Magnetic flux ropes are twisted magnetic field lines that are commonly observed in space and astrophysical plasmas. At Mars, these structures are especially interesting because the planet does not have a global magnetic field like Earth, but instead has remanent magnetic fields preserved in its crust. In this study, we report a close conjunction observation by MAVEN and Tianwen-1 of a magnetic flux rope within the Martian ionosphere. The two spacecraft observed closely related magnetic signatures at near-identical locations and altitudes, allowing us to examine the spatial structure of the event. Our analysis suggests that the observed flux rope may have a loop-like geometry, with magnetic-field lines connected to the Martian dayside ionosphere at both ends. This structure may have formed or evolved through ionospheric instabilities under unusually low solar-wind dynamic pressure or internal reconnection between neighboring crustal magnetic fields. This event shows that Mars may produce a loop-like magnetic flux rope that resembles, in geometry, twisted magnetic loops seen in the solar atmosphere, providing a useful connection between planetary and solar plasma processes.

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.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.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.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.

The interaction between Mars and the solar wind results in different plasma regimes separated by several boundaries, among which the separation between the sheath flow and the ionosphere is complicated. Previous studies have provided different and sometimes opposite findings regarding this region. In this study, we utilize observations from the Mars Atmospheric and Volatile EvolutioN (MAVEN) mission to revisit boundaries within this region and perhaps reconcile some differences. More specifically, we start with the photoelectron boundary (PEB), a topological boundary that separates magnetic field lines having access to the dayside ionosphere (open or closed) from those connected to the solar wind on both ends (draped). We find that large gradients in the planetary ion densiti occur across the PEB and that the dominant ion switches from heavy planetary ions to protons near the PEB, indicating that the PEB falls within the ion composition boundary (ICB). Furthermore, our results show that the PEB is not a pressure balance boundary; rather the magnetic pressure dominates both sides of the PEB. Meanwhile, we find that the PEB is located where the shocked solar wind flow stops penetrating deeper into the ionosphere. These findings suggest the PEB marks the top of the Mars dayside ionosphere and also the interface where the sheath plasma flow deflects around the obstacle going downstream.

# Shogo Inui[1]; Kanako Seki[2]; Shotaro Sakai[2]; Kazunari Matsunaga[3]; David A. Brain[4]; James P. McFadden[5]; Takuya Hara[5]; Jasper S. Halekas[6]; David L. Mitchell[5]; John E. P. Connerney[7]; Bruce M. Jakosky[8] [1] Earth and Planetary Science, Univ. of Tokyo; [2] Dept. Earth & Planetary Sci., Science, Univ. Tokyo; [3] ISEE, Nagoya Univ.; [4] LASP, Univ. of Colorado at Boulder, USA; [5] SSL, UC Berkeley; [6] Dept. Phys. & Astron., Univ. Iowa; [7] NASA GSFC; [8] LASP, CU Boulder

ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of ∼20–45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below ∼15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of ∼20–24 and ∼36–40 amu. Although many of the observations have properties consistent with a surface or near‐surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.

Following the onset of reconnection, the first reconnecting flux tubes move away from the reconnection site creating an over-dense region in front of their leading edge, with a low density region lagging behind. The initial front observed at the magnetic equator has a fairly well distinguishable magnetic signature, which in space observation constitute a sub category of a broader group classified as magnetic pile-up events (or, alternatively, as dipolarization events). The first reconnecting flux tubes at the magnetic equator do not form a classic shock, but are associated with lower hybrid drift instabilities and whistler waves. As has been shown in work by others, the first reconnecting flux tubes are associated with strong dissipation, especially ion dissipation. In the high density region, the electrons and ions are decelerated and redirected perpendicular to the ejected exhaust. Near the first reconnecting flux tubes the ions gain energy and the electrons consist of two populations, one bi-streaming and the other more energetic (warmer) in the perpendicular direction. The latter population is most likely the source of the observed whistlers. Behind the first reconnecting flux tubes is a region that electrons have difficulty reaching, which observationally looks like an electron void. In this presentation comparisons between observations and simulations will be made.

Determining the characteristics that are overrepresented in work-zone crashes will give direction to safety-enhancement efforts. Several years of computerized crash data in Alabama, Michigan and Tennessee are reviewed, and common work-zone crash characteristics are identified.

Contact DermatitisVolume 40, Issue 2 p. 112-113 Adverse cutaneous reactions to cosmetic allergens A. Goossens, A. Goossens University Hospital Sint-Rafaël, Leuven, BelgiumSearch for more papers by this authorM. H. Beck, M. H. Beck Dermatology Centre, Salford, United KingdomSearch for more papers by this authorE. Haneke, E. Haneke Ferdinand-Sauerbruch-Hospital, Wuppertal, GermanySearch for more papers by this authorJ. P. McFadden, J. P. McFadden Hillingdon Hospital, London, United KingdomSearch for more papers by this authorS. Nolting, S. Nolting University Hospital, Münster, GermanySearch for more papers by this authorG. Durupt, G. Durupt Johnson & Johnson European Skin Care Research Center, Paris, FranceSearch for more papers by this authorG Ries, G Ries Johnson & Johnson European Skin Care Research Center, Paris, FranceSearch for more papers by this author A. Goossens, A. Goossens University Hospital Sint-Rafaël, Leuven, BelgiumSearch for more papers by this authorM. H. Beck, M. H. Beck Dermatology Centre, Salford, United KingdomSearch for more papers by this authorE. Haneke, E. Haneke Ferdinand-Sauerbruch-Hospital, Wuppertal, GermanySearch for more papers by this authorJ. P. McFadden, J. P. McFadden Hillingdon Hospital, London, United KingdomSearch for more papers by this authorS. Nolting, S. Nolting University Hospital, Münster, GermanySearch for more papers by this authorG. Durupt, G. Durupt Johnson & Johnson European Skin Care Research Center, Paris, FranceSearch for more papers by this authorG Ries, G Ries Johnson & Johnson European Skin Care Research Center, Paris, FranceSearch for more papers by this author First published: 14 February 2007 https://doi.org/10.1111/j.1600-0536.1999.tb06004.xCitations: 63AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References 1 Goossens A, Merckx L. L'allergie de contact aux cosmétiques. In: Progrès en dermato-allergologie, vol. III. Marseille : Ed. Mediscript, 1997. 2 Jacobs M-C, White I R, Rycroft R J G et al. Patch testing with preservatives at St. John's from 1982–1993. Contact Dermatitis 1995: 33: 247– 254. 3 Dooms-Goossens A, Kerre S, Drieghe J et al. Cosmetic products and their allergens. Eur J Dermatol 1992: 2: 465– 468. 4 Perrenoud D, Bircher A, Hunziker T et al. Frequency of sensitisation to 13 common preservatives in Switzerland. Contact Dermatitis 1994: 30: 276– 279. 5 Calnan C D. Ditertiairy-butylhydroquinone in eyeshadow. Cont Derm Newsletter 1973: 13: 368. 6 De Groot A C. Adverse reactions to cosmetics. Thesis. State University of Groningen, Groningen, The Netherlands, 1988. Citing Literature Volume40, Issue2February 1999Pages 112-113 ReferencesRelatedInformation