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43 results on '"Hofstadter, Mark D."'

1. Cassini spacecraft reveals global energy imbalance of Saturn

Author

Wang, Xinyue, Li, Liming, Jiang, Xun, Fry, Patrick M., West, Robert A., Nixon, Conor A., Guan, Larry, Karandana G, Thishan D., Albright, Ronald, Colwell, Joshua E., Guillot, Tristan, Hofstadter, Mark D., Kenyon, Matthew E., Mallama, Anthony, Perez-Hoyos, Santiago, Sanchez-Lavega, Agustin, Simon, Amy A., Wenkert, Daniel, and Zhang, Xi

Published
2024
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2. CO2-driven surface changes in the Hapi region on Comet 67P/Churyumov-Gerasimenko

Author

Davidsson, Björn J. R., Schloerb, F. Peter, Fornasier, Sonia, Oklay, Nilda, Gutiérrez, Pedro J., Buratti, Bonnie J., Chmielewski, Artur B., Gulkis, Samuel, Hofstadter, Mark D., Keller, H. Uwe, Sierks, Holger, Güttler, Carsten, Küppers, Michael, Rickman, Hans, Choukroun, Mathieu, Lee, Seungwon, Lellouch, Emmanuel, Lethuillier, Anthony, Da Deppo, Vania, Groussin, Olivier, Kührt, Ekkehard, Thomas, Nicolas, Tubiana, Cecilia, El-Maarry, M. Ramy, La Forgia, Fiorangela, Mottola, Stefano, and Pajola, Maurizio

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Between 2014 December 31 and 2015 March 17, the OSIRIS cameras on Rosetta documented the growth of a 140m wide and 0.5m deep depression in the Hapi region on Comet 67P/Churyumov-Gerasimenko. This shallow pit is one of several that later formed elsewhere on the comet, all in smooth terrain that primarily is the result of airfall of coma particles. We have compiled observations of this region in Hapi by the microwave instrument MIRO on Rosetta, acquired during October and November 2014. We use thermophysical and radiative transfer models in order to reproduce the MIRO observations. This allows us to place constraints on the thermal inertia, diffusivity, chemical composition, stratification, extinction coefficients, and scattering properties of the surface material, and how they evolved during the months prior to pit formation. The results are placed in context through long-term comet nucleus evolution modelling. We propose that: 1) MIRO observes signatures that are consistent with a solid-state greenhouse effect in airfall material; 2) CO2 ice is sufficiently close to the surface to have a measurable effect on MIRO antenna temperatures, and likely is responsible for the pit formation in Hapi observed by OSIRIS; 3) the pressure at the CO2 sublimation front is sufficiently strong to expel dust and water ice outwards, and to compress comet material inwards, thereby causing the near-surface compaction observed by CONSERT, SESAME, and groundbased radar, manifested as the "consolidated terrain" texture observed by OSIRIS., Comment: 32 pages, 41 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review

Published
2022
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3. Spatial Distribution of Ultraviolet Emission from Cometary Activity at 67P/Churyumov-Gerasimenko

Author

Noonan, John W., Bockelée-Morvan, Dominique, Feldman, Paul D., Stern, S. Alan, Keeney, Brian A., Parker, Joel Wm., Biver, Nicolas, Knight, Matthew M., Feaga, Lori M., Hofstadter, Mark D., Lee, Seungwon, Vervack Jr., Ronald J., Steffl, Andrew J., Schindhelm, Rebecca N., Pineau, Jon, Medina, Richard, Weaver, Harold A., Bertaux, Jean-Loup, and A'Hearn, Michael F.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Alice ultraviolet spectrograph on board the \textit{Rosetta} orbiter provided the first near-nucleus ultraviolet observations of a cometary coma from arrival at comet 67P/Churyumov-Gerasimenko in 2014 August through 2016 September. The characterization of atomic and molecular emissions in the coma revealed the unexpected contribution of dissociative electron impact emission at large heliocentric distances and during some outbursts. This mechanism also proved useful for compositional analysis, and Alice observed many cases that suggested elevated levels of the supervolatile \ce{O2}, identifiable in part to their emissions resulting from dissociative electron impact. In this paper we present the first two-dimensional UV maps constructed from Alice observations of atomic emission from 67P during an increase in cometary activity on 2015 November 7-8. Comparisons to observations of background coma and of an earlier collimated jet are used to describe possible changes to the near-nucleus coma and plasma. To verify the mapping method and place the Alice observations in context, comparisons to images derived from the MIRO and VIRTIS-H instruments are made. The spectra and maps we present show an increase in dissociative electron impact emission and an \ce{O2}/\ce{H2O} ratio of $\sim$0.3 for the activity; these characteristics have been previously identified with cometary outbursts seen in Alice data. Further, UV maps following the increases in activity show the spatial extent and emission variation experienced by the near-nucleus coma, informing future UV observations of comets that lack the same spatial resolution., Comment: 22 pages, 14 figures, 2 tables

Published
2021
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4. The science case for spacecraft exploration of the Uranian satellites: Candidate ocean worlds in an ice giant system

