Please note that you can contact me for any of the papers if you do not have access to them.
Current Research: Saturnian Rings || Saturnian Moon Craters
Saturnian Rings
2007-2010; 2013-2015
Larry Esposito and Glen Stewart, PIs
The second project I worked on as a graduate student was to perform N-body simulations (simulations of N number of particles) of Saturn's rings with the goal of estimating how much mass could hide in clumps and clusters and strands. The end result of that research, finally published two years into when I started working on Mars craters, was a paper that estimated the mass of Saturn's rings to be about twice as large as previously thought, meaning that they could be much older than previously thought.
Due to funding issues in 2013, and very generous people with whom I had worked previously (never burn bridges!), I resumed work for a year from summer 2013 to summer 2014 on N-body simulations with the goal of testing ideas put forward by Larry Esposito in a 2012 paper (Esposito et al., 2012). The question is, can transient large features that are observed in the rings be explained by a classic "preditor-prey" scenario? The classic example is a population of rabbits and foxes where the rabbit population increases, so the fox population increases, causing the rabbit population to fall, and the fox population falls due to less food, and then the cycle repeats.
He thinks something similar may happen in the rings between mass clumps and particle velocity: No velocity dispersion means that particles can clump together due to self-gravity, which revs up the velocities due to a larger gravitational mass, but the larger velocities break off particles when they collide which shrinks the mass clumps which then lets the velocities settle down due to random collisions which ... and the cycle repeats. My work was to determine if his analytic solution - which showed this happening - works in dynamic simulations.
Papers:
Robbins, S.J., Stewart, G.R., Lewis, M.C., Colwell, J.E., and M. Sremčević. (2010). Estimating the Masses of Saturn's A and B Rings from High-Optical Depth N-Body Simulations and Stellar Occultations. Icarus, 206, p. 431-445. doi: 10.1016/j.icarus. 2009.09.012.
Abstracts:
Robbins, S.J., Stewart, G.R., and L.W. Esposito. (2014) Particle Clustering in Periodically Forced Planetary Rings. Planetary Rings Workshop
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Robbins, S.J., Stewart, G.R., Colwell, J.E., and M.C. Lewis. (2008) Self-Gravity Wakes in Saturnian Rings: Effects of Varying Location, Particle Density and Introducing a Particle Size Distribution. Division of Planet. Sci. Meeting, pp. 424, 40:21.05.
Robbins, S.J., Stewart, G.R., Colwell, J.E., and M.C. Lewis. (2007) Simulations of Clumping Effects in High-Optical Depth Rings. Division of Planet. Sci. Meeting, 38, pp. 420.
Stewart, G.R., Robbins, S.J., and J.E. Colwell. (2007) Evidence for a Primordial Origin of Saturn's Rings. Division of Planet. Sci. Meeting, 38, pp. 420.
Saturnian Moon Craters
2014-present
Luke Dones, PI || Beau Bierhaus, Kevin Zahnle as Co-Is
In early 2014, I started work identifying craters on several Saturnian satellites to form the observational dataset for work done by Luke Dones at Southwest Research Institute. The end-goal is to better understand how particles move throughout a dense satellite system (hence forming impact craters). Beau Bierhaus and I are identifying craters to form the observational constraints, while Kevin Zahnle and Luke Dones are doing the dynamic modeling.
Abstracts:
Kirchoff, M.R., Bierhaus, E.B., Dones, L.H., Robbins, S.J., Singer, K.N., Wagner, R.J., and K.J. Zahnle (2016) Cratering Histories in the Saturnian System
Bierhaus, E.B., Dones, L.H., and S.J. Robbins (2016) The Unusual Role of Secondaries in the Evolution of Crater Populations on Enceladus, and Consequences for Age Estimation
Dones, L.H., et al. (2016) Could the Craters on the Mid-Sized Moons of Saturn Have Been Made by Satellite Debris? Div. Dynamical Astr., 47, #303.01.
Bierhaus, E.B., Dones, L.H., and S.J. Robbins (2015) From One Come Many: A Diversity of Crater Populations from a Single Impacting Population, with Application to the Saturnian (and Galilean) Satellites. DPS, 47, #508.01.
Dones, H.C.L., Charnoz, S., Robbins, S.J., and E.B. Bierhaus. (2015) Recent Formation of Saturnian Moons: Constraints from Their Cratering Records. Div. Dynamical Astr., 46, #304.01.
Robbins, S.J., Bierhaus, E.B., and L.H. Dones. (2015) Craters of the Saturnian Satellite System: II. Mimas and Rhea
Bierhaus, E.B., Robbins, S.J., and L.H. Dones. (2014) Towards a Unified Theory of Impacts and Crater Populations on Icy Satellites. DPS, 46, #405.09.
Robbins, S.J., Bierhaus, E.B., and L.H. Dones. (2014) Craters of the Saturnian Satellite System: I. Mimas