Magnetic Field, Force, and Inductance Computations for an Axially Symmetric Solenoid

The pumping of liquid oxygen (LOX) by magnetic fields (B field), using an array of electromagnets, is a current topic of research and development at Kennedy Space Center, FL. Oxygen is paramagnetic so that LOX, like a ferrofluid, can be forced in the direction of a B field gradient. It is well known that liquid oxygen has a sufficient magnetic susceptibility that a strong magnetic gradient can lift it in the earth's gravitational field. It has been proposed that this phenomenon can be utilized in transporting (i.e., pumping) LOX not only on earth, but on Mars and in the weightlessness of space. In order to design and evaluate such a magnetic pumping system, it is essential to compute the magnetic and force fields, as well as inductance, of various types of electromagnets (solenoids). In this application, it is assumed that the solenoids are air wrapped, and that the current is essentially time independent

Dust Removal Technology Demonstration for a Lunar Habitat

We have developed an Electrodynamic Dust Shield (EDS), an active dust mitigation technology with applications to solar panels, thermal radiators, optical systems, visors, seals and connectors. This active technology is capable of removing dust and granular material with diameters as large as several hundred microns. In this paper, we report on the development of three types of EDS systems for NASA's Habitat Demonstration Unit (HDU). A transparent EDS 20 cm in diameter with indium tin oxide electrodes on a 0.1 mm-thick polyethylene terephtalate (PET) film was constructed for viewport dust protection. Two opaque EDS systems with copper electrodes on 0.1 mm-thick Kapton were also built to demonstrate dust removal on the doors of the HDU. A lotus coating that minimizes dust adhesion was added to one of the last two EDS systems to demonstrate the effectiveness of the combined systems

Integration of the Electrodynamic Dust Shield on a Lunar Habitat Demonstration Unit

NASA is developing a Habitat Demonstration Unit (HDU) to investigate the feasibility of lunar surface technologies and lunar ground operations. The HDU will define and validate lunar scenario architecture through field analog testing. It will contain a four-port vertical habitat module with docking demonstration capabilities. The Electrodynamic Oust Shield (EDS) is being incorporated into the HDU to demonstrate dust removal from a viewport and from a door prior to docking procedures. In this paper, we will describe our efforts to scale up the EDS to protect a viewport 20 cm in diameter. We will also describe the development of several 20 cm x 25 cm EDS patches to demonstrate dust removal from one of the HDU doors

A multi-wavelength view of the Galactic center dust ridge reveals little star formation

The Galactic center dust ridge consists of a narrow string of massive condensations, first identified in submillimeter dust continuum emission. To determine whether new high-mass stars are forming in this region, we performed new observations at 870 μm with the Atacama Pathfinder EXperiment (APEX) telescope and at 8.4 GHz with the Very Large Array. We complement our data with recent maser and mid-infrared results. The ridge’s clouds are dark at mid-infrared wavelengths, indicating the presence of cold, high column density material. In combination with existing temperature measurements in the dust ridge, we determine masses of the largest clouds. The results show that the dust ridge contains a very massive reservoir of molecular material. We find five radio continuum sources at 8.4 GHz in the general dust ridge vicinity, but outside of the dust ridge clouds. They are likely all excited by massive young stars, whose properties we constrain. Our observations exclude the existence of zero age main sequence stars with spectral types earlier than B0.5 within the dust ridge clouds. The only indication of ongoing high-mass star formation inside the clouds are class II methanol masers that are found in two of the clouds. Except for a weak water maser, found in previous observations, no signs of star formation are detected in the most massive cloud, M0.25+0.012

High field x-ray diffraction study on a magnetic-field-induced valence transition in YbInCu4

We report the first high-field x-ray diffraction experiment using synchrotron x-rays and pulsed magnetic fields exceeding 30 T. Lattice deformation due to a magnetic-field-induced valence transition in YbInCu4 is studied. It has been found that the Bragg reflection profile at 32 K changes significantly at around 27 T due to the structural transition. In the vicinity of the transition field the low-field and the high-field phases are observed simultaneously as the two distinct Bragg reflection peaks: This is a direct evidence of the fact that the field-induced valence state transition is the first order phase transition. The field-dependence of the low-field-phase Bragg peak intensity is found to be scaled with the magnetization.Comment: 5 pages, 6 figures, submitted to J. Phys. Soc. Jp

SARS-CoV-2 / COVID-19 in patients on the Swiss national transplant waiting list.

