The Experts below are selected from a list of 2781 Experts worldwide ranked by ideXlab platform

Roger J Phillips - One of the best experts on this subject based on the ideXlab platform.

  • 3d imaging of Mars polar ice caps using orbital radar data
    2017
    Co-Authors: F J Foss, N E Putzig, Bruce A Campbell, Roger J Phillips
    Abstract:

    Since its arrival in early 2006, various instruments aboard NASA's Mars Reconnaissance Orbiter (MRO) have been collecting a variety of scientific and engineering data from orbit around Mars. Among these is the Shallow Radar (SHARAD) instrument, supplied by Agenzia Spaziale Italiana (ASI) and designed for subsurface sounding in the 15–25 MHz frequency band. As of this writing, MRO has completed more than 46,000 nearly polar orbits of Mars, 30% of which have included active SHARAD data collection. By 2009, a sufficient density of SHARAD coverage had been obtained over the polar regions to support 3D processing and analysis of the data. Using tools and techniques commonly employed in terrestrial seismic data processing, we have processed subsets of the resulting collection of SHARAD observations covering the north and south polar regions as SHARAD 3D volumes, imaging the interiors of the north and south polar ice caps known, respectively, as Planum Boreum and Planum Australe. After overcoming a series of cha...

  • effects of the passage of comet c 2013 a1 siding spring observed by the shallow radar sharad on Mars Reconnaissance Orbiter
    2015
    Co-Authors: Marco Restano, Bruce A Campbell, R Seu, Jeffrey J Plaut, Y Gim, D C Nunes, Fabrizio Bernardini, A F Egan, Roger J Phillips
    Abstract:

    The close passage of Comet C/2013 A1 (Siding Spring) to Mars provided a unique opportunity to observe the interaction of cometary materials with the Martian ionosphere and atmosphere using the sounding radar SHARAD (SHAllow RADar) aboard Mars Reconnaissance Orbiter. In two nightside observations, acquired in the 10 h following the closest approach, the SHARAD data reveal a significant increase of the total electron content (TEC). The observed TEC values are typical for daylight hours just after dawn or before sunset but are unprecedented this deep into the night. Results support two predictions indicating that cometary pickup O+ ions, or ions generated from the ablation of cometary dust, are responsible for the creation of an additional ion layer.

  • Imaging the subsurface structure of Planum Boreum with the Mars Reconnaissance Orbiter Shallow Radar
    2010
    Co-Authors: N E Putzig, Bruce A Campbell, Roger J Phillips, Frederick J. Foss
    Abstract:

    We review prior mapping of the subsurface structure of Planum Boreum that was conducted with 2-D sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter (MRO). Widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD) occur throughout the 1,000,000-km2 area. A dome-shaped zone of diffuse reflectivity up to ~1 km thick underlies two-thirds of the NPLD. This zone is associated with a basal unit identified in image data as Amazonian sand-rich layered deposits. In other areas, the NPLD base is remarkably flat-lying and co-planar with the exposed surface of the surrounding Vastitas Borealis materials. Within the NPLD, radar-layer packets that extend throughout the deposits have been mapped as five units with a total volume of 821,000 km3, exclusive of the basal unit. Application of a 3-D imaging technique commonly used in processing seismic data to the polar grid of 2-D SHARAD observations is expected to yield an improved representation of the subsurface layering geometry and greatly reduce the effects of surface clutter.

  • subsurface structure of planum boreum from Mars Reconnaissance Orbiter shallow radar soundings
    2009
    Co-Authors: N E Putzig, Bruce A Campbell, Roger J Phillips, Jeffrey J Plaut, Fabrizio Bernardini, A F Egan, J W Holt, L M Carter, A Safaeinili
    Abstract:

