A comparison between the two lobes of comet 67P/Churyumov–Gerasimenko based on D/H ratios in H2O measured with the Rosetta/ROSINA DFMS

ABSTRACT The nucleus of the Jupiter-family comet 67P/Churyumov–Gerasimenko was discovered to be bi-lobate in shape when the European Space Agency spacecraft Rosetta first approached it in 2014 July. The bi-lobate structure of the cometary nucleus has led to much discussion regarding the possible manner of its formation and on how the composition of each lobe might compare with that of the other. During its two-year-long mission from 2014 to 2016, Rosetta remained in close proximity to 67P/Churyumov–Gerasimenko, studying its coma and nucleus in situ. Based on lobe-specific measurements of HDO and H2O performed with the ROSINA Double Focusing Mass Spectrometer (DFMS) on board Rosetta, the deuterium-to-hydrogen (D/H) ratios in water from the two lobes can be compared. No appreciable difference was observed, suggesting that both lobes formed in the same region and are homogeneous in their D/H ratios.

Download Full-text

16O/18O ratio in water in the coma of comet 67P/Churyumov-Gerasimenko measured with the Rosetta/ROSINA double-focusing mass spectrometer

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833806 ◽

2019 ◽

Vol 630 ◽

pp. A29 ◽

Cited By ~ 8

Author(s):

Isaac R. H. G. Schroeder I ◽

Kathrin Altwegg ◽

Hans Balsiger ◽

Jean-Jacques Berthelier ◽

Johan De Keyser ◽

...

Keyword(s):

Solar System ◽

Mass Spectrometer ◽

European Space Agency ◽

Space Agency ◽

Close Proximity ◽

Terrestrial Water ◽

Double Focusing ◽

Comet 67P ◽

Almost Continuous

The European Space Agency spacecraft Rosetta accompanied the Jupiter-family comet 67P/Churyumov-Gerasimenko for over 2 yr along its trajectory through the inner solar system. Between 2014 and 2016, it performed almost continuous in situ measurements of the comet’s gaseous atmosphere in close proximity to its nucleus. In this study, the 16O/18O ratio of H2O in the coma of 67P/Churyumov-Gerasimenko, as measured by the ROSINA DFMS mass spectrometer onboard Rosetta, was determined from the ratio of H216O/H218O and 16OH/18OH. The value of 445 ± 35 represents an ~11% enrichment of 18O compared with the terrestrial ratio of 498.7 ± 0.1. This cometary value is consistent with the comet containing primordial water, in accordance with leading self-shielding models. These models predict primordial water to be between 5 and 20% enriched in heavier oxygen isotopes compared to terrestrial water.

Download Full-text

Two years with comet 67P/Churyumov-Gerasimenko: H2O, CO2, and CO as seen by the ROSINA/RTOF instrument of Rosetta

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834226 ◽

2019 ◽

Vol 630 ◽

pp. A33 ◽

Cited By ~ 6

Author(s):

M. Hoang ◽

P. Garnier ◽

H. Gourlaouen ◽

J. Lasue ◽

H. Rème ◽

...

Keyword(s):

