2,975 research outputs found

    Variations in solar wind fractionation as seen by ACE/SWICS over a solar cycle and the implications for Genesis Mission results

    Get PDF
    We use ACE/SWICS elemental composition data to compare the variations in solar wind fractionation as measured by SWICS during the last solar maximum (1999-2001), the solar minimum (2006-2009) and the period in which the Genesis spacecraft was collecting solar wind (late 2001 - early 2004). We differentiate our analysis in terms of solar wind regimes (i.e. originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-FIP ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of solar wind speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.Comment: Accepted for publication in Ap

    Characterisation of Float Rocks at Ireson Hill, Gale Crater

    Get PDF
    Float rocks discovered by surface missions on Mars have given unique insights into the sedimentary, diagenetic and igneous processes that have operated throughout the planets history. In addition, Gale sedimentary rocks, both float and in situ, record a combination of source compositions and diagenetic overprints. We examine a group of float rocks that were identified by the Mars Science Laboratory missions Curiosity rover at the Ireson Hill site, circa. sol 1600 using ChemCam LIBS, APXS and images from the MastCam, Mars Hand Lens Imager (MAHLI) and ChemCam Remote Micro-Imager (RMI) cameras. Geochemical data provided by the APXS and ChemCam instruments allow us to compare the compositions of these rocks to known rock types from Gale crater, as well as elsewhere on Mars. Ireson Hill is a 15 m long butte in the Murray formation with a dark cap-ping unit with chemical and stratigraphic consistency with the Stimson formation. A total of 6 float rocks have been studied on the butte

    Concepts of visual consciousness and their measurement.

    Get PDF
    Although visual consciousness can be manipulated easily (e.g., by visual masking), it is unresolved whether it can be assessed accurately with behavioral measures such as discrimination ability and self-report. Older theories of visual consciousness postulated a sensory threshold and distinguished between subjective and objective thresholds. In contrast, newer theories distinguish among three aspects: phenomenal, access, and reflexive consciousness. This review shows that discrimination ability and self-report differ in their sensitivity to these aspects. Therefore, both need to be assessed in the study of visual consciousness

    Postcards from Mars: Insights into Martian Geochemical Processes from the Curiosity Rover

    Get PDF
    With the successful landing of the Mars Curiosity Rover in August 2012, we now have the most capable geochemical laboratory ever to travel to another planet roving Mars’ Gale crater. The geochemical instrument suite includes the Chemistry Camera (ChemCam), which uses a laser to vaporize geologic targets and performs atomic emission spectroscopy on the vapor from distances of up to 7m. This provides a geochemical surveying capability that enables rapid identification of unique specimens and accumulation of a large set of rock and fines compositions as the rover traverses. The Alpha Particle X-ray Spectrometer (APXS) provides high quality “bulk” elemental analyses for major, minor and a few trace elements through a touch deployment on the surface of a rock or soil, and is an upgraded version of similar instruments previously flown to Mars. The addition of x-ray diffraction through the Chemistry and Mineralogy (CheMin) instrument and volatile, isotope, and organic analyses with the Sample Analysis at Mars (SAM) instrument suite, give Curiosity the capability to assess the geochemical history of the planet more deeply than previously possible. Both CheMin and SAM accept sieved fines from either Curiosity’s scoop or drill. To date, sampling has occurred at the Rocknest aeolian drift deposit and a fine-grained mudstone called John Klein. At Rocknest, CheMin found a mix of primary igneous minerals and amorphous materials. SAM found that Rocknest fines contain significant bound volatiles that can be released upon heating, largely associated with the amorphous material. Because APXS and ChemCam data support the fines being representative of those found at other sites on Mars, Curiosity results show that martian fines are a good source of water, CO2 and other volatiles that could be leveraged by living organisms, including future human explorers. At John Klein, early results are consistent with an ancient aqueous habitable environment. Analyses of isotopes and organics also provide exciting windows into martian habitability and volatile evolution. These early geochemical results will be discussed

    Broadband seismic deployments in East Antarctica: IPY contribution to understand the Gamburtsev Province -AGAP/GAMSEIS– \n

    Get PDF
    第30回極域地学シンポジウム「極域から探る固体地球ダイナミクス」12月3日(金) 国語研究所 2階講
    corecore