    Abstract We map the subsurface structure of Planum Boreum using sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter. Radar coverage throughout the 1,000,000-km2 area reveals widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD). A dome-shaped zone of diffuse reflectivity up to 12 μs (∼1-km thick) underlies two-thirds of the NPLD, predominantly in the main lobe but also extending into the Gemina Lingula lobe across Chasma Boreale. We equate this zone with a basal unit identified in image data as Amazonian sand-rich layered deposits [Byrne, S., Murray, B.C., 2002. J. Geophys. Res. 107, 5044, 12 pp. doi:10.1029/2001JE001615; Fishbaugh, K.E., Head, J.W., 2005. Icarus 174, 444–474; Tanaka, K.L., Rodriguez, J.A.P., Skinner, J.A., Bourke, M.C., Fortezzo, C.M., Herkenhoff, K.E., Kolb, E.J., Okubo, C.H., 2008. Icarus 196, 318–358]. Elsewhere, the NPLD base is remarkably flat-lying and co-planar with the exposed surface of the surrounding Vastitas Borealis materials. Within the NPLD, we delineate and map four units based on the radar-layer packets of Phillips et al. [Phillips, R.J., and 26 colleagues, 2008. Science 320, 1182–1185] that extend throughout the deposits and a fifth unit confined to eastern Gemina Lingula. We estimate the volume of each internal unit and of the entire NPLD stack (821,000 km3), exclusive of the basal unit. Correlation of these units to models of insolation cycles and polar deposition [Laskar, J., Levrard, B., Mustard, J.F., 2002. Nature 419, 375–377; Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772] is consistent with the 4.2-Ma age of the oldest preserved NPLD obtained by Levrard et al. [Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772]. We suggest a dominant layering mechanism of dust–content variation during accumulation rather than one of lag production during periods of sublimation.

  • sharad sounding radar on the Mars Reconnaissance Orbiter
    2007
    Co-Authors: R Seu, Bruce A Campbell, Roger J Phillips, A Safaeinili, D Biccari, R Orosei, A Masdea, G Picardi, Jeffrey J Plaut, L Marinangeli
    Abstract:

    [1] SHARAD (SHAllow RADar) is a sounding radar provided by Agenzia Spaziale Italiana (ASI) as a Facility Instrument on the Mars Reconnaissance Orbiter mission. Its 20-MHz center frequency and 10-MHz bandwidth complement the lower-frequency, relatively narrower bandwidth capability of the MarsIS sounding radar. A joint Italian-U.S. team has guided the experiment development and is responsible for data analysis and interpretation. The radar transmits signals at a 700 Hz pulse repetition frequency (PRF) and collects reflections from both the surface and near subsurface of Mars. Vertical and horizontal resolutions are, respectively, 15 m (free-space) and 3–6 km (cross-track) by 0.3–1 km (along-track). The scientific objective of SHARAD is to map, in selected locales, dielectric interfaces to at least several hundred meters depth in the Martian subsurface and to interpret these results in terms of the occurrence and distribution of expected materials, including competent rock, soil, water, and ice. A signal-to-noise ratio of ∼50 dB (for a specular surface return) is achieved with 10 W of radiated power by using range and azimuth focusing in ground data processing. Preprocessed data as well as range- and azimuth-focused data will be formatted according to Planetary Data System (PDS) standards and be made available from the ASI Science Data Center (ASDC) and from the Geosciences Node of the Planetary Data System (PDS). Important targets for SHARAD include the polar layered deposits, sedimentary stacks (especially in Terra Meridiani), buried channel systems, buried impact craters, volcanic complexes, and shallow ice deposits in equilibrium with the atmosphere.

Bruce A Campbell - One of the best experts on this subject based on the ideXlab platform.

  • calibration of Mars Reconnaissance Orbiter shallow radar sharad data for subsurface probing and surface reflectivity studies
    2021
    Co-Authors: Bruce A Campbell, Fabrizio Bernardini, G A Morgan, N E Putzig, Daniel Nunes, Jeffrey J Plaut
    Abstract:

    Abstract The Shallow Radar (SHARAD) instrument on the Mars Reconnaissance Orbiter (MRO) has been operating since 2006, revealing the detailed layered structure of the polar caps, mid-latitude glacial deposits, and a range of volcanic features. Here we address the major sources of change in the effective gain and signal-to-noise ratio of data collected by SHARAD: (1) the altitude and background noise level, (2) the configuration of the solar arrays (SA) and high-gain antenna (HGA), (3) ionospheric attenuation, and (4) the roll angle of MRO. Background noise fluctuations have a range of ~5 dB, and electromagnetic interference may significantly affect comparisons among limited bands of the full spectrum. We use the dense spatial coverage of sounder data to define a model for gain as a function of SA and HGA orientations, and demonstrate its predictive capability over a 4-dB range with radargrams collected under different configurations. Ionospheric attenuation as a function of the phase distortion correction used in radargram processing is refined through a larger dataset than available in earlier studies. Gain improvements due to MRO rolls up to 28o are also a function of the SA-HGA configuration, such that the maximum span of combined SHARAD gain contributions is about 7 dB. After calibration, Planum Boreum in the north polar layered deposits is ~3 dB less reflective than Planum Australe, and multi-band analysis suggests destructive interference occurs in the more densely layered shallow structure of the northern cap. The new calibration model allows targeting of future observations during optimum conditions over features of interest.