Northern Hemisphere ◽

Mass Spectrometer ◽

Cometary Nucleus ◽

Mass Spectrometers ◽

Rosetta Mission ◽

Show Evidence ◽

Temporal And Spatial ◽

Double Focusing ◽

Comet 67P ◽

Strong Erosion

Context. The ESA Rosetta mission investigated the environment of comet 67P/Churyumov-Gerasimenko (hereafter 67P) from August 2014 to September 2016. One of the experiments on board the spacecraft, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) included a COmet Pressure Sensor (COPS) and two mass spectrometers to analyze the composition of neutrals and ions, the Reflectron-type Time-Of-Flight mass spectrometer (RTOF), and the Double Focusing Mass Spectrometer (DFMS). Aims. RTOF species detections cover the whole mission. This allows us to study the seasonal evolution of the main volatiles (H2O, CO2, and CO) and their spatial distributions. Methods. We studied the RTOF dataset during the two-year long comet escort phase focusing on the study of H2O, CO2, and CO. We also present the detection by RTOF of O2, the fourth main volatile recorded in the coma of 67P. This work includes the calibration of spectra and the analysis of the signature of the four volatiles. We present the analysis of the dynamics of the main volatiles and visualize the distribution by projecting our results onto the surface of the nucleus. The temporal and spatial heterogeneities of H2O, CO2, and CO are studied over the two years of mission, but the O2 is only studied over a two-month period. Results. The global outgassing evolution follows the expected asymmetry with respect to perihelion. The CO/CO2 ratio is not constant through the mission, even though both species appear to originate from the same regions of the nucleus. The outgassing of CO2 and CO was more pronounced in the southern than in the northern hemisphere, except for the time from August to October 2014. We provide a new and independent estimate of the relative abundance of O2. Conclusions. We show evidence of a change in molecular ratios throughout the mission. We observe a clear north-south dichotomy in the coma composition, suggesting a composition dichotomy between the outgassing layers of the two hemispheres. Our work indicates that CO2 and CO are located on the surface of the southern hemisphere as a result of the strong erosion during the previous perihelion. We also report a cyclic occurrence of CO and CO2 detections in the northern hemisphere. We discuss two scenarios: devolatilization of transported wet dust grains from south to north, and different stratigraphy for the upper layers of the cometary nucleus between the two hemispheres.

Download Full-text

OLCI A/B Tandem Phase Analysis, Part 1: Level 1 Homogenisation and Harmonisation

Remote Sensing ◽

10.3390/rs12111804 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1804 ◽

Cited By ~ 6

Author(s):

Nicolas Lamquin ◽

Sébastien Clerc ◽

Ludovic Bourg ◽

Craig Donlon

Keyword(s):

European Space Agency ◽

Companion Paper ◽

The Other ◽

Satellite Mission ◽

Space Agency ◽

The Future ◽

Level 1 ◽

Level 2 ◽

Very High ◽

Sentinel 2

Copernicus is a European system for monitoring the Earth in support of European policy. It includes the Sentinel-3 satellite mission which provides reliable and up-to-date measurements of the ocean, atmosphere, cryosphere, and land. To fulfil mission requirements, two Sentinel-3 satellites are required on-orbit at the same time to meet revisit and coverage requirements in support of Copernicus Services. The inter-unit consistency is critical for the mission as more S3 platforms are planned in the future. A few weeks after its launch in April 2018, the Sentinel-3B satellite was manoeuvred into a tandem configuration with its operational twin Sentinel-3A already in orbit. Both satellites were flown only thirty seconds apart on the same orbit ground track to optimise cross-comparisons. This tandem phase lasted from early June to mid October 2018 and was followed by a short drift phase during which the Sentinel-3B satellite was progressively moved to a specific orbit phasing of 140° separation from the sentinel-3A satellite. In this paper, an output of the European Space Agency (ESA) Sentinel-3 Tandem for Climate study (S3TC), we provide a full methodology for the homogenisation and harmonisation of the two Ocean and Land Colour Instruments (OLCI) based on the tandem phase. Homogenisation adjusts for unavoidable slight spatial and spectral differences between the two sensors and provide a basis for the comparison of the radiometry. Persistent radiometric biases of 1–2% across the OLCI spectrum are found with very high confidence. Harmonisation then consists of adjusting one instrument on the other based on these findings. Validation of the approach shows that such harmonisation then procures an excellent radiometric alignment. Performed on L1 calibrated radiances, the benefits of harmonisation are fully appreciated on Level 2 products as reported in a companion paper. Whereas our methodology aligns one sensor to behave radiometrically as the other, discussions consider the choice of the reference to be used within the operational framework. Further exploitation of the measurements indeed provides evidence of the need to perform flat-fielding on both payloads, prior to any harmonisation. Such flat-fielding notably removes inter-camera differences in the harmonisation coefficients. We conclude on the extreme usefulness of performing a tandem phase for the OLCI mission continuity as well as for any optical mission to which the methodology presented in this paper applies (e.g., Sentinel-2). To maintain the climate record, it is highly recommended that the future Sentinel-3C and Sentinel-3D satellites perform tandem flights when injected into the Sentinel-3 time series.

