Feasibility of Enceladus plume biosignature analysis: Successful capture of organic ice particles in hypervelocity impacts

Enceladus is a compelling destination for astrobiological analyses due to the presence of simple and complex organic constituents in cryovolcanic plumes that jet from its subsurface ocean. Enceladus plume capture during a flyby or orbiter mission is an appealing method for obtaining pristine ocean samples for scientific studies of this organic content because of the high science return, reduced planetary protection challenges, and lower risk and expense compared to a landed mission. However, this mission profile requires sufficient amounts of plume material for sensitive analysis. To explore the feasibility and optimization of the required capture systems, light gas gun experiments were carried out to study organic ice particle impacts on indium surfaces. An organic fluorescent tracer dye, Pacific Blue™, was dissolved in borate buffer and frozen into saline ice projectiles. During acceleration, the ice projectile breaks up in flight into micron‐sized particles that impact the target. Quantitative fluorescence microscopic analysis of the targets demonstrated that under certain impact conditions, 10–50% of the entrained organic molecules were captured in over 25% of the particle impacts. Optimal organic capture was observed for small particles (d ~ 5–15 µm) with velocities ranging from 1 to 2 km s$^{−1}$. Our results reveal how organic capture efficiency depends on impact velocity and particle size; capture increases as particles get smaller and as velocity is reduced. These results demonstrate the feasibility of collecting unmodified organic molecules from the Enceladus ice plume for sensitive analysis with modern in situ instrumentation such as microfluidic capillary electrophoresis (CE) analysis with ppb organic sensitivity

Mineralogy and Petrology of COMET WILD2 Nucleus Samples

The sample return capsule of the Stardust spacecraft will be recovered in northern Utah on January 15, 2006, and under nominal conditions it will be delivered to the new Stardust Curation Laboratory at the Johnson Space Center two days later. Within the first week we plan to begin the harvesting of aerogel cells, and the comet nucleus samples they contain for detailed analysis. By the time of the LPSC meeting we will have been analyzing selected removed grains for more than one month. This presentation will present the first results from the mineralogical and petrological analyses that will have been performed

Stardust@home: A Massively Distributed Public Search for Interstellar Dust in the Stardust Interstellar Dust Collector

In January 2006, the Stardust mission will return the first samples from a solid solar system body beyond the Moon. Stardust was in the news in January 2004, when it encountered comet Wild2 and captured a sample of cometary dust. But Stardust carries an equally important payload: the first samples of contemporary interstellar dust ever collected. Although it is known that interstellar (IS) dust penetrates into the inner solar system [2, 3], to date not even a single contemporary interstellar dust particle has been captured and analyzed in the laboratory. Stardust uses aerogel collectors to capture dust samples. Identification of interstellar dust impacts in the Stardust Interstellar Dust Collector probably cannot be automated, but will require the expertise of the human eye. However, the labor required for visual scanning of the entire collector would exceed the resources of any reasonably-sized research group. We are developing a project to recruit the public in the search for interstellar dust, based in part on the wildly popular SETI@home project, which has five million subscribers. We call the project Stardust@home. Using sophisticated chemical separation techniques, certain types of refractory ancient IS particles (so-called presolar grains) have been isolated from primitive meteorites (e.g., [4] ). Recently, presolar grains have been identified in Interplanetary Dust Particles[6]. Because these grains are not isolated chemically, but are recognized only by their unusual isotopic compositions, they are probably less biased than presolar grains isolated from meteorites. However, it is entirely possible that the typical interstellar dust particle is isotopically solar in composition. The Stardust collection of interstellar dust will be the first truly unbiased one

Mixing fraction of inner solar system material in comet 81P/Wild2

The presence of crystalline silicates in the comae of comets, inferred through infrared observations, has been a long-standing puzzle. Crystalline silicates are unexpectedif comets are composed of pristine interstellar material, since interstellar silicates are almost entirely amorphous. Heating to> 1100 K can anneal silicates to crystallinity,but no protoplanetary heating sources have been identified that were sufficiently strong to heat materials in the outer nebula to such high temperatures. This conundrum led to the suggestion that large-scalemixing was important in theprotoplanetary disk. Reports of refractory calcium - aluminum-rich inclusion-like objects and large concentrations of noble gases in Stardust samples underscore the need for such mixing. However, the evidence from the Stardust samples until now has been largely anecdotal, and it has not been possible to place quantitative constraints on the mixing fraction. Here we report synchrotron-based X-ray microprobe measurements of the relative concentrations of the chemical state of iron in material from a known comet, the Jupiter-family comet 81P/Wild2. We find that the comet is rich in iron sulfides. The elemental S/Fe ratio based on the sulfide concentration, S/Fe> 0.31(2 sigma), is higher than in most chondritic meteorites. We also found that Fe-bearing silicates are at least 50percent crystalline. Based on these measurements, we estimate the fraction psi of inner nebular material in 81P/Wild2. With the lower bound on the crystalline Fe-bearing silicate fraction, we find that psi> 0.5. If the observed S depletion in the inner solar system predated or was contemporaneous with large-scale mixing, our lower bound on the S/Fe ratio gives an upper bound on psi of ~;; 0.65. This measurement may be used to test mixing models of the early solar system