The impact of coronavirus disease 2019 (COVID-19) on patients listed for solid organ transplantation has not been systematically investigated to date. Thus, we assessed occurrence and effects of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on patients on the Swiss national waiting list for solid organ transplantation. Patient data were retrospectively extracted from the Swiss Organ Allocation System (SOAS). From 16 March to 31 May 2020, we included all patients listed for solid organ transplantation on the Swiss national waiting list who were tested positive for SARS-CoV-2. Severity of COVID-19 was categorised as follows: stage I, mild symptoms; stage II, moderate to severe symptoms; stage III, critical symptoms; stage IV, death. We compared the incidence rate (laboratory-confirmed cases of SARS-CoV-2), the hospital admission rate (number of admissions of SARS-CoV-2-positive individuals), and the case fatality rate (number of deaths of SARS-CoV-2-positive individuals) in our study population with the general Swiss population during the study period, calculating age-adjusted standardised incidence ratios and standardised mortality ratios, with 95% confidence intervals (CIs). A total of 1439 patients were registered on the Swiss national solid organ transplantation waiting list on 31 May 31 2020. Twenty-four (1.7%) waiting list patients were reported to test positive for SARS-CoV-2 in the study period. The median age was 56 years (interquartile range 45.3–65.8), and 14 (58%) were male. Of all patients tested positive for SARS-CoV-2, two patients were asymptomatic, 14 (58%) presented in COVID-19 stage I, 3 (13%) in stage II, and 5 (21%) in stage III. Eight patients (33%) were admitted to hospital, four (17%) required intensive care, and three (13%) mechanical ventilation. Twenty-two patients (92%) of all those infected recovered, but two male patients aged >65 years with multiple comorbidities died in hospital from respiratory failure. Comparing our study population with the general Swiss population, the age-adjusted standardised incidence ratio was 4.1 (95% CI 2.7–6.0). The overall rate of SARS-CoV-2 infections in candidates awaiting solid organ transplantation was four times higher than in the Swiss general population; however, the frequency of testing likely played a role. Given the small sample size of affected patients, conclusions have to be drawn cautiously and results need verification in larger cohorts

Electrodynamic Dust Shield for Surface Exploration Activities on the Moon and Mars

The Apollo missions to the moon showed that lunar dust can hamper astronaut surface activities due to its ability to cling to most surfaces. NASA's Mars exploration landers and rovers have also shown that the problem is equally hard if not harder on Mars. In this paper, we report on our efforts to develop and electrodynamic dust shield to prevent the accumulation of dust on surfaces and to remove dust already adhering to those surfaces. The parent technology for the electrodynamic dust shield, developed in the 1970s, has been shown to lift and transport charged and uncharged particles using electrostatic and dielectrophoretic forces. This technology has never been applied for space applications on Mars or the moon due to electrostatic breakdown concerns. In this paper, we show that an appropriate design can prevent the electrostatic breakdown at the low Martian atmospheric pressures. We are also able to show that uncharged dust can be lifted and removed from surfaces under simulated Martian environmental conditions. This technology has many potential benefits for removing dust from visors, viewports and many other surfaces as well as from solar arrays. We have also been able to develop a version of the electrodynamic dust shield working under. hard vacuum conditions. This version should work well on the moon

Cratering Soil by Impinging Jets of Gas, with Application to Landing Rockets on Planetary Surfaces

Several physical mechanisms are involved in excavating granular materials beneath a vertical jet of gas. These occur, for example, beneath the exhaust plume of a rocket landing on the soil of the Moon or Mars. A series of experiments and simulations have been performed to provide a detailed view of the complex gas/soil interactions. Measurements have also been taken from the Apollo lunar landing videos and from photographs of the resulting terrain, and these help to demonstrate how the interactions extrapolate into the lunar environment. It is important to understand these processes at a fundamental level to support the ongoing design of higher-fidelity numerical simulations and larger-scale experiments. These are needed to enable future lunar exploration wherein multiple hardware assets will be placed on the Moon within short distances of one another. The high-velocity spray of soil from landing spacecraft must be accurately predicted and controlled lest it erosively damage the surrounding hardware