Scouring the surface: Ejecta dynamics and the LCROSS impact event

Hermalyn, B.; Schultz, P. H.; Shirley, M.; Ennico, Kimberly; Colaprete, A.

doi:10.1016/j.icarus.2011.12.025

Cited by 33 publications

(43 citation statements)

References 21 publications

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“…Most early predictions for the LCROSS mission that were based on computational models and crater scaling relations 15 included a single plume component 16,17 . However, impact experiments conducted at the NASA Ames Vertical Range Gun in support of the LCROSS mission that used hollow projectiles demonstrated a bimodal ejecta plume structure consistent with the LCROSS SSc observations 4,18 . In these laboratory experiments, solid projectiles produced the standard, single-component plume (dubbed the 'low-angle' plume), whereas hollow projectiles produced a two-component plume (a 'low-angle' plus a 'high-angle' plume), with the low-angle plume excavating material from greater depths than the high-angle plume 18 .…”

Section: Resultssupporting

confidence: 61%

“…However, impact experiments conducted at the NASA Ames Vertical Range Gun in support of the LCROSS mission that used hollow projectiles demonstrated a bimodal ejecta plume structure consistent with the LCROSS SSc observations 4,18 . In these laboratory experiments, solid projectiles produced the standard, single-component plume (dubbed the 'low-angle' plume), whereas hollow projectiles produced a two-component plume (a 'low-angle' plus a 'high-angle' plume), with the low-angle plume excavating material from greater depths than the high-angle plume 18 . We tested both single-and multiple-component plume morphologies based on these results (which may be a parameterization of a continuum physical process).…”

Section: Resultssupporting

confidence: 61%

“…3 grid boxes labelled 'a' was sensitive to the average particle ejection angles, with the best-match angle to be 35 ± 5°f rom horizontal, compared with the B45°found experimentally for hollow projectiles fired into particulate targets 18 . These lower ejection angles are consistent with impacts into lower density, 'fluffy' target materials 18 . Our best-match low-angle plume ejection velocities ranged up to 500 m s À 1 , although our results proved relatively insensitive to the upper limit.…”

Section: Discussionmentioning

confidence: 90%

“…Results of laboratory impacts show that ejecta velocity drops off with increasing time after impact 18 . As a result, slower particles in the high-angle plume are inferred to originate at greater depths than those of the faster particles.…”

Section: Discussionmentioning

confidence: 97%

“…Our plume model assigned initial velocities and ejection angles to B200,000 particles at the time of impact and tracked their trajectories individually throughout the time of our observations. The low-angle plume particles were assigned ejection velocities and angles according to scaled values derived from laboratory experiments of impacts at similar velocities 18 . Our model allowed for adjusting the relative particle density of the low-angle and high-angle plumes as well as specifying separate mass-velocity and mass-angle relationships for the two components.…”

Section: Methodsmentioning

confidence: 99%

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Characterization of the LCROSS impact plume from a ground-based imaging detection

et al. 2013

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The Lunar CRater Observation and Sensing Satellite (LCROSS) mission was designed to search for evidence of water in a permanently shadowed region near the lunar south pole. An instrumented Shepherding Spacecraft followed a kinetic impactor and provided -from a nadir perspective -the only images of the debris plume. With independent observations of the visible debris plume from a more oblique view, the angles and velocities of the ejecta from this unique cratering experiment are better constrained. Here we report the first visible observations of the LCROSS ejecta plume from Earth, thereby ascertaining the morphology of the plume to contain a minimum of two separate components, placing limits on ejecta velocities at multiple angles, and permitting an independent estimate of the illuminated ejecta mass. Our mass estimate implies that the lunar volatile inventory in the Cabeus permanently shadowed region includes a water concentration of 6.3 ± 1.6% by mass.

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Section: Resultssupporting

confidence: 61%

Section: Resultssupporting

confidence: 61%

Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

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Characterization of the LCROSS impact plume from a ground-based imaging detection

et al. 2013

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Predictions for impactor contamination on Ceres based on hypervelocity impact experiments

Daly

Schultz

2015

Geophysical Research Letters

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New experiments predict that Ceres should be extensively contaminated with meteoritic debris derived from the asteroid belt. All types of impactors likely contribute to the contamination. Ceres may accrete debris more efficiently if it is ice‐rich because of enhanced projectile survival and retention in porous ice targets. Experiments indicate that if a silicate regolith lag protects subsurface ice, then some of the projectile should be injected into the regolith during high‐angle impacts, thereby hiding part of the projectile component from view. If impacts excavate ice, sublimation will gradually concentrate projectile relics into a surficial lag. In contrast, if the near‐surface lacks ice, then accreted meteoritic debris should be distributed throughout a vertically mixed regolith. High‐resolution images may reveal pristine projectile relics lining some crater floors. Moreover, we predict that the surface of Ceres is not exclusively endogenic and may be dominated by delivered exogenic debris.

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The outbursts of the comet 29P/Schwassmann‐Wachmann 1: A new approach to the old problem

Gronkowski

2014

Astron Nachr

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As far as outbursts activity is concerned, the 29P/Schwassmann-Wachmann 1 is the exceptional comet. This Centaur object shows quasi-regular flares with periodicities of 50 days (Trigo-Rodriguez et al. 2010). In the introductory part of the presented paper the most well-known hypotheses which try to explain this cometary behaviour are reviewed. The second, actual part of this paper presents the new model for the outburst activity of this comet. The model is based on the idea of Ipatov (2012), according to which there are large cavities below a considerable fraction of the comet's surface containing material under high gas pressure. In favourite conditions the surface layers over the cavities are thrown away and the interior of these cavities is exposed. Consequently, an outburst of the comet's brightness may be observed. The main characteristics of an outburst of this comet, the brightness jump, is calculated. Numerical simulations were carried out for wide range of possible cometary parameters. The obtained results are in good agreement with the observations.

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Scouring the surface: Ejecta dynamics and the LCROSS impact event

Cited by 33 publications

References 21 publications

Characterization of the LCROSS impact plume from a ground-based imaging detection

Characterization of the LCROSS impact plume from a ground-based imaging detection

Predictions for impactor contamination on Ceres based on hypervelocity impact experiments

The outbursts of the comet 29P/Schwassmann‐Wachmann 1: A new approach to the old problem

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