Cosmic ray measurements on board Helios 1 from December 1974 to September 1975: Quiet time spectra, radial gradients, and solar events

The University of Kiel cosmic ray experiment on board Helios 1 measures nucleons above 1. 7 MeV/nucleon and electrons above 0.3 MeV in the inner solar system between 1.0 and 0.3 AU from the Sun. A first survey is given on quiet time proton and Helium spectra which are compared near Earth and close to perihelion. The anomalous Helium component is also present at radial distances within 0.4 AU. Quiet time Helium spectra from 3.8 to 48 MeV/nucleon gradually increase between December 1974 and June 1975. For the integral radial gradient (protons above 51 MeV) we estimate a value of (11±2.5) %/AU during a period of slowly increasing cosmic ray intensity. We discuss solar particle events on January 5 (at 0.93 AU), March 7 (at 0.41 AU), and March 19, 1975 (at 0.32 AU). The March 19 event was measured closer to the Sun than any other event before. It exhibits sharp temporal structures, differences in the time profiles of various particle species, and a large abundance of Helium 3, with a 3He/4He ratio of 2 to 3 in the range 5 to 7 MeV/nucleon. This event occurred close to the peak of a high speed solar wind stream.           ARK: https://n2t.net/ark:/88439/y032443 Permalink: https://geophysicsjournal.com/article/183 &nbsp

The effects of coronal mass ejection on galactic cosmic rays in the high latitude heliosphere: Observations from Ulysses` first orbit

During its first solar orbit the Ulysses spacecraft detected several coronal mass ejections (CMEs) at high heliographic latitudes. The authors present first observations on the effects of these high latitude CMEs on galactic cosmic rays (GCRs) using measurements from the Kiel Electron Telescope (KET) which is part of the Cosmic Ray and Solar Particle Investigation (COSPIN) experiment, the Los Alamos SWOOPS (Solar Wind Observations Over the Poles of the Sun) experiment and the magnetic field experiments. They find the passage of these CMEs over the spacecraft to be associated with short term decreases of GCR intensities The relatively weak shocks in these events, driven by the CMEs` over-expansion, had no strong influence on the GCRs. The intensity minimums of GCRs occurred on closed magnetic field lines inside the CMEs themselves as indicated by bidirectional fluxes of suprathermal electrons. Short episodes of intensity increases of GCRs inside CMEs at times when the bidirectional fluxes of suprathermal electrons disappeared, can be interpreted as evidence that GCRs can easily access the interior of those CMEs in which open magnetic field lines are embedded

Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale crater, Mars

H₂O, CO₂, SO₂, O₂, H₂, H₂S, HCl, chlorinated hydrocarbons, NO and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H₂O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO₂. Concurrent evolution of O₂ and chlorinated hydrocarbons suggest the presence of oxychlorine phase(s). Sulfides are likely sources for S-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic C sources may be preserved in the mudstone; however, the C source for the chlorinated hydrocarbons is not definitively of martian origin

A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars

The Curiosity rover discovered fine-grained sedimentary rocks, inferred to represent an ancient lake, preserve evidence of an environment that would have been suited to support a Martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. C, H, O, S, N, and P were measured directly as key biogenic elements, and by inference N and P are assumed to have been available. The environment likely had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars

The Petrochemistry of Jake_M: A Martian Mugearite

“Jake_M,” the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (>15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes)

X-ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater

The Mars Science Laboratory rover Curiosity scooped samples of soil from the Rocknest aeolian bedform in Gale crater. Analysis of the soil with the Chemistry and Mineralogy (CheMin) x-ray diffraction (XRD) instrument revealed plagioclase (~An57), forsteritic olivine (~Fo62), augite, and pigeonite, with minor K-feldspar, magnetite, quartz, anhydrite, hematite, and ilmenite. The minor phases are present at, or near, detection limits. The soil also contains 27 ± 14 weight percent x-ray amorphous material, likely containing multiple Fe^(3+)- and volatile-bearing phases, including possibly a substance resembling hisingerite. The crystalline component is similar to the normative mineralogy of certain basaltic rocks from Gusev crater on Mars and of martian basaltic meteorites. The amorphous component is similar to that found on Earth in places such as soils on the Mauna Kea volcano, Hawaii

Shielding from cosmic radiation for interplanetary missions: Active and passive methods

Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magnets. The TT identified a number of open research questions to be addressed, including development and testing of novel shielding materials, studies on the angular distributions of energetic solar particles, and cooling systems for magnetic lenses in space. A detailed report to the ESA will be published within a few months. A summary of the TT conclusions and recommendations will be discussed in this paper, with emphasis on active shielding using superconducting magnets