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| European Mars Science and Exploration Conference (EMSEC) |
| Edited by Dr. Angelo Pio Rossi and Dr. Olivier Witasse.
This Special Issue of Planetary and Space Science contains 15 papers; the majority of which were presented at the European Mars Science and Exploration Conference (EMSEC) - Mars Express & ExoMars.
There are several geoscience-related contributions covering volcanic, hydrologic, stratigraphic and geomorphologic investigations.
The EMSEC conference was held 12-16 November 2007 at ESA ESTEC, Noordwijk, The Netherlands (see right-hand menu for conference programme).
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| Publication date: 15 Jul 2009 |
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Mars Express
The Scientific Investigations |
| This ESA special publication is dedicated to the scientific investigations of Mars by Mars Express, giving a detailed overview of the scientific results of the mission so far.
Contents:
| Foreword |
| Overview |
Mars Express: Summary of Scientific Results
A. Chicarro, O.G. Witasse & A.P. Rossi | 1 |
| Scientific Instruments |
HRSC: High Resolution Stereo Camera
G. Neukum, R. Jaumann and the Co-Investigator Team | 15 |
OMEGA: Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité
J.-P. Bibring, Y. Langevin, F. Altieri et al. | 75 |
MARSIS: Mars Advanced Radar for Subsurface and Ionospheric Sounding
J.J. Plaut, G. Picardi, T.W. Watters et al. | 97 |
PFS: Planetary Fourier Spectrometer
V. Formisano, F. Angrilli, G. Arnold et al. | 115 |
SPICAM: Spectroscopy for the Investigation of the Characteristics of the Atmospheric of Mars
J.-L. Bertaux, O. Korablev, D. Fonteyn et al. | 139 |
ASPERA-3: Analyser of Space Plasmas and Energetic Neutral Atoms
R. Lundin, S. Barabash and the ASPERA-3 team | 199 |
MaRS: Mars Express Radio Science Experiment
M. Pätzold, S. Tellmann, T. Andert et al. | 217 |
| Operations and Archiving |
Mars Express Science Planning and Operations
R. Pischel & T. Zegers | 249 |
Spacecraft and Payload Data Handling
J. Zender, F. Delhaise, C. Arviset et al. | 257 |
| Acronyms and Abbreviations | 279 |
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| Publication date: 15 Jun 2009 |
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| Strong Release of Methane on Mars in Northern Summer 2003 |
| Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane could be a signature of either origin. Using high-dispersion infrared spectrometers at three ground-based telescopes, we measured methane and water vapor simultaneously on Mars over several longitude intervals in northern early and late summer in 2003 and near the vernal equinox in 2006. When present, methane occurred in extended plumes, and the maxima of latitudinal profiles imply that the methane was released from discrete regions. In northern midsummer, the principal plume contained ~19,000 metric tons of methane, and the estimated source strength (>=0.6 kilogram per second) was comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, California. |
| Publication date: 20 Feb 2009 |
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| Mineralogical composition, structure, morphology, and geological history of Aram Chaos crater fill on Mars derived from OMEGA Mars Express data |
| Aram Chaos is a crater 280 km in diameter centered at 2.5°N, 338.5°E. It is filled by chaotic terrains overlain by a dome-shaped, layered 900 m thick formation displaying
spectral signatures of ferric oxides on Thermal Emission Spectrometer (TES) and Observatoire pour la Mineralogie, L'Eau, les Glaces et L'Activite (OMEGA) medium spatial resolution data. We describe in detail the mineralogical composition, structure, and morphology of this crater fill using high-resolution data (OMEGA, Mars Orbiter Laser
Altimeter, Mars Orbiter Camera, TES, Thermal Emission Imaging System, and High-Resolution Imaging Science Experiment). We infer the following formation scenario: the crater was first filled by a geological formation, the composition of which remains unclear because it is covered by dust. Widespread fracturing of this formation led to the development of chaotic terrains. Later, a second layered formation, presently dome
shaped, was emplaced unconformably on the chaotic terrains. This younger unit is composed of a bright, poorly consolidated material that contains both monohydrated sulfates and ferric oxides according to OMEGA data. The surface of this formation is partially covered by dust and displays landforms indicating that the bright material has
been mobilized by wind during or after its deposition. After its emplacement, this formation has been grooved down to various depths by large eolian erosion corridors. In these corridors, eolian removal of the bright material with a sulfate-rich matrix has left debris fans, sand sheets, and dunes, which display some of the strongest spectral
