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203. MAVEN Case Studies of Plasma Dynamics in Low‐Altitude Crustal Magnetic Field at Mars 1: Dayside Ion Spikes Associated With Radial Crustal Magnetic Fields

Author

Soobiah, Y. I. J., primary, Espley, Jared R., additional, Connerney, John E. P., additional, Gruesbeck, Jacob R., additional, DiBraccio, Gina A., additional, Halekas, Jasper, additional, Andersson, Laila, additional, Fowler, Christopher M., additional, Lillis, Robert J., additional, Mitchell, David L., additional, Mazelle, Christian, additional, Harada, Yuki, additional, Hara, Takuya, additional, Collinson, Glyn, additional, Brain, David, additional, Xu, Shaosui, additional, Curry, Shannon M., additional, Mcfadden, James P., additional, Benna, Mehdi, additional, and Jakosky, Bruce M., additional

Published
2019
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204. Solutions to the chronic wounds problem in Australia: A call to action

Author

Pacella, Rosana, Tulleners, Ruth, Cheng, Qinglu, Burkett, Ellen, Edwards, Helen, Yelland, Stephen, Brain, David, Bingley, John, Lazzarini, Peter, Warnock, Jason, Barnsbee, Louise, Pacella, Tamzin, Clark, Kevin, Smith, Michele, Iddir, Aisling, Griffiths, Ian, Sussman, Geoff, Van Netten, Jaap, Gibb, Michelle, Gordon, Jodie, Harvey, Gillian, Hickling, Donna, Lee, Xing, Ploderer, Bernd, Vallejo, Alison, Whalley, Sharon, Graves, Nicholas, Pacella, Rosana, Tulleners, Ruth, Cheng, Qinglu, Burkett, Ellen, Edwards, Helen, Yelland, Stephen, Brain, David, Bingley, John, Lazzarini, Peter, Warnock, Jason, Barnsbee, Louise, Pacella, Tamzin, Clark, Kevin, Smith, Michele, Iddir, Aisling, Griffiths, Ian, Sussman, Geoff, Van Netten, Jaap, Gibb, Michelle, Gordon, Jodie, Harvey, Gillian, Hickling, Donna, Lee, Xing, Ploderer, Bernd, Vallejo, Alison, Whalley, Sharon, and Graves, Nicholas

Abstract

Chronic wounds are an under-recognised issue in Australian healthcare, and are under-considered in terms of both research and public policy receiving little attention and investment compared to other chronic conditions...

Published
2018

205. Reducing length of stay to improve Clostridium difficile-related health outcomes

Author

Brain, David, Barnett, Adrian, Yakob, Laith, Clements, Archie, Riley, Thomas, Balcon, Kate, Graves, Nicholas, Brain, David, Barnett, Adrian, Yakob, Laith, Clements, Archie, Riley, Thomas, Balcon, Kate, and Graves, Nicholas

Abstract

Background Clostridium difficile infection is a serious hospital-acquired infection, causing negative outcomes for those who are afflicted by it. Hospital length of stay is known to be a risk factor for transmission and significant reductions in infection numbers can be realised if transmission is reduced. Methods A Markov model was constructed to compare the impact that five alternative healthcare scenarios had on total C. difficile infections, QALYs gained and total number of patients requiring treatment in ICU. A previously published stochastic transmission model for C. difficile informed scenario effectiveness, while other parameters were estimated from published literature, administrative datasets and expert opinion. Results Reducing inpatient LOS disrupts transmission of C. difficile and results in a large reduction of total infections. In turn, an increase in QALYs is expected when the number of infections is reduced. A reduction in infections reduces the number of ICU admissions, which is likely to have a large economic benefit in the Australian setting. Coupling a reduction in overall inpatient LOS with a ‘traditional’ infection control intervention, such as hand hygiene or antimicrobial stewardship, improves results further than reducing LOS on its own. Conclusion Implementing a LOS-focused intervention would be a practical challenge, especially for clinicians who already juggle high demand. However, it is not unattainable with the right local endorsement and could have significant benefits for health services.