Author

Cartwright, Richard J., Beddingfield, Chloe B., Nordheim, Tom A., Elder, Catherine M., Castillo-Rogez, Julie C., Neveu, Marc, Bramson, Ali M., Sori, Michael M., Buratti, Bonnie J., Pappalardo, Robert T., Roser, Joseph E., Cohen, Ian J., Leonard, Erin J., Ermakov, Anton I., Showalter, Mark R., Grundy, William M., Turtle, Elizabeth P., and Hofstadter, Mark D.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The 27 satellites of Uranus are enigmatic, with dark surfaces coated by material that could be rich in organics. Voyager 2 imaged the southern hemispheres of Uranus' five largest 'classical' moons Miranda, Ariel, Umbriel, Titania, and Oberon, as well as the largest ring moon Puck, but their northern hemispheres were largely unobservable at the time of the flyby and were not imaged. Additionally, no spatially resolved datasets exist for the other 21 known moons, and their surface properties are essentially unknown. Because Voyager 2 was not equipped with a near-infrared mapping spectrometer, our knowledge of the Uranian moons' surface compositions, and the processes that modify them, is limited to disk-integrated datasets collected by ground- and space-based telescopes. Nevertheless, images collected by the Imaging Science System on Voyager 2 and reflectance spectra collected by telescope facilities indicate that the five classical moons are candidate ocean worlds that might currently have, or had, liquid subsurface layers beneath their icy surfaces. To determine whether these moons are ocean worlds, and investigate Uranus' ring moons and irregular satellites, close-up observations and measurements made by instruments onboard a Uranus orbiter are needed., Comment: Accepted in AAS Planetary Science Journal. arXiv admin note: text overlap with arXiv:2007.07284

Published
2021

5. Keys of a Mission to Uranus or Neptune, the Closest Ice Giants

Author

Guillot, Tristan, Fortney, Jonathan, Rauscher, Emily, Marley, Mark S., Parmentier, Vivien, Line, Mike, Wakeford, Hannah, Kaspi, Yohai, Helled, Ravit, Ikoma, Masahiro, Knutson, Heather, Menou, Kristen, Valencia, Diana, Durante, Daniele, Ida, Shigeru, Bolton, Scott J., Li, Cheng, Stevenson, Kevin B., Bean, Jacob, Cowan, Nicolas B., Hofstadter, Mark D., Hueso, Ricardo, Leconte, Jeremy, Li, Liming, Mordasini, Christoph, Mousis, Olivier, Nettelmann, Nadine, Soderlund, Krista, and Wong, Michael H.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

Uranus and Neptune are the archetypes of "ice giants", a class of planets that may be among the most common in the Galaxy. They hold the keys to understand the atmospheric dynamics and structure of planets with hydrogen atmospheres inside and outside the solar system; however, they are also the last unexplored planets of the Solar System. Their atmospheres are active and storms are believed to be fueled by methane condensation which is both extremely abundant and occurs at low optical depth. This means that mapping temperature and methane abundance as a function of position and depth will inform us on how convection organizes in an atmosphere with no surface and condensates that are heavier than the surrounding air, a general feature of giant planets. Owing to the spatial and temporal variability of these atmospheres, an orbiter is required. A probe would provide a reference atmospheric profile to lift ambiguities inherent to remote observations. It would also measure the abundances of noble gases which can be used to reconstruct the history of planet formation in the Solar System. Finally, mapping the planets' gravity and magnetic fields will be essential to constrain their global composition, atmospheric dynamics, structure and evolution. An exploration of Uranus or Neptune will be essential to understand these planets and will also be key to constrain and analyze data obtained at Jupiter, Saturn, and for numerous exoplanets with hydrogen atmospheres., Comment: arXiv admin note: substantial text overlap with arXiv:1908.02092

Published
2020

6. Ice Giant Circulation Patterns: Implications for Atmospheric Probes

Author

Fletcher, Leigh N., de Pater, Imke, Orton, Glenn S., Hofstadter, Mark D., Irwin, Patrick G. J., Roman, Michael, and Toledo, Daniel

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Atmospheric circulation patterns derived from multi-spectral remote sensing can serve as a guide for choosing a suitable entry site for a future in situ probe mission. Since the Voyager-2 flybys in the 1980s, three decades of observations from ground- and space-based observatories have generated a picture of Ice Giant circulation that is complex, perplexing, and altogether unlike that seen on the Gas Giants. This review seeks to reconcile the various competing circulation patterns from an observational perspective, accounting for spatially-resolved measurements of: zonal albedo contrasts and banded appearances; cloud-tracked zonal winds; temperature and para-H$_2$ measurements above the condensate clouds; and equator-to-pole contrasts in condensable volatiles (methane and hydrogen sulphide) in the deeper troposphere. These observations identify three distinct latitude domains: an equatorial domain of deep upwelling and upper-tropospheric subsidence, potentially bounded by peaks in the retrograde zonal jet and analogous to Jovian cyclonic belts; a mid-latitude transitional domain of upper-tropospheric upwelling, vigorous cloud activity, analogous to Jovian anticyclonic zones; and a polar domain of strong subsidence, volatile depletion, and small-scale (and potentially seasonally-variable) convective activity. Taken together, the multi-wavelength observations suggest a tiered structure of stacked circulation cells (at least two in the troposphere and one in the stratosphere), potentially separated in the vertical by (i) strong molecular weight gradients associated with cloud condensation, and by (ii) transitions from a thermally-direct circulation regime at depth to a wave-driven circulation regime at high altitude. The inferred circulation can be tested in the coming decade by 3D simulations and by observations from future world-class facilities. [Abridged], Comment: 29 pages, 8 figures, review article accepted to SSRv special issue on "In Situ Exploration of the Ice Giants"

