Showing papers by "Colin Wilson published in 2019"
Belgian Institute for Space Aeronomy1, Russian Academy of Sciences2, INAF3, Spanish National Research Council4, Goddard Space Flight Center5, Université Paris-Saclay6, University of Oxford7, Space Science Institute8, University of Winnipeg9, University of Liège10, National Academy of Sciences of Ukraine11, Polish Academy of Sciences12, Royal Observatory of Belgium13, Open University14, University of Paris-Sud15, University of Bristol16, York University17, Centre national de la recherche scientifique18, European Space Research and Technology Centre19
TL;DR: The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
Abstract: Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
134 citations
Russian Academy of Sciences1, Belgian Institute for Space Aeronomy2, Université Paris-Saclay3, Centre national de la recherche scientifique4, University of Oxford5, National Academy of Sciences of Ukraine6, Open University7, INAF8, Spanish National Research Council9, Babeș-Bolyai University10, National Institute of Geophysics and Volcanology11, European Space Research and Technology Centre12
TL;DR: Highly sensitive measurements of the atmosphere of Mars with the ExoMars Trace Gas Orbiter do not detect any methane over a range of latitudes in both hemispheres, in contrast to previous local or remote detections.
Abstract: The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2,3,4,5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere6,7, which—given methane’s lifetime of several centuries—predicts an even, well mixed distribution of methane1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater4 would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally.
111 citations
TL;DR: In this article, the vertical profiles of the 18O/16O and 17O/ 16O ratios in atmospheric water vapour were measured with the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter.
Abstract: Oxygen isotope ratios provide important constraints on the history of the Martian volatile system, revealing the impact of several processes that might fractionate them, such as atmospheric loss into space or interaction with the surface. We report infrared measurements of the Martian atmosphere obtained with the mid-infrared channel (MIR) of the Atmospheric Chemistry Suite (ACS), onboard the ExoMars Trace Gas Orbiter. Absorption lines of the three main oxygen isotopologues of water vapour (H216O, H218O, and H217O) observed in the transmission spectra allow, for the first time, the measurement of vertical profiles of the 18O/16O and 17O/16O ratios in atmospheric water vapour. The observed ratios are enriched with respect to Earth-like values (δ18O = 200 ± 80‰ and δ17O = 230 ± 110‰ corresponding to the Vienna Standard Mean Ocean Water). The vertical structure of these ratios does not appear to show significant evidence of altitudinal variations.
27 citations
Belgian Institute for Space Aeronomy1, Russian Academy of Sciences2, INAF3, Spanish National Research Council4, Goddard Space Flight Center5, Université Paris-Saclay6, University of Oxford7, Space Science Institute8, University of Winnipeg9, University of Liège10, National Academy of Sciences of Ukraine11, Polish Academy of Sciences12, Royal Observatory of Belgium13, Open University14, University of Paris-Sud15, University of Bristol16, York University17, Centre national de la recherche scientifique18, European Space Research and Technology Centre19
TL;DR: The surname of author Cathy Quantin-nataf was misspelled ‘Quantin-Nataf’ , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists.
Abstract: The surname of author Cathy Quantin-Nataf was misspelled ‘Quantin-Nata’ , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.
8 citations
15 Sep 2019
TL;DR: In this paper, the authors present the analysis of two analogous datasets, namely IRTF/iSHELL ground-based observations onthe nightside of Venus, and the most recent reanalay-sis of the Venus Express/SPICAV-UV dataset on thedayside of Venus.
Abstract: One of the primary objectives of the preselected En-Vision M5 proposal is the monitoring of volcanogenicspecies in Venus’ atmosphere, one of the most promi-nent being sulphur dioxide (SO2). Monitoring SO2below the clouds can be performed on the night-side near2.4μm, and is one science objective of theVenSpec-H channel (P.I.: A. C. Vandaele, BIRA) on-board EnVision. Monitoring SO2above the cloudscan be performed on the dayside in the200-300 nmrange, and is the main science objective of theVenSpec-U channel (P.I.: E. Marcq, LATMOS). Herewe present the analysis of two analogous datasets,namely IRTF/iSHELL ground based observations onthe nightside of Venus, and the most recent reanalay-sis of the Venus Express/SPICAV-UV dataset on thedayside of Venus
15 Sep 2019
TL;DR: The Atmospheric Chemistry Suite (ACS) instrument onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter (TGO) is dedicated to measurements of the Martian atmosphere, in particular implementing the solar occultation technique for sensitive measurement of trace atmospheric gases as mentioned in this paper.
Abstract: ACS (the Atmospheric Chemistry Suite) [1] instrument onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter (TGO) is dedicated to measurements of the Martian atmosphere, in particular implementing the solar occultation technique for sensitive measurement of trace atmospheric gases TGO has started science observations from April 2018 (Ls=162°; MY34), and has observed two major perihelion dust events, the global dust storm 2018A in June till August 2018, and the regional storm in the beginning of 2019. Here we will give a status update of the ACS results, obtained from the data collected during the first year of observations in the orbit of Mars.