Published
2018

206. Economic evaluation of interventions designed to reduce Clostridium difficile infection

Author

Brain, David, Yakob, Laith, Barnett, Adrian, Riley, Thomas, Clements, Archie, Balcon, Kate, Graves, Nicholas, Brain, David, Yakob, Laith, Barnett, Adrian, Riley, Thomas, Clements, Archie, Balcon, Kate, and Graves, Nicholas

Abstract

Introduction Healthcare decision-makers are increasingly expected to balance increasing demand for health services with a finite budget. The role of economic evaluation in healthcare is increasing and this research provides decision-makers with new information about the management of Clostridium difficile infection, from an economic perspective. Methods A model-based economic evaluation was undertaken to identify the most cost-effective healthcare intervention relating to the reduction of Clostridium difficile transmission. Efficacy evidence was synthesised from the literature and was used to inform the effectiveness of both bundled approaches and stand-alone interventions, where appropriate intervention combinations were coupled together. Changes in health outcomes were estimated by combining information about intervention effectiveness and its subsequent impact on quality of life. Results A bundled approach of improving hand hygiene and environmental cleaning produces the best combination of increased health benefits and cost-savings. It has the highest mean net monetary benefit when compared to all other interventions. This intervention remains the optimal decision under different clinical circumstances, such as when mortality rate and patient length of stay are increased. Bundled interventions offered the best opportunity for health improvements. Conclusion These findings provide healthcare decision-makers with novel information about the allocation of scarce resources relating to Clostridium difficile. If investments are not made in interventions that clearly yield gains in health outcomes, the allocation and use of scarce healthcare resources is inappropriate and improvements in health outcomes will be forgone.

Published
2018

210. Assessment of health‐related quality of life and health utilities in Australian patients with cirrhosis.

Author

McPhail, Steven M, Amarasena, Samath, Stuart, Katherine A, Hayward, Kelly, Gupta, Rohit, Brain, David, Hartel, Gunter, Rahman, Tony, Clark, Paul J, Bernardes, Christina M, Skoien, Richard, Mckillen, Benjamin, Lee, Andrew, Pillay, Leshni, Lin, Lei, Khaing, Myat Myat, Horsfall, Leigh, Powell, Elizabeth E, and Valery, Patricia C

Subjects
CIRRHOSIS of the liver, QUALITY of life
Abstract

Background and Aim: Health‐related quality‐of‐life measurements are important to understand lived experiences of patients who have cirrhosis. These measures also inform economic evaluations by modelling quality‐adjusted life years (QALYs). We aimed to describe health‐related quality of life, specifically multiattribute utility (scale anchors of death = 0.00 and full health = 1.00), across various stages and etiologies of cirrhosis. Methods: Face‐to‐face interviews were used to collect Short Form 36 (SF‐36) questionnaire responses from CirCare study participants with cirrhosis (June 2017 to December 2018). The severity of cirrhosis was assessed using the Child‐Pugh score classified as class A (5–6 points), B (7–9), or C (10–15) and by the absence ("compensated") versus presence ("decompensated") of cirrhosis‐related complications. Results: Patients (n = 562, average 59.8 years [SD = 11.0], male 69.9%) had a range of primary etiologies (alcohol‐related 35.2%, chronic hepatitis C 25.4%, non‐alcoholic fatty liver disease (NAFLD) 25.1%, chronic hepatitis B 5.9%, "other" 8.4%). Significantly lower (all P < 0.001) mean multiattribute utility was observed in the health states of patients with decompensated (mean = 0.62, SD = 0.15) versus compensated cirrhosis (mean = 0.68, SD = 0.12), Child‐Pugh class C (mean = 0.59, SD = 0.15) or B (mean = 0.63, SD = 0.15) versus A (mean = 0.68, SD = 0.16), and between those of working age (18–64 years; mean = 0.64, SD = 0.16) versus those aged 65+ years (mean = 0.70, SD = 0.16). The greatest decrements in health‐related quality of life relative to Australian population norms were observed across physical SF‐36 domains. Conclusions: Persons with more advanced cirrhosis report greater life impacts. Estimates from this study are suitable for informing economic evaluations, particularly cost‐utility modelling, which captures the benefits of effective prevention, surveillance, and treatments on both the quality and quantity of patients' lives. [ABSTRACT FROM AUTHOR]

Published
2021
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211. On the origins of magnetic flux ropes in near-Mars magnetotail current sheets

Author

Hara, Takuya, Harada, Yuki, Mitchell, David L., Dibraccio, Gina A., Espley, Jared R., Brain, David A., Halekas, Jasper S., Seki, Kanako, Luhmann, Janet G., Mcfadden, James P., Mazelle, Christian, Jakosky, Bruce M., Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
magnetotail, [SDU]Sciences of the Universe [physics], current sheet, Physics::Space Physics, reconnection, Astrophysics::Solar and Stellar Astrophysics, Mars, MAVEN, Astrophysics::Earth and Planetary Astrophysics, flux rope
Abstract

International audience; We analyze Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of magnetic flux ropes embedded in Martian magnetotail current sheets, in order to evaluate the role of magnetotail reconnection in their generations. We conduct a minimum variance analysis to infer the generation processes of magnetotail flux ropes from the geometrical configuration of the individual flux rope axial orientation with respect to the overall current sheet. Of 23 flux ropes detected in current sheets in the near-Mars (∼1-3 Martian radii downstream) magnetotail, only 3 (possibly 4) can be explained by the magnetotail reconnection scenario, while the vast majority of the events (19 events) are more consistent with flux ropes that are originally generated in the dayside ionosphere and subsequently transported into the nightside magnetotail. The mixed origins of the detected flux ropes imply complex nature of generation and transport of Martian magnetotail flux ropes.

