Studies of a Lacustrine-Volcanic Mars Analog Field Site with Mars-2020-like Instruments

On the upcoming Mars‐2020 rover two remote sensing instruments, Mastcam‐Z and SuperCam, and two microscopic proximity science instruments, SHERLOC and PIXL, will collect compositional (mineralogy, chemistry, and organics) data essential for paleoenvironmental reconstruction. The synergies between and limitations of these instruments were evaluated via study of a Mars analog field site in the Mojave Desert, using instruments approximating the data that will be returned by Mars‐2020. A ground truth dataset was generated for comparison to validate the results. The site consists of a succession of clay‐rich mudstones of lacustrine origin, interbedded tuffs, a carbonate‐silica travertine deposit, and gypsiferous mudstone strata. The major geological units were mapped successfully using simulated Mars‐2020 data. Simulated Mastcam‐Z data identified unit boundaries and Fe‐bearing weathering products. Simulated SuperCam passive shortwave infrared and green Raman data were essential in identifying major mineralogical composition and changes in lacustrine facies at distance; this was possible even with spectrally downsampled passive IR data. LIBS and simulated PIXL data discriminated and mapped major element chemistry. Simulated PIXL revealed mm‐scale zones enriched in zirconium, of interest for age dating. SHERLOC‐like data mapped sulfate and carbonate at sub‐mm scale; silicates were identified with increased laser pulses/spot or by averaging of hundreds of spectra. Fluorescence scans detected and mapped varied classes of organics in all samples, characterized further with follow‐on spatially targeted deep‐UV Raman spectra. Development of dedicated organics spectral libraries is needed to aid interpretation. Given these observations, the important units in the outcrop would be sampled and cached for sample return

Aeroheating Testing and Predictions for Project Orion CEV at Turbulent Conditions

An investigation of the aeroheating environment of the Project Orion Crew Exploration Vehicle was performed in the Arnold Engineering Development Center Hypervelocity Wind Tunnel No. 9 Mach 8 and Mach 10 nozzles and in the NASA Langley Research Center 20 - Inch Mach 6 Air Tunnel. Heating data were obtained using a thermocouple-instrumented approx.0.035-scale model (0.1778-m/7-inch diameter) of the flight vehicle. Runs were performed in the Tunnel 9 Mach 10 nozzle at free stream unit Reynolds numbers of 1x10(exp 6)/ft to 20x10(exp 6)/ft, in the Tunnel 9 Mach 8 nozzle at free stream unit Reynolds numbers of 8 x 10(exp 6)/ft to 48x10(exp 6)/ft, and in the 20-Inch Mach 6 Air Tunnel at free stream unit Reynolds numbers of 1x10(exp 6)/ft to 7x10(exp 6)/ft. In both facilities, enthalpy levels were low and the test gas (N2 in Tunnel 9 and air in the 20-Inch Mach 6) behaved as a perfect-gas. These test conditions produced laminar, transitional and turbulent data in the Tunnel 9 Mach 10 nozzle, transitional and turbulent data in the Tunnel 9 Mach 8 nozzle, and laminar and transitional data in the 20- Inch Mach 6 Air Tunnel. Laminar and turbulent predictions were generated for all wind tunnel test conditions and comparisons were performed with the experimental data to help define the accuracy of computational method. In general, it was found that both laminar data and predictions, and turbulent data and predictions, agreed to within less than the estimated 12% experimental uncertainty estimate. Laminar heating distributions from all three data sets were shown to correlate well and demonstrated Reynolds numbers independence when expressed in terms of the Stanton number based on adiabatic wall-recovery enthalpy. Transition onset locations on the leeside centerline were determined from the data and correlated in terms of boundary-layer parameters. Finally turbulent heating augmentation ratios were determined for several body-point locations and correlated in terms of the boundary-layer momentum Reynolds number

Experimental Investigation of Project Orion Crew Exploration Vehicle Aeroheating in AEDC Tunnel 9

An investigation of the aeroheating environment of the Project Orion Crew Entry Vehicle has been performed in the Arnold Engineering Development Center Tunnel 9. The goals of this test were to measure turbulent heating augmentation levels on the heat shield and to obtain high-fidelity heating data for assessment of computational fluid dynamics methods. Laminar and turbulent predictions were generated for all wind tunnel test conditions and comparisons were performed with the data for the purpose of helping to define uncertainty margins for the computational method. Data from both the wind tunnel test and the computational study are presented herein

Studies of a Lacustrine-Volcanic Mars Analog Field Site with Mars-2020-like Instruments

On the upcoming Mars‐2020 rover two remote sensing instruments, Mastcam‐Z and SuperCam, and two microscopic proximity science instruments, SHERLOC and PIXL, will collect compositional (mineralogy, chemistry, and organics) data essential for paleoenvironmental reconstruction. The synergies between and limitations of these instruments were evaluated via study of a Mars analog field site in the Mojave Desert, using instruments approximating the data that will be returned by Mars‐2020. A ground truth dataset was generated for comparison to validate the results. The site consists of a succession of clay‐rich mudstones of lacustrine origin, interbedded tuffs, a carbonate‐silica travertine deposit, and gypsiferous mudstone strata. The major geological units were mapped successfully using simulated Mars‐2020 data. Simulated Mastcam‐Z data identified unit boundaries and Fe‐bearing weathering products. Simulated SuperCam passive shortwave infrared and green Raman data were essential in identifying major mineralogical composition and changes in lacustrine facies at distance; this was possible even with spectrally downsampled passive IR data. LIBS and simulated PIXL data discriminated and mapped major element chemistry. Simulated PIXL revealed mm‐scale zones enriched in zirconium, of interest for age dating. SHERLOC‐like data mapped sulfate and carbonate at sub‐mm scale; silicates were identified with increased laser pulses/spot or by averaging of hundreds of spectra. Fluorescence scans detected and mapped varied classes of organics in all samples, characterized further with follow‐on spatially targeted deep‐UV Raman spectra. Development of dedicated organics spectral libraries is needed to aid interpretation. Given these observations, the important units in the outcrop would be sampled and cached for sample return

