Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars.

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater's sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

An olivine cumulate outcrop on the floor of Jezero crater, Mars.

The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigated the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We found that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multistage cooling of a thick magma body.

Characteristics, Origins, and Biosignature Preservation Potential of Carbonate-Bearing Rocks Within and Outside of Jezero Crater.

Carbonate minerals have been detected in Jezero crater, an ancient lake basin that is the landing site of the Mars 2020 Perseverance rover, and within the regional olivine-bearing (ROB) unit in the Nili Fossae region surrounding this crater. It has been suggested that some carbonates in the margin fractured unit, a rock unit within Jezero crater, formed in a fluviolacustrine environment, which would be conducive to preservation of biosignatures from paleolake-inhabiting lifeforms. Here, we show that carbonate-bearing rocks within and outside of Jezero crater have the same range of visible-to-near-infrared carbonate absorption strengths, carbonate absorption band positions, thermal inertias, and morphologies. Thicknesses of exposed carbonate-bearing rock cross-sections in Jezero crater are ∼75-90 m thicker than typical ROB unit cross-sections in the Nili Fossae region, but have similar thicknesses to ROB unit exposures in Libya Montes. These similarities in carbonate properties within and outside of Jezero crater is consistent with a shared origin for all of the carbonates in the Nili Fossae region. Carbonate absorption minima positions indicate that both Mg- and more Fe-rich carbonates are present in the Nili Fossae region, consistent with the expected products of olivine carbonation. These estimated carbonate chemistries are similar to those in martian meteorites and the Comanche carbonates investigated by the Spirit rover in Columbia Hills. Our results indicate that hydrothermal alteration is the most likely formation mechanism for non-deltaic carbonates within and outside of Jezero crater.

Perseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, Mars.

Observations from orbital spacecraft have shown that Jezero crater on Mars contains a prominent fan-shaped body of sedimentary rock deposited at its western margin. The Perseverance rover landed in Jezero crater in February 2021. We analyze images taken by the rover in the 3 months after landing. The fan has outcrop faces, which were invisible from orbit, that record the hydrological evolution of Jezero crater. We interpret the presence of inclined strata in these outcrops as evidence of deltas that advanced into a lake. In contrast, the uppermost fan strata are composed of boulder conglomerates, which imply deposition by episodic high-energy floods. This sedimentary succession indicates a transition from sustained hydrologic activity in a persistent lake environment to highly energetic short-duration fluvial flows.

Pre-Flight Calibration of the Mars 2020 Rover Mastcam Zoom (Mastcam-Z) Multispectral, Stereoscopic Imager.

The NASA Perseverance rover Mast Camera Zoom (Mastcam-Z) system is a pair of zoomable, focusable, multi-spectral, and color charge-coupled device (CCD) cameras mounted on top of a 1.7 m Remote Sensing Mast, along with associated electronics and two calibration targets. The cameras contain identical optical assemblies that can range in focal length from 26 mm ( 25.5 ∘ × 19.1 ∘ FOV ) to 110 mm ( 6.2 ∘ × 4.2 ∘ FOV ) and will acquire data at pixel scales of 148-540 µm at a range of 2 m and 7.4-27 cm at 1 km. The cameras are mounted on the rover's mast with a stereo baseline of 24.3 ± 0.1  cm and a toe-in angle of 1.17 ± 0.03 ∘ (per camera). Each camera uses a Kodak KAI-2020 CCD with 1600 × 1200 active pixels and an 8 position filter wheel that contains an IR-cutoff filter for color imaging through the detectors' Bayer-pattern filters, a neutral density (ND) solar filter for imaging the sun, and 6 narrow-band geology filters (16 total filters). An associated Digital Electronics Assembly provides command data interfaces to the rover, 11-to-8 bit companding, and JPEG compression capabilities. Herein, we describe pre-flight calibration of the Mastcam-Z instrument and characterize its radiometric and geometric behavior. Between April 26 t h and May 9 t h , 2019, ∼45,000 images were acquired during stand-alone calibration at Malin Space Science Systems (MSSS) in San Diego, CA. Additional data were acquired during Assembly Test and Launch Operations (ATLO) at the Jet Propulsion Laboratory and Kennedy Space Center. Results of the radiometric calibration validate a 5% absolute radiometric accuracy when using camera state parameters investigated during testing. When observing using camera state parameters not interrogated during calibration (e.g., non-canonical zoom positions), we conservatively estimate the absolute uncertainty to be < 10 % . Image quality, measured via the amplitude of the Modulation Transfer Function (MTF) at Nyquist sampling (0.35 line pairs per pixel), shows MTF Nyquist = 0.26 - 0.50 across all zoom, focus, and filter positions, exceeding the > 0.2 design requirement. We discuss lessons learned from calibration and suggest tactical strategies that will optimize the quality of science data acquired during operation at Mars. While most results matched expectations, some surprises were discovered, such as a strong wavelength and temperature dependence on the radiometric coefficients and a scene-dependent dynamic component to the zero-exposure bias frames. Calibration results and derived accuracies were validated using a Geoboard target consisting of well-characterized geologic samples. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11214-021-00795-x.