Published
2019
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15. CO2-driven surface changes in the Hapi region on Comet 67P/Churyumov–Gerasimenko

Author

Davidsson, Björn J R, primary, Schloerb, F Peter, additional, Fornasier, Sonia, additional, Oklay, Nilda, additional, Gutiérrez, Pedro J, additional, Buratti, Bonnie J, additional, Chmielewski, Artur B, additional, Gulkis, Samuel, additional, Hofstadter, Mark D, additional, Keller, H Uwe, additional, Sierks, Holger, additional, Güttler, Carsten, additional, Küppers, Michael, additional, Rickman, Hans, additional, Choukroun, Mathieu, additional, Lee, Seungwon, additional, Lellouch, Emmanuel, additional, Lethuillier, Anthony, additional, Da Deppo, Vania, additional, Groussin, Olivier, additional, Kührt, Ekkehard, additional, Thomas, Nicolas, additional, Tubiana, Cecilia, additional, El-Maarry, M Ramy, additional, La Forgia, Fiorangela, additional, Mottola, Stefano, additional, and Pajola, Maurizio, additional

Published
2022
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16. Uranus Pathfinder: exploring the origins and evolution of Ice Giant planets

Author

Arridge, Christopher S., Agnor, Craig B., André, Nicolas, Baines, Kevin H., Fletcher, Leigh N., Gautier, Daniel, Hofstadter, Mark D., Jones, Geraint H., Lamy, Laurent, Langevin, Yves, Mousis, Olivier, Nettelmann, Nadine, Russell, Christopher T., Stallard, Tom, Tiscareno, Matthew S., Tobie, Gabriel, Bacon, Andrew, Chaloner, Chris, Guest, Michael, Kemble, Steve, Peacocke, Lisa, Achilleos, Nicholas, Andert, Thomas P., Banfield, Don, Barabash, Stas, Barthelemy, Mathieu, Bertucci, Cesar, Brandt, Pontus, Cecconi, Baptiste, Chakrabarti, Supriya, Cheng, Andy F., Christensen, Ulrich, Christou, Apostolos, Coates, Andrew J., Collinson, Glyn, Cooper, John F., Courtin, Regis, Dougherty, Michele K., Ebert, Robert W., Entradas, Marta, Fazakerley, Andrew N., Fortney, Jonathan J., Galand, Marina, Gustin, Jaques, Hedman, Matthew, Helled, Ravit, Henri, Pierre, Hess, Sebastien, Holme, Richard, Karatekin, Özgur, Krupp, Norbert, Leisner, Jared, Martin-Torres, Javier, Masters, Adam, Melin, Henrik, Miller, Steve, Müller-Wodarg, Ingo, Noyelles, Benoît, Paranicas, Chris, de Pater, Imke, Pätzold, Martin, Prangé, Renée, Quémerais, Eric, Roussos, Elias, Rymer, Abigail M., Sánchez-Lavega, Agustin, Saur, Joachim, Sayanagi, Kunio M., Schenk, Paul, Schubert, Gerald, Sergis, Nick, Sohl, Frank, Sittler, Jr., Edward C., Teanby, Nick A., Tellmann, Silvia, Turtle, Elizabeth P., Vinatier, Sandrine, Wahlund, Jan-Erik, and Zarka, Philippe

Published
2012
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17. Spatial Distribution of Ultraviolet Emission from Cometary Activity at 67P/Churyumov-Gerasimenko

Author

Noonan, John W., primary, Bockelée-Morvan, Dominique, additional, Feldman, Paul D., additional, Alan Stern, S., additional, Keeney, Brian A., additional, Parker, Joel Wm., additional, Biver, Nicolas, additional, Knight, Matthew M., additional, Feaga, Lori M., additional, Hofstadter, Mark D., additional, Lee, Seungwon, additional, Vervack, Ronald J., additional, Steffl, Andrew J., additional, Schindhelm, Rebecca N., additional, Pineau, Jon, additional, Medina, Richard, additional, Weaver, Harold A., additional, Bertaux, Jean-Loup, additional, and A’Hearn, Michael F., additional

Published
2021
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18. The Science Case for Spacecraft Exploration of the Uranian Satellites: Candidate Ocean Worlds in an Ice Giant System

