Radiation Tolerance of Low-Cost Magnetometer for Space Applications

Knowing the three-dimensional magnetic field configuration and dynamics in space environments is key to understand the physical processes taking place. Plasma dynamics depend on the local orientation of the magnetic field, and key quantities such as pitch angle and dynamical processes such as waves and reconnection cannot be studied without in-situ measurements of the fields. For this reason, magnetometers are one of the most important instruments for space physics-focused missions. This is true both for spacecraft and also for landed missions, particularly on atmosphere-less bodies, where the space environment interacts directly with the surface. To enable the next generation of small spacecraft and landers, sensors need to be low-cost and withstand the harsh radiation environment present in space. Here we present the latest advances in the characterization of a commercial-off-the-shelf three-dimensional magnetometer,summarizing previous and newresults from radiation tests. The sensor shows tolerance up to a total ionization dose (TID) of 300 krad, levels well beyond those typical for a low-Earth orbit mission, and compliant with those expected during a landed mission on the Jovian moon Europa

The case for studying other planetary magnetospheres and atmospheres in Heliophysics

Heliophysics is the field that "studies the nature of the Sun, and how it influences the very nature of space - and, in turn, the atmospheres of planetary bodies and the technology that exists there." However, NASA's Heliophysics Division tends to limit study of planetary magnetospheres and atmospheres to only those of Earth. This leaves exploration and understanding of space plasma physics at other worlds to the purview of the Planetary Science and Astrophysics Divisions. This is detrimental to the study of space plasma physics in general since, although some cross-divisional funding opportunities do exist, vital elements of space plasma physics can be best addressed by extending the expertise of Heliophysics scientists to other stellar and planetary magnetospheres. However, the diverse worlds within the solar system provide crucial environmental conditions that are not replicated at Earth but can provide deep insight into fundamental space plasma physics processes. Studying planetary systems with Heliophysics objectives, comprehensive instrumentation, and new grant opportunities for analysis and modeling would enable a novel understanding of fundamental and universal processes of space plasma physics. As such, the Heliophysics community should be prepared to consider, prioritize, and fund dedicated Heliophysics efforts to planetary targets to specifically study space physics and aeronomy objectives

Out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation in patients with normal electrocardiograms:results from a multicentre long-term registry

AIMS : To define the clinical characteristics and long-term clinical outcomes of a large cohort of patients with idiopathic ventricular fibrillation (IVF) and normal 12-lead electrocardiograms (ECGs). METHODS AND RESULTS: Patients with ventricular fibrillation as the presenting rhythm, normal baseline, and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular conduction abnormalities, and without structural heart disease were included in a registry. A total of 245 patients (median age: 38 years; males 59%) were recruited from 25 centres. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in four of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, P = 0.001). Fifty-two patients (21%) experienced an arrhythmic recurrence. Age ≤16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.18-0.92; P = 0.03]. CONCLUSION : Patients with IVF and persistently normal ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences

New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission

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Photoionization Loss of Mercury's Sodium Exosphere: Seasonal Observations by MESSENGER and the THEMIS Telescope

We present the first investigation and quantification of the photoionization loss process to Mercury’s sodium exosphere from spacecraft and ground‐based observations. We analyze plasma and neutral sodium measurements from NASA’s MESSENGER spacecraft and the THEMIS telescope. We find that the sodium ion (Na+) content and therefore the significance of photoionization varies with Mercury’s orbit around the Sun (i.e., true anomaly angle: TAA). Na+ production is affected by the neutral sodium solar‐radiation acceleration loss process. More Na+ was measured on the inbound leg of Mercury’s orbit at 180°–360° TAA because less neutral sodium is lost downtail from radiation acceleration. Calculations using results from observations show that the photoionization loss process removes ∼1024 atoms/s from the sodium exosphere (maxima of 4 × 1024 atoms/s), showing that modeling efforts underestimate this loss process. This is an important result as it shows that photoionization is a significant loss process and larger than loss from radiation acceleration.Plain Language SummaryMercury has a thin sodium collision‐less atmosphere (i.e., an exosphere). A variety of processes add or subtract sodium particles to and from the exosphere. Photoionization is a loss process, and we investigate it in this paper by analyzing data from NASA’s MESSENGER spacecraft and ground‐based observations made by the THEMIS telescope. Mercury has an eccentric (noncircular) orbit, which means the planet’s distance from the Sun changes throughout its orbit. This, first of all, affects how much sodium is lost due to acceleration of neutral sodium by radiation (i.e., how much sodium is accelerated away from Mercury by radiation from the Sun). This subsequently affects how much sodium is left to be photoionized. Therefore, the amount of sodium lost due to photoionization varies throughout a Mercury‐year. We calculate that ∼1024 atoms/s of sodium are lost due to photoionization, and that it is a significant loss process in comparison to acceleration by radiation.Key PointsPhotoionization can be a significant loss process to the sodium exosphere with peak loss estimates of 4 × 1024 atoms/sThe photoionization loss process of Mercury’s sodium exosphere varies throughout the planet’s orbit around the SunMore sodium is lost due to photoionization on the inbound leg (true anomaly angle of 180°–360°) of Mercury’s orbit than the outbound legPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/167426/1/grl62199.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167426/2/grl62199_am.pd