Download Full-text

The Rosetta Mission to Primitive Bodies of the Solar System

Symposium - International Astronomical Union ◽

10.1017/s0074180900046660 ◽

1994 ◽

Vol 160 ◽

pp. 381-394

Author(s):

Yves Langevin

Keyword(s):

Remote Sensing ◽

Solar System ◽

European Space Agency ◽

Time Span ◽

Main Belt ◽

Space Agency ◽

Rosetta Mission ◽

One Year ◽

Definition Of

The European Space Agency (ESA) has selected Rosetta as the next cornerstone mission, to be launched in 2003. The goal is to perfom one or more fly-bys to main belt asteroids, followed by a rendez-vous with an active comet. Advanced in situ analysis, both in the coma and on the surfaces of the nucleus, will be possible, as well as monitoring by remote sensing instruments of the nucleus and of the inner coma for a time span of more than one year, until perihelion. This paper outlines the scientific and technological choices done in the definition of the mission.

Download Full-text

The gas production of 14 species from comet 67P/Churyumov–Gerasimenko based on DFMS/COPS data from 2014 to 2016

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2643 ◽

2020 ◽

Vol 498 (3) ◽

pp. 3995-4004 ◽

Cited By ~ 2

Author(s):

Matthias Läuter ◽

Tobias Kramer ◽

Martin Rubin ◽

Kathrin Altwegg

Keyword(s):

Error Bounds ◽

Temporal Evolution ◽

Gas Production ◽

Total Production ◽

Time Intervals ◽

Triangular Elements ◽

Double Focusing ◽

Comet 67P ◽

Northern And Southern Hemispheres

ABSTRACT The coma of comet 67P/Churyumov–Gerasimenko has been probed by the Rosetta spacecraft and shows a variety of different molecules. The ROSINA COmet Pressure Sensor and the Double Focusing Mass Spectrometer provide in situ densities for many volatile compounds including the 14 gas species H2O, CO2, CO, H2S, O2, C2H6, CH3OH, H2CO, CH4, NH3, HCN, C2H5OH, OCS, and CS2. We fit the observed densities during the entire comet mission between 2014 August and 2016 September to an inverse coma model. We retrieve surface emissions on a cometary shape with 3996 triangular elements for 50 separated time intervals. For each gas, we derive systematic error bounds and report the temporal evolution of the production, peak production, and the time-integrated total production. We discuss the production for the two lobes of the nucleus and for the Northern and Southern hemispheres. Moreover, we provide a comparison of the gas production with the seasonal illumination.

Download Full-text

AIDA: Asteroid Impact and Deflection Assessment

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314011855 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 480-480 ◽

Cited By ~ 1

Author(s):

Patrick Michel ◽

A. Cheng ◽

A. Galvez ◽

C. Reed ◽

I. Carnelli ◽

...

Keyword(s):

European Space Agency ◽

The Other ◽

Applied Physics ◽

Binary Asteroid ◽

Jet Propulsion ◽

Asteroid Impact ◽

Space Agency ◽

Goddard Space Flight Center ◽

Asteroid Deflection ◽

Joint Mission

AbstractAIDA (Asteroid Impact and Deflection Assessment) is a project of a joint mission demonstration of asteroid deflection and characterisation of the kinetic impact effects. It involves the Johns Hopkins Applied Physics Laboratory (with support from members of NASA centers including Goddard Space Flight Center, Johnson Space Center, and the Jet Propulsion Laboratory), and the European Space Agency (with support from members of the french CNRS/Cte dAzur Observatory and the german DLR). This assessment will be done using a binary asteroid target. AIDA consists of two independent but mutually supporting mission concepts, one of which is the asteroid kinetic impactor and the other is the characterisation spacecraft. The objective and status of the project will be presented.

