Current Research
The Volcanic History of Mars, As Told by the Visible Calderas of Nineteen Major Volcanoes
I'm fairly proud of this li'l project as it was fairly completely my idea, originally (where "originally" means that, yes, others have done it before, but not this way and it wasn't my advisor's idea). One reason why this is important to me at this stage is that I've been somewhat worried that, as I pursue a career in research, I would not be able to come up with new ideas of what to research on my own. That I came up with this alone seems to indicate that I actually may posses that capability.
Anyhow, the basic idea was to use the workflow that I had developed with my crater work (see below) to identify craters within the volcanic calderae of Mars' major volcanoes and use them to date the last visible eruptions. I used the Mars Reconnaissance Orbiter's ConteXT (CTX) camera data for this work, which lead me to learn how to use ISIS software to process and mosaic the images together.
The entire process once I actually got going was about 2 months from start to finish, though this was spread over 5 months due to other work and deadlines. Another goal of this project was to help me get more experience with geologic mapping - required because the calderae were not always clear where one started and another began. In truth, to speed things up, my advisor's post-doc did do a significant portion of the mapping, though I had to "sign off" on everything before he sent me the maps to use.
This turned into an LPSC abstract and we are writing a paper that will hopefully be done and submitted by Summer 2010.
Brian Hynek is the advisor.
Abstract:
Robbins, S. J.; Di Achille, G.; and B. M. Hynek. (2010). Dating the Most Recent Episodes of Volcanic Activity from Mars' Main Volcanic Calderae. LPSC XLI, #2257. Click for the Poster.
Global Catalog of Martian Impact Craters, Complete to 1.5-km in Diameter
This research is a multi-stage process of identification and analysis. It involves going through global THEMIS Daytime IR mosaics of Mars (or Viking MDIM 2.1 where THEMIS has gaps) and literally circling every crater that's resolved. I do this at ~500 m per point resolution, and I limit myself to ≥5 points along a crater rim which limits the diameter to ~700-800 meters. I estimate my statistical completeness to be at ~1.5 km.
The purpose of this catalog is that none yet exists and to use it to act as a comparison for my layered ejecta crater analysis (see below). Nadine Barlow created the first global catalog in the 1980s from Viking data for craters ≥5 km, but it is somewhat incomplete, and it obviously lacks smaller craters. It contains ~42,000 craters. My catalog presently (March 2010) contains ~285,000 craters, about 165,000 of them with a diameter larger than 1.5 km.
The applications of this catalog will be several-fold, though it was initially conceived to act as a "control" crater population with which to study the layered ejecta craters on Mars (see below). Additional applications - once completed - include revising martian geologic ages, extensive use in Ken Tanaka (and colleagues') revision of the mars geologic maps (ongoing - possible collaboration later on), testing global dust deposition models and resurfacing models, characterizing craters on terrains of different ages, and other things.
No published papers yet, but abstracts! The ETA for the final catalog is my Ph.D. thesis ... May 2011. Unfortunately, this is the kind of project that does not easily lend itself to intermediate results, but once completed we expect several papers to almost literally fall out of it (and a thesis ...).
Brian Hynek is the advisor.
Abstracts:
Robbins, S. J.; and B. M. Hynek. (2010). Progress Towards a New Global Catalog of Martian Craters and Layered Ejecta Properties, Complete to 1.5 km. LPSC XLI, #2257. Click for the Poster.
Robbins, S. J.; and B. M. Hynek. (2009). Progress Towards a New Global Catalog of Martian Craters and Layered Ejecta Properties, Complete to 1.5 km. 12th Mars Crater Conference, #1207.
Robbins, S. J.; and B. M. Hynek. (2009). Towards a New Catalog of Lobed Martian Craters Compared with a New Global Crater Database, Complete to 1.5 km. LPSC XL, #2460. Click for the Poster.
An In-Depth Analysis of Properties of Lobed Craters on Mars
This is a NASA Fellowship that I won (my first grant) back in 2007 - a 3-year grant that started in the academic year of 2007-2008 and will end in 2009-2010. It is through the NASA NESSF program.
The purpose of this research is to re-do the global database of lobed craters (see a connection with the above?) and to analyze them in terms of basic depth/diameter vs. latitude/longitude as well as properties of their lobes, plus to correlate all the data with other, modern data sets such as thermal inertia, subsurface water/ice, mineralogy, and any other dataset I can get my hands on.
Brian Hynek is the advisor and technically the PI on the Fellowship. Because this work goes hand-in-hand with the above crater cataloging, abstracts that are relevant are the same.
Abstracts:
Robbins, S. J.; and B. M. Hynek. (2010). Progress Towards a New Global Catalog of Martian Craters and Layered Ejecta Properties, Complete to 1.5 km. LPSC XLI, #2257. Click for the Poster.
Robbins, S. J.; and B. M. Hynek. (2009). Progress Towards a New Global Catalog of Martian Craters and Layered Ejecta Properties, Complete to 1.5 km. 12th Mars Crater Conference, #1207.
Robbins, S. J.; and B. M. Hynek. (2009). Towards a New Catalog of Lobed Martian Craters Compared with a New Global Crater Database, Complete to 1.5 km. LPSC XL, #2460. Click for the Poster.
High-Optical Depth N-Body Simulations of Saturn's Rings
This work was started back in 2006, where I was go basically explore the properties of Saturn's rings on the scale of ~10-500 meters through N-body simulations, and how they changed with distance from Saturn (B ring at 100 Mm and A ring at 130 Mm) and optical depth.
