Ejecta from impacts at 0.2–2.3 m/s in low gravity

Colwell, Joshua; Sture, Stein; Cintala, M. J.; Durda, Dan; Hendrix, Amanda; Goudie, Tyler; Curtis, Darren; Ashcom, Daniel J.; Kanter, Matthew; Keohane, Thomas; Lemos, Andreas; Lupton, Michael; Route, Matthew

doi:10.1016/j.icarus.2007.12.019

Cited by 40 publications

(45 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are only a few studies of free dust collisions where both collision partners are larger than 1 cm (Beitz et al 2011;Schräpler et al 2012). Other collision modes at larger sizes studied, e.g., include one solid impactor, colliding with a dusty medium (Colwell et al 2008). In all these collisions, there is a lot of fragmentation, but mass gain in certain low-velocity regimes below 2 m s −1 is also possible.…”

Section: Introductionmentioning

confidence: 99%

Colliding Decimeter Dust

Deckers

Teiser

2013

ApJ

View full text Add to dashboard Cite

Collisional evolution is a key process in planetesimal formation and decimeter bodies play a key role in the different models. However, the outcome of collisions between two dusty decimeter bodies has never been studied experimentally. Therefore, we carried out microgravity collision experiments in the Bremen drop tower. The agglomerates consist of quartz with irregularly shaped micrometer-sized grains and the mean volume filling factor is 0.437 ± 0.004. The aggregates are cylindrical with 12 cm in height and 12 cm in diameter, and typical masses are 1.5 kg. These are the largest and most massive dust aggregates studied in collisions to date. We observed rebound and fragmentation but no sticking in the velocity range between 0.8 and 25.7 cm s −1 . The critical fragmentation velocity for split up of an aggregate is 16.2 ± 0.4 cm s −1 . At lower velocities the aggregates bounce off each other. In this velocity range, the coefficient of restitution decreases with increasing collision velocity from 0.8 to 0.3. While the aggregates are very weak, the critical specific kinetic energy for fragmentation Q μ=1 is a factor of six larger than expected. Collisions of large bodies in protoplanetary disks are supposed to be much faster and the generation of smaller fragments is likely. In planetary rings, collision velocities are of the order of a few cm s −1 and are thereby in the same range investigated in these experiments. The coefficient of restitution of dust agglomerates and regolith-covered ice particles, which are common in planetary rings, are similar.

show abstract

Section: Introductionmentioning

confidence: 99%

Colliding Decimeter Dust

Deckers

Teiser

2013

ApJ

View full text Add to dashboard Cite

show abstract

“…However, for many actual particle collision processes [21][22][23][24][25], the projectile often obliquely impacts the surface of the granular media. Such oblique impact phenomena are commonly found in the particle-bed collision for the formation of sand dunes and ripples [26][27][28], secondary impacts on the Moon or Mars [29][30][31], etc. The variation of impact angles may significantly affect the trajectories of projectiles [32], the morphology and scaling of impact craters [15], and the basic dynamic processes [33].…”

Section: Introductionmentioning

confidence: 99%

Influence of particle rotation on the oblique penetration in granular media

Wang

Zheng

2012

Phys. Rev. E

View full text Add to dashboard Cite

The rotation of a particle has significant influence on the dynamic response of a granular bed subjected to the oblique impact of a spherical projectile. Based on the discrete element method, the dynamical behavior of two-dimensional granular media impacted obliquely by rotating particles has been examined in this work, especially for the influence of rotational angular velocity on its penetration depth. The simulations show that the incident rotational velocity will not only act on the characteristics of velocity distribution of the bed after impacting, but also influence the trajectory of the projectile qualitatively. For low angular velocities, particle rotations will significantly increase the vertical penetration depths, while the different directions of rotation will exert opposite effects on the horizontal penetration depths. In addition, the influence of particle rotation on its penetration depth will be enhanced with increasing angular velocity, but such effect will reach an asymptotic plateau for sufficiently large angular velocities. This indicates that the angular velocity has an obvious criticality. Furthermore, the variation of critical angular velocity may be linear with the impact velocity and square with the impacting angle, approximately. Finally, the influence of the initial particle rotation on the scaling law of penetration depth is also considered, and we find that the linear scaling with impact velocity is still applicable for most impact conditions.

show abstract

“…Commonly used methods are scale models, pendulums with inclined planes, sideways impacts and using weights to balance out Earth's gravity (Seiff et al, 2005;Hilchenbach et al, 2004;Reid et al, 2014). Impacts of projectiles and small spacecraft (cm sized) into analogue regoliths under reduced gravity can be investigated using parabolic flights (Colwell et al, 2008), drop towers or Atwood machines (Goldman & Umbanhowar, 2008). Atwood machines accelerate the target at a fraction of Earth's gravitational acceleration by using a balancing weight while the impactor falls freely in Earth's gravity.…”

Section: The Test Rigmentioning

confidence: 99%

Detection of structure in asteroid analogue materials and Titan’s regolith by a landing spacecraft

Paton

Green

Ball

et al. 2016

Advances in Space Research

View full text Add to dashboard Cite

We compare measurements made by two impact penetrometers of different sizes and with different tip shapes to further understand penetrometer design for performing pentrometry on an asteroid. To this end we re-visit the interpretation of data from the Huygens' penetrometer, ACC-E, that impacted Titan's surface. In addition we investigate the potential of a spacecraft fitted with a penetrometer to bounce using a test rig, built at The Open University (UK).Analysis of ACC-E laboratory data, obtained from impacts into ∼4 mm diameter gravel, was found to produce an unusual decrease in resistance with depth (force-depth gradient) which was also seen in the Huygens' ACC-E data from Titan and originally interpreted as a wet or moist sand. The downward trend could also be reproduced in a hybrid Discrete Element Model (DEM) if it was assumed that the near surface particles are more readily * Corresponding author mobilised than those deeper in the target. With regard to penetrometer design penetration resistance was found to be sensitive to the ratio of particle to tip diameter. A clear trend was observed with a conical tip penetrometer, X-PEN, of decreasing force-depth gradients with increasing particle sizes most likely due to a transformation from a bulk displacement of material by the penetrating tip to more local interactions. ACC-E, which has a hemispherical tip, was found to produce a wider range of force-depth gradients than X-PEN, which had a conical tip, possibly due to difficulties dislodging jammed particles. Both penetrometers were able to determine particle diameter and mass after post-processing of the data.Laboratory simulations of landings with the test rig suggest that a large impact penetrometer under certain circumstances could absorb a significant amount of the elastic energy of the spacecraft possibly aiding landing. Alternatively a small impact penetrometer would allow the spacecraft to bounce freely off the surface to make a measurement at another location.

show abstract

Ejecta from impacts at 0.2–2.3 m/s in low gravity

Cited by 40 publications

References 24 publications

Colliding Decimeter Dust

Colliding Decimeter Dust

Influence of particle rotation on the oblique penetration in granular media

Detection of structure in asteroid analogue materials and Titan’s regolith by a landing spacecraft

Contact Info

Product

Resources

About