Download Full-text

Joint Discussion 6: Sun and Heliosphere - Challenges for Solar-Terrestrial Physics, Magneto-and Hydrodynamics

Highlights of Astronomy ◽

10.1017/s1539299600011230 ◽

1995 ◽

Vol 10 ◽

pp. 291-293

Author(s):

Martin C.E. Huber ◽

Arne Pedersen ◽

Claus Fröhlich

Keyword(s):

Spatial Scales ◽

Plasma Heating ◽

European Space Agency ◽

Three Dimensional ◽

Plasma Boundary ◽

Small Scale ◽

Space Agency ◽

Terrestrial Magnetosphere ◽

Surrounding Space

There is one astrophysical system, where the sites of a star’s mass loss can be localised and observed in detail, and where the behaviour of the resulting stellar wind in the star’s environment and around orbiting obstacles can be investigated in situ: it is the Sun, the heliosphere and the surroundings of planets — among the latter most prominently the terrestrial magnetosphere. Indeed, within a year or so a fleet of satellites equipped with sophisticated remote-sensing and in-situ instruments will make this astronomical paradigm, or more precisely, the solar-terrestrial system accessible to intensive, multi-disciplinary study.Four identical CLUSTER spacecraft, orbiting the Earth within the magnetosphere, the surrounding space and the particularly interesting plasma boundary layers will perform a three-dimensional in-situ study of plasma-heating, particle-acceleration and other small-scale plasma processes (Schmidt and Goldstein,1988). A number of other missions — some of them already in orbit, like GEOTAIL and WIND, some to be launched within one or two years, like INTERBALL and POLAR — will provide information about the Earth’s magnetosphere and the solar wind on larger spatial scales. These missions are described in a Brochure issued jointly by the European Space Agency, NASA, the Japanese Institute of Space and Astronomical Science and the Rssian Space Agency, which can be obtained from A. Pedersen at the above address.

Download Full-text

Evaluation of the Performance of SM2RAIN-Derived Rainfall Products over Brazil

Remote Sensing ◽

10.3390/rs11091113 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1113 ◽

Cited By ~ 9

Author(s):

Franklin Paredes-Trejo ◽

Humberto Barbosa ◽

Carlos A. C. dos Santos

Keyword(s):

Soil Moisture ◽

Pearson Correlation ◽

European Space Agency ◽

Rainfall Events ◽

Error Components ◽

Space Agency ◽

Daily Scale ◽

Bioclimatic Conditions ◽

Heavy Rainfall Events

Microwave-based satellite soil moisture products enable an innovative way of estimating rainfall using soil moisture observations with a bottom-up approach based on the inversion of the soil water balance Equation (SM2RAIN). In this work, the SM2RAIN-CCI (SM2RAIN-ASCAT) rainfall data obtained from the inversion of the microwave-based satellite soil moisture (SM) observations derived from the European Space Agency (ESA) Climate Change Initiative (CCI) (from the Advanced SCATterometer (ASCAT) soil moisture data) were evaluated against in situ rainfall observations under different bioclimatic conditions in Brazil. The research V7 version of the Tropical Rainfall Measurement Mission Multi-satellite Precipitation Analysis (TRMM TMPA) was also used as a state-of-the-art rainfall product with an up-bottom approach. Comparisons were made at daily and 0.25° scales, during the time-span of 2007–2015. The SM2RAIN-CCI, SM2RAIN-ASCAT, and TRMM TMPA products showed relatively good Pearson correlation values (R) with the gauge-based observations, mainly in the Caatinga (CAAT) and Cerrado (CER) biomes (R median > 0.55). SM2RAIN-ASCAT largely underestimated rainfall across the country, particularly over the CAAT and CER biomes (bias median < −16.05%), while SM2RAIN-CCI is characterized by providing rainfall estimates with only a slight bias (bias median: −0.20%), and TRMM TMPA tended to overestimate the amount of rainfall (bias median: 7.82%). All products exhibited the highest values of unbiased root mean square error (ubRMSE) in winter (DJF) when heavy rainfall events tend to occur more frequently, whereas the lowest values are observed in summer (JJA) with light rainfall events. The SM2RAIN-based products showed larger contribution of systematic error components than random error components, while the opposite was observed for TRMM TMPA. In general, both SM2RAIN-based rainfall products can be effectively used for some operational purposes on a daily scale, such as water resources management and agriculture, whether the bias is previously adjusted.

