Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep space exploration?

Schwadron, N. A.; Blake, J. B.; Case, A. W.; Joyce, Colin J.; Kasper, J. C.; Mazur, J. E.; Petro, N. E.; Quinn, M.; Porter, Jared M.; Smith, Charles W.; Smith, S. S.; Spence, H. E.; Townsend, Lawrence W.; Turner, Robert F.; Wilson, J. K.; Zeitlin, C.

doi:10.1002/2014sw001084

Cited by 65 publications

(86 citation statements)

References 51 publications

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“…As shown in Figure , the degrees of the effects of all parameters depend on the HMF polarity and the most remarkable differences are seen in the case of α (right). Our model therefore can provide more practical predictions of the GCR modulation and the resultant radiation dose than those made by other authors without assuming the drift effect [ Barnard et al , ; Smith et al , ; Schwadron et al , ].…”

Section: Discussionmentioning

confidence: 89%

“…Similarly, the prediction without the assumption of the drift effect would overestimate the degree of the radiation exposure by GCRs. Schwadron et al [] adopted the variation of the solar modulation parameter related to the HMF strength and the solar wind speed and evaluated the radiation dose observed by CRaTER on the Lunar Reconnaissance Orbiter during the coming solar cycle. From this result, they predicted that the dose equivalent rates in interplanetary space in next solar minimum will be ∼20% higher than that during the solar cycle 23/24.…”

Section: Discussionmentioning

confidence: 99%

“…Then they evaluated the counting rate of neutron monitors (NM) and GCR energy spectra during the coming decade. Schwadron et al [] also predicted the dose equivalent rates in the interplanetary space at the coming solar minimum ∼20% higher than that in the last cycle by presuming a Dalton‐like and a Gleissberg‐like minimum.…”

Section: Introductionmentioning

confidence: 99%

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Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25

2017

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Weak solar activity and high cosmic ray flux during the coming solar cycle are qualitatively anticipated by the recent observations that show the decline in the solar activity levels. We predict the cosmic ray modulation and resultant radiation exposure at flight altitude by using the time‐dependent and three‐dimensional model of the cosmic ray modulation. Our galactic cosmic ray (GCR) model is based on the variations of the solar wind speed, the strength of the heliospheric magnetic field, and the tilt angle of the heliospheric current sheet. We reproduce the 22 year variation of the cosmic ray modulation from 1980 to 2015 taking into account the gradient‐curvature drift motion of GCRs. The energy spectra of GCR protons obtained by our model show good agreement with the observations by the Balloon‐borne Experiment with a Superconducting magnetic rigidity Spectrometer (BESS) and the Payload for Antimatter Matter Exploration and Light‐nuclei Astrophysics (PAMELA) except for a discrepancy at the solar maximum. Five‐year annual radiation dose around the solar minimum at the solar cycle 24/25 will be approximately 19% higher than that in the last cycle. This is caused by the charge sign dependence of the cosmic ray modulation, such as the flattop profiles in a positive polarity.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

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Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25

2017

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“…The amount of energy deposited is represented as one of 4,096 energy channels, and the thin and thick detectors have different, but overlapping, energy ranges. CRaTER's primary data have been used for nearly every study to date, including solar cycle trends (e.g., Schwadron et al, ) shielding effects and dose rates (e.g., Zeitlin et al, ), solar particle events (e.g., Joyce et al, ), and the albedo proton mapping studies.…”

Section: Introductionmentioning

confidence: 99%

Precise Detections of Solar Particle Events and a New View of the Moon

Wilson

Spence

Schwadron

et al. 2020

Geophysical Research Letters

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We have invented a new method for detecting solar particle events using data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Using a simple function of the total particle detection rates from four of CRaTER's six detectors, we can precisely identify solar energetic particle event periods in the CRaTER data archive. During solar quiet periods we map the distribution of a mare‐associated mixture of elements in the lunar regolith using this new method. The new map of the moon probably reflects an as‐yet unknown combination of lunar albedo protons, neutrons, and gamma rays, and most closely resembles Lunar Prospector maps of gamma rays characteristic of thorium and iron. This result will lead to multiple follow‐up studies of lunar albedo particles and may also contribute to the study of diurnally varying hydrogenation of the lunar regolith.

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“…Solar energetic particles (SEPs) above 100 MeV in energy with proton intensities nearly 5 orders of magnitude more than galactic cosmic rays pose a serious radiation hazard to both instrumentation and humans in space [Schwadron et al, 2014]. Identifying the sources and underlying physics that produce these SEPs is critical if we are to reliably forecast such events at 1 AU.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive suite of suprathermal ion sensors

Allegrini

Desai

et al. 2016

JGR Space Physics

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Ions with energies from a few times the solar wind plasma thermal energy up to hundreds of keV/e are called suprathermal (ST) ions. ST ions are ubiquitous throughout the heliosphere and comprise material from many sources that vary in time and space. ST ions constitute a key source of material for solar energetic particles and other higher‐energy interplanetary particle populations. Measuring the energy spectra and composition (ionic charge and elemental) of ST ions in the heliosphere has proved to be rather difficult. This is because their energy region lies between that sampled by solar wind instruments, which require long integration times to acquire adequate statistics at these energies, and that by the energetic particle instruments, which typically do not extend down into the lower part of the ST regime due to the low‐energy thresholds (~25–50 keV) of solid‐state detectors. We present two novel concepts that, when combined, measure ST ions with high time, mass, and charge state resolution to address these challenges. Both use electrostatic analyzers that essentially serve as spectrographs. They simultaneously select ions over a broad range of energy‐per‐charge (E/q), thus requiring fewer voltage steps to cover the entire energy range. Their sensitivity is large compared to current instruments because each E/q is sampled for a longer period of time while the geometric factor is comparable. We describe the results obtained with laboratory prototypes. We also present a list of potential options for the detector section.

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Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep space exploration?

Cited by 65 publications

References 51 publications

Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25

Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25

Precise Detections of Solar Particle Events and a New View of the Moon

A comprehensive suite of suprathermal ion sensors

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