  • 3d imaging of Mars polar ice caps using orbital radar data
    2017
    Co-Authors: F J Foss, N E Putzig, Bruce A Campbell, Roger J Phillips
    Abstract:

    Since its arrival in early 2006, various instruments aboard NASA's Mars Reconnaissance Orbiter (MRO) have been collecting a variety of scientific and engineering data from orbit around Mars. Among these is the Shallow Radar (SHARAD) instrument, supplied by Agenzia Spaziale Italiana (ASI) and designed for subsurface sounding in the 15–25 MHz frequency band. As of this writing, MRO has completed more than 46,000 nearly polar orbits of Mars, 30% of which have included active SHARAD data collection. By 2009, a sufficient density of SHARAD coverage had been obtained over the polar regions to support 3D processing and analysis of the data. Using tools and techniques commonly employed in terrestrial seismic data processing, we have processed subsets of the resulting collection of SHARAD observations covering the north and south polar regions as SHARAD 3D volumes, imaging the interiors of the north and south polar ice caps known, respectively, as Planum Boreum and Planum Australe. After overcoming a series of cha...

  • effects of the passage of comet c 2013 a1 siding spring observed by the shallow radar sharad on Mars Reconnaissance Orbiter
    2015
    Co-Authors: Marco Restano, Bruce A Campbell, R Seu, Jeffrey J Plaut, Y Gim, D C Nunes, Fabrizio Bernardini, A F Egan, Roger J Phillips
    Abstract:

    The close passage of Comet C/2013 A1 (Siding Spring) to Mars provided a unique opportunity to observe the interaction of cometary materials with the Martian ionosphere and atmosphere using the sounding radar SHARAD (SHAllow RADar) aboard Mars Reconnaissance Orbiter. In two nightside observations, acquired in the 10 h following the closest approach, the SHARAD data reveal a significant increase of the total electron content (TEC). The observed TEC values are typical for daylight hours just after dawn or before sunset but are unprecedented this deep into the night. Results support two predictions indicating that cometary pickup O+ ions, or ions generated from the ablation of cometary dust, are responsible for the creation of an additional ion layer.

  • Imaging the subsurface structure of Planum Boreum with the Mars Reconnaissance Orbiter Shallow Radar
    2010
    Co-Authors: N E Putzig, Bruce A Campbell, Roger J Phillips, Frederick J. Foss
    Abstract:

    We review prior mapping of the subsurface structure of Planum Boreum that was conducted with 2-D sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter (MRO). Widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD) occur throughout the 1,000,000-km2 area. A dome-shaped zone of diffuse reflectivity up to ~1 km thick underlies two-thirds of the NPLD. This zone is associated with a basal unit identified in image data as Amazonian sand-rich layered deposits. In other areas, the NPLD base is remarkably flat-lying and co-planar with the exposed surface of the surrounding Vastitas Borealis materials. Within the NPLD, radar-layer packets that extend throughout the deposits have been mapped as five units with a total volume of 821,000 km3, exclusive of the basal unit. Application of a 3-D imaging technique commonly used in processing seismic data to the polar grid of 2-D SHARAD observations is expected to yield an improved representation of the subsurface layering geometry and greatly reduce the effects of surface clutter.