Author

Cartwright, Richard J., primary, Beddingfield, Chloe B., additional, Nordheim, Tom A., additional, Elder, Catherine M., additional, Castillo-Rogez, Julie C., additional, Neveu, Marc, additional, Bramson, Ali M., additional, Sori, Michael M., additional, Buratti, Bonnie J., additional, Pappalardo, Robert T., additional, Roser, Joseph E., additional, Cohen, Ian J., additional, Leonard, Erin J., additional, Ermakov, Anton I., additional, Showalter, Mark R., additional, Grundy, William M., additional, Turtle, Elizabeth P., additional, and Hofstadter, Mark D., additional

Published
2021
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19. Keys of a Mission to Uranus or Neptune, the Closest Ice Giants

Author

Guillot, Tristan, primary, Fortney, Jonathan, additional, Rauscher, Emily, additional, Marley, Mark S., additional, Parmentier, Vivien, additional, Line, Mike, additional, Wakeford, Hannah, additional, Kaspi, Yohai, additional, Helled, Ravit, additional, Ikoma, Masahiro, additional, Knutson, Heather, additional, Menou, Kristen, additional, Valencia, Diana, additional, Durante, Daniele, additional, Ida, Shigeru, additional, Bolton, Scott J, additional, Li, Cheng, additional, Stevenson, Kevin B., additional, Bean, Jacob, additional, Cowan, Nicolas B, additional, Hofstadter, Mark D., additional, Alonso, Ricardo Hueso, additional, Leconte, Jérémy, additional, Li, Liming, additional, Mordasini, Christoph, additional, Mousis, Olivier, additional, Nettelmann, Nadine, additional, Soderlund, Krista, additional, and Wong, Mike, additional

Published
2021
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20. Seasonal change in the deep atmosphere of Uranus

Author

Hofstadter, Mark D. and Butler, Bryan J.

Subjects
Troposphere -- Observations, Seasons -- Observations, Uranus (Planet) -- Observations, Astronomy, Earth sciences
Abstract

We present high-resolution radio maps of Uranus, made from data collected in 1994 at wavelengths of 2 and 6 cm, which show large-scale changes occurring deep and rapidly in the troposphere. Brightness features in these maps are significantly different from those observed throughout the 1980's. These differences are not due to the changing viewing geometry, but result from atmospheric changes in the 5 to 50 bar region. All the observations show strong latitudinal variations in absorber abundance and/or temperature, causing the South Pole to appear brighter than lower latitudes. The transition between bright pole and darker latitudes is always near -45 [degrees], but between 1989 and 1994 the contrast between the regions increased significantly. This suggests that the large-scale circulation in the upper 50 bars of the uranian Southern Hemisphere changed. Older, disk-averaged microwave observations have suggested that seasonal variability occurs, but these new maps are the first to provide detailed timing and location information which can be used to test dynamical models. Keywords: Uranus; Giant planet; Microwave

Published
2003

21. AIRS/AMSU/HSB validation

Author

Fetzer, Eric, McMillin, Larry M., Tobin, David, Aumann, Hartmut H., Gunson, Michael R., McMillan, W. Wallace, Hagan, Denise E., Hofstadter, Mark D., Yoe, James, Whiteman, David N., Barnes, John E., Bennartz, Ralf, Vomel, Holger, Walden, Von, Newchurch, Michael, Minnett, Peter J., Atlas, Robert, Schmidlin, Francis, Olsen, Edward T., Goldberg, Mitchell D., Zhou, Sisong, Ding, HanJung, Smith, William L., and Revercomb, Hank

Subjects
Artificial satellites in remote sensing -- Methods, Artificial satellites in remote sensing -- Equipment and supplies, Atmospheric research -- Equipment and supplies, Infrared spectroscopy -- Equipment and supplies, Radiometers -- Usage, Radiometers -- Evaluation, Business, Earth sciences, Electronics and electrical industries
Abstract

The Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit/Humidity Sounder for Brazil (AIRS/AMSU/HSB) instrument suite onboard Aqua observes infrared and microwave radiances twice daily over most of the planet. AIRS offers unprecedented radiometric accuracy and signal to noise throughout the thermal infrared. Observations from the combined suite of AIRS, AMSU, and HSB are processed into retrievals of atmospheric parameters such as temperature, water vapor, and trace gases under all but the cloudiest conditions. A more limited retrieval set based on the microwave radiances is obtained under heavy cloud cover. Before measurements and retrievals from AIRS/AMSU/HSB instruments can be fully utilized they must be compared with the best possible in situ and other ancillary 'truth' observations. Validation is the process of estimating the measurement and retrieval uncertainties through comparison with a set of correlative data of known uncertainties. The ultimate goal of the validation effort is retrieved product uncertainties constrained to those of radiosondes: tropospheric rms uncertainties of 1.0[degrees]C over a 1-km layer for temperature, and 10% over 2-km layers for water vapor. This paper describes the data sources and approaches to be used for validation of the AIRS/AMSU/HSB instrument suite, including validation of the forward models necessary for calculating observed radiances, validation of the observed radiances themselves, and validation of products retrieved from the observed radiances. Constraint of the AIRS product uncertainties to within the claimed specification of 1 K/1 km over well-instrumented regions is feasible within 12 months of launch, but global validation of all AIRS/AMSU/HSB products may require considerably more time due to the novelty and complexity of this dataset and the sparsity of some types of correlative observations. Index Terms--Atmospheric measurements, infrared spectroscopy, inverse problems, microwave radiometry, remote sensing, terrestrial atmosphere.

