An Automated Tracking Method to Study Particle Motion in Microgravity

Metzger, J.; Brisset, Julie; Colwell, Joshua; Dove, Adrienne

doi:10.1061/9780784479971.006

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…Numbers over 100% indicate that the tracking tool detected more particles than present (uneven spots on the images). ware (Metzger et al 2016). After a significant amount of image processing, this software was able to produce particle tracks for about 80% of the particles that were not JSC-1.…”

Section: Analysis Methodsmentioning

confidence: 99%

Multi-particle collisions in microgravity: Coefficient of restitution and sticking threshold for systems of mm-sized particles

Brisset

Miletich

Metzger

et al. 2019

A&A

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Context. The current model of planet formation lacks a good understanding of the growth of dust particles inside the protoplanetary disk beyond mm sizes. A similar collisional regime exists in dense planetary rings. In order to investigate the low-velocity collisions between this type of particles, the NanoRocks experiment was flown on the International Space Station (ISS) between September 2014 and March 2016. We present the results of this experiment. Aims. The objectives of our data analysis are the quantification of the damping of energy in systems of multiple particles in the 0.1 to 1 mm size range while they are in the bouncing regime, and the study of the formation of clusters through sticking collisions between particles. Methods. We developed statistical methods for the analysis of the large quantity of collision data collected by the experiment. We measured the average motion of particles, the moment of clustering, and the cluster size formed. In addition, we ran simple numerical simulations in order to validate our measurements. Results. We computed the average coefficient of restitution (COR) of collisions and find values ranging from 0.55 for systems including a population of fine grains to 0.94 for systems of denser particles. We also measured the sticking threshold velocities and find values around 1 cm/s, consistent with the current dust collision models based on independently collected experimental data. Conclusions. Our findings have the following implications that can be useful for the simulation of particles in PPDs and planetary rings: (1) The average COR of collisions between same-sized free-floating particles at low speeds (< 2 cm/s) is not dependent on the collision velocity; (2) The simplified approach of using a constant COR value will accurately reproduce the average behavior of a particle system during collisional cooling; (3) At speeds below 5 mm/s, the influence of particle rotation becomes apparent on the collision behavior; (4) Current dust collision models predicting sticking thresholds are robust.

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Section: Analysis Methodsmentioning

confidence: 99%

Multi-particle collisions in microgravity: Coefficient of restitution and sticking threshold for systems of mm-sized particles

Brisset

Miletich

Metzger

et al. 2019

A&A

View full text Add to dashboard Cite

show abstract

“…Previous data analysis could be performed manually (particle tracking in particular) due to the limited amount of data collected, but manual analysis was not a viable option for the amount of data produced by NanoRocks. Automated tracking has enabled us to validate statistical analysis of the evolution of particle velocities 21,22 . The video recording of a full experiment run can be found at youtube.com/watch?v=x QmLBT25JA.…”

Section: Experiments Performancementioning

confidence: 99%

NanoRocks: Design and performance of an experiment studying planet formation on the International Space Station

Brisset

Colwell

Dove

et al. 2017

Review of Scientific Instruments

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In an effort to better understand the early stages of planet formation, we have developed a 1.5U payload that flew on the International Space Station (ISS) in the NanoRacks NanoLab facility between September 2014 and March 2016. This payload, named NanoRocks, ran a particle collision experiment under long-term microgravity conditions. The objectives of the experiment were (a) to observe collisions between mm-sized particles at relative velocities of < 1 cm/s and (b) to study the formation and disruption of particle clusters for different particle types and collision velocities. Four types of particles were used: mm-sized acrylic, glass, and copper beads and 0.75 mm-sized JSC-1 lunar regolith simulant grains. The particles were placed in sample cells carved out of an aluminum tray. This tray was attached to one side of the payload casing with three springs. Every 60 s, the tray was agitated, and the resulting collisions between the particles in the sample cells were recorded by the experiment camera. During the 18 months the payload stayed on ISS, we obtained 158 videos, thus recording a great number of collisions. The average particle velocities in the sample cells after each shaking event were around 1 cm/s. After shaking stopped, the inter-particle collisions damped the particle kinetic energy in less than 20 s, reducing the average particle velocity to below 1 mm/s, and eventually slowing them to below our detection threshold. As the particle velocity decreased, we observed the transition from bouncing to sticking collisions. We recorded the formation of particle clusters at the end of each experiment run. This paper describes the design and performance of the NanoRocks ISS payload.

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An Automated Tracking Method to Study Particle Motion in Microgravity

Cited by 2 publications

References 7 publications

Multi-particle collisions in microgravity: Coefficient of restitution and sticking threshold for systems of mm-sized particles

Multi-particle collisions in microgravity: Coefficient of restitution and sticking threshold for systems of mm-sized particles

NanoRocks: Design and performance of an experiment studying planet formation on the International Space Station

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