in a subset of 76 positive sera, we still detected 93.42% of positives, almost doubling the detection of the commercial assay. The higher sensitivity of SCOVAM is especially relevant to screen sera for convalescent plasma‐based treatments, high‐throughput antibody response monitoring after vaccination or evaluation of vaccine efficiency.
We have developed a test to discriminate antibodies against SARS‐CoV‐2 in the blood serum. It detects IgM and IgG antibodies against the Spike, Nucleocapsid and Main protease of the virus, simultaneously. We printed these viral proteins on slides forming microarrays and incubated them with human sera for fluorescent detection. We established the limit of detection and an algorithm for automated diagnostics. Our test resulted twice as sensitive as a commercial test, being able to better follow antibody response through time, what will be very useful to track the epidemiology of COVID‐19 and the effectivity of the developed vaccines.
Environmental biomonitoring approaches require the measurement of either unequivocal biomarkers or specific biological profiles. Antibody microarrays constitute new tools for fast and reliable ...analysis of up to hundreds of biomarkers simultaneously. Herein we report 150 new polyclonal antibodies against microbial strains and environmental extracts, as well as the construction and validation of an antibody microarray (EMCHIP200, for “Environmental Monitoring Chip”) containing 200 different antibodies. Each antibody was tested against its antigen for its specificity and cross-reactivity by a sandwich microarray immunoassay. The limit of detection was 0.2 ng mL−1 for some proteins and 104−105 cells mL−1 for bacterial cells and spores. Partial biochemical characterization allowed identification of polymeric compounds (proteins and polysaccharides) as some of the targets recognized by the antibodies. We have successfully used the EMCHIP200 for the detection of biological polymers in samples from extreme environments around the world (e.g., a deep South African mine, Antarctica’s dry valleys, Yellowstone National Park, Iceland, and Rio Tinto surface and subsurface). Clustering analysis permitted us to associate similar immunoprofiles or patterns to samples from apparently very different environments, indicating that they indeed share similar universal biomarkers. Our EMCHIP200 constitutes a new generation of immunosensors for biomarker detection and profiling, for either environmental, industrial, biotechnological, or astrobiological applications.
The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its ...salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg(-1)) and perchlorate (41.13 μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g(-1)) or formate (76.06 μg g(-1)) as electron donors, and sulfate (15875 μg g(-1)), nitrate (13490 μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.
Future efforts towards Mars exploration should include a discussion about the effects that the strict application of Planetary Protection policies is having on the astrobiological exploration of ...Mars, which is resulting in a continued delay in the search for Martian life. As proactive steps in the path forward, here we propose advances in three areas. First, we suggest that a redefinition of Planetary Protection and Special Regions is required for the case of Mars. Particularly, we propose a definition for special places on Mars that we can get to in the next 10–20 years with rovers and landers, where try to address questions regarding whether there is present-day near-surface life on Mars or not, and crucially doing so before the arrival of manned missions. We propose to call those special places “Astrobiology Priority Exploration” regions (APEX regions). Second, we stress the need for the development of robotic tools for the characterization of complex organic compounds as unequivocal signs of life, and particularly new generations of complex organic chemistry and biosignature detection instruments, including advances in DNA sequencing. And third, we advocate for a change from the present generation of SUV-sized landers and rovers to new robotic assets that are much easier to decontaminate such as microlanders: they would be very small with limited sensing capabilities, but there would be many of them available for launch and coordination from an orbiting platform. Implementing these changes will help to move forward with an exploration approach that is much less risky to the potential Mars biosphere, while also being much more scientifically rigorous about the exploration of the “life on Mars” question – a question that needs to be answered both for astrobiological discovery and for learning more definitive lessons on Planetary Protection.
•The meteorology is controlled by interacting circulations and dynamical instabilities from the planetary scale down to the microscale.•The northern winter season is unique; the air mass in the ...crater mixes with external crater air due to the breaking of large amplitude mountain waves.•At other seasons, the mixing between the air in the floor of Gale Crater and air external to the crater may be more limited.•It is difficult to reconcile the putative methane detection with the Gale Crater circulation.
Numerical modeling results from the Mars Regional Atmospheric Modeling System are used to interpret the landed meteorological data from the Rover Environmental Monitoring Station onboard the Mars Science Laboratory rover Curiosity. In order to characterize seasonal changes throughout the Martian year, simulations are conducted at Ls 0, 90, 180 and 270. Two additional simulations at Ls 225 and 315 are explored to better understand the unique meteorological setting centered on Ls 270. The synergistic combination of model and observations reveals a complex meteorological environment within the crater. Seasonal planetary circulations, the thermal tide, slope flows along the topographic dichotomy, mesoscale waves, slope flows along the crater slopes and Mt. Sharp, and turbulent motions all interact in nonlinear ways to produce the observed weather. Ls 270 is shown to be an anomalous season when air within and outside the crater is well mixed by strong, flushing northerly flow and large amplitude, breaking mountain waves. At other seasons, the air in the crater is more isolated from the surrounding environment. The potential impact of the partially isolated crater air mass on the dust, water, noncondensable and methane cycles is also considered. In contrast to previous studies, the large amplitude diurnal pressure signal is attributed primarily to necessary hydrostatic adjustments associated with topography of different elevations, with contributions of less than 25% to the diurnal amplitude from the crater circulation itself. The crater circulation is shown to induce a suppressed boundary layer.
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