The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation.

Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 µrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 µrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.

Spectral, Compositional, and Physical Properties of the Upper Murray Formation and Vera Rubin Ridge, Gale Crater, Mars.

During 2018 and 2019, the Mars Science Laboratory Curiosity rover investigated the chemistry, morphology, and stratigraphy of Vera Rubin ridge (VRR). Using orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars, scientists attributed the strong 860 nm signal associated with VRR to the presence of red crystalline hematite. However, Mastcam multispectral data and CheMin X-ray diffraction (XRD) measurements show that the depth of the 860 nm absorption is negatively correlated with the abundance of red crystalline hematite, suggesting that other mineralogical or physical parameters are also controlling the 860 nm absorption. Here, we examine Mastcam and ChemCam passive reflectance spectra from VRR and other locations to link the depth, position, and presence or absence of iron-related mineralogic absorption features to the XRD-derived rock mineralogy. Correlating CheMin mineralogy to spectral parameters showed that the ~860 nm absorption has a strong positive correlation with the abundance of ferric phyllosilicates. New laboratory reflectance measurements of powdered mineral mixtures can reproduce trends found in Gale crater. We hypothesize that variations in the 860 nm absorption feature in Mastcam and ChemCam observations of VRR materials are a result of three factors: (1) variations in ferric phyllosilicate abundance due to its ~800-1,000 nm absorption; (2) variations in clinopyroxene abundance because of its band maximum at ~860 nm; and (3) the presence of red crystalline hematite because of its absorption centered at 860 nm. We also show that relatively small changes in Ca-sulfate abundance is one potential cause of the erosional resistance and geomorphic expression of VRR.

Synergistic Ground and Orbital Observations of Iron Oxides on Mt. Sharp and Vera Rubin Ridge.

Visible/short-wave infrared spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) show absorptions attributed to hematite at Vera Rubin ridge (VRR), a topographic feature on northwest Mt. Sharp. The goals of this study are to determine why absorptions caused by ferric iron are strongly visible from orbit at VRR and to improve interpretation of CRISM data throughout lower Mt. Sharp. These goals are achieved by analyzing coordinated CRISM and in situ spectral data along the Curiosity Mars rover's traverse. VRR bedrock within areas that have the deepest ferric absorptions in CRISM data also has the deepest ferric absorptions measured in situ. This suggests strong ferric absorptions are visible from orbit at VRR because of the unique spectral properties of VRR bedrock. Dust and mixing with basaltic sand additionally inhibit the ability to measure ferric absorptions in bedrock stratigraphically below VRR from orbit. There are two implications of these findings: (1) Ferric absorptions in CRISM data initially dismissed as noise could be real, and ferric phases are more widespread in lower Mt. Sharp than previously reported. (2) Patches with the deepest ferric absorptions in CRISM data are, like VRR, reflective of deeper absorptions in the bedrock. One model to explain this spectral variability is late-stage diagenetic fluids that changed the grain size of ferric phases, deepening absorptions. Curiosity's experience highlights the strengths of using CRISM data for spectral absorptions and associated mineral detections and the caveats in using these data for geologic interpretations and strategic path planning tools.

Evidence for a Diagenetic Origin of Vera Rubin Ridge, Gale Crater, Mars: Summary and Synthesis of Curiosity's Exploration Campaign.

This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray-colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe-rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric-related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.

First Report of Brown Ring Patch Caused by Waitea circinata var. circinata on Poa annua in Wisconsin and Minnesota.