  • subsurface structure of planum boreum from Mars Reconnaissance Orbiter shallow radar soundings
    2009
    Co-Authors: N E Putzig, Bruce A Campbell, Roger J Phillips, Jeffrey J Plaut, Fabrizio Bernardini, A F Egan, J W Holt, L M Carter, A Safaeinili
    Abstract:

    Abstract We map the subsurface structure of Planum Boreum using sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter. Radar coverage throughout the 1,000,000-km2 area reveals widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD). A dome-shaped zone of diffuse reflectivity up to 12 μs (∼1-km thick) underlies two-thirds of the NPLD, predominantly in the main lobe but also extending into the Gemina Lingula lobe across Chasma Boreale. We equate this zone with a basal unit identified in image data as Amazonian sand-rich layered deposits [Byrne, S., Murray, B.C., 2002. J. Geophys. Res. 107, 5044, 12 pp. doi:10.1029/2001JE001615; Fishbaugh, K.E., Head, J.W., 2005. Icarus 174, 444–474; Tanaka, K.L., Rodriguez, J.A.P., Skinner, J.A., Bourke, M.C., Fortezzo, C.M., Herkenhoff, K.E., Kolb, E.J., Okubo, C.H., 2008. Icarus 196, 318–358]. Elsewhere, the NPLD base is remarkably flat-lying and co-planar with the exposed surface of the surrounding Vastitas Borealis materials. Within the NPLD, we delineate and map four units based on the radar-layer packets of Phillips et al. [Phillips, R.J., and 26 colleagues, 2008. Science 320, 1182–1185] that extend throughout the deposits and a fifth unit confined to eastern Gemina Lingula. We estimate the volume of each internal unit and of the entire NPLD stack (821,000 km3), exclusive of the basal unit. Correlation of these units to models of insolation cycles and polar deposition [Laskar, J., Levrard, B., Mustard, J.F., 2002. Nature 419, 375–377; Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772] is consistent with the 4.2-Ma age of the oldest preserved NPLD obtained by Levrard et al. [Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772]. We suggest a dominant layering mechanism of dust–content variation during accumulation rather than one of lag production during periods of sublimation.

Jeffrey J Plaut - One of the best experts on this subject based on the ideXlab platform.

  • calibration of Mars Reconnaissance Orbiter shallow radar sharad data for subsurface probing and surface reflectivity studies
    2021
    Co-Authors: Bruce A Campbell, Fabrizio Bernardini, G A Morgan, N E Putzig, Daniel Nunes, Jeffrey J Plaut
    Abstract:

    Abstract The Shallow Radar (SHARAD) instrument on the Mars Reconnaissance Orbiter (MRO) has been operating since 2006, revealing the detailed layered structure of the polar caps, mid-latitude glacial deposits, and a range of volcanic features. Here we address the major sources of change in the effective gain and signal-to-noise ratio of data collected by SHARAD: (1) the altitude and background noise level, (2) the configuration of the solar arrays (SA) and high-gain antenna (HGA), (3) ionospheric attenuation, and (4) the roll angle of MRO. Background noise fluctuations have a range of ~5 dB, and electromagnetic interference may significantly affect comparisons among limited bands of the full spectrum. We use the dense spatial coverage of sounder data to define a model for gain as a function of SA and HGA orientations, and demonstrate its predictive capability over a 4-dB range with radargrams collected under different configurations. Ionospheric attenuation as a function of the phase distortion correction used in radargram processing is refined through a larger dataset than available in earlier studies. Gain improvements due to MRO rolls up to 28o are also a function of the SA-HGA configuration, such that the maximum span of combined SHARAD gain contributions is about 7 dB. After calibration, Planum Boreum in the north polar layered deposits is ~3 dB less reflective than Planum Australe, and multi-band analysis suggests destructive interference occurs in the more densely layered shallow structure of the northern cap. The new calibration model allows targeting of future observations during optimum conditions over features of interest.

  • effects of the passage of comet c 2013 a1 siding spring observed by the shallow radar sharad on Mars Reconnaissance Orbiter
    2015
    Co-Authors: Marco Restano, Bruce A Campbell, R Seu, Jeffrey J Plaut, Y Gim, D C Nunes, Fabrizio Bernardini, A F Egan, Roger J Phillips
    Abstract:

    The close passage of Comet C/2013 A1 (Siding Spring) to Mars provided a unique opportunity to observe the interaction of cometary materials with the Martian ionosphere and atmosphere using the sounding radar SHARAD (SHAllow RADar) aboard Mars Reconnaissance Orbiter. In two nightside observations, acquired in the 10 h following the closest approach, the SHARAD data reveal a significant increase of the total electron content (TEC). The observed TEC values are typical for daylight hours just after dawn or before sunset but are unprecedented this deep into the night. Results support two predictions indicating that cometary pickup O+ ions, or ions generated from the ablation of cometary dust, are responsible for the creation of an additional ion layer.