Published
2017
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212. Statistical Study of Relations Between the Induced Magnetosphere, Ion Composition, and Pressure Balance Boundaries Around Mars Based On MAVEN Observations

Author

Matsunaga, Kazunari, Seki, Kanako, Brain, David A., Hara, Takuya, Masunaga, Kei, Mcfadden, James P., Halekas, Jasper S., Mitchell, David L., Mazelle, Christian, Espley, J. R., Gruesbeck, Jacob, Jakosky, Bruce M., Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
induced magnetosphere boundary, [SDU]Sciences of the Universe [physics], ion composition boundary, Mars, MAVEN, pressure balance boundary
Abstract

International audience; Direct interaction between the solar wind (SW) and the Martian upper atmosphere forms a characteristic region, called the induced magnetosphere between the magnetosheath and the ionosphere. Since the SW deceleration due to increasing mass loading by heavy ions plays an important role in the induced magnetosphere formation, the ion composition is also expected to change around the induced magnetosphere boundary (IMB). Here we report on relations of the IMB, the ion composition boundary (ICB), and the pressure balance boundary based on a statistical analysis of about 8 months of simultaneous ion, electron, and magnetic field observations by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We chose the period when MAVEN observed the SW directly near its apoapsis to investigate their dependence on SW parameters. Results show that IMBs almost coincide with ICBs on the dayside and locations of all three boundaries are affected by the SW dynamic pressure. A remarkable feature is that all boundaries tend to locate at higher altitudes in the southern hemisphere than in the northern hemisphere on the nightside. This clear geographical asymmetry is permanently seen regardless of locations of the strong crustal B fields in the southern hemisphere, while the boundary locations become higher when the crustal B fields locate on the dayside. On the nightside, IMBs usually locate at higher altitude than ICBs. However, ICBs are likely to be located above IMBs in the nightside, southern, and downward ESW hemisphere when the strong crustal B fields locate on the dayside.

Published
2017
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213. MAVEN observations of a giant ionospheric flux rope near Mars resulting from interaction between the crustal and interplanetary draped magnetic fields

Author

Brain, David A., Mitchell, David L., Luhmann, Janet G., Mcfadden, James P., Halekas, Jasper S., Espley, Jared R., Harada, Yuki, Livi, Roberto, DiBraccio, Gina A., Connerney, John E. P., Mazelle, Christian, Andersson, Laila, Jakosky, Bruce M., Hara, Takuya, Seki, Kanako, Hasegawa, Hiroshi, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université de Toulouse (UT)

Subjects
010504 meteorology & atmospheric sciences, Flux, Mars, MAVEN, ionosphere, 01 natural sciences, flux rope, Physics::Geophysics, ICME, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Grad-Shafranov equation, Pitch angle, Interplanetary magnetic field, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Martian, Physics, Mars Exploration Program, Atmosphere of Mars, Geophysics, Magnetic flux, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Interplanetary spaceflight
Abstract

著者人数: 16名, Accepted: 2016-12-07, 資料番号: SA1160336000

Published
2017
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214. The Spatial Structure of Martian Magnetic Flux Ropes Recovered by the Grad-Shafranov Reconstruction Technique

Author

Brain, David A., Hara, Takuya, Seki, Kanako, Hasegawa, Hiroshi, Matsunaga, Kazunari, and Saito, Miho H.

Subjects
Solar minimum, Physics, Martian, Astrophysics::High Energy Astrophysical Phenomena, Flux, Geophysics, Geodesy, Magnetic flux, Magnetic field, Orders of magnitude (time), Space and Planetary Science, Martian surface, Physics::Space Physics, Zenith
Abstract

Accepted: 2014-01-17, 資料番号: SA1004631000

Published
2014

215. A study of the effects of micro-gravity on seed germination

Author

Klein, Lynn Suzanne, Mckibben, Mark, Brain, David A, Johnson, Theodore C, and Dannenberg, Konrad K

Subjects
Life Sciences (General)
Abstract

This study will identify characteristics of seed germination dependent upon gravity. To accomplish this objective, four different seed types will be germinated in space and then be compared to a control group germinated on Earth. Both the experimental and control groups will be analyzed on the cellular level for the size of cells, structural anomalies, and gravitational effects. The experiment will be conducted in a Get Away Special Canister (GAS Can no. 608) owned by the U.S. Space and Rocket Center and designed for students. The GAS Can will remain in the cargo bay of the Space Shuttle with minimal astronaut interaction.