signatures of ferric oxides on Mars. Similar residual deposits enriched in ferric oxides, overlying a layered formation containing both ferric oxides and sulfates, have been observed by the Opportunity rover in Meridiani Planum, suggesting a common formation process. |
| Publication date: 09 Dec 2008 |
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| Large-scale spring deposits on Mars? |
| We present a large-scale spring hypothesis for the formation of various enigmatic light-toned deposits (LTDs) on Mars. Layered to massive LTDs occur extensively in Valles Marineris, chaotic terrains, and several large craters, in particular, those located in Arabia Terra. Most of these deposits are not easily explained with either a single process or multiple ones, either in combination or occurring sequentially. Spring deposits can have a very wide range of internal facies and exhibit complex architectural variations. We propose the concept of large-scale spring deposits for explaining LTDs on Mars. Stable volcano-tectonic settings, such as the ones typical on Mars, are compatible with a large-scale, long-term, multistage formation of spring deposits. The large-scale spring deposit model can explain the formation of LTDs with a common process, although active in different times and locations, compatible with coeval local or regional processes and deposits, such as volcaniclastic ones. LTDs, if formed as spring deposits derived from subsurface fluids, could potentially offer favorable conditions both to life and to the fossilization of past life forms.
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| Publication date: 22 Aug 2008 |
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| Observations of aurorae by SPICAM ultraviolet spectrograph on board Mars Express: Simultaneous ASPERA-3 and MARSIS measurements |
| We present a new set of observations of Martian aurorae obtained by Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express (MEX). Using nadir viewing, several auroral events have been identified on the Martian nightside, all near regions of crustal magnetic fields. For most of these events, two to three consecutive events with variable intensities and separated by a few seconds to several tens of seconds have been observed, whereas simultaneous observations with Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) and Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) have been possible. In this paper, we present the data set for these events and discuss the possible correlation between the measured UV emission by SPICAM, the measured downward and/or upward flux of electrons by ASPERA-3 and the total electron content recorded by MARSIS. Despite the limited coverage of SPICAM ultraviolet spectrograph (UVS) on the Martian nightside (essentially in regions of high crustal magnetic fields), there is however a very good correlation between the regions with the locally smallest probability to be on closed crustal magnetic field lines, as derived from Mars Global Surveyor/Electron Reflectometer (MGS/MAG-ER), and the position of an aurora event. This suggests that the crustal magnetic fields, when organized into cusp-like structure, can trigger the few aurorae identified by SPICAM UVS. It confirms also the good probability, in the cases where SPICAM UVS measured UV emissions, that the increase in the measured total electron content by MARSIS and the simultaneous measured precipitating electron flux by the ASPERA-3/Electron Spectrometer may be related to each other. |
| Publication date: 22 Aug 2008 |
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| Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument |
| Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability. |
| Publication date: 16 Jul 2008 |
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| Accurate Mars Express orbits to improve the determination of the mass and ephemeris of the Martian moons |
| The determination of the ephemeris of the Martian moons has benefited from observations of their plane-of-sky positions derived from images taken by cameras onboard spacecraft orbiting Mars. Images obtained by the Super Resolution Camera (SRC) onboard Mars Express (MEX) have been used to derive moon positions relative to Mars on the basis of a fit of a complete dynamical model of their motion around Mars. Since, these positions are computed from the relative position of the spacecraft when the images are taken, those positions need to be known as accurately as possible. An accurate MEX orbit is obtained by fitting two years of tracking data of the Mars Express Radio Science (MaRS) experiment onboard MEX. The average accuracy of the orbits has been estimated to be around 20-25 m. From these orbits, we have re-derived the positions of Phobos and Deimos at the epoch of the SRC observations and compared them with the positions