  • subsurface structure of planum boreum from Mars Reconnaissance Orbiter shallow radar soundings
    2009
    Co-Authors: N E Putzig, Bruce A Campbell, Roger J Phillips, Jeffrey J Plaut, Fabrizio Bernardini, A F Egan, J W Holt, L M Carter, A Safaeinili
    Abstract:

    Abstract We map the subsurface structure of Planum Boreum using sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter. Radar coverage throughout the 1,000,000-km2 area reveals widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD). A dome-shaped zone of diffuse reflectivity up to 12 μs (∼1-km thick) underlies two-thirds of the NPLD, predominantly in the main lobe but also extending into the Gemina Lingula lobe across Chasma Boreale. We equate this zone with a basal unit identified in image data as Amazonian sand-rich layered deposits [Byrne, S., Murray, B.C., 2002. J. Geophys. Res. 107, 5044, 12 pp. doi:10.1029/2001JE001615; Fishbaugh, K.E., Head, J.W., 2005. Icarus 174, 444–474; Tanaka, K.L., Rodriguez, J.A.P., Skinner, J.A., Bourke, M.C., Fortezzo, C.M., Herkenhoff, K.E., Kolb, E.J., Okubo, C.H., 2008. Icarus 196, 318–358]. Elsewhere, the NPLD base is remarkably flat-lying and co-planar with the exposed surface of the surrounding Vastitas Borealis materials. Within the NPLD, we delineate and map four units based on the radar-layer packets of Phillips et al. [Phillips, R.J., and 26 colleagues, 2008. Science 320, 1182–1185] that extend throughout the deposits and a fifth unit confined to eastern Gemina Lingula. We estimate the volume of each internal unit and of the entire NPLD stack (821,000 km3), exclusive of the basal unit. Correlation of these units to models of insolation cycles and polar deposition [Laskar, J., Levrard, B., Mustard, J.F., 2002. Nature 419, 375–377; Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772] is consistent with the 4.2-Ma age of the oldest preserved NPLD obtained by Levrard et al. [Levrard, B., Forget, F., Montmessin, F., Laskar, J., 2007. J. Geophys. Res. 112, E06012, 18 pp. doi:10.1029/2006JE002772]. We suggest a dominant layering mechanism of dust–content variation during accumulation rather than one of lag production during periods of sublimation.

  • radar sounding evidence for buried glaciers in the southern mid latitudes of Mars
    2008
    Co-Authors: J W Holt, A Safaeinili, R Seu, Jeffrey J Plaut, J W Head, R J Phillips, Scott D Kempf, Prateek Choudhary, Duncan A Young, N E Putzig
    Abstract:

    Lobate features abutting massifs and escarpments in the middle latitudes of Mars have been recognized in images for decades, but their true nature has been controversial, with hypotheses of origin such as ice-lubricated debris flows or glaciers covered by a layer of surface debris. These models imply an ice content ranging from minor and interstitial to massive and relatively pure. Soundings of these deposits in the eastern Hellas region by the Shallow Radar on the Mars Reconnaissance Orbiter reveal radar properties entirely consistent with massive water ice, supporting the debris-covered glacier hypothesis. The results imply that these glaciers formed in a previous climate conducive to glaciation at middle latitudes. Such features may collectively represent the most extensive nonpolar ice yet recognized on Mars.

  • sharad sounding radar on the Mars Reconnaissance Orbiter
    2007
    Co-Authors: R Seu, Bruce A Campbell, Roger J Phillips, A Safaeinili, D Biccari, R Orosei, A Masdea, G Picardi, Jeffrey J Plaut, L Marinangeli
    Abstract:

