References of "Stiepen, Arnaud"
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See detailHighlights from two years of remote sensing at Mars with MAVEN’s Imaging Ultraviolet Spectrograph
Chaffin; Schneider; Deighan et al

Poster (2017, April 27)

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission’s Imaging Ultraviolet Spectrograph (IUVS) observes Mars in the far and mid ultraviolet (110-340 nm), investigating lower and upper atmospheric ... [more ▼]

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission’s Imaging Ultraviolet Spectrograph (IUVS) observes Mars in the far and mid ultraviolet (110-340 nm), investigating lower and upper atmospheric structure and indirectly probing neutral atmospheric escape. After two Earth years in orbit (one Mars year), IUVS has assembled a large quantity of data and made many discoveries, some of which we report here. Among the key results obtained by IUVS are: (1) discovery of the widespread occurrence of a diffuse proton aurora, representing a newly discovered means of energy deposition into the atmospheres of unmagnetized planets; (2) continued investigation of time-variability in H and O escape, which have dessicated the planet over its history; and (3) synoptic characterization of thermospheric variability and response to solar input. We will present an overview of these results and a discussion of their implications for the state of the atmosphere and its evolution. [less ▲]

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See detailObjectif Mars
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

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See detailEmbarquement pour Mars: défi et opportunité
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

Detailed reference viewed: 13 (1 ULg)
See detailEmbarquement pour Mars
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

Detailed reference viewed: 22 (4 ULg)
See detailObjectif Mars: défi ou utopie?
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

Detailed reference viewed: 11 (1 ULg)
See detailMars Ozone mapping with MAVEN IUVS
Lefèvre; Stiepen, Arnaud ULg; IUVS team

Conference (2017, January 20)

Detailed reference viewed: 13 (1 ULg)
See detailCharacterization of High Altitude Clouds at the Martian Limb and Terminator Using MAVEN IUVS Observations
Deighan; Stiepen, Arnaud ULg; IUVS team

Conference (2017, January 20)

Detailed reference viewed: 8 (1 ULg)
See detailGlobal Simulation of UV atmospheric Emissions
Gonzalez-Galindo; Lopez-Valverde; Forget et al

Poster (2017, January 19)

Detailed reference viewed: 13 (1 ULg)
See detailA persistent meteoric layer in Mars' atmosphere
Crismani; Schneider; Plane et al

Poster (2017, January 18)

Detailed reference viewed: 13 (0 ULg)
See detailThree Types of Aurora observed by MAVEN/IUVS: Implications for Mars’ upper Atmosphere Energy Budget
Connour; Schneider; Jain et al

Poster (2017, January 17)

Detailed reference viewed: 30 (4 ULg)
See detailGlobal UV Imaging by MAVEN/IUVS: Diurnal Cloud Formation, Dust Storms and Atmospheric Scattering.
Schneider; Deighan; Jain et al

Conference (2017, January 17)

Detailed reference viewed: 13 (1 ULg)
See detailNO Nightglow studies status
Stiepen, Arnaud ULg; Jain; Deighan et al

Conference (2017, January 16)

Detailed reference viewed: 9 (1 ULg)
See detailEmbarquement pour Mars
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

Detailed reference viewed: 9 (1 ULg)
See detailSeasonal Transport in Mars’ Mesosphere revealed by Nitric Oxide Nightglow vertical profiles and global images from IUVS/MAVEN
Stiepen, Arnaud ULg; Stewart; Jain et al

Conference (2017)

We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emis- sions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly ... [more ▼]

We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emis- sions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They preferentially descend in the nightside mesosphere in the winter hemisphere, where they can radiatively recombine to form NO(C2Π). The excited molecules promptly relax by emitting photons in the UV δ bands and in the γ bands through cascades via the A2Σ, v’ = 0 state. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars’ nightside and the winter descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015). Observations of these emissions have been accumulated on a large dataset of nightside disk images and vertical profiles obtained at the limb by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) instrument when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at its apoapsis and its periapsis phases along its orbit, respectively. We present discussion on the variability in the brightness, altitude and topside scale height of the emission with season, geographical position and local time and possible interpretation for local and global changes in the meso- sphere dynamics. IUVS images and limb scans reveal unexpected complex structure of the emission. The brightest emission is observed close to the winter pole. The emission is also surprisingly more intense in some sectors located close to the equator : at 120 ̊ and 150 ̊ longitude. Observations also reveal spots and streaks, indicating irregularities in the wind circulation pattern and possible impact of waves and tides. The disk images and limb profiles are compared to the LMD-MGCM model (Gonzàlez-Galindo et al., 2009 ; Lopez-Valverde et al., 2011) to focus on the seasonal, local time and geographical influences on the NO Nightglow emission. We will also provide a statistical study of the regions of enhanced brightness (i.e. splotches and streaks) and discuss possible interpretation from the comparison to the GCM. [less ▲]

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See detailNitric Oxide nightglow from IUVS disk images
Stiepen, Arnaud ULg; Schneider; Gonzàlez-Galindo et al

Conference (2016, November)