Published
1992

219. Evidence for Crustal Magnetic Field Control of Ions Precipitating Into the Upper Atmosphere of Mars

Author

Hara, Takuya, primary, Luhmann, Janet G., additional, Leblanc, François, additional, Curry, Shannon M., additional, Halekas, Jasper S., additional, Seki, Kanako, additional, Brain, David A., additional, Harada, Yuki, additional, Mcfadden, James P., additional, DiBraccio, Gina A., additional, Soobiah, Yasir I. J., additional, Mitchell, David L., additional, Xu, Shaosui, additional, Mazelle, Christian, additional, and Jakosky, Bruce M., additional

Published
2018
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222. The Three-Dimensional Bow Shock of Mars as Observed by MAVEN

Author

Gruesbeck, Jacob R., primary, Espley, Jared R., additional, Connerney, John E. P., additional, DiBraccio, Gina A., additional, Soobiah, Yasir I., additional, Brain, David, additional, Mazelle, Christian, additional, Dann, Julian, additional, Halekas, Jasper, additional, and Mitchell, David L., additional

Published
2018
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224. Modeling Martian Atmospheric Losses over Time: Implications for Exoplanetary Climate Evolution and Habitability

Author

Dong, Chuanfei, primary, Lee, Yuni, additional, Ma, Yingjuan, additional, Lingam, Manasvi, additional, Bougher, Stephen, additional, Luhmann, Janet, additional, Curry, Shannon, additional, Toth, Gabor, additional, Nagy, Andrew, additional, Tenishev, Valeriy, additional, Fang, Xiaohua, additional, Mitchell, David, additional, Brain, David, additional, and Jakosky, Bruce, additional

Published
2018
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225. The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

Author

DiBraccio, Gina A., primary, Luhmann, Janet G., additional, Curry, Shannon M., additional, Espley, Jared R., additional, Xu, Shaosui, additional, Mitchell, David L., additional, Ma, Yingjuan, additional, Dong, Chuanfei, additional, Gruesbeck, Jacob R., additional, Connerney, John E. P., additional, Harada, Yuki, additional, Ruhunusiri, Suranga, additional, Halekas, Jasper S., additional, Soobiah, Yasir, additional, Hara, Takuya, additional, Brain, David A., additional, and Jakosky, Bruce M., additional

Published
2018
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227. Ionizing Electrons on the Martian Nightside: Structure and Variability

Author

Lillis, Robert J., primary, Mitchell, David L., additional, Steckiewicz, Morgane, additional, Brain, David, additional, Xu, Shaosui, additional, Weber, Tristan, additional, Halekas, Jasper, additional, Connerney, Jack, additional, Espley, Jared, additional, Benna, Mehdi, additional, Elrod, Meredith, additional, Thiemann, Edward, additional, and Eparvier, Frank, additional

Published
2018
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231. Martian magnetism with orbiting sub-millimeter sensor:simulated retrieval system

Author

Larsson, Richard, Milz, Mathias, Ericksson, Patrick, Mendrok, Jana, Kasai, Yasuko, Buehler, Stefan Alexander, Dieval, Catherine Carmen Gisele, Brain, David, Harthog, Paul, Larsson, Richard, Milz, Mathias, Ericksson, Patrick, Mendrok, Jana, Kasai, Yasuko, Buehler, Stefan Alexander, Dieval, Catherine Carmen Gisele, Brain, David, and Harthog, Paul

Abstract

A Mars-orbiting sub-millimeter sensor can be used to retrieve the magnetic field at low altitudes over large areas of significant planetary crustal magnetism of the surface of Mars from measurements of circularly polarized radiation emitted by the 368 GHz ground-state molecular oxygen absorption line. We design a full retrieval system for one example orbit to show the expected accuracies on the magnetic field components that one realization of such a Mars satellite mission could achieve. For one set of measurements around a tangent profile, we find that the two horizontal components of the magnetic field can be measured at about 200 nT error with a vertical resolution of around 4 km from 6 up to 70 km in tangent altitude. The error is similar regardless of the true strength of the magnetic field, and it can be reduced by repeated measurements over the same area. The method and some of its potential pitfalls are described and discussed.