    [1] SHARAD (SHAllow RADar) is a sounding radar provided by Agenzia Spaziale Italiana (ASI) as a Facility Instrument on the Mars Reconnaissance Orbiter mission. Its 20-MHz center frequency and 10-MHz bandwidth complement the lower-frequency, relatively narrower bandwidth capability of the MarsIS sounding radar. A joint Italian-U.S. team has guided the experiment development and is responsible for data analysis and interpretation. The radar transmits signals at a 700 Hz pulse repetition frequency (PRF) and collects reflections from both the surface and near subsurface of Mars. Vertical and horizontal resolutions are, respectively, 15 m (free-space) and 3–6 km (cross-track) by 0.3–1 km (along-track). The scientific objective of SHARAD is to map, in selected locales, dielectric interfaces to at least several hundred meters depth in the Martian subsurface and to interpret these results in terms of the occurrence and distribution of expected materials, including competent rock, soil, water, and ice. A signal-to-noise ratio of ∼50 dB (for a specular surface return) is achieved with 10 W of radiated power by using range and azimuth focusing in ground data processing. Preprocessed data as well as range- and azimuth-focused data will be formatted according to Planetary Data System (PDS) standards and be made available from the ASI Science Data Center (ASDC) and from the Geosciences Node of the Planetary Data System (PDS). Important targets for SHARAD include the polar layered deposits, sedimentary stacks (especially in Terra Meridiani), buried channel systems, buried impact craters, volcanic complexes, and shallow ice deposits in equilibrium with the atmosphere.

J T Schofield - One of the best experts on this subject based on the ideXlab platform.

  • initial results from radio occultation measurements with the Mars Reconnaissance Orbiter a nocturnal mixed layer in the tropics and comparisons with polar profiles from the Mars climate sounder
    2014
    Co-Authors: Robert M. Haberle, A Kleinbohl, J T Schofield, D P Hinson, S W Asmar, Daniel Kahan, Varoujan Akopian, Aymeric Spiga, W A Abdou
    Abstract:

    Abstract The Mars Reconnaissance Orbiter (MRO) performs radio occultation (RO) measurements on selected orbits, generally once per day. We have retrieved atmospheric profiles from two subsets of data, yielding a variety of new results that illustrate the scientific value of the observations. One set of measurements sounded the tropics in northern summer at a local time ∼1 h before sunrise. Some of these profiles contain an unexpected layer of neutral stability with a depth of ∼4 km and a pressure at its upper boundary of ∼160 Pa. The mixed layer is bounded above by a temperature inversion and below by another strong inversion adjacent to the surface. This type of structure is observed near Gale Crater, in the Tharsis region, and at a few other locations, whereas profiles in Amazonis Planitia and Elysium Planitia show no sign of a detached mixed layer with an overlying inversion. We supplemented the measurements with numerical simulations by the NASA Ames Mars General Circulation Model, which demonstrate that water ice clouds can generate this distinctive type of temperature structure through their influence on radiative transfer at infrared wavelengths. In particular, the simulations predict the presence of a nocturnal cloud layer in the Tharsis region at a pressure of ∼150 Pa (∼10 km above the surface), and the nighttime radiative cooling at cloud level is sufficient to produce a temperature inversion above the cloud as well as convective instability below the cloud, consistent with the observations. The second set of measurements sounded mid-to-high northern latitudes in spring, when carefully coordinated observations by the MRO Mars Climate Sounder (MCS) are also available. The differences between the RO and MCS temperature profiles are generally consistent with the expected performance of the two instruments. Within this set of 21 comparisons the average temperature difference is less than 1 K where the aerosol opacities are smaller than 10 - 3 km - 1 , at pressures of 10–50 Pa, whereas it increases to ∼2 K where the aerosol opacities exceed this threshold, at pressures of 50–300 Pa. The standard deviation of the temperature difference is ∼2 K, independent of pressure. The second set of RO measurements also provides unique information about the stability of the annual CO 2 cycle and the dynamics near the edge of the seasonal CO 2 ice cap.

  • structure and dynamics of the martian lower and middle atmosphere as observed by the Mars climate sounder 2 implications of the thermal structure and aerosol distributions for the mean meridional circulation
    2011
    Co-Authors: N G Heavens, David M Kass, A Kleinbohl, D J Mccleese, M I Richardson, J T Schofield
    Abstract:

    [1] Retrievals of temperature, dust, and water ice from data collected by the Mars Climate Sounder (MCS) on Mars Reconnaissance Orbiter (MRO) illustrate for the first time the seasonal and diurnal variability of both the thermal structure of the middle atmosphere (above 40 km) and also the vertical distribution of aerosols. These retrievals reveal clear signatures of significant mean meridional cells in the middle and lower atmosphere at both the solstices and equinoxes. We investigate the degree to which the lower and middle atmospheric circulations are kinematically coupled and conclude that kinematic coupling is strong in the tropics throughout the year but weak near the pole except during the “polar warming” events associated with dust storm activity.