derived by using the MEX orbits provided by the ESOC navigation team. After fit of the orbital model of Phobos and Deimos, the gain in precision in the Phobos position is roughly 30 m, corresponding to the estimated gain of accuracy of the MEX orbits. A new solution of the GM of the Martian moons has also been obtained from the accurate MEX orbits, which is consistent with previous solutions and, for Phobos, is more precise than the solution from the Mars Global Surveyor (MGS) and Mars Odyssey (ODY) tracking data. It will be further improved with data from MEX-Phobos closer encounters (at a distance less than 300 km). This study also demonstrates the advantage of combining observations of the moon positions from a spacecraft and from the Earth to assess the real accuracy of the spacecraft orbit. In turn, the natural satellite ephemerides can be improved and participate to a better knowledge of the origin and evolution of the Martian moons. |
| Publication date: 01 May 2008 |
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| Phobos observations by the OMEGA/Mars Express hyperspectral imager |
Abstract No. 1832 As a complement to Mars observations,
Phobos spectral imaging was implemented in
order to acquired compositional mapping with the
prime objective to answer to the following questions: - Is Phobos a "primitive" (undifferentiated) body, or is its mass sufficient for this small body to have suffered some degree of internal differentiation, so as to
exhibit surface compositional variations reflecting
variation with depth?
- Can one detect surface material containing either
volatile or organic compounds ?
We will present an overview of the results acquired,
and discuss them in terms of planetary differentiation. |
| Publication date: 10 Mar 2008 |
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| Dust haze in Valles Marineris observed by HRSC and OMEGA on board Mars Express |
| We present analysis of a bright haze observed inside Valles Marineris, which formed in mid northern spring. The data were collected by the High Resolution Stereo Camera (HRSC) and the imaging spectrometer, Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA), aboard Mars Express. This study provides a case example of the power of simultaneous multiple emission angle and hyperspectral imaging for study of aerosols and clouds in the Martian atmosphere. The haze appeared thinner after three days and disappeared in nine days. It was limited to a 2-km layer at the bottom of the canyon. The color was redder than the underlying surface. The analysis of the OMEGA spectra indicates that this haze was composed of dust particles. The dust layer appeared brighter with the HRSC stereo channels than the nadir channel due to longer scattering paths. We have estimated the optical depth of the haze by fitting both HRSC and OMEGA data with radiative transfer calculations. The retrieval of the optical depth is very sensitive to the aerosol scattering model used and the reflectance of the surface. Applying an aerosol scattering model derived from sky surveys at a constant elevation by the Imager for Mars Pathfinder, the optical depth of the haze is estimated from HRSC data to be within 1.7 to 2.3 at the wavelength of 0.675 micron. The wavelength dependence is obtained from OMEGA spectrum. It increases to 2.2-2.6 at lambda = 1.35 micron and moderately decreases to 1.2-1.8 at lambda = 2.4 micron. |
| Publication date: 09 Feb 2008 |
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| Radar Sounding of the Medusae Fossae Formation Mars: Equatorial Ice or Dry, Low-Density Deposits? |
| The equatorial Medusae Fossae Formation (MFF) is enigmatic and perhaps among the youngest geologic deposits on Mars. They are thought to be composed of volcanic ash, eolian sediments, or an ice-rich material analogous to polar layered deposits. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the Mars Express Spacecraft has detected nadir echoes offset in time-delay from the surface return in orbits over MFF material. These echoes are interpreted to be from the subsurface interface between the MFF material and the underlying terrain. The delay time between the MFF surface and subsurface echoes is consistent with massive deposits emplaced on generally planar lowlands materials with a real dielectric constant of ~2.9 ± 0.4. The real dielectric constant and the estimated dielectric losses are consistent with a substantial component of water ice. However, an anomalously low-density, ice-poor material cannot be ruled out. If ice-rich, the MFF must have a higher percentage of dust and sand than polar layered deposits. The volume of water in an ice-rich MFF deposit would be comparable to that of the south polar layered deposits. |
| Publication date: 16 Nov 2007 |
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| Revealing the Red Planet - Mars Express Provides an Unprecedented View |