Published
2017

232. MAVEN observations of a giant ionospheric flux rope near Mars resulting from interaction between the crustal and interplanetary draped magnetic fields

Author

Hara, Takuya, Brain, David A., Mitchell, David L., Luhmann, Janet G., Seki, Kanako, Hasegawa, Hiroshi, Mcfadden, James P., Halekas, Jasper S., Espley, Jared R., Harada, Yuki, Livi, Roberto, DiBraccio, Gina A., Connerney, John E. P., Mazelle, Christian, Andersson, Laila, Jakosky, Bruce M., 原, 拓也, 関, 華奈子, 長谷川, 洋, Hara, Takuya, Brain, David A., Mitchell, David L., Luhmann, Janet G., Seki, Kanako, Hasegawa, Hiroshi, Mcfadden, James P., Halekas, Jasper S., Espley, Jared R., Harada, Yuki, Livi, Roberto, DiBraccio, Gina A., Connerney, John E. P., Mazelle, Christian, Andersson, Laila, Jakosky, Bruce M., 原, 拓也, 関, 華奈子, and 長谷川, 洋

Abstract

著者人数: 16名, Accepted: 2016-12-07

Published
2017

233. Economic evaluation of fecal microbiota transplantation for the treatment of recurrent Clostridium difficile infection in Australia

Author

Merlo, Gregory, Graves, Nicholas, Brain, David, Connelly, Luke B., Merlo, Gregory, Graves, Nichola, Brain, David, and Connelly, LUKE BRIAN

Subjects
economic evaluation, Time Factors, Hepatology, Clostridioides difficile, Cost-Benefit Analysis, Gastroenterology, Australia, cost-effectivene, Health Care Costs, Fecal Microbiota Transplantation, Drug Costs, Markov Chains, Anti-Bacterial Agents, Gastrointestinal Microbiome, Intestines, Models, Economic, Treatment Outcome, Cost Savings, Recurrence, Vancomycin, Clostridium difficile infection, Quality of Life, Humans, Quality-Adjusted Life Years, Enterocolitis, Pseudomembranous
Abstract

Background and Aim: Clostridium difficile is the most common cause of hospital-acquired diarrhea in Australia. In 2013, a randomized controlled trial demonstrated the effectiveness of fecal microbiota transplantation (FMT) for the treatment of recurrent Clostridium difficile infection (CDI). The aim of this study is to evaluate the cost-effectiveness of fecal microbiota transplantation—via either nasoduodenal or colorectal delivery—compared with vancomycin for the treatment of recurrent CDI in Australia. Methods: A Markov model was developed to compare the cost-effectiveness of fecal microbiota transplantation compared with standard antibiotic therapy. A literature review of clinical evidence informed the structure of the model and the choice of parameter values. Clinical effectiveness was measured in terms of quality-adjusted life years. Uncertainty in the model was explored using probabilistic sensitivity analysis. Results: Both nasoduodenal and colorectal FMT resulted in improved quality of life and reduced cost compared with vancomycin. The incremental effectiveness of either FMT delivery compared with vancomycin was 1.2 (95% CI: 0.1, 2.3) quality-adjusted life years, or 1.4 (95% CI: 0.4, 2.4) life years saved. Treatment with vancomycin resulted in an increased cost of AU$4094 (95% CI: AU$26, AU$8161) compared with nasoduodenal delivery of FMT and AU$4045 (95% CI: −AU$33, AU$8124) compared with colorectal delivery. The mean difference in cost between colorectal and nasoduodenal FMT was not significant. Conclusions: If FMT, rather than vancomycin, became standard care for recurrent CDI in Australia, the estimated national healthcare savings would be over AU$4000 per treated person, with a substantial increase in quality of life.

Published
2014

234. MAVEN observations of atmospheric loss at Mars

Author

Curry, Shannon, Luhmann, Janet, Jakosky, Bruce M., Brain, David, Leblanc, Francis, Modolo, Ronan, Halekas, Jasper S., Schneider, Nicholas M., Deighan, Justin, Mcfadden, James, Espley, Jared R., Mitchell, David L., Connerney, J. E. P., Dong, Yaxue, Dong, Chuanfei, Ma, Yingjuan, Cohen, Ofer, Fränz, Markus, Holmström, Mats, Ramstad, Robin, Hara, Takuya, Lillis, Robert J., Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Département de physique et d'astronomie, Université de Moncton, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], NASA Goddard Space Flight Center (GSFC), Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Swedish Institute of Space Physics [Kiruna] (IRF), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
Physics::Space Physics, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics
Abstract