  • water ice clouds over the martian tropics during northern summer
    2010
    Co-Authors: N G Heavens, J L Benson, David M Kass, A Kleinbohl, W A Abdou, D J Mccleese, M I Richardson, J T Schofield, J H Shirley
    Abstract:

    [1] Atmospheric models suggest that infrared heating due to water ice clouds over the tropics of Mars during early northern summer has a significant impact on the thermal structure of the tropics at cloud level and of the middle atmosphere near the south pole. Retrievals from limb observations by the Mars Climate Sounder on Mars Reconnaissance Orbiter during early northern summer show that water ice clouds over the northern tropics are thinner and higher than in published model results. Later in this season, the latitudinal extent, apparent mass mixing ratio (and infrared heating rate), and altitude of nighttime tropical clouds significantly increase, reaching a maximum just before northern fall equinox. Published model results do not show this transition. By underestimating the altitude at which water ice clouds form, models also may underestimate the intensity of the meridional circulation at higher altitudes in the tropics during northern summer.

  • Mars climate sounder an investigation of thermal and water vapor structure dust and condensate distributions in the atmosphere and energy balance of the polar regions
    2007
    Co-Authors: D J Mccleese, David M Kass, J T Schofield, P L Read, F W Taylor, S B Calcutt, M C Foote, Conway B Leovy, D A Paige, R W Zurek
    Abstract:

    [1] Against a backdrop of intensive exploration of the Martian surface environment, intended to lead to human exploration, some aspects of the modern climate and the meteorology of Mars remain relatively unexplored. In particular, there is a need for detailed measurements of the vertical profiles of atmospheric temperature, water vapor, dust, and condensates to understand the intricately related processes upon which the surface conditions, and those encountered during descent by landers, depend. The most important of these missing data are accurate and extensive temperature measurements with high vertical resolution. The Mars Climate Sounder experiment on the 2005 Mars Reconnaissance Orbiter, described here, is the latest attempt to characterize the Martian atmosphere with the sort of coverage and precision achieved by terrestrial weather satellites. If successful, it is expected to lead to corresponding improvements in our understanding of meteorological phenomena and to enable improved general circulation models of the Martian atmosphere for climate studies on a range of timescales.

  • atmospheric temperature sounding on Mars and the climate sounder on the 2005 Reconnaissance Orbiter
    2006
    Co-Authors: F W Taylor, D J Mccleese, J T Schofield, S R Lewis, P L Read, S B Calcutt, R W Zurek
    Abstract:

    Detailed measurements of the vertical profiles of atmospheric temperature, water vapour, dust and condensates in the Martian atmosphere are needed to characterize the present-day Martian climate and to understand the intricately related processes upon which it depends. Among the most important of these are accurate and extensive temperature measurements. Progress to date, key problems still to be addressed and upcoming new approaches to the measurement task are briefly reviewed, and expectations for the Mars Climate Sounder experiment on the 2005 Mars Reconnaissance Orbiter are described. Some even more advanced methods for temperature, humidity and condensate sounding in the decade beyond MCS/MRO, and promising approaches to achieving these are also considered.

Bruce A. Cantor - One of the best experts on this subject based on the ideXlab platform.

  • reconstruction of atmospheric properties from Mars science laboratory entry descent and landing
    2014
    Co-Authors: Allen Chen, Bruce A. Cantor, David M Kass, Alicia Dwyer Cianciolo, A R Vasavada, Christopher D Karlgaard, Jeff Barnes, Scot C R Rafkin, Dan Tyler
    Abstract:

    The successful Mars Science Laboratory entry, descent, and landing returned a wealth of in situ data that, when combined with Orbiter remote sensing data and numerical modeling results, can be used to determine the state of the atmosphere. The entry atmosphere reconstruction included data from several sources: 1) temperature and pressure data from the Mars Reconnaissance Orbiter and Mars Climate Sounder instrument, 2) density derived from the Mars entry, descent, and landing instrument suite, 3) density derived from the vehicle’s inertial measurement unit and knowledge of the vehicle aerodynamics, and 4) numerical mesoscale model results. No single data set is sufficient to understand the atmospheric state along the path flown by the spacecraft. Rather, the reconstructed profile of density is pieced together from the available data, along with some assumptions and inferences. The strategy used to combine the various data sets required a clear understanding of each source’s strengths and weaknesses. The va...