The beginning of time? Evidence for catastrophic drought in Baringo in the early nineteenth century

New developments in the collection of palaeo-data over the past two decades have transformed our understanding of climate and environmental history in eastern Africa. This article utilises instrumental and proxy evidence of historical lake-level fluctuations from Baringo and Bogoria, along with other Rift Valley lakes, to document the timing and magnitude of hydroclimate variability at decadal to century time scales since 1750. These data allow us to construct a record of past climate variation not only for the Baringo basin proper, but also across a sizable portion of central and northern Kenya. This record is then set alongside historical evidence, from oral histories gathered amongst the peoples of northern Kenya and the Rift Valley and from contemporary observations recorded by travellers through the region, to offer a reinterpretation of human activity and its relationship to environmental history in the nineteenth century. The results reveal strong evidence of a catastrophic drought in the early nineteenth century, the effects of which radically alters our historical understanding of the character of settlement, mobility and identity within the Baringo–Bogoria basin

Longitudinal Spin Transfer to Λ\Lambda and Λˉ\bar{\Lambda} Hyperons in Polarized Proton-Proton Collisions at s\sqrt{s} = 200 GeV

The longitudinal spin transfer, $D_{LL}$, from high energy polarized protons to $\Lambda$ and $\bar{\Lambda}$ hyperons has been measured for the first time in proton-proton collisions at $\sqrt{s} = 200 \mathrm{GeV}$ with the STAR detector at RHIC. The measurements cover pseudorapidity, $\eta$, in the range $|\eta| < 1.2$ and transverse momenta, $p_\mathrm{T}$, up to $4 \mathrm{GeV}/c$. The longitudinal spin transfer is found to be $D_{LL}= -0.03\pm 0.13(\mathrm{stat}) \pm 0.04(\mathrm{syst})$ for inclusive $\Lambda$ and $D_{LL} = -0.12 \pm 0.08(\mathrm{stat}) \pm 0.03(\mathrm{syst})$ for inclusive $\bar{\Lambda}$ hyperons with $= 0.5$ and $= 3.7 \mathrm{GeV}/c$. The dependence on $\eta$ and $p_\mathrm{T}$ is presented.Comment: 5 pages, 4 figure

Inclusive pi^0, eta, and direct photon production at high transverse momentum in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV

We report a measurement of high-p_T inclusive pi^0, eta, and direct photon production in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV at midrapidity (0 gamma gamma were detected in the Barrel Electromagnetic Calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross section measurement by STAR is also presented, the signal was extracted statistically by subtracting the pi^0, eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading order perturbative QCD calculations.Comment: 28 pages, 30 figures, 6 tables, the updated version that was accepted by Phys. Rev.

Identified high-pTp_{T} spectra in Cu+Cu collisions at sNN\sqrt{s_{NN}}=200 GeV

We report new results on identified (anti)proton and charged pion spectra at large transverse momenta (3<$p_{T}$<10 GeV/c) from Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-$p_{T}$ and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au+Au data, and allow the detailed exploration for the on-set of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.Comment: Submitted to Phys. Rev. C, 9 pages, 5 figure

Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sNN\sqrt{s_{NN}} = 200 GeV

Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and $\textit{p+p}$ collisions at $\sqrt{s_{NN}}$ = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.Comment: 6 pages, 3 figures The abstract has been slightly modifie

Charged and strange hadron elliptic flow in Cu+Cu collisions at sNN\sqrt{s_{NN}} = 62.4 and 200 GeV

We present the results of an elliptic flow analysis of Cu+Cu collisions recorded with the STAR detector at 62.4 and 200GeV. Elliptic flow as a function of transverse momentum is reported for different collision centralities for charged hadrons and strangeness containing hadrons $K_{S}^{0}$, $\Lambda$, $\Xi$, $\phi$ in the midrapidity region $|eta|<1.0$. Significant reduction in systematic uncertainty of the measurement due to non-flow effects has been achieved by correlating particles at midrapidity, $|\eta|<1.0$, with those at forward rapidity, $2.5<|\eta|<4.0$. We also present azimuthal correlations in p+p collisions at 200 GeV to help estimating non-flow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au+Au collisions at 200 GeV. We observe that $v_{2}$($p_{T}$) of strange hadrons has similar scaling properties as were first observed in Au+Au collisions, i.e.: (i) at low transverse momenta, $p_T<2GeV/c$, $v_{2}$ scales with transverse kinetic energy, $m_{T}-m$, and (ii) at intermediate $p_T$, $2<p_T<4GeV/c$, it scales with the number of constituent quarks, $n_q$. We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of $v_{2}$($p_{T}$) for $K_{S}^{0}$ and $\Lambda$. Eccentricity scaled $v_2$ values, $v_{2}/\epsilon$, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au+Au collisions which go further in density shows $v_{2}/\epsilon$ depend on the system size, number of participants $N_{part}$. This indicates that the ideal hydrodynamic limit is not reached in Cu+Cu collisions, presumably because the assumption of thermalization is not attained.Comment: 18 pages, 14 figure