Sorcha

The sea of planetesimals within the Solar System are the remanent building blocks left after the formation of the Solar System. Studying thse objects can serve as artifacts that give insight into the Solar System's formation and past evolution. Our team set out to accurately predict how many new Solar System objects would be discovered during the LSST, when these small bodies would be found, and how many observations each one would receive throughout the duration of the survey. A detailed understanding of the numbers and kinds of Solar System objects that will be discovered at different points in the 10-year survey can help astronomers get ready for the LSST and better plan follow-up observations with other facilities. We have spent the last five years building Sorcha, a powerful software tool that simulates the LSST.

Sorcha predicts which of the objects in an input model (representing a population of Solar System planetoids with specified orbits, sizes, surface colors) should be "found" by the survey. Sorcha calculates the locations of the model orbits on-sky and figures out which of the model objects land within the survey images and would be bright enough to be detected by the Rubin Observatory's data analysis pipelines and Solar System moving object search pipeline. Sorcha uses a database of where the Rubin Observatory searched on the sky and the weather conditions during the LSST (or currently a simulation of where the survey pointed provided by Rubin Observatory), the properties of the LSST Camera, and properties of Rubin Observatory's software pipelines to figures out which of the input model objects should be found the survey.

Sorcha is built to handle the massive scale of LSST data, crucially allowing astronomers to compare model Solar Systems to the one we live in. Thanks to Sorcha, astronomers can Sorcha can predict what the "found" by the LSST would have found if the model represents the Solar System and compare the results to what was actually found by the survey In the future these simulated "surveys" can be compared to the real LSST. Using this technique, astronomers can adjust the input model parameters/distribution of model population's properties until the discoveries in the simulated version of the LSST mates matches the real LSST discoveries. This technique is very powerful, enabling estimates of the total number of objects, distribution of orbits, sizes, rotational variability, and surface properties for any of the small body populations within the Solar System.

Sorcha is freely accessible to download and use. You can learn more about Sorcha here. I serve as the Sorcha team PI (principal investigator), and I use Sorcha to predict what the LSST should discover and in the future plan to use Sorcha to help translate what the LSST small body discoveries can tell us about their parent populations. The Sorcha team is also working on incorporating other surveys into Sorcha for joint analysis with the Rubin Solar System detections

Layup

Fitting orbits (the process of taking the observed on-sky positions and velocities of newly discovered moving Solar System objects and transforming them into orbital parameters) is essential to LSST Solar System science. Tere is no orbit fitting package that can support the needs of the planetary community in the Rubin Observatory era. My research group is part of the Layup Team led by Matt Holman (Center for Astrophysics | Harvard & Smithsonian). Layup is fast and accurate python orbit fitting and orbit utilities python package currently under development that will handle fitting roughly a billion astrometric points divided among roughly 3 million objects that are expected to be observed and monitored by Rubin Observatory.

Cometary Activity in Centaurs

The Centaurs are a transitory small body population that sits between the Kuiper belt in the Outer Solar System and the Jupiter Family/short period comets in the Inner Solar System. The Centaurs are temporary residents of the Middle Solar System, as most orbits are unstable and relatively short lived compared to the age of the Solar System. Centaurs are gravitationally perturbed/scattered by the giant planets like a pinball hitting the bumpers in an arcade machine. Most Centaurs will be “bouncing” around for ∼10 Myrs before being ejected into interstellar space. About 30$ of Centaurs, survive their turn in the Solar System’s pinball game, becoming Jupiter-family comets. Studying this transitory population can provide insights into the life cycle of Jupiter Family Comets as well as a view into the small sized members of the Kuiper belt that are difficult to view beyond 30 au with Earth-based telescopes. Members of my research group have used wide-field surveys and targeted telescope observations to study a recent new or enhanced epoch of cometary activty on Chiron, one of the largest Centaurs .

Seasonal Processes on the Martian South Polar Region

Mars' south pole is sculpted by the never-ending cycle of freezing and thawing of exposed carbon dioxide ice. In the summer, carbon dioxide jets loft dust and dirt through cracks in the thawing carbon dioxide ice sheet to the surface where winds blow the material into the hundreds of thousands of dark fans observed from orbit. Understanding the direction, frequency, and appearance of these fans