Download Full-text

The surface distributions of the production of the major volatile species, H2O, CO2, CO and O2, from the nucleus of comet 67P/Churyumov-Gerasimenko throughout the Rosetta Mission as measured by the ROSINA double focusing mass spectrometer

Icarus ◽

10.1016/j.icarus.2019.113421 ◽

2020 ◽

Vol 335 ◽

pp. 113421 ◽

Cited By ~ 20

Author(s):

Michael Combi ◽

Yinsi Shou ◽

Nicolas Fougere ◽

Valeriy Tenishev ◽

Kathrin Altwegg ◽

...

Keyword(s):

Mass Spectrometer ◽

Volatile Species ◽

Rosetta Mission ◽

Double Focusing ◽

Comet 67P

Download Full-text

Combining ExoMars’ Ma_MISS and Drill data

10.5194/epsc2020-882 ◽

2020 ◽

Author(s):

Alessandro Frigeri ◽

Maria Cristina De Sanctis ◽

Francesca Altieri ◽

Simone De Angelis ◽

Marco Ferrari ◽

...

Keyword(s):

Mechanical Properties ◽

Water Content ◽

Large Scale ◽

Mechanical Response ◽

European Space Agency ◽

Volcanic Rocks ◽

Space Agency ◽

Geophysical Imaging

The ExoMars Rover and Surface Platform planned for launch in 2022 is a large international cooperation between the European Space Agency and Roscosmos with a scientific contribution from NASA.&#160; Thales Alenia Space is the ExoMars mission industrial prime contractor.&#160; Besides sensors and instruments characterizing the surface at large scale, the ExoMars&#8217; rover Rosalind Franklin payload features some experiments devoted specifically to the characterization of the first few meters of the Martian subsurface. These experiments are particularly critical for the main ExoMars objective of detecting traces of present or past life forms on Mars, which may have been preserved within the shallow Martian underground [1]. Rosalind Franklin will be able to perform both non-invasive geophysical imaging of the underground [2] and subsurface in situ measurements thanks to the Drill unit installed on the rover. The Drill has been developed by Leonardo and its purposes are 1) to collect core samples to be analyzed in the Analytical Laboratory Drawer (ALD) onboard the Rover and 2) to drive the miniaturized spectrometer Ma_MISS within the borehole.&#160;&#160;&#160; Ma_MISS (Mars Multispectral Imager for Subsurface Studies, [3]) will collect mineralogic measurements from the rocks exposed into the borehole created by the Drill with a spatial resolution of 120 &#956;m down to 2 meters into the Martian subsurface. Rocks are composed of grains of minerals, and their reaction to an applied stress is related to the mechanical behavior of the minerals that compose the rock itself. The mechanical properties of a mineral depend mainly on the strength of the chemical bonds, the orientation of crystals, and the number of impurities in the crystal lattice. In this context, the integration of Ma_MISS measurements and drill telemetry are of great importance.&#160; The mechanical properties of rocks coupled with their mineralogic composition provide a rich source of information to characterize the nature of rocks being explored by ExoMars rover&#8217;s drilling activity. Within our study, we are starting to collect telemetry recorded during the Drill unit tests on several samples ranging from sedimentary to volcanic rocks with varying degrees of weathering and water content.&#160; In this first phase of the study, we focused our attention on the variation of torque and penetration speed between different samples, which have been found to be indicative of a particular type of rock or group of rocks and their water content.&#160;&#160; We are planning to analyze the same rocks with the Ma_MISS breadboard creating the link between the mineralogy and the mechanical response of the Drill.&#160;&#160;&#160;&#160;&#160;&#160; This will put the base for a more comprehensive and rich characterization of the in situ subsurface observation by Rosalind Franklin planned at Oxia Planum, Mars in 2023.&#160; &#160; Acknowledgments: We thank the European Space Agency (ESA) for developing the ExoMars Project, ROSCOSMOS and Thales Alenia Space for rover development, and Italian Space Agency (ASI) for funding the Ma_MISS experiment (ASI-INAF contract n.2017-48-H.0 for ExoMars MA_MISS phase E/science). &#160; References [1] Vago et al., 2017. Astrobiology, 17 6-7. [2] Ciarletti et al., 2017. Astrobiology, 17 6-7. [3] De Sanctis et al., 2017. Astrobiology, 17 6-7.

Download Full-text