International audience; The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been making observations of the Martian upper atmosphere and its escape to space since November 2014. The subject of atmospheric loss at terrestrial planets is a subject of intense interest not only because of the implications for past and present water reservoirs, but also for its impacts on the habitability of a planet. Atmospheric escape may have been especially effective at Mars, relative to Earth or Venus, due to its smaller size as well as the lack of a global dynamo magnetic field. Not only is the atmosphere less gravitationally bound, but also the lack of global magnetic field allows the impinging solar wind to interact directly with the Martian atmosphere. When the upper atmosphere is exposed to the solar wind, planetary neutrals can be ionized and 'picked up' by the solar wind and swept away.Both neutral and ion escape have played significant roles the long term climate change of Mars, and the MAVEN mission was designed to directly measure both escaping planetary neutrals and ions with high energy, mass, and time resolution. We will present 1.5 years of observations of atmospheric loss at Mars over a variety of solar and solar wind conditions, including extreme space weather events. We will report the average ion escape rate and the spatial distribution of escaping ions as measured by MAVEN and place them in context both with previous measurements of ion loss by other spacecraft (e.g. Phobos 2 and Mars Express) and with estimates of neutral escape rates by MAVEN. We will then report on the measured variability in ion escape rates with different drivers (e.g. solar EUV, solar wind pressure, etc.) and the implications for the total ion escape from Mars over time. Additionally, we will also discuss the implications for atmospheric escape at exoplanets, particularly weakly magnetized planetary bodies orbiting M-dwarfs, and the dominant escape mechanisms that may drive atmospheric erosion in other stellar systems.

Published
2016

235. Plasma acceleration in the Martian magnetotail

Author

Esteban Hernandez, Rosa, Modolo, Ronan, Leblanc, François, Chaufray, Jean-Yves, Curry, Shannon M., Steckiewicz, Morgane, Connerney, John E. P., Mcfadden, James P., Jakosky, Bruce M., Brain, David A., DiBraccio, Gina A., Romanelli, Norberto, Halekas, Jasper S., Mitchell, David L., HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Instituto de Astronomía y Física del Espacio [Buenos Aires] (IAFE), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad de Buenos Aires [Buenos Aires] (UBA), Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; Since November 2014, the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been collecting data from Mars’s upper atmosphere and induced magnetosphere (Jakosky et al., 2015). Evidences of escaping planetary ions have been reported from earlier missions as Mars-Express (Barabash et al., 2007) and more recently from MAVEN (e.g. Dong et al., 2015, Brain et al., 2015). Our goal is to determine the acceleration mechanism responsible for the energization of planetary ions in the Martian plasma sheet. MAVEN has a full plasma package with a magnetometer and plasma particles instruments, which allow to address the question of plasma particle acceleration.According to Dubinin et al. (2011), the j x B force due to magnetic shear stresses of the draped field lines is expected to play a major role in such energization process. On MAVEN data, we have first identified and characterized current sheet crossings taking place in Mars’ magnetotail and then tested the Walén relation to infer the significance of the j x B force in the particle’s energization. To characterize the plasma sheet crossing we have worked with MAVEN magnetometer (MAG, Connerney et al., SSR, 2015) and mass spectrometer (STATIC, McFadden et al., SSR, 2015) data, focusing on a particular event. We have performed a minimum variance analysis, on the magnetic field observations which allows to characterize the current sheet. We present results of the Walén test and our conclusions on planetary plasma acceleration in the plasma sheet region.

Published
2016

236. Mars-solar wind interaction: LatHyS, an improved parallel 3-D multispecies hybrid model

Author

Modolo, Ronan, Hess, Sebastien, Mancini, Marco, Leblanc, François, Chaufray, Jean-Yves, Brain, David, Leclercq, Ludivine, Esteban Hernandez, Rosa, Chanteur, Gérard, Weill, Philippe, González-Galindo, Francisco, Forget, François, Yagi, Manabu, Mazelle, Christian, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Toulouse], ONERA, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Tohoku University [Sendai], Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Agence Nationale de la Recherche (ANR), Centre National d'Etudes Spatiales (CNES), International Space Science Institute (ISSI), European Commission, ANR-09-BLAN-0223,HELIOSARES,Relation Soleil ? Mars: description et analyse des échanges présents et passés entre magnétosphère et atmosphère(2009), European Project: 262863,EC:FP7:SPA,FP7-SPACE-2010-1,IMPEX(2011), 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), HEPPI - LATMOS, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-École polytechnique (X)-Sorbonne Universités-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, magnetosphere, interaction, Mars, plasma, Simulation
Abstract

International audience In order to better represent Mars-Solar wind interaction, we present an unprecedented model achieving spatial resolution down to 50 km, a so far unexplored resolution for global kinetic models of the Martian ionized environment. Such resolution approaches the ionospheric plasma scale height. In practice, the model is derived from a first version described in Modolo et al. [2005]. An important effort of parallelization has been conducted and is presented here. A better description of the ionosphere was also implemented including ionospheric chemistry, electrical conductivities and a drag force modelling the ion-neutral collisions in the ionosphere. This new version of the code, named LatHyS (Latmos Hybrid Simulation), is here used to characterize the impact of various spatial resolutions on simulation results. In addition, and following a global model challenge effort [Brain et al., 2010], we present the results of simulation run for three cases which allows addressing the effect of the supra-thermal corona and of the solar EUV activity on the magnetospheric plasma boundaries and on the global escape. Simulation results showed that global patterns are relatively similar for the different spatial resolution runs but finest grid runs provide a better representation of the ionosphere and display more details of the planetary plasma dynamic. Simulation results suggest that a significant fraction of escaping O+ ions is originated from below 1200 km altitude.