Detailed reference viewed: 20 (1 ULg)
See detailA study of ion emissions in MAVEN/IUVS data
Connour, Kyle; Schneider, Nicholas M.; Deighan, Justin et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2016, October 01)

The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutionN (MAVEN) mission is designed to measure radiances of several of the most abundant species present in ... [more ▼]

The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutionN (MAVEN) mission is designed to measure radiances of several of the most abundant species present in Mars' atmosphere. Many spectral features are associated with ions; one of the most prominent spectral features in the mid-ultraviolet region is the CO[SUB]2[/SUB][SUP]+[/SUP] Ultraviolet Doublet (UVD) at 289 nm. However this emission, and many others, results from several radiative processes, some of which originate from the ionization process and is therefore not diagnostic of the ion densities. Several other emissions are diagnostic of ion densities, especially at high altitudes, and therefore lend themselves to density retrievals based on inclusion of all radiative processes. The most promising of these is the Fox-Duffendack-Barker (FDB) (3,0) band at 314 nm, near the long-wavelength limit of the IUVS instrument. We report on a new process for performing density retrievals of CO[SUB]2[/SUB][SUP]+[/SUP] with particular attention to the credibility of high-altitude signal in the FDB bands as well as the associated uncertainties. We also investigate the feasibility of C[SUP]+[/SUP] and other ion density retrievals. [less ▲]

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See detailScience highlights from MAVEN/IUVS after two years in Mars orbit
Schneider, Nicholas M.; Deighan, Justin; Stiepen, Arnaud ULg et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2016, October 01)

The broad capabilities of the Imaging UltraViolet Spectrograph on the MAVEN mission are enabling new science ranging from Mars' lower atmosphere up though the escaping corona. After two years in Mars ... [more ▼]

The broad capabilities of the Imaging UltraViolet Spectrograph on the MAVEN mission are enabling new science ranging from Mars' lower atmosphere up though the escaping corona. After two years in Mars orbit, the instrument has yielded insights on the Mars dayglow, season cycles, nightglow, aurora, meteor showers, clouds, solar-planetary interactions and atmospheric escape. In this presentation we will highlight several new discoveries. First, IUVS has observed a third type of aurora not previously seen at Mars, indicative of a new kind of solar-planet interaction for non-magnetized planets. Second, spatial mapping of nitric oxide nightglow reveals regions of atmospheric downwelling necessitating substantial changes to global atmospheric circulation models. Finally, a new high-spatial-resolution UV imaging mode allows unprecedented determinations of Mars' low-altitude ozone, as well as detection of clouds from nadir to limb. [less ▲]

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See detailMeasurements of D and H in the Upper Atmosphere of Mars with the MAVEN IUVS Echelle Channel
Clarke, John T.; Mayyasi, Majd A.; Bhattacharyya, Dolon et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2016, October 01)

The enhanced ratio of D/H in the martian atmosphere has long been interpreted to provide evidence for the historic loss rate of water into space, with the enhancement resulting from the mass ratio of the ... [more ▼]

The enhanced ratio of D/H in the martian atmosphere has long been interpreted to provide evidence for the historic loss rate of water into space, with the enhancement resulting from the mass ratio of the species. Understanding the dependence of the enrichment of D on the loss rate of water requires that one understand the controlling factors, including all sources of exospheric hydrogen and the present-day transport of D and H into the upper atmosphere. Toward this end the MAVEN mission has included an echelle channel in the IUVS instrument that resolves the D and H Lyman alpha emissions produced by resonant scattering of bright solar emission. In this mode it has now been possible to measure the upper atmospheric D and H abundances over most of a martian year. The results are surprising, with larger than expected changes in the D and H abundances and a changing ratio of D/H with a strong seasonal dependence. This talk will present the D and H data to date (Mars will be near perihelion by the time of the DPS meeting) and discuss the interpretation of the large changes that have been observed. [less ▲]

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See detailH Escape Rates Inferred from MAVEN/IUVS Observations of the Mars Hydrogen Corona
Chaffin, Michael S.; Chaufray, Jean-Yves; Deighan, Justin et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2016, October 01)

H escape oxidizes and dessicates the Mars atmosphere and surface, providing a key control on the present-day chemistry and long-term evolution of the planet. Recently, large variations in the escape rate ... [more ▼]

H escape oxidizes and dessicates the Mars atmosphere and surface, providing a key control on the present-day chemistry and long-term evolution of the planet. Recently, large variations in the escape rate of H as a function of season have been reported by several studies, making continued observation of the variation a high priority. We present escape rates derived from Mars Atmosphere and Volatile EvolutioN (MAVEN) mission Imaging UltraViolet Spectrograph (IUVS) observations of the extended atmosphere of Mars at H Lyman alpha (121.6 nm), which must be interpreted with a coupled density/radiative transfer model owing to the optically thick nature of the emission and the small fraction of H present in the corona on escaping trajectories. We recover densities, temperatures, and escape rates under the assumption of spherical symmetry for multiple periods across MAVEN's mission so far, beginning in December 2014 (escape rates ~4e8/cm2/s). We describe the observed variation and compare it with previously observed seasonal variation in retrieved H escape rates, providing a necessary input for future photochemical modeling studies and estimates of water loss from Mars over its history. [less ▲]

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