Io Volcanic Plumes: Spacecraft Flythrough Hazard Evaluation

Lorenz, Ralph D.

doi:10.2514/1.a33188

Cited by 7 publications

(4 citation statements)

References 25 publications

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“…A general approach is to model the expanding flow through a convergingdiverging nozzle, and to calculate the acceleration of a particle by the drag of the gas, as calculated, for example, for comet jets (Yelle et al 2004) or Enceladus (Schmidt et al 2008;Degruyter and Manga 2011). However, a much more succinct method, suitable for expansion into a vacuum (as per Lorenz 2015Lorenz , 2016, is to simply consider the energies involved. The energy acquired by the particle during its acceleration by the gas is ∼wr 2 P t .…”

Section: Ventmentioning

confidence: 99%

“…The maximum particle size must be due to the physical processes which produce the particles at the water–gas interface; it is not the result of gravity, e.g. Lorenz (2015). The lower limit on the particle size is harder to constrain but data from the CDA and RPWS suggests that the mass contribution of particles below 0.2 µm drops significantly.Unfortunately, there is no upper size limit directly indicated by in-situ measurements.…”

Section: Nominal Modelmentioning

confidence: 99%

“…2008; Degruyter and Manga 2011). However, a much more succinct method, suitable for expansion into a vacuum (as per Lorenz 2015, 2016), is to simply consider the energies involved. The energy acquired by the particle during its acceleration by the gas is ~ wr 2 P t .…”

Section: Nominal Modelmentioning

confidence: 99%

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Collecting amino acids in the Enceladus plume

Guzman

Lorenz

Hurley

et al. 2018

International Journal of Astrobiology

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We numerically model the dynamics of the Enceladus plume ice grains and define our nominal plume model as having a particle size distribution n(R) ~ R−q with q = 4 and a total particulate mass rate of 16 kg s−1. This mass rate is based on average plume brightness observed by Cassini across a range of orbital positions. The model predicts sample volumes of ~1600 µg for a 1 m2 collector on a spacecraft making flybys at 20–60 km altitudes above the Enceladus surface. We develop two scenarios to predict the concentration of amino acids in the plume based on these assumed sample volumes. We specifically consider Glycine, Serine, α-Alanine, α-Aminoisobutyric acid and Isovaline. The first ‘abiotic’ model assumes that Enceladus has the composition of a comet and finds abundances between 2 × 10−6 to 0.003 µg for dissolved free amino acids and 2 × 10−5 to 0.3 µg for particulate amino acids. The second ‘biotic’ model assumes that the water of Enceladus's ocean has the same amino acid composition as the deep ocean water on Earth. We compute the expected captured mass of amino acids such as Glycine, Serine, and α-Alanine in the ‘biotic’ model to be between 1 × 10−5 to 2 × 10−5 µg for dissolved free amino acids and dissolved combined amino acids and about 0.0002 µg for particulate amino acids. Both models consider enhancements due to bubble bursting. Expected captured mass of amino acids is calculated for a 1 m2 collector on a spacecraft making flybys with a closest approach of 20 km during mean plume activity for the given nominal particle size distribution.

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Section: Ventmentioning

confidence: 99%

Section: Nominal Modelmentioning

confidence: 99%

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Collecting amino acids in the Enceladus plume

Guzman

Lorenz

Hurley

et al. 2018

International Journal of Astrobiology

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“…Depending on density, there may also be heating or dynamic effects on the spacecraft structure. Grains or dust embedded in the plume could degrade sensitive instruments, coatings, or solar panels leading to reduced performance ( Lorenz, 2015;Landgraf et al, 2004;Liechty, 2007 ).…”

Section: Introductionmentioning

confidence: 99%