Published
2003

22. Formulation and validation of simulated data for the Atmospheric Infrared Sounder (AIRS)

Author

Fishbein, Evan, Farmer, C.B., Granger, S.L., Gregorich, David T., Gunson, Michael R., Hannon, Scott E., Hofstadter, Mark D., Lee, Sung-Yung, Leroy, S.S, and Strow, L. Larrabee

Subjects
Artificial satellites in remote sensing -- Equipment and supplies, Business, Earth sciences, Electronics and electrical industries
Abstract

Models for synthesizing radiance measurements by the Atmospheric Infrared Sounder (AIRS) are described. Synthetic radiances have been generated for developing and testing data processing algorithms. The radiances are calculated from geophysical states derived from weather forecasts and climatology using the AIRS rapid transmission algorithm. The data contain horizontal variability at the spatial resolution of AIRS from the surface and cloud fields. This is needed to test retrieval algorithms under partially cloudy conditions. The surface variability is added using vegetation and International Geosphere Biosphere Programme surface type maps, while cloud variability is added randomly. The radiances are spectrally averaged to create High Resolution Infrared Sounder (HIRS) data, and this is compared with actual HIRS2 data on the NOAA 14 satellite. The simulated data underrepresent high-altitude equatorial cirrus clouds and have too much local variability. They agree in the mean to within 1-4 K, and global standard deviation agrees to better than 2 K. Simulated data have been a valuable tool for developing retrieval algorithms and studying error characteristics and will continue to be so after launch. Index Terms--Algorithm development, atmospheric retrieval, cloud scene modeling, data simulation, High Resolution Infrared Sounder (HIRS), satellite remote sensing.

Published
2003

23. AIRS/Vis near IR instrument

Author

Gautier, Catherine, Shiren, Yang, and Hofstadter, Mark D.

Subjects
Clouds -- Research, Cloud physics -- Research, Business, Earth sciences, Electronics and electrical industries
Abstract

A component of the Atmospheric Infrared Sounder (AIRS) instrument system is the AIRS/Visible Near InfraRed (Vis/NIR) instrument. With a nadir ground resolution of 2.28 km and four channels, the Vis/NIR instrument provides diagnostic support to the infrared retrievals from the AIRS instrument and several research products, including surface solar flux studies. The AIRS Vis/NIR is composed of three narrowband (channel 1: 0.40-0.44 [micro]m; channel 2:0.58-0.68 [micro]m, and channel 3: 0.71-0.92 [micro]m) and one broadband (channel 4: 0.49-0.94 [micro]m) channel, each a linear detector array of nine pixels. It is calibrated onboard with three tungsten lamps. Vicarious calibrations using ground targets of known reflectance and a cross-calibration with the Moderate Resolution Imaging Spectroradiometer (MODIS) augment the onboard calibration. One of AIRS Vis/NIR's principal supporting functions is the detection of low clouds to flag these conditions for atmospheric temperature retrievals. Once clouds are detected, a cloud height index is obtained based on the ratio (channel 2--channel 3)/channel 1 that is sensitive to the partitioning of water vapor absorption above and below clouds. The determination of the surface solar radiation flux is principally based on channel 4 broadband measurements and the well-established relationship between top-of-the atmosphere (broadband) radiance and the surface irradiance. Index Terms--Calibration, cloud detection, cloud height, surface irradiance, surface solar radiation, three-dimensional (3-D) cloud effects, visible, near Infra-Red.

Published
2003

24. Science Opportunity Analyzer (SOA) Version 8

Author

Witoff, Robert J, Polanskey, Carol A, Aguinaldo, Anna Marie A, Liu, Ning, and Hofstadter, Mark D

