Disk Of Mars Research Articles

A deep search for the release of volcanic gases on Mars using ground-based high-resolution infrared and submillimeter spectroscopy: Sensitive upper limits for OCS and SO2

Recent volcanic activity has long been considered a distinct possibility that would place major constraints on the evolution of Mars’ interior. Volcanic activity would result in the outgassing of sulfur-bearing species. As part of our multi-band search for active release of volcanic gases on Mars, we looked for carbonyl sulfide (OCS) at its combination band (ν1+ν3) at 3.42 µ m (2924 cm−1), and sulfur dioxide (SO2) at 346.652 GHz, in two successive Mars years during its late Northern spring and mid Northern summer seasons (Ls= 43°–144°). The targeted volcanic districts, Tharsis and Syrtis Major, were observed during the two intervals, 15 Dec. 2011 to 6 Jan. 2012 in the first year, and 23 May 2014 to 12 June 2014 in the second year using the high resolution infrared spectrometer CSHELL on the NASA Infrared Telescope Facility, and the high resolution heterodyne receiver HARP at the James Clerk Maxwell Telescope atop Maunakea, Hawaii. No active release of such gases was detected, and we report 2σ upper limits of 1.8 ppbv and 3.1 ppbv for OCS and SO2, respectively, compared to 0.3 ppbv for SO2 (Encrenaz, T. et al. [2011] Astron. & Astrophys. 530, A37; Krasnopolsky, V.A. [2012] Icarus 217, 144–152) over the disk of Mars. Our retrieved upper limit on the SO2 outgassing rate of 156 tons/day (1.8 kg/s), corresponds to a mass rate of magma that is able to degas the SO2 of 104 kilotons/day (1200 kg/s), or 40,000 m3/day (0.46 m3/s). Our campaign places stringent limits on the concentration of sulfur-bearing species into the atmosphere of Mars.

The 1.3mm Full-Stokes Polarization System at CARMA

The CARMA 1.3[Formula: see text]mm polarization system consists of dual-polarization receivers that are sensitive to right- (R) and left-circular (L) polarization, and a spectral-line correlator that measures all four cross polarizations ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) on each of the 105 baselines connecting the 15 telescopes. Each receiver comprises a single feed horn, a waveguide circular polarizer, an orthomode transducer (OMT), two heterodyne mixers, and two low-noise amplifiers (LNAs), all mounted in a cryogenically cooled dewar. Here we review the basics of polarization observations, describe the construction and performance of key receiver components (circular polarizer, OMT, and mixers — but not the correlator), and discuss in detail the calibration of the system, particularly the calibration of the R–L phase offsets and the polarization leakage corrections. The absolute accuracy of polarization position angle measurements was checked by mapping the radial polarization pattern across the disk of Mars. Transferring the Mars calibration to the well-known polarization calibrator 3C286, we find a polarization position angle of [Formula: see text] for 3C286 at 225[Formula: see text]GHz, consistent with other observations at millimeter wavelengths. Finally, we consider what limitations in accuracy are expected due to the signal-to-noise ratio, dynamic range, and primary beam polarization.

X-rays from solar system objects

During the last few years our knowledge about the X-ray emission from bodies within the solar system has significantly improved. Several new solar system objects are now known to shine in X-rays at energies below 2 keV. Apart from the Sun, the known X-ray emitters now include planets (Venus, Earth, Mars, Jupiter, and Saturn), planetary satellites (Moon, Io, Europa, and Ganymede), all active comets, the Io plasma torus (IPT), the rings of Saturn, the coronae (exospheres) of Earth and Mars, and the heliosphere. The advent of higher-resolution X-ray spectroscopy with the Chandra and XMM-Newton X-ray observatories has been of great benefit in advancing the field of planetary X-ray astronomy. Progress in modeling X-ray emission, laboratory studies of X-ray production, and theoretical calculations of cross-sections, have all contributed to our understanding of processes that produce X-rays from the solar system bodies. At Jupiter and Earth, both auroral and non-auroral disk X-ray emissions have been observed. X-rays have been detected from Saturn's disk, but no convincing evidence of an X-ray aurora has been observed. The first soft (0.1–2 keV) X-ray observation of Earth's aurora by Chandra shows that it is highly variable. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, those from the disk of Mars, Venus, and Moon, and from the rings of Saturn, are mainly produced by scattering of solar X-rays. The spectral characteristics of X-ray emission from comets, the heliosphere, the geocorona, and the Martian halo are quite similar, but they appear to be quite different from those of Jovian auroral X-rays. X-rays from the Galilean satellites and the IPT are mostly driven by impact of Jovian magnetospheric particles. This paper reviews studies of the soft X-ray emission from the solar system bodies, excluding the Sun. Processes of production of solar system X-rays are discussed and an overview is provided of the main source mechanisms of X-ray production at each object. A brief account on recent development in the area of laboratory studies of X-ray production is also provided.