In summer of 2008, two turfgrass samples were submitted to the Turfgrass Diagnostic Lab at the University of Wisconsin-Madison. The samples were from golf courses in Beaver Dam, WI on 12 June and Minneapolis, MN on 14 July. Both samples were collected from 40-year-old native soil putting greens mowed at 3.2 mm that had received annual sand topdressing since 1992. The putting greens were a mixture of approximately 75% annual bluegrass (Poa annua L.) and 25% creeping bentgrass (Agrostis stolonifera L.) Stand symptoms observed in the field were bright yellow, sunken rings that were approximately 5 cm thick and 15 to 35 cm in diameter. Some rings were incomplete, giving a scalloped appearance. Affected plants were severely chlorotic and lacked any discrete lesions or spots. Symptoms were more prominent on annual bluegrass than creeping bentgrass. Upon incubation of samples at room temperature in a moist chamber for 24 h, fungal mycelia with septations and right-angle branching were observed in the foliage and thatch layer. Two isolates were obtained from affected annual bluegrass in each sample. Isolations were performed by washing affected leaves in 0.5% NaOCl solution for 2 min, blotting the tissue dry, and plating the tissue on potato dextrose agar (PDA) amended with chloramphenicol (0.05 g/liter), streptomycin (0.05 g/liter), and tetracycline (0.05 g/liter). After incubation for 2 days at 23°C, isolates were transferred and maintained on PDA. All four isolates had multinucleate hyphae and displayed sclerotial characteristics similar to those reported for Waitea circinata var. circinata (2). Sequencing the ITS1F/ITS4-amplified rDNA internal transcribed spacer (ITS) region confirmed the isolates as W. circinata var. circinata, with ≥99% sequence similarity to published W. circinata var. circinata ITS sequences (GenBank Accession No. FJ755849) (1,2,4). To confirm pathogenicity, isolates were inoculated onto 6-week-old annual bluegrass (True Putt/DW184) grown in 10-cm-diameter pots containing calcined clay (Turface; Profile Products LLC., Buffalo Grove, IL). Two 4-mm-diameter agar plugs for each isolate were removed from the margins of 3-day-old colonies grown on PDA and placed near the soil surface to ensure contact with the lower leaf blades. Each isolate was placed in four separate pots to have four replicated tests per isolate, and four noninfested pots were utilized as negative controls. All pots were placed in moist chambers at 28°C with a 12-h light/dark cycle. Within 4 to 6 days, inoculated plants exhibited severe chlorosis and a minor amount of aerial mycelium was observed. Inoculated plants became necrotic after 15 to 20 days, while the noninoculated plants remained healthy. W. circinata var. circinata was reisolated from inoculated plants and its identity was confirmed by morphological and molecular characteristics. This pathogen was previously reported as a causal agent of brown ring patch of creeping bentgrass in Japan and annual bluegrass in the western United States (2,4). To our knowledge, this is the first report of brown ring patch in Minnesota and Wisconsin. Intensive fungicide practices are needed to control brown ring patch; therefore, this disease could have significant economic impact throughout the Upper Midwest (3). References: (1) C. M. Chen et al. Plant Dis. 93:906, 2009 (2) K. de la Cerda et al. Plant Dis. 91:791, 2007. (3) J. Kaminski and F. Wong. Golf Course Manage. 75(9):98, 2007. (4) T. Toda et al. Plant Dis. 89:536, 2005.

The safety and immunogenicity of a human immunodeficiency virus type 1 (HIV-1) recombinant gp160 candidate vaccine in humans. NIAID AIDS Vaccine Clinical Trials Network.

OBJECTIVE: To evaluate the safety and immunogenicity of a human immunodeficiency virus type 1 (HIV-1) recombinant envelope glycoprotein (rgp 160) candidate vaccine in humans. SUBJECTS: Healthy adults (72) who were seronegative for HIV-1 were randomly assigned to one of four groups. INTERVENTIONS: The subjects were randomly assigned to receive 40 or 80 micrograms of rgp 160, 10 micrograms of hepatitis B vaccine, or placebo in three doses (on days 0, 30, and 180), with an elective, nonblinded administration of a fourth dose on day 540. MEASUREMENTS AND MAIN RESULTS: Neither clinical nor laboratory toxicity was encountered during a follow-up period exceeding 21 months. No effect of immunization was noted on lymphocyte counts, mitogenic responses, or delayed-type hypersensitivity. Serum antibody responses to HIV envelope proteins detected by Western blot were seen in 30 of 33 subjects (91%; 95% CI, 71% to 97%) receiving either 40- or 80-micrograms doses of rgp160 and were most commonly of weakly reactive intensity. Responses were first noted by Western blot after the second dose. They markedly increased in frequency after the third dose and declined over the next 12 to 18 months. The administration of a fourth dose resulted in homologous neutralizing activity in sera from 5 to 24 subjects (21%; CI, 7% to 37%) as well as in complement-mediated antibody-dependent enhancement in sera from 6 of 24 subjects (25%; CI, 10% to 42%). Antibody responses were detected by enzyme-linked immunosorbent assay (ELISA) less frequently than by Western blot, and these responses persisted for a shorter time. CONCLUSIONS: The administration of rgp160 was well tolerated and safe, resulted in a high rate of antibody response by Western blot after the administration of the third and fourth doses, and generated serum neutralizing activity and complement-mediated antibody-dependent enhancement in some subjects after the fourth dose.