Subjects
Man/System Technology And Life Support
Abstract

SOA allows scientists to plan spacecraft observations. It facilitates the identification of geometrically interesting times in a spacecraft s orbit that a user can use to plan observations or instrument-driven spacecraft maneuvers. These observations can then be visualized multiple ways in both two- and three-dimensional views. When observations have been optimized within a spacecraft's flight rules, the resulting plans can be output for use by other JPL uplink tools. Now in its eighth major version, SOA improves on these capabilities in a modern and integrated fashion. SOA consists of five major functions: Opportunity Search, Visualization, Observation Design, Constraint Checking, and Data Output. Opportunity Search is a GUI-driven interface to existing search engines that can be used to identify times when a spacecraft is in a specific geometrical relationship with other bodies in the solar system. This function can be used for advanced mission planning as well as for making last-minute adjustments to mission sequences in response to trajectory modifications. Visualization is a key aspect of SOA. The user can view observation opportunities in either a 3D representation or as a 2D map projection. Observation Design allows the user to orient the spacecraft and visualize the projection of the instrument field of view for that orientation using the same views as Opportunity Search. Constraint Checking is provided to validate various geometrical and physical aspects of an observation design. The user has the ability to easily create custom rules or to use official project-generated flight rules. This capability may also allow scientists to easily assess the cost to science if flight rule changes occur. Data Output allows the user to compute ancillary data related to an observation or to a given position of the spacecraft along its trajectory. The data can be saved as a tab-delimited text file or viewed as a graph. SOA combines science planning functionality unique to both JPL and the sponsoring spacecraft. SOA is able to ingest JPL SPICE Kernels that are used to drive the tool and its computations. A Percy search engine is then included that identifies interesting time periods for the user to build observations. When observations are then built, flight-like orientation algorithms replicate spacecraft dynamics to closely simulate the flight spacecraft s dynamics. SOA v8 represents large steps forward from SOA v7 in terms of quality, reliability, maintainability, efficiency, and user experience. A tailored agile development environment has been built around SOA that provides automated unit testing, continuous build and integration, a consolidated Web-based code and documentation storage environment, modern Java enhancements, and a focus on usability

Published
2013

25. Ice sublimation and rheology - Implications for the Martian polar layered deposits

Author

Hofstadter, Mark D and Murray, Bruce C

Subjects
Lunar And Planetary Exploration
Abstract

If the sublimation and creep of water ice are important processes in the Martian polar layered deposits, ice-rich scenario formation and evolution schemes must invoke a mechanism for the inhibition of sublimation, such as a dust layer derived from the residue of the sublimating deposits. This layer could be of the order of 1 m in thickness. If the deposits are ice-rich, flows of more than 1 km should have occurred. It is noted that the dust particles in question may be cemented by such ice that may be present, but that impurities may also have served to cement dust particles together even in the absence of ice.

Published
1990
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26. Vertical motions in the Uranian atmosphere - An analysis of radio observations

Author

Hofstadter, Mark D, Berge, Glenn L, and Muhleman, Duane O

Subjects
Lunar And Planetary Exploration
Abstract

The present, 6-cm radio map of Uranus indicates latitudinal features which may be due to vertical motions of the atmosphere. It appears in light of Voyager IR measurements as well as previously obtained radio data that these large-scale vertical motions, which have not undergone significant changes over the course of 8 years, extend from the 0.1- to the 45-bar levels; this span corresponds to a height of the order of 250 km. The latitudinal structures are believed to be primarily caused by horizontal variations of absorber abundances.

Published
1990
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27. Inhomogeneity in composition and surface morphology implied from continuum observations of 67P/Churyumov-Gerasimenko with Microwave Instrument on the Rosetta Orbiter (MIRO)

Author

Allmen, Paul Von, Allen, Mark, Beaudin, Gérard, Biver, Nicolas, Bockelée-Morvan, Dominique, Choukroun, Mathieu, Crovisier, Jacques, Encrenaz, Pierre J., Encrenaz, Thérèse, Frerking, Margaret A., Gulkis, Samuel, Hartough, Paul, Hofstadter, Mark D., Ip, W., Janssen, Michael A., Jarchow, Christopher, Keihm, Stephen, Lellouch, Emmanuel, Leyrat, Cédric, Rezac, Ladislav, Schloerb, Peter, Spilker, Thomas R., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2014

28. Millimeter and Submillimeter Observations of comet 67P/C-G with the MIRO Instrument

Author

Hofstadter, Mark D., Allen, Mark, Allmen, Paul Von, Beaudin, Gérard, Biver, Nicolas, Bockelée-Morvan, Dominique, Choukroun, Mathieu, Crovisier, Jacques, Encrenaz, Pierre J., Encrenaz, Thérèse, Frerking, Margaret A., Gulkis, Samuel, Hartogh, Paul, Ip, W., Janssen, Michael A., Jarchow, Christopher, Kamp, Lucas W., Keihm, Stephen, Lee, Seungwon, Lellouch, Emmanuel, Leyrat, Cédric, Rezac, Ladislav, Schloerb, Frederick P., Spilker, Thomas R., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2014

29. Evolution of H2O coma of comet 67P/Churuymov-Gerasimenko observed from the Microwave Instrument on the Rosetta Orbiter (MIRO)

Author

Lee, Seungwon, Biver, Nicolas, Rezac, Ladislav, Allmen, Paul Von, Allen, Mark, Beaudin, Gérard, Bockelée-Morvan, Dominique, Choukroun, Mathieu, Crovisier, Jacques, Encrenaz, Pierre J., Encrenaz, Thérèse, Frerking, Margaret A., Gulkis, Samuel, Hartogh, Paul, Hofstadter, Mark D., Ip, W., Janssen, Michael A., Jarchow, Christopher, Keihm, Stephen, Lellouch, Emmanuel, Leyrat, Cédric, Schloerb, Frederick P., Spilker, Thomas R., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2014

30. Analogy: The vital talent that fuels our minds

Author

Hofstadter, Mark D., Emmanuel, Sander, and Paragraphe, Laboratoire

Subjects
[SHS.PSY] Humanities and Social Sciences/Psychology, [SHS] Humanities and Social Sciences
Published
2013