| Mars Express arrived at its destination in December 2003 to probe every facet of the Red Planet, from the interior to the ionosphere, in unprecedented detail. In addition to these global studies, the mission's unifying theme is the search for water in its various forms everywhere on the planet. The mission has been extended into 2009, and could last even longer. |
| Publication date: 15 Nov 2007 |
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| First numerical ephemerides of the Martian moons |
| We present new ephemerides of Phobos and Deimos that are fit to observations from 1877 to 2005 and include recent spacecraft observations by Mars Global Surveyor and Mars Express. In contrast to earlier models, this is the first completely numerical one. In particular, the tidal effects have been modeled by the tidal bulge raised by each moon on the planet, instead of fitting secular accelerations in the satellite longitudes. This partly avoids absorbing the Deimos observational errors in its related tidal acceleration. Moreover, applying this model to other systems will be easier. Our estimate of the Martian dissipation is Q = 79.91±0.69 (1sigma-formal error) when assuming k2 = 0.152 for the Martian Love number and GmPh= 0.68 X 106 m3/s2 for the Phobos mass. We also report the possibility of fitting the Phobos oblateness gravity field. We suspect a non-uniform density for Phobos or a bias in either the observations or the Martian gravity field. A FORTRAN subroutine that computes the Martian moons' ephemerides is available on request. |
| Publication date: 03 Apr 2007 |
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| Subsurface Radar Sounding of the South Polar Layered Deposits of Mars |
| The ice-rich south polar layered deposits of Mars were probed with the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express orbiter. The radar signals penetrate deep into the deposits (more than 3.7 kilometers). For most of the area, a reflection is detected at a time delay that is consistent with an interface between the deposits and the substrate. The reflected power from this interface indicates minimal attenuation of the signal, suggesting a composition of nearly pure water ice. Maps were generated of the topography of the basal interface and the thickness of the layered deposits. A set of buried depressions is seen within 300 kilometers of the pole. The thickness map shows an asymmetric distribution of the deposits and regions of anomalous thickness. The total volume is estimated to be 1.6 × 106 cubic kilometers, which is equivalent to a global water layer approximately 11 meters thick. |
| Publication date: 15 Mar 2007 |
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| MARSIS radar sounder evidence of buried basins in the northern lowlands of Mars |
| A hemispheric dichotomy on Mars is marked by the sharp contrast between the sparsely cratered northern lowland plains and the heavily cratered southern highlands. Mechanisms proposed to remove ancient crust or form younger lowland crust include one or more giant impacts, subcrustal transport by mantle convection, the generation of thinner crust by plate tectonics, and mantle overturn following solidification of an early magma ocean. The age of the northern lowland crust is a significant constraint on these models. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument on the European Space Agency's Mars Express spacecraft is providing new constraints on the martian subsurface. Here we show evidence of buried impact basins ranging in diameter from about 130 km to 470 km found over 14 per cent of the northern lowlands. The number of detected buried basins >200 km in diameter indicates that the lowland crust is ancient, dating back to the Early Noachian epoch. This crater density is a lower limit because of the likelihood that not all buried basins in the area surveyed by MARSIS have been detected. An Early Noachian age for the lowland crust has been previously suggested on the basis of a large number of quasi-circular topographic depressions interpreted to be evidence of buried basins. Only a few of these depressions in the area surveyed by MARSIS, however, correlate with the detected subsurface echoes. On the basis of the MARSIS data, we conclude that the northern lowland crust is at least as old as the oldest exposed highland crust. This suggests that the crustal dichotomy formed early in the geologic evolution of Mars. |
| Publication date: 14 Dec 2006 |
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| Origins of the Martian aurora observed by Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express |