This evolved into a project (after I started working on Mars, and then later when I got a much faster computer for myself that could actually do these simulations in a realistic timeframe) where I have explored a large parameter space of over 190 simulations showing different distances from Saturn, internal particle density, different size distributions of particles, and especially different optical depths.
The key, big-picture finding from this is that Saturn's rings are very effective at "hiding" material in self-gravity wakes and clumps. So while I can keep increasing the amount of material (number of particles) in a fixed space, the resulting optical depth hardly increases at all. This has serious implications for the overall mass of the rings, since estimating the mass required to get an observed optical depth is how it's pretty much done. The simulations so far have shown that the mass of the rings is - conservatively - at least 2 times more than has been previously estimated. This then has implications for the age of the rings as more massive rings are more likely to be older (for several reasons, but not ones that I study).
I have a paper that's been submitted to and accepted by Icarus and likely will be out in the Icarus special edition for Cassini at Saturn around April 2010. I also have two DPS abstracts from this, one from 2007, and the other from 2008. I will have at least one additional paper from this, and I may be an author on a third paper because one of the simulations formed a small moonlet.
Glen Stewart is the advisor.
Paper!!:
Robbins, S. J.; Stewart, G.R.; M.C. Lewis; Colwell, J.E.; and M. Sremcevic. (2010). Estimating the masses of Saturn’s A and B rings from high-optical depth N-body simulations and stellar occultations. (in press). doi: 10.1016/j.icarus.2009.09.012.
Abstracts:
Robbins, S. J.; Stewart, G.R.; Colwell, J.E.; and M.C. Lewis. (2007). Simulations of Clumping Effects in High-Optical Depth Rings. 39:07.05.
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. pp. 424, 40:21.05.
Past Research that I Have Published
New Clues from Old Craters About the History of Arabia Terra, Mars
Something that Brian had money for before I won my NESSF award. Effectively creating a localized catalog of the depth and diameter properties of the craters over ~15% of the planet, covering Arabia Terra and the neighboring Southern Highlands. The purpose was to use the craters to test hypotheses for the formation and modification history of Arabia Terra (tested two main ones). The results were that neither was confirmed and the region is still very confusing, though I have now made my own hypothetical history of the region based on the data.
I used this to get my M.S., three Mars Crater Conference abstracts and talks, and an LPSC abstract and poster. I will also be writing this up as a paper to submit to Icarus or JGR.
Abstracts:
Robbins, S. J.; and B. M. Hynek. (2008). MOLA Data May Introduce Significant Artifacts in Crater Diameters. 11th Mars Crater Conference, #1107.
Robbins, S. J.; Haber, R.; and B. M. Hynek. (2008). depth/Diameter Ratios of 2.5+ km Craters in Arabia Terra, Mars, and Hints at Refining the Region's History. 11th Mars Crater Conference, #1108.
Robbins, S. J.; and B. M. Hynek. (2008). Testing Formation Theories of NW Arabia Terra, Mars: New Clues from Old Craters. LPSC XXXIX, pp. 2417. Click for the Poster.
Robbins, S. J.; and B. M. Hynek. (2007). A New Automated Method of Determining Depth, Diameter, and Volume of Known Craters. 10th Mars Crater Conference, #1006.
Io Plasma Torus Analysis
I worked on this with Nick Schneider the first summer I came to Colorado. I found it less interesting than I had thought I would, but I did at least get an authorship on a 2005 DPS abstract that I think ended up being a poster presentation.
Abstract: Schneider, N.M.; Robbins, S.J.; Delamere, P.A.; and A.J. Steffl. Ion Temperature Control of the Io Plasma Torus. Bulletin of the American Astronomical Society. pp. 758, 37:3 (2005).
Forecasting Solar Wind Speed from Coronal Holes
This was done at an NSO REU in the summer of 2004. I worked with Carl Heney and Jack Harvey to determine if there was a way to use coronal holes (on the sun) to predict the velocity of the solar wind at Earth - basically space weather forecasting. I did get a paper out of this, published in the journal Solar Physics. I also got two abstracts and poster presentations out of it, one at the 2005 January AAS meeting and the other at the 2005 SPD meeting.
Publication: Robbins, S. J.; Henney, C. J.; and J. W. Harvey. (2006). Solar Wind Forecasting with Coronal Holes. Solar Physics, 233, No. 2. Also available online at http://arxiv.org/pdf/astro-ph/0701275.
Abstracts:
Robbins, S. J.; Henney, C. J.; and J. W. Harvey. Solar Wind Forecasting with SOLIS-VSM. (2005). Click for the Poster.
Robbins, S. J.; Henney, C. J.; and J. W. Harvey. Solar Wind Forecasting with Coronal Holes. Bulletin of the American Astronomical Society. pp. 1350, 36:5 (2004).
Nucleosynthesis Web-Based Tools
My REU the year before, 2003, at Clemson through the SARA REU program. I worked with Brad Meyer and created a web-based Java interface for his nucleosynthesis code. A January 2004 AAS meeting abstract and poster was the result, along with a paper for SARA's own journal, the IAPPP.
Publication: Robbins, S. J.; Meyer, B. S.; and G. C. Jordan, IV. Modeling Nucleosynthesis: Web-Based Tools. IAPPP. pp. 22-29, 94, (2003).
Abstract: Robbins, S. J.; Meyer, B. S.; and G. C. Jordan, IV. Modeling Nucleosynthesis: Web-Based Tools. Bulletin of the American Astronomical Society. pp. 1209, 35:5 (2003). Click for the Poster.