Published
2016
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237. Proton cyclotron waves occurrence rate upstream from Mars observed by MAVEN: associated variability of the Martian upper atmosphere

Author

Romanelli, Norberto, Mazelle, Christian, Chaufray, Jean-Yves, Meziane, Karim, Shan, Lican, Ruhunusiri, Suranga, Connerney, Jack E. P., Espley, Jared R., Eparvier, Francis, Thiemann, Edward M. B., Halekas, Jasper S., Mitchell, David L., Mcfadden, James P., Brain, David, Jakosky, Bruce M., Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Physics Department [UNB], University of New Brunswick (UNB), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), NASA Goddard Space Flight Center (GSFC), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley], and University of California-University of California

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], H exosphere, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Temporal variability, Mars, EUV flux, PCWs
Abstract

International audience; Measurements provided by the Magnetometer and the Extreme Ultraviolet Monitor (EUVM) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft together with atomic H exospheric densities derived from numerical simulations are studied for the time interval from October 2014 up to March 2016. We determine the proton cyclotron waves (PCWs) occurrence rate observed upstream from Mars at different times. We also study the relationship with temporal variabilities of the high altitude Martian hydrogen exosphere and the solar EUV flux reaching the Martian environment. We find that the abundance of PCWs is higher when Mars is close to perihelion, and decreases to lower and approximately constant values after the Martian Northern Spring Equinox. We also conclude that these variabilities cannot be associated with biases in MAVEN's spatial coverage or changes in the background magnetic field orientation. Higher H exospheric densities on the Martian day side are also found when Mars is closer to perihelion, as a result of changes in the thermospheric response to variability in the ultraviolet flux reaching Mars at different orbital distances. A consistent behavior is also observed in the analyzed daily irradiances measured by the MAVEN EUVM. The latter trends point towards an increase in the planetary proton densities upstream from the Martian bow shock near perihelion. These results then suggest a method to indirectly monitor the variability of the H exosphere up to very high altitudes during large time intervals (compared to direct measurements of neutral particles), based on the observed abundance of PCWs.

Published
2016
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238. High‐Altitude Closed Magnetic Loops at Mars Observed by MAVEN

Author

Xu, Shaosui, primary, Mitchell, David, additional, Luhmann, Janet, additional, Ma, Yingjuan, additional, Fang, Xiaohua, additional, Harada, Yuki, additional, Hara, Takuya, additional, Brain, David, additional, Weber, Tristan, additional, Mazelle, Christian, additional, and DiBraccio, Gina A., additional

Published
2017
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240. Statistical Study of Relations Between the Induced Magnetosphere, Ion Composition, and Pressure Balance Boundaries Around Mars Based On MAVEN Observations

Author

Matsunaga, Kazunari, primary, Seki, Kanako, additional, Brain, David A., additional, Hara, Takuya, additional, Masunaga, Kei, additional, Mcfadden, James P., additional, Halekas, Jasper S., additional, Mitchell, David L., additional, Mazelle, Christian, additional, Espley, J. R., additional, Gruesbeck, Jacob, additional, and Jakosky, Bruce M., additional

Published
2017
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244. MAVEN observations of tail current sheet flapping at Mars

Author

DiBraccio, Gina A., primary, Dann, Julian, additional, Espley, Jared R., additional, Gruesbeck, Jacob R., additional, Soobiah, Yasir, additional, Connerney, John E. P., additional, Halekas, Jasper S., additional, Harada, Yuki, additional, Bowers, Charles F., additional, Brain, David A., additional, Ruhunusiri, Suranga, additional, Hara, Takuya, additional, and Jakosky, Bruce M., additional

Published
2017
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247. MAVEN observations of a giant ionospheric flux rope near Mars resulting from interaction between the crustal and interplanetary draped magnetic fields

