1,291 research outputs found
The Character of the Solar Wind, Surface Interactions, and Water
We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system
Effects of an ICME on the Lunar Exosphere
The lunar exosphere is produced in part by the sputtering of atoms off of the Moon's surface by solar wind ions. We present simulations of He, Na, K, Mg, and Ca in the lunar exosphere under nominal conditions. Next, we examine the resulting exospheric enhancement that occurs during the passage of an Interplanetary Coronal Mass Ejection (ICME). Enhanced sputtering under ICME conditions can increase the mass of the lunar exosphere 10-50 times the nominal value. The increase occurs rapidly within the onset of the ICME. Similarly, after the storm passes the Moon, the return to nominal exospheric density is also rapid. Because sputtered particles are energetic, many escape the Moon. Thus ICMEs induce a mass loss from the Moon. However, the implantation of solar wind into the lunar regolith is also enhanced during an ICME, resulting in mass addition to the Moon. This partially mitigates the mass loss caused by ICME sputtering. We present model estimates of the net lunar mass loss induced by ICME
The Exploration Portable Electrostatic Detector (xPED)
Astronauts and rovers, while exploring dynamic environments, can experience charge buildup through Tribo-charging (contact electrification). Charge levels can become substantially high. especially in areas where photoelectric and plasma currents are reduced (e.g. lunar polar crater). Tribo-charging in areas that have little to no charge dissipative path can be severe, leaving an astronaut or roving object to remain charged for extended periods of time. Charge buildup on space suits and/or rovers is expected to present significant hazards to missions, such as electrostatic discharge and arcing, dust adhesion to space suits/equipment, and destruction of equipment. The avoidance of hazards associated with charge buildup is critical for future NASA missions to near earth objects, the Moon and Mars. The Exploration Portable Electrostatic Device (xPED) will allow astronauts to determine their charge state, and also characterize the electrical environment from their excursions. xPED would benefit manned, as well as robotic missions
Doubly-Shadowed Regions in Lunar Polar Craters: Hydrogen Accumulation in the Presence of Recursive Plasma Wakes
Permanently shadowed regions (PSRs) of the Moon have been identified as unique environments of extreme cold and comprise a natural cold trap for sequestering volatiles [Paige et al. 2010]. The diverse chemical composition of the LCROSS impact plume provided evidence for a volatile-rich and chemically-complex PSR environment [Cola prete et al. 2010, Schultz et al. 2010]. Additionally, the polar electrostatic environment is highly complex, with the possibility of strong, localized electric fields that divert solar wind ions directly into polar cold traps [Farrell et al. 2010, Zimmerman et al. 2011]. Thus, regional plasma physics processes couple directly with volatile sequestration. In the present work, kinetic simulations show that recursive plasma wake structure arises in the presence of step-like topographic features (Le. doubly-shadowed craters). Combining the plasma code with a numerical sputtering model demonstrates that solar wind protons can be either a hydrogen source via implantation or a volatile loss mechanism via sputtering, depending on properties of the regolith and solar wind. The present model provides a novel theoretical pathway toward understanding the lunar surface/solar wind physical and chemical interactions for complex topography near the poles
Effect on the Lunar Exosphere of a CME Passage
It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that the sputter yield can be noticeably increased in the case of a good insulating surface. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. The heavy ion component, especially the He++ component, greatly enhances the total sputter yield during times when the heavy ion population is enhanced, most notably during a coronal mass ejection. To simulate the effect on the lunar exosphere of a CME passage past the Moon, we ran a Monte Carlo code for the species Na, K, Mg and Ca
Magnetic antenna using metallic glass
A lightweight search-coil antenna or sensor assembly for detecting magnetic fields and including a multi-turn electromagnetic induction coil wound on a spool type coil form through which is inserted an elongated coil loading member comprised of metallic glass material wrapped around a dielectric rod. The dielectric rod consists of a plastic or a wooden dowel having a length which is relatively larger than its thickness so as to provide a large length-to-diameter ratio. A tri-axial configuration includes a housing in which is located three substantially identical mutually orthogonal electromagnetic induction coil assemblies of the type described above wherein each of the assemblies include an electromagnetic coil wound on a dielectric spool with an elongated metallic glass coil loading member projecting therethrough
The Lunar Dust Pendulum
Shadowed regions on the lunar surface acquire a negative potential. In particular, shadowed craters can have a negative potential with respect to the surrounding lunar regolith in sunlight, especially near the terminator regions. Here we analyze the motion of a positively charged lnnar dust grain in the presence of a shadowed crater at a negative potential in vacuum. Previous models describing the transport of charged lunar dust close to the surface have typically been limited to one-dimensional motion in the vertical direction, e.g. electrostatic levitation; however. the electric fields in the vicinity of shadowed craters will also have significant components in the horizontal directions. We propose a model that includes both the horizontal and vertical motion of charged dust grains near shadowed craters. We show that the dust grains execute oscillatory trajectories and present an expression for the period of oscillation drawing an analogy to the motion of a pendulum
An Evaluation of Diverse Therapeutic Interventions for Substance Use Disorders: Serotonergic Hallucinogens, Immunotherapy, and Transcranial Magnetic Stimulation
Substance Use Disorders are a substantial public health concern whose treatment remains challenging. High rates of relapse are in fact a hallmark of drug addiction despite the wide variety of psychotherapeutic and pharmacotherapeutic approaches. This chapter discusses three innovative and controversial therapeutic approaches for Substance Use Disorders that have received considerable attention: the use of classic serotonergic hallucinogenic drugs (LSD and psilocybin), addiction immunotherapy and anti-addiction vaccines, and the use of transcranial magnetic stimulation. These treatments are not necessarily new but are discussed because they represent a diverse set of approaches that address varied aspects of drug addiction. Furthermore, they have an accumulated body of research from which to assess their future viability. For each of these therapeutic approaches this chapter considers the theoretical basis for use, history, status of the literature supporting their use, limitations, and potential applications. While these three interventions represent highly varied approaches to the treatment of Substance Use Disorders, this diversity may be necessary given the complex nature of addictive disorders
Phases of hadron-quark matter in (Proto) neutron stars
In the first part of this paper, we investigate the possible existence of a structured hadron-quark mixed phase in the cores of neutron stars. This phase, referred to as the hadron-quark pasta phase, consists of spherical blob, rod, and slab rare phase geometries. Particular emphasis is given to modeling the size of this phase in rotating neutron stars. We use the relativistic mean-field theory to model hadronic matter and the non-local three-flavor Nambu–Jona-Lasinio model to describe quark matter. Based on these models, the hadron-quark pasta phase exists only in very massive neutron stars, whose rotational frequencies are less than around 300 Hz. All other stars are not dense enough to trigger quark deconfinement in their cores. Part two of the paper deals with the quark-hadron composition of hot (proto) neutron star matter. To this end we use a local three-flavor Polyakov–Nambu–Jona-Lasinio model which includes the’t Hooft (quark flavor mixing) term. It is found that this term leads to non-negligible changes in the particle composition of (proto) neutron stars made of hadron-quark matter.Fil: Weber, Fridolin. San Diego State University; Estados Unidos. University of California at San Diego; Estados UnidosFil: Farrell, Delaney. San Diego State University; Estados UnidosFil: Spinella, William M.. Wentworth Institute of Technology; Estados UnidosFil: Malfatti, Germán. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata; ArgentinaFil: Orsaria, Milva Gabriela. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata; ArgentinaFil: Contrera, Gustavo AnÃbal Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto de FÃsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de FÃsica La Plata; ArgentinaFil: Maloney, Ian. San Diego State University; Estados Unido
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