  • Mars Reconnaissance Orbiter Mars color imager marci instrument description calibration and performance
    2009
    Co-Authors: J F Bell, Bruce A. Cantor, Wendy M. Calvin, Kenneth S. Edgett, Michael A. Caplinger, Michael J Wolff, M C Malin, R T Clancy, Laurence J Edwards, J Fahle
    Abstract:

    [1] The Mars Color Imager (MARCI) instrument aboard the NASA Mars Reconnaissance Orbiter spacecraft is a wide-angle, multispectral Charge-Coupled Device (CCD) “push frame” imaging camera designed to provide frequent, synoptic-scale color imaging of the Martian atmosphere and surface. MARCI uses a 1024 × 1024 pixel interline transfer CCD detector that has seven narrowband interference filters bonded directly to the CCD. Five of the filters are in the visible to short-wave near-infrared wavelength range (437, 546, 604, 653, and 718 nm) and two are in the ultraviolet range (258 and 320 nm). Here we describe the scientific objectives of the MARCI investigation and the basic characteristics, calibration, and in-flight performance of the MARCI instrument. We include several examples of early scientific results and investigations enabled by an extensive preflight and in-flight calibration program and by validation of the performance of the instrument in flight.

  • climate weather and north polar observations from the Mars Reconnaissance Orbiter Mars color imager
    2008
    Co-Authors: Michael C Malin, Bruce A. Cantor, Wendy M. Calvin, Robert M. Haberle, Todd R Clancy, P B James, P C Thomas, Michael J Wolff, J F Bell, Steven W Lee
    Abstract:

    The Mars Reconnaissance Orbiter observes Mars from a nearly circular, polar orbit. From this vantage point, the Mars Color Imager extends the ∼5 Mars years record of Mars Global Surveyor global, visible-wavelength multi-color observations of meteorological events and adds measurements at three additional visible and two ultraviolet wavelengths. Observations of the global distribution of ozone (which anti-correlates with water vapor) and water ice and dust clouds allow tracking of atmospheric circulation. Regional and local observations emphasize smaller scale atmospheric dynamics, especially those related to dust lifting and subsequent motion. Polar observations detail variations related to the polar heat budget, including changes in polar frosts and ices, and storms generated at high thermal contrast boundaries.

  • Context Camera Investigation on board the Mars Reconnaissance Orbiter
    2007
    Co-Authors: Michael C Malin, Bruce A. Cantor, Wendy M. Calvin, R. Todd Clancy, Kenneth S. Edgett, Michael A. Caplinger, James F. Bell, Lawrence Edwards, Robert M. Haberle, Philip B. James
    Abstract:

    The Context Camera (CTX) on the Mars Reconnaissance Orbiter (MRO) is a Facility Instrument (i.e., government-furnished equipment operated by a science team not responsible for design and fabrication) designed, built, and operated by Malin Space Science Systems and the MRO Mars Color Imager team (MARCI). CTX will (1) provide context images for data acquired by other MRO instruments, (2) observe features of interest to NASA's Mars Exploration Program (e.g., candidate landing sites), and (3) conduct a scientific investigation, led by the MARCI team, of geologic, geomorphic, and meteorological processes on Mars. CTX consists of a digital electronics assembly; a 350 mm f/3.25 Schmidt-type telescope of catadioptric optical design with a 5.7° field of view, providing a ∼30-km-wide swath from ∼290 km altitude; and a 5000-element CCD with a band pass of 500–700 nm and 7 μm pixels, giving ∼6 m/pixel spatial resolution from MRO's nearly circular, nearly polar mapping orbit. Raw data are transferred to the MRO spacecraft flight computer for processing (e.g., data compression) before transmission to Earth. The ground data system and operations are based on 9 years of Mars Global Surveyor Mars Orbiter Camera on-orbit experience. CTX has been allocated 12% of the total MRO data return, or about ≥3 terabits for the nominal mission. This data volume would cover ∼9% of Mars at 6 m/pixel, but overlapping images (for stereo, mosaics, and observation of changes and meteorological events) will reduce this area. CTX acquired its first (instrument checkout) images of Mars on 24 March 2006.