Author

Hara, Takuya, primary, Brain, David A., additional, Mitchell, David L., additional, Luhmann, Janet G., additional, Seki, Kanako, additional, Hasegawa, Hiroshi, additional, Mcfadden, James P., additional, Halekas, Jasper S., additional, Espley, Jared R., additional, Harada, Yuki, additional, Livi, Roberto, additional, DiBraccio, Gina A., additional, Connerney, John E. P., additional, Mazelle, Christian, additional, Andersson, Laila, additional, and Jakosky, Bruce M., additional

Published
2017
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248. MAVEN observations on a hemispheric asymmetry of precipitating ions toward the Martian upper atmosphere according to the upstream solar wind electric field

Author

Hara, Takuya, primary, Luhmann, Janet G., additional, Leblanc, François, additional, Curry, Shannon M., additional, Seki, Kanako, additional, Brain, David A., additional, Halekas, Jasper S., additional, Harada, Yuki, additional, McFadden, James P., additional, Livi, Roberto, additional, DiBraccio, Gina A., additional, Connerney, John E. P., additional, and Jakosky, Bruce M., additional

Published
2017
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249. A comet engulfs Mars: MAVEN observations of comet Siding Spring's influence on the Martian magnetosphere: SIDING SPRING AND MARS' MAGNETOSPHERE

Author

Espley, Jared R., DiBraccio, Gina A., Connerney, John E. P., Brain, David, Gruesbeck, Jacob, Soobiah, Yasir, Halekas, Jasper, Combi, Michael, Luhmann, Janet, Ma, Yingjuan, Jia, Yingdong, and Jakosky, Bruce

Abstract

The nucleus of comet C/2013 A1 (Siding Spring) passed within 141,000 km of Mars on 19 October 2014. Thus, the cometary coma and the plasma it produces washed over Mars for several hours producing significant effects in the Martian magnetosphere and upper atmosphere. We present observations from Mars Atmosphere and Volatile EvolutioN's (MAVEN's) particles and field's instruments that show the Martian magnetosphere was severely distorted during the comet's passage. We note four specific major effects: (1) a variable induced magnetospheric boundary, (2) a strong rotation of the magnetic field as the comet approached, (3) severely distorted and disordered ionospheric magnetic fields during the comet's closest approach, and (4) unusually strong magnetosheath turbulence lasting hours after the comet left. We argue that the comet produced effects comparable to that of a large solar storm (in terms of incident energy) and that our results are therefore important for future studies of atmospheric escape, MAVEN's primary science objective.

Published
2015

250. Two Types of Aurora on Mars as Observed by MAVEN's Imaging UltraViolet Spectrograph

Author

Schneider, Nicholas M., Deighan, Justin, Jain, Sonal K., Stiepen, Arnaud, Larson, Davin, Mitchell, D. L., Lee, Christina O., Lillis, Robert, Brain, David, Mcclintock, William E., Chaffin, Michael Scott, Crismani, Matteo, Holsclaw, Greg M., Jakosky, Bruce M., Mazelle, Christian, Evans, J. Scott, Stewart, A. Ian F., Stevens, M. H., Clarke, John T., Montmessin, Franck, Lefèvre, Franck, Lo, Daniel, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Computational Physics, Inc., Naval Research Laboratory (NRL), Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, University of California [Berkeley], University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics::Space Physics, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; The Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft has detected two distinct types of auroral emission on Mars. First, we report the discovery of a low altitude, diffuse aurora spanning much of Mars’ northern hemisphere coincident with a solar energetic particle outburst. IUVS observed northerly latitudes during late December 2014, detecting auroral emission in virtually all nightside observations for ~5 days spanning virtually all geographic longitudes. The vertical profile showed emission down to ~70 km altitude (1 microbar), deeper than confirmed at any other planet. The onset and duration of emission coincide with the observed arrival of solar energetic particles up to 200 keV precipitating directly and deeply into the atmosphere. Preliminary modeling of the precipitation, energy deposition and spectral line emission yields good matches to the observations. These observations represent a new class of planetary auroras produced in the Martian middle atmosphere. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit aurora more globally than Earth.Second, we confirm the existence of small patches of discrete aurora near crustal magnetic fields in Mars' southern hemisphere, as observed previously by SPICAM on Mars Express (Bertaux et al., Nature, 435, 790-794 (2005)). IUVS observed southern latitudes in July and August 2015, detecting discrete auroral emission in ~1% of suitable observations. Limb scans resolved both vertically and along-slit indicate this type of auroral emission was patchy on the scale of ~40 km, and located at higher altitudes ~140 km. The higher altitudes imply a lower energy of precipitating particles. The mix of spectral emissions also differed signficiantly from the diffuse aurora, indicating different excitation and quenching processes.We will discuss the observed properties of the aurora and associated charged particle precipitation, as well as the broader implications of this high-energy deposition into Mars' atmopshere.

Published
2015

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