31. Pourquoi fonctionnons-nous par analogie

Author

Hofstadter, Mark D., Sander, Emmanuel, and Paragraphe, Laboratoire

Subjects
[SHS.PSY] Humanities and Social Sciences/Psychology, [SHS] Humanities and Social Sciences
Published
2013

32. Sub-millimeter Observation of Water Vapor at 557 GHz in Comet C/2002 T7 (LINEAR)

Author

Lee, Seungwon, Hofstadter, Mark D., Frerking, Margaret A., Gulkis, Samuel, Allmen, Paul Von, Kamp, Lucas W., Crovisier, Jacques, Biver, Nicolas, Bockelée-Morvan, Dominique, Choukroun, Mathieu, Keihm, Stephen, Janssen, Michael A., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

33. Surfaces and Essences: Analogy as the fuel and fire of thinking

Author

Sander, Emmanuel, Hofstadter, Mark D., Laboratoire Paragraphe (PARAGRAPHE), Université Paris 8 Vincennes-Saint-Denis (UP8)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), and Paragraphe, Laboratoire

Subjects
[SHS.PSY] Humanities and Social Sciences/Psychology, [SHS.PSY]Humanities and Social Sciences/Psychology, [SHS] Humanities and Social Sciences, ComputingMilieux_MISCELLANEOUS, [SHS]Humanities and Social Sciences
Abstract

International audience

Published
2013

34. L’Analogie : coeur de la pensée

Author

Hofstadter, Mark D., Emmanuel, Sander, Paragraphe, Laboratoire, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Laboratoire Paragraphe (PARAGRAPHE), Université Paris 8 Vincennes-Saint-Denis (UP8)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine

Subjects
[SHS.PSY] Humanities and Social Sciences/Psychology, [SHS.PSY]Humanities and Social Sciences/Psychology, [SHS] Humanities and Social Sciences, ComputingMilieux_MISCELLANEOUS, [SHS]Humanities and Social Sciences
Abstract

International audience

Published
2013

35. MIRO Observation of Comet C/2002 T7 (LINEAR) Water Line Spectrum

Author

Lee, S., Frerking, Margaret A., Hofstadter, Mark D., Gulkis, Samuel, Allmen, Paul Von, Crovisier, Jacques, Biver, Nicolas, Bockelée-Morvan, Dominique, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2011

36. Mapping of CO and HCN emission in Neptune's stratosphere

Author

Moullet, Arielle, Gurwell, Mark A., Hofstadter, Mark D., Lellouch, Emmanuel, Moreno, Raphaël, Butler, B., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2011

37. Spatially Resolved Thermal Imaging and Spectroscopy of Uranus and Neptune

Author

Orton, Glenn S., Hofstadter, Mark D., Leyrat, Cédric, Encrenaz, Thérèse, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2007

38. Microwave instrument for the Rosetta orbiter (MIRO)

Author

Deschamps, André, Allen, Mark, Beaudin, Gérard, Biver, Nicolas, Bockelée-Morvan, Dominique, Crovisier, Jacques, Despois, Didier, Encrenaz, Pierre J., Encrenaz, Thérèse, Frerking, Margaret A., Gulkis, Samuel, Hartogh, Paul, Hofstadter, Mark D., Ip, W., Janssen, Michael A., Jarchow, Christopher, Koch, Timothy, Krieg, Jean-Michel, Lellouch, Emmanuel, Mann, Ingrid, Muhleman, Duane, Schloerb, Peter, Spilker, Thomas R., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2005

39. Microwave Instrument for the Rosetta Orbiter (MIRO)

Author

Gulkis, Samuel, Allen, Mark, Beaudin, Gérard, Biver, Nicolas, Bockelée-Morvan, Dominique, Crovisier, Jacques, Despois, Didier, Encrenaz, Pierre J., Encrenaz, Thérèse, Frerking, Margaret A., Hartogh, Paul, Hofstadter, Mark D., Ip, W., Janssen, Michael A., Lellouch, Emmanuel, Mann, Ingrid, Muhleman, Duane, Rauer, Heike, Schloerb, Frederick P., Spilker, Thomas R., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2003

40. DSS-28: a novel wide bandwidth radio telescope devoted to educational outreach

Author

Stepp, Larry M., Gilmozzi, Roberto, Hall, Helen J., Jones, Glenn, Weinreb, Sander, Mani, Hamdi, Smith, Stephen, Teitelbaum, Lawrence, Hofstadter, Mark D., Kuiper, Thomas B. H., Imbriale, William A., Dorcey, Ryan, Leflang, John, Stepp, Larry M., Gilmozzi, Roberto, Hall, Helen J., Jones, Glenn, Weinreb, Sander, Mani, Hamdi, Smith, Stephen, Teitelbaum, Lawrence, Hofstadter, Mark D., Kuiper, Thomas B. H., Imbriale, William A., Dorcey, Ryan, and Leflang, John

