scholarly journals The Mars system revealed by the Martian Moons eXploration mission

2022 ◽  
Vol 74 (1) ◽  
Author(s):  
Kazunori Ogohara ◽  
Hiromu Nakagawa ◽  
Shohei Aoki ◽  
Toru Kouyama ◽  
Tomohiro Usui ◽  
...  

AbstractJapan Aerospace Exploration Agency (JAXA) plans a Phobos sample return mission (MMX: Martian Moons eXploration). In this study, we review the related works on the past climate of Mars, its evolution, and the present climate and weather to describe the scientific goals and strategies of the MMX mission regarding the evolution of the Martian surface environment. The MMX spacecraft will retrieve and return a sample of Phobos regolith back to Earth in 2029. Mars ejecta are expected to be accumulated on the surface of Phobos without being much shocked. Samples from Phobos probably contain all types of Martian rock from sedimentary to igneous covering all geological eras if ejecta from Mars could be accumulated on the Phobos surface. Therefore, the history of the surface environment of Mars can be restored by analyzing the returned samples. Remote sensing of the Martian atmosphere and monitoring ions escaping to space while the spacecraft is orbiting Mars in the equatorial orbit are also planned. The camera with multi-wavelength filters and the infrared spectrometer onboard the spacecraft can monitor rapid transport processes of water vapor, dust, ice clouds, and other species, which could not be traced by the previous satellites on the sun-synchronous polar orbit. Such time-resolved pictures of the atmospheric phenomena should be an important clue to understand both the processes of water exchange between the surface/underground reservoirs and the atmosphere and the drivers of efficient material transport to the upper atmosphere. The mass spectrometer with unprecedented mass resolution can observe ions escaping to space and monitor the atmospheric escape which has made the past Mars to evolve towards the cold and dry surface environment we know today. Together with the above two instruments, it can potentially reveal what kinds of atmospheric events can transport tracers (e.g., H2O) upward and enhance the atmospheric escape. Graphical Abstract

2019 ◽  
Author(s):  
Yunjiang Zhang ◽  
Olivier Favez ◽  
Jean-Eudes Petit ◽  
Francesco Canonaco ◽  
Francois Truong ◽  
...  

Abstract. Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly-time resolved year-round characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of Aerosol Chemical Speciation Monitor (ACSM) and multi-wavelength aethalometer from November 2011 to March 2018 at a background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase of LO-OOA concentrations and contributions (50–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely high concentrations and OA contributions (32–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter, and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about 200 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil fuel and biomass burning black carbon components), and no trend for LO-OOA over the 6+-year investigated period.


2019 ◽  
Vol 622 ◽  
pp. A211 ◽  
Author(s):  
Francesco Coti Zelati ◽  
Alessandro Papitto ◽  
Domitilla de Martino ◽  
David A. H. Buckley ◽  
Alida Odendaal ◽  
...  

We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4−650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of ∼20.1 (3300–10500 Å). The optical emission was variable on timescales from hundreds to thousands of seconds. The spectrum showed prominent emission lines with variable profiles at different epochs. Simultaneous XMM-Newton and NuSTAR observations revealed a bimodal distribution of the X-ray count rates on timescales as short as tens of seconds, as well as sporadic flaring activity. The average broad-band (0.3–79 keV) spectrum was adequately described by an absorbed power law model with photon index of Γ = 1.63  ±  0.01 (at 1σ c.l.), and the X-ray luminosity was (2.16  ±  0.04)  ×  1034 erg s−1 for a distance of 4 kpc. Based on observations with different instruments, the X-ray luminosity has remained relatively steady over the past ∼15 years. J1109 is spatially associated with the gamma-ray source FL8Y J1109.8−6500, which was detected with Fermi at an average luminosity of (1.5  ±  0.2)  ×  1034 erg s−1 (assuming the distance of J1109) over the 0.1–300 GeV energy band between 2008 and 2016. The source was undetected during ATCA radio observations that were simultaneous with NuSTAR, down to a 3σ flux upper limit of 18 μJy beam−1 (at 7.25 GHz). We show that the phenomenological properties of J1109 point to a binary transitional pulsar candidate currently in a sub-luminous accretion disk state, and that the upper limits derived for the radio emission are consistent with the expected radio luminosity for accreting neutron stars at similar X-ray luminosities.


2005 ◽  
Vol 4 (5) ◽  
pp. 527-537 ◽  
Author(s):  
P. Taroni ◽  
L. Spinelli ◽  
A. Torricelli ◽  
A. Pifferi ◽  
G.M. Danesini ◽  
...  