Photoionization Loss of Mercury’s Sodium Exosphere: Seasonal Observations by MESSENGER and the THEMIS Telescope

We present the first investigation and quantification of the photoionization loss process to Mercury’s sodium exosphere from spacecraft and ground‐based observations. We analyze plasma and neutral sodium measurements from NASA’s MESSENGER spacecraft and the THEMIS telescope. We find that the sodium ion (Na+) content and therefore the significance of photoionization varies with Mercury’s orbit around the Sun (i.e., true anomaly angle: TAA). Na+ production is affected by the neutral sodium solar‐radiation acceleration loss process. More Na+ was measured on the inbound leg of Mercury’s orbit at 180°–360° TAA because less neutral sodium is lost downtail from radiation acceleration. Calculations using results from observations show that the photoionization loss process removes ∼1024 atoms/s from the sodium exosphere (maxima of 4 × 1024 atoms/s), showing that modeling efforts underestimate this loss process. This is an important result as it shows that photoionization is a significant loss process and larger than loss from radiation acceleration.Plain Language SummaryMercury has a thin sodium collision‐less atmosphere (i.e., an exosphere). A variety of processes add or subtract sodium particles to and from the exosphere. Photoionization is a loss process, and we investigate it in this paper by analyzing data from NASA’s MESSENGER spacecraft and ground‐based observations made by the THEMIS telescope. Mercury has an eccentric (noncircular) orbit, which means the planet’s distance from the Sun changes throughout its orbit. This, first of all, affects how much sodium is lost due to acceleration of neutral sodium by radiation (i.e., how much sodium is accelerated away from Mercury by radiation from the Sun). This subsequently affects how much sodium is left to be photoionized. Therefore, the amount of sodium lost due to photoionization varies throughout a Mercury‐year. We calculate that ∼1024 atoms/s of sodium are lost due to photoionization, and that it is a significant loss process in comparison to acceleration by radiation.Key PointsPhotoionization can be a significant loss process to the sodium exosphere with peak loss estimates of 4 × 1024 atoms/sThe photoionization loss process of Mercury’s sodium exosphere varies throughout the planet’s orbit around the SunMore sodium is lost due to photoionization on the inbound leg (true anomaly angle of 180°–360°) of Mercury’s orbit than the outbound legPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/167426/1/grl62199.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167426/2/grl62199_am.pd

A CO2 Cycle on Ariel? Radiolytic Production and Migration to Low-latitude Cold Traps

CO _2 ice is present on the trailing hemisphere of Ariel but is mostly absent from its leading hemisphere. The leading/trailing hemispherical asymmetry in the distribution of CO _2 ice is consistent with radiolytic production of CO _2 , formed by charged particle bombardment of H _2 O ice and carbonaceous material in Ariel’s regolith. This longitudinal distribution of CO _2 on Ariel was previously characterized using 13 near-infrared reflectance spectra collected at “low” sub-observer latitudes between 30°S and 30°N. Here we investigated the distribution of CO _2 ice on Ariel using 18 new spectra: 2 collected over low sub-observer latitudes, 5 collected at “mid” sub-observer latitudes (31°N–44°N), and 11 collected over “high” sub-observer latitudes (45°N–51°N). Analysis of these data indicates that CO _2 ice is primarily concentrated on Ariel’s trailing hemisphere. However, CO _2 ice band strengths are diminished in the spectra collected over mid and high sub-observer latitudes. This sub-observer latitudinal trend may result from radiolytic production of CO _2 molecules at high latitudes and subsequent migration of this constituent to low-latitude cold traps. We detected a subtle feature near 2.13 μ m in two spectra collected over high sub-observer latitudes, which might result from a “forbidden” transition mode of CO _2 ice that is substantially stronger in well-mixed substrates composed of CO _2 and H _2 O ice, consistent with regolith-mixed CO _2 ice grains formed by radiolysis. Additionally, we detected a 2.35 μ m feature in some low sub-observer latitude spectra, which might result from CO formed as part of a CO _2 radiolytic production cycle

Enceladus and Titan: emerging worlds of the Solar System

Some of the major discoveries of the recent Cassini-Huygens mission have put Titan and Enceladus firmly on the Solar System map. The mission has revolutionised our view of Solar System satellites, arguably matching their scientific importance with that of their host planet. While Cassini-Huygens has made big surprises in revealing Titan's organically rich environment and Enceladus' cryovolcanism, the mission's success naturally leads us to further probe these findings. We advocate the acknowledgement of Titan and Enceladus science as highly relevant to ESA's long-term roadmap, as logical follow-on to Cassini-Huygens. In this White Paper, we will outline important science questions regarding these satellites and identify the science themes we recommend ESA cover during the Voyage 2050 planning cycle. Addressing these science themes would make major advancements to the present knowledge we have about the Solar System, its formation, evolution, and likelihood that other habitable environments exist outside the Earth's biosphere