Surface drilling technologies for Mars

Rock drilling and coring conceptual designs for the surface activities associated with a manned Mars mission are proposed. Straightforward extensions of equipment and procedures used on Earth are envisioned for the sample coring and shallow high explosive shot holes needed for tunneling and seismic surveying. A novel rocket exhaust jet piercing method is proposed for very rapid drilling of shot holes required for explosive excavation of emergency radiation shelters. Summaries of estimated equipment masses and power requirements are provided, and the indicated rotary coring rigs are scaled from terrestrial equipment and use compressed CO2 from the Martian atmosphere for core bit cooling and cuttings removal. A mass of 120 kg and power of 3 kW(e) are estimated for a 10 m depth capability. A 100 m depth capacity core rig requires about 1150 kg and 32 km(e). The rocket exhaust jet equipment devised for shallow (3m) explosive emplacement shot holes requires no surface power beyond an electrical ignition system, and might have a 15 kg mass

Measurement of electron density and temperature in plasmas

Application of two laser wavelengths passing through plasma measures electron density and temperature. Function depends on determining absorption of light at two wavelengths. Nature of reaction is explained and schematic diagram of equipment is included

Evidence of Erosional Self-Channelization of Pyroclastic Density Currents Revealed by Ground-Penetrating Radar Imaging at Mount St. Helens, Washington (USA)

The causes and effects of erosion are among the least understood aspects of pyroclastic density current (PDC) dynamics. Evidence is especially limited for erosional self-channelization, a process whereby PDCs erode a channel that confines the body of the eroding flow or subsequent flows. We use ground-penetrating radar imaging to trace a large PDC scour and fill from outcrop to its point of inception and discover a second, larger PDC scour and fill. The scours are among the largest PDC erosional features on record, at \u3e200 m wide and at least 500 m long; estimated eroded volumes are on the order of 106 m3. The scours are morphologically similar to incipient channels carved by turbidity currents. Erosion may be promoted by a moderate slope (5–15°), substrate pore pressure retention, and pulses of increased flow energy. These findings are the first direct evidence of erosional self-channelization by PDCs, a phenomenon that may increase flow velocity and runout distance through confinement and substrate erosion

Retrospective Epidemiologic Analysis of Influenza Pandemics in Arkansas, A

This study compares influenza mortality in Arkansas during the pandemics of: 1918 (aka Spanish flu), 1957, 1968, and 2009 (H1N1, aka Swine flu). Death certificate and U.S. census data were gathered and analyzed for statistical differences in mortalities based on sex, age, and geographic regions of Arkansas for each pandemic. The geographic regions were defined by the five Public Health Units classified by the Arkansas Department of Health. Regional mortalities were also analyzed across all pandemics to investigate how the different pandemics affected each individual region. Chi-square analyses for each pandemic showed only the 1918 pandemic had statistical differences between male and female mortalities (p0.5). Data showed urban regions sustained higher proportional mortalities than rural regions. Over time, the four pandemics resulted in decreased flu mortalities throughout the state. Regional mortality rates suggest areas for increased public health efforts during future influenza outbreaks in Arkansas, and more efficient distribution of resources may reduce mortality rates of future pandemics

Snowmobiles in Antarctica

Snowmobiles are the main form of land transportation for field parties in Antarctica. Recently the United States Antarctic program turned almost exclusively to Ski-Doo Alpine 640-ER snowmobiles, the use and maintenance of which require specialized techniques. The first extensive Antarctic field test of these snowmobiles was made during three months of 1977-1978 while engaged in reconnaissance geologic and topographic exploration of the Orville Coast area. Snowmobiles are used to pull large loads of food and gear on two Nansen sledges. When crossing crevasse fields, they are driven remotely by persons on skis. To do this, modifications are made to the stock throttle to enable the engine both to be set at a constant speed and to be shorted out by pulling on a cord that trails behind the snowmobile; steering is by ropes attached to the front ski of the snowmobile. Proper "night" storage is necessary to ensure easiest starting in the morning and to minimize the effects of storms. A routine of trouble-shooting that rapidly isolated and corrected engine problems included first checking spark-plugs or gas-line filters, followed by checking carburetor jet adjustments, drive belt and oil/gas ratio. We found that Ski-Doos are well suited to Antarctica but would be more useful if carburetor fuel filters were replaced by in-line fuel filters and if snowmobiles were equipped with remote throttle controls, tachometers, speedometers, odometers, and a low-gear option

On the α−\alpha-decay of deformed actinide nuclei

$\alpha-$decay through a deformed potential barrier produces significant mixing of angular momenta when mapped from the nuclear interior to the outside. Using experimental branching ratios and either semi-classical or coupled-channels transmission matrices, we have found that there is a set of internal amplitudes which are essentially constant for all even--even actinide nuclei. These same amplitudes also give good results for the known anisotropic $\alpha-$particle emission of the favored decays of odd nuclei in the same mass region. PACS numbers: 23.60.+e, 24.10.Eq, 27.90.+bComment: 5 pages, latex (revtex style), 2 embedded postscript figures uuencoded gz-compressed .tar file To appear in Physical Review Letter