| On the 11 August 2004, the UV spectrograph Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express made the first observation of auroral-type emission on the Martian nightside. In this paper, we describe the results of a new analysis of the observed emission owing to a better calibration of SPICAM UV channel and the use of all spectral information obtained during this observation. Several possibilities for the origin of this emission are discussed. We discussed, in particular, the possible exact geometry of the observation and the possible origins of the Martian aurorae. The emissions measured by SPICAM ultraviolet spectrometer have most probably been produced by electrons with an energy distribution peaking at few tens of eV rather than by electron distributions peaking above 100 eV. |
| Publication date: 22 Sep 2006 |
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| CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice |
| The martian polar caps are among the most dynamic regions on Mars, growing substantially in winter as a significant fraction of the atmosphere freezes out in the form of CO2 ice. Unusual dark spots, fans and blotches form as the south-polar seasonal CO2 ice cap retreats during spring and summer. Small radial channel networks are often associated with the location of spots once the ice disappears. The spots have been proposed to be simply bare, defrosted ground; the formation of the channels; has remained uncertain. Here we report infrared and visible observations that show that the spots and fans remain at CO2 ice temperatures well into summer, and must be granular materials that have been brought up to the surface of the ice, requiring a complex suite of processes to get them there. We propose that the seasonal ice cap forms an impermeable, translucent slab of CO2 ice that sublimates from the base, building up high-pressure gas beneath the slab. This gas levitates the ice, which eventually ruptures, producing high-velocity CO2 vents that erupt sand-sized grains in jets to form the spots and erode the channels. These processes are unlike any observed on Earth. |
| Publication date: 17 Aug 2006 |
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| No signature of clear CO2 ice from the cryptic regions in Mars' south seasonal polar cap |
| The seasonal polar ice caps of Mars are composed mainly of CO2 ice. A region of low (< 30%) albedo has been observed within the south seasonal cap during early to mid-spring. The low temperature of this 'cryptic region' has been attributed to a clear slab of nearly pure CO2 ice, with the low albedo resulting from absorption by the underlying surface. Here we report near-infrared imaging
spectroscopy of the south seasonal cap. The deep and broad CO2 absorption bands that are expected in the near-infrared with a thick transparent slab of CO2 ice are not observed. Models of the observed spectra indicate that the low albedo results from extensive dust contamination close to the surface of a CO2 ice layer, which could be linked to atmospheric circulation patterns. The strength of the CO2 absorption increases after mid-spring, so part of the dust is either carried away or buried more deeply in the ice layer during the CO2 ice sublimation process. |
| Publication date: 17 Aug 2006 |
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| ESA SP-1296: ESA's Report to the 36th COSPAR Meeting |
Scientific editor: R. Marsden
Editor: A. Wilson
The report for the 36th COSPAR Meeting covers, as in previous issues, the missions of the Scientific Programme of ESA in the areas of astronomy, Solar System science and fundamental physics. This year's COSPAR meeting will take place only weeks before the end of the SMART-1 mission to the Moon, a technology project that provided the first European look at our natural satellite from lunar orbit.In October of this year, a new mission will be launched: COROT. ESA, together with a number of countries, is contributing to this unique, French-led project that will provide an insight into the interior of the stars, by means of the asteroseismology technique successfully applied by SOHO. COROT will also perform a systematic search for new extrasolar planets using photometric transits.
The record number of ESA Science Programme missions in operation established at the time of the last report was maintained in 2006 (Huygens having been replaced in the list by Venus Express). Eleven different missions, involving 14 operating spacecraft, are providing excellent science to the worldwide scientific community. The Research and Scientific Support Department (RSSD) is responsible for the science operations of these missions and makes every effort to ensure the best possible science return. The Department also supports the realisation of approved projects in all phases of their development. |
| Publication date: 15 Jun 2006 |
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| Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data |
| Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet. |
| Publication date: 21 Apr 2006 |
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