Abstract

We have recently equipped the 34-meter DSS-28 radio telescope at the Goldstone Deep Space Communications Complex with a novel wide bandwidth radiometer and digital signal processor as part of the Goldstone Apple Valley Radio Telescope (GAVRT) educational outreach program operated by the Jet Propulsion Laboratory and the Lewis Center for Educational Research. The system employs a cryogenically cooled wide bandwidth quad-ridge feed and InP low noise amplifiers to achieve excellent noise performance from 2.7 to 14 GHz; a fractional bandwidth better than 4:1. Four independently tunable dual-polarization receivers each down-convert a 2 GHz block to baseband, providing access to 8 GHz of instantaneous bandwidth. A flexible FPGA-based signal processor has been constructed using CASPER FPGA hardware and tools to take advantage of this enormous bandwidth. This system demonstrates many of the enabling wide bandwidth technologies that will be crucial to maximizing the utility of future large centimeter-wavelength arrays, in particular the Square Kilometer Array. The GAVRT program has previously used narrow bandwidth total power radiometers to study flux variability of quasars and the outer planets. The versatility of DSS-28 will enable other projects including spectroscopy and SETI. Finally, the wide instantaneous bandwidth available makes this system uniquely suited for studying transient radio pulses. A configuration of the digital signal processor has been developed which provides the capability of recording a burst of raw baseband voltage data triggered by a real-time incoherent dedispersion system which is very sensitive to pulses from a known source, such as the Crab Nebula pulsar.

Published
2010

41. Uranus Pathfinder: exploring the origins and evolution of Ice Giant planets

Author

Arridge, Christopher S., primary, Agnor, Craig B., additional, André, Nicolas, additional, Baines, Kevin H., additional, Fletcher, Leigh N., additional, Gautier, Daniel, additional, Hofstadter, Mark D., additional, Jones, Geraint H., additional, Lamy, Laurent, additional, Langevin, Yves, additional, Mousis, Olivier, additional, Nettelmann, Nadine, additional, Russell, Christopher T., additional, Stallard, Tom, additional, Tiscareno, Matthew S., additional, Tobie, Gabriel, additional, Bacon, Andrew, additional, Chaloner, Chris, additional, Guest, Michael, additional, Kemble, Steve, additional, Peacocke, Lisa, additional, Achilleos, Nicholas, additional, Andert, Thomas P., additional, Banfield, Don, additional, Barabash, Stas, additional, Barthelemy, Mathieu, additional, Bertucci, Cesar, additional, Brandt, Pontus, additional, Cecconi, Baptiste, additional, Chakrabarti, Supriya, additional, Cheng, Andy F., additional, Christensen, Ulrich, additional, Christou, Apostolos, additional, Coates, Andrew J., additional, Collinson, Glyn, additional, Cooper, John F., additional, Courtin, Regis, additional, Dougherty, Michele K., additional, Ebert, Robert W., additional, Entradas, Marta, additional, Fazakerley, Andrew N., additional, Fortney, Jonathan J., additional, Galand, Marina, additional, Gustin, Jaques, additional, Hedman, Matthew, additional, Helled, Ravit, additional, Henri, Pierre, additional, Hess, Sebastien, additional, Holme, Richard, additional, Karatekin, Özgur, additional, Krupp, Norbert, additional, Leisner, Jared, additional, Martin-Torres, Javier, additional, Masters, Adam, additional, Melin, Henrik, additional, Miller, Steve, additional, Müller-Wodarg, Ingo, additional, Noyelles, Benoît, additional, Paranicas, Chris, additional, de Pater, Imke, additional, Pätzold, Martin, additional, Prangé, Renée, additional, Quémerais, Eric, additional, Roussos, Elias, additional, Rymer, Abigail M., additional, Sánchez-Lavega, Agustin, additional, Saur, Joachim, additional, Sayanagi, Kunio M., additional, Schenk, Paul, additional, Schubert, Gerald, additional, Sergis, Nick, additional, Sohl, Frank, additional, Sittler, Edward C., additional, Teanby, Nick A., additional, Tellmann, Silvia, additional, Turtle, Elizabeth P., additional, Vinatier, Sandrine, additional, Wahlund, Jan-Erik, additional, and Zarka, Philippe, additional

Published
2011
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42. Latitudinal variations of ammonia in the atmosphere of Uranus - An analysis of microwave observations

Author

Hofstadter, Mark D and Muhleman, Duane O

Subjects
Lunar And Planetary Exploration
Abstract

A 2-cm wavelength VLA map of Uranus is found upon analysis to display strong limb darkening and a lack of symmetry about the subearth point, perhaps due to a latitudinally varying NH3 mixing ratio. The change in NH3 abundance occurs near -45 deg latitude, and the calculated NH3 molar mixing ratios in the 5-20 bar region average 4.9 + or - 0.7 x 10 to the -7th at -90 to -45 deg latitudes, and 1.3 + or - 0.4 x 10 to the -6th at -45 to -15 deg latitudes. The model is in agreement both with previous work indicating the depletion of ammonia relative to solar abundance and a preliminary analysis of 6-cm data.

Published
1989
Full Text
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