Psychosocial functioning in children and young adults with juvenile arthritis.

A questionnaire survey of 363 children and young adults with juvenile arthritis was conducted to assess the relations among disease severity, psychosocial functioning, and adjustment in three age groups--primary school, high school, and young adult. Parents were surveyed separately to determine which characteristics of the ill child at different ages most significantly impact the well-being of the family. Indices of psychologic functioning and disease severity were associated with adjustment in the primary school and high school groups, whereas measures of social relationships were strongly associated with adjustment only in the high school group. Relations among measures of psychologic functioning, social relationships, disease severity, and adjustment in young adults were minimal. Level of disease severity was associated with the presence of financial concerns, emotional problems, and physical strain in parents of high school children and young adults. The results emphasize the importance of using a developmental model for understanding the adjustment of individuals with chronic juvenile arthritis and their families.

Scanning electron microscopy of glomerular and non glomerular red blood cells.

Phase contrast microscopic examination of the urine has been recently shown to be of value in predicting whether hematuria is due to glomerulonephritis or lesions of the lower urinary tract. Glomerular red cells show variations in size and shape and have distorted surfaces. Non glomerular red cells are uniform in size and shape and have smooth surfaces. Scanning electron microscopy was performed on urine sediment containing either glomerular or non glomerular red cells to better define their surface characteristics. Glomerular red cells exhibited a variety of forms, most cells having lumpy projections from the surface, some showing fragmentation of the membrane and others showing gross distortion. In contrast non glomerular red cells show smooth surfaces and usually maintain the normal biconcave disc shape of peripheral red blood cells. Scanning electron microscopy can better define surface structural abnormalities of urinary glomerular and non glomerular red blood cells.

Beta 2-microglobulin excretion and urinary cytology in analgesic nephropathy.

Patients with analgesic nephropathy are at risk from uro-epithelial malignancy. Enhanced secretion of beta 2-microglobulin occurs from epithelial cancer cells. In order to find a screening test for malignancy in analgesic nephropathy, urinary levels of this protein were measured in patients with analgesic nephropathy with urine cytological abnormalities and were compared to a control group with glomerulonephritis. Mean fractional excretion of beta 2-microglobulin was higher (8.61 +/- 1.76 SEM) in patients with analgesic nephropathy than in those with glomerulonephritis (1.13 +/- 0.76) (P less than 0.025). Those patients with analgesic nephropathy who had malignant cells in the urine had higher mean fractional excretion (18.56 +/- 5.77) than those with only atypical cells (8.5 +/- 2.0) (P less than 0.05) who in turn had higher mean values than those with normal cytology (2.12 +/- 0.62) (P less than 0.0025). It is suggested that the increased beta 2-microglobulin excretion in analgesic nephropathy is due to secretion from abnormal urothelial cells as well as reduced tubular catabolism. Beta 2-microglobulin may be of use as a screening test for malignancy in analgesic nephropathy.

Detection of glomerular bleeding by phase-contrast microscopy.

Midstream urine specimens from 303 consecutive patients with haematuria were examined with phase-contrast microscopy to determine whether the source of the haematuria could be predicted on the basis of urinary red-cell morphology. In 253 patients a definite diagnosis was made but the data for the other 50 were inadequate to allow a definite diagnosis. With phase-contrast microscopy the origin of haematuria was considered to be glomerular in 120 patients (115 had proven glomerulonephritis and 5 had lesions of the lower urinary tract) and non-glomerular in 105 patients (100 had lesions of the lower urinary tract and 5 had proven glomerulonephritis). A mixed picture of glomerular and non-glomerular red cells was seen in 28 patients, most commonly in association with IgA nephropathy and renal calculi. The assessment of urinary red-cell morphology by means of phase-contrast microscopy can add importantly to clinical information and, together with the presence of red-cell casts and protein in the urine, can help the clinician decide on initial investigations in patients with haematuria.