Polar warming in the middle atmosphere of Mars

We report ground-based laser heterodyne spectroscopy of non-thermal emission in the cores of the 10.33- μm R(8) and 10.72- μm P(32) lines of 12C 16O 2, obtained at 23 locations on the disk of Mars during the 1984 opposition, at L s = 130°. The data were obtained at a sub-Doppler spectral resolution, and the temperature of the middle Martian atmosphere (50–85 km) is derived from the frequency width and intensity of the R(8) emission, and from the total intensity of the P(32) emission. We find that the temperature of the middle Martian atmosphere varies with latitude. Near the subsolar latitude, the average 50- to 85-km temperature is close to the radiative equilibrium value for a CO 2 atmosphere. However, at high latitudes in both the northern (summer) and southern (winter) hemispheres the 50- to 85-km temperature exceeds the CO 2 radiative equilibrium value; a meridional gradient in the range of 0.4 – 0.9°K per degree of latitude is indicated by our data. The highest temperatures are seen at high latitudes in the winter hemisphere, reminiscent of the seasonal effects seen at the Earth's mesopause. As in the terrestrial case, this winter polar warming in the Martian middle atmosphere necessitates departures from radiative equilibrium; dynamical heating of order 4 × 10 2 ergs g −1 sec −1 is required at the edge of the winter polar night. A comparison with 2-D circulation models shows that the presence of atmospheric dust may enhance this dynamical heating at high winter latitudes, and may also account for heating at high latitudes in the summer hemisphere.

Mariner 6 and 7 Ultraviolet Spectrometer Experiment: Analysis of hydrogen Lyman-alpha data

Four Lyman alpha airglow measurements of the limb and disk of Mars, made by ultraviolet spectrometers on Mariner 6 and 7 in 1969 and Mariner 9 in 1971, are analyzed to determine the amount and distribution of atomic hydrogen above 80 km. The variation of atomic hydrogen with altitude is calculated by using time-independent chemical diffusion models from 80 to 250 km, and an exospheric model is used above 250 km. By employing radiative transfer theory that includes effects of pure absorption and accounts for temperature variations in the atmosphere, a spherical model of the airglow Lyman alpha emission is used to produce theoretical intensities for comparison with the data. It is found that (1) the exospheric temperature and distribution in 1971 are consistent with those determined in 1969, (2) the vertical optical depth above 80 km was 2.2 in 1969 and 5 in 1971, and (3) the derived atomic hydrogen distribution from 80 to 250 km requires a source of atomic hydrogen above 80 km. Comparison of observed profiles with chemical diffusion models implies a large downward flow of atomic hydrogen at 80 km coupled with a large upward flow of molecular hydrogen.-

Mars: Narrow-Band Photometry, from 0.3 to 2.5 Microns, of Surface Regions during the 1969 Apparition

view Abstract Citations (88) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mars: Narrow-Band Photometry, from 0.3 to 2.5 Microns, of Surface Regions during the 1969 Apparition McCord, Thomas B. ; Westphal, James A. Abstract Narrow-band spectrophotometric observations were made of areas on Mars 200 km in diameter and of the whole disk of Mars during the 1969 apparition. The spectral region from 0.3 to 2.5 was covered with a resolution of 0.02-0.07 . The spectral reflectivities of six Martian areas relative to the bright region Arabia were obtained near opposition. Syrtis Major and Arabia were also observed before opposition. Geometric albedos have been calculated for five areas between 0.3 and 1.1 and for two additional areas and the whole disk of Mars between 0.3 and 2.5 , . Martian bright areas are very red in color, reaching a maximum geometric albedo of 0.42 in the near-infrared; dark areas are less red. Absorption features appear in the spectral reflectivity curves at 0.95 for biight regions and at 1.00 for dark regions. Absorption features which differ between Arabia and Syrtis Major appear in the relative reflection spectra near the position of the absorption bands of water and water ice. There seems to be a spectrum of Martian spectral reflectivity properties in which the bright area Arabia and the dark area Syrtis Major (of the areas observed) represent the end members. Between March and May 1969, Arabia became brighter and redder but the spectral reflectivity of Syrtis Major remained the same, in conflict with traditional seasonal "darkening wave" observations. A difference of the scattering properties with solar phase angle for bright and dark regions may exist. Limb darkening increases from near zero at about 0.42 to a maximum near 1 M, and remains about constant beyond I . The albedo of a small area at the center of the Martian disk reaches 1.6 times the average of the Martian disk at 1 . Publication: The Astrophysical Journal Pub Date: August 1971 DOI: 10.1086/151069 Bibcode: 1971ApJ...168..141M full text sources ADS |

Interpretation of high resolution spectra of Mars—III. Calculations of CO abundance and rotational temperature

High-resolution spectra for the whole disk of Mars (1) have been reanalyzed to obtain a mean rotational temperature of T rot = 205±7°K (standard deviation) using four distributions for the collision-broadened line half width. A line-by-line calculation using Voigt line profiles has been performed to fit the measured equivalent widths for a range of Martian surface pressures. This fit indicates a carbon monoxide abundance of 47 > w co > 40 cm atm is in the total path for 5 < p s < 6 mb if a constant line width is assumed. If a 25 per-cent error has been made in measuring the equivalent widths, we find for p s = 5 mb that w co = 47 +32 -24 cm atm. Depending upon the distribution of line widths assumed, for line widths which vary throughout the band, we find 57 > w co > 27 cm atm in the total path for 5 < p s < 6 mb.

Optical Properties of the Atmosphere and Surface of the Planet Mars

O ALL the planets of the solar system, Mars attracts the most attention. The study of the surface and atmosphere of Mars is important. Observations of Mars show vastly different details in all parts of the spectrum, excluding the violet part. Besides that, it is known that extinction in the terrestrial atmosphere in the visible spectral range is practically caused only by scattering, because true absorption, concentrated in the comparatively few and shallow telluric bands, plays an insignificant role in reducing the total light flux. In the visual range of Mars' spectrum, in general, no absorption bands caused by the atmosphere of this planet have been detected. Hence, it is considered that the role of absorption in the atmosphere of Mars is still smaller than in the terrestrial. Good visibility of details on Mars, assuming that it has a scattering atmosphere, makes it possible to consider that the optical thickness of its atmosphere in the visible part of the spectrum is small. Many published calculations of the optical thickness and density of the atmosphere of Mars were based on this assumption (1-4). At the same time, in certain articles devoted to interpreting photometric observations of Mars, the opinion is stated that the atmosphere of this planet differs from the terrestrial in that true absorption plays a noticeable part in it. And so, neglecting scattering, attempts were made to interpret the observational data and in particular the coloration of Mars (5). Such a difference of opinions concerning the optical properties of Mars' atmosphere, compels us, in determination of quantities characterizing optical properties of the planet's atmosphere, to abandon the assumption that Mars has either a scattering or an absorbing atmosphere. Both effects must be considered. Only a subsequent comparison of theoretical calculations with the observational data makes it possible to explain the correlation between scattering and absorption in the atmosphere of Mars. Sharonov (6) has studied the role of true absorption in the atmosphere of Mars. He showed that observations of the distribution of brightness across the disk of Mars can be explained on the assumption of a purely scattering atmosphere. However, he took into account scattering of light of the first order only. It is very important to analyze that same problem, while taking into account scattering of all orders. In this work, an attempt is made to interpret the observational data by taking into account multiple scattering.