A time-resolved optical mammograph operating at 7 wavelengths (637, 683, 785, 832, 905, 916, and 975 nm) in compressed breast geometry was developed. Its clinical application was started on patients bearing malignant and benign lesions. Late gated intensity images are used to obtain information on the spatial distribution of the absorption properties of breast. Scattering images derived from the diffusion theory are also applied for lesion detection and characterization. Cancers are identified in intensity images at short wavelengths, due to the high blood content, while cysts are typically characterized by low scattering at all wavelengths. The increase (from 4 to 7) in the number of wavelengths as compared to the previous versions of the instrument aims at improving the robustness of the fitting procedures for a better estimate of tissue composition and structure and of physiological parameters. Moreover, the new wavelengths contribute to the qualitatively identify tissue composition from intensity images, and could assist lesion detection.


The functional properties of proteins in the crystalline state have been investigated over the past 30 years by a variety of methods, including single crystal polarized absorption spectroscopy. This technique has provided information on the accumulation and equilibrium distribution of protein-ligand complexes in the crystal and, in a few cases, on the rates of interconversion of catalytic intermediates. It has been possible to detect synergistic effects in the binding of different ligands, cooperativity and half-site reactivity and even formation of active multiprotein complexes, obtained by diffusion of one small protein in the pre-formed crystals of the other. Lattice interactions restrain the conformational transitions of some proteins existing in multiple states in solution. The crystal offers the unique opportunity to analyse not only the structure but also the function of a single form of the protein. The relevance of these data to the planning and interpretation of structural studies, especially in the perspectives of time-resolved crystallography, will be discussed with reference to well-characterized systems.


Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 854
Author(s):  
Ki Hyun Nam

Radiation damage and cryogenic sample environment are an experimental limitation observed in the traditional X-ray crystallography technique. However, the serial crystallography (SX) technique not only helps to determine structures at room temperature with minimal radiation damage, but it is also a useful tool for profound understanding of macromolecules. Moreover, it is a new tool for time-resolved studies. Over the past 10 years, various sample delivery techniques and data collection strategies have been developed in the SX field. It also has a wide range of applications in instruments ranging from the X-ray free electron laser (XFEL) facility to synchrotrons. The importance of the various approaches in terms of the experimental techniques and a brief review of the research carried out in the field of SX has been highlighted in this editorial.


2020 ◽  
Author(s):  
Quentin Nénon ◽  
Andrew R Poppe ◽  
Ali Rahmati ◽  
James P McFadden

<p>Mars has lost and is losing its atmosphere into space. Strong evidences of this come from the observation of planetary singly charged heavy ions (atomic oxygen, molecular oxygen, carbon dioxide ions) by Mars Express and MAVEN. Phobos, the closest moon of Mars, orbits only 6,000 kilometers above the red planet’s surface and is therefore a unique vantage point of the planetary atmospheric escape, with the escaping ions being implanted within the regolith of Phobos and altering the properties of the moon’s surface.</p> <p>In this presentation, we aggregate all ion observations gathered in-situ close to the orbit of Phobos by three ion instruments onboard MAVEN, from 2015 to 2019, to constrain the long-term averaged ion environment seen by the Martian moon at all longitudes along its orbit. In particular, the SupraThermal and Thermal Ion Composition (STATIC) instrument onboard MAVEN distinguishes between solar wind and planetary ions. The newly constrained long-term ion environment seen by Phobos is combined with numerical simulations of ion transport and effects in matter.</p> <p>This way, we find that planetary ions are implanted on the near side of Phobos (pointing towards Mars) inside the uppermost tens of nanometers of regolith grains. The composition of near-side grains that may be sampled by future Phobos sample return missions is therefore not only contaminated by planetary ions, as seen in lunar samples with the terrestrial atmosphere, but may show a unique record of the past atmosphere of Mars.</p> <p>The long-term fluxes of planetary ions precipitating onto Phobos are so intense that these ions weather the moon’s surface as much as or more than solar wind ions. In particular, Martian ions accelerate the long-term sputtering and amorphization of the near side regolith by a factor of 2. Another implication is that ion weathering is highly asymmetric between the near side and far side of Phobos.</p>


Author(s):  
P. Taroni ◽  
L. Pallaro ◽  
A. Pifferi ◽  
L. Spinelli ◽  
A. Torricelli ◽  
...  

2013 ◽  
Vol 756-759 ◽  
pp. 108-111
Author(s):  
Fan Da Zeng ◽  
Ya Ping Han ◽  
Jin Xin Wang ◽  
Shao Ze Wang

nanosized copper thin film was prepared on glass substrates by magnetron sputtering. 800 nm pump and 400nm probe technique were used to measure time-resolved reflectivity of copper thin film, and the heat transport processes of copper film were experimentally studied. Thermal transport processes in the copper film were numerically simulated by using Parabolic Two-Step (PTS) model with Finite Difference method. The result of the PTS model can well evaluate the measure date.


2007 ◽  
Author(s):  
D. Chorvat, Jr. ◽  
A. Mateasik ◽  
J. Kirchnerova ◽  
A. Chorvatova

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