A genome-wide meta-analysis yields 46 new loci associating with biomarkers of iron homeostasis

Iron is essential for many biological functions and iron deficiency and overload have major health implications. We performed a meta-analysis of three genome-wide association studies from Iceland, the UK and Denmark of blood levels of ferritin (N=246,139), total iron binding capacity (N=135,430), iron (N=163,511) and transferrin saturation (N=131,471). We found 62 independent sequence variants associating with iron homeostasis parameters at 56 loci, including 46 novel loci. Variants at DUOX2, F5, SLC11A2 and TMPRSS6 associate with iron deficiency anemia, while variants at TF, HFE, TFR2 and TMPRSS6 associate with iron overload. A HBS1L-MYB intergenic region variant associates both with increased risk of iron overload and reduced risk of iron deficiency anemia. The DUOX2 missense variant is present in 14% of the population, associates with all iron homeostasis biomarkers, and increases the risk of iron deficiency anemia by 29%. The associations implicate proteins contributing to the main physiological processes involved in iron homeostasis: iron sensing and storage, inflammation, absorption of iron from the gut, iron recycling, erythropoiesis and bleeding/menstruation.Participants in the INTERVAL randomised controlled trial were recruited with the active collaboration of NHS Blood and Transplant England (www.nhsbt.nhs.uk), which has supported field work and other elements of the trial. DNA extraction and genotyping was co-funded by the National Institute for Health Research (NIHR), the NIHR BioResource (http://bioresource.nihr.ac.uk/) and the NIHR [Cambridge Biomedical Research Centre at the Cambridge University Hospitals NHS Foundation Trust] [*]. The academic coordinating centre for INTERVAL was supported by core funding from: NIHR Blood and Transplant Research Unit in Donor Health and Genomics (NIHR BTRU-2014-10024), UK Medical Research Council (MR/L003120/1), British Heart Foundation (SP/09/002; RG/13/13/30194; RG/18/13/33946) and the NIHR [Cambridge Biomedical Research Centre at the Cambridge University Hospitals NHS Foundation Trust] [The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care]. A complete list of the investigators and contributors to the INTERVAL trial is provided in reference 73. The academic coordinating centre would like to thank blood donor centre staff and blood donors for participating in the INTERVAL trial. Professor John Danesh is funded by the National Institute for Health Research [Senior Investigator Award]. Will Astle, Joanna Howson and Tao Jiang are funded by the National Institute for Health Research [Cambridge Biomedical Research Centre at the Cambridge University Hospitals NHS Foundation Trust]. Angela M Wood and Elias Allara are supported by EC-Innovative Medicines Initiative (BigData@Heart). Praveen Surendran is supported by a Rutherford Fund Fellowship from the Medical Research Council grant MR/S003746/1. This work was supported by Health Data Research UK, which is funded by the UK Medical Research Council, Engineering and Physical Sciences Research Council, Economic and Social Research Council, Department of Health and Social Care (England), Chief Scientist Office of the Scottish Government Health and Social Care Directorates, Health and Social Care Research and Development Division (Welsh Government), Public Health Agency (Northern Ireland), British Heart Foundation and Wellcome. The Novo Nordisk Foundation (NNF14CC0001 and NNF17OC0027594). The Innovative Medicines Initiative 2 Joint Undertaking under grant agreement no. 115881 (RHAPSODY) (Karina Banasik and Søren Brunak). The Danish Administrative Regions; The Danish Administrative Regions’ Bio- and Genome Bank; The authors thank all the blood banks in Denmark for both collecting and contributing data to this study. Danish Blood Donor Research Fund. Aarhus University, Copenhagen University Hospital Research Fund. Competing interests: Henrik Ullum received an unrestricted research grant form Novartis. Cristian Erikstrup received an unrestricted research grant from Abbott. Søren Brunak reports grants from Innovation Fund Denmark, grants from Novo Nordisk Foundation during the conduct of the study; and personal fees from Intomics A/S and Proscion A/S, outside the submitted work. For the authors who are affiliated with deCODE genetics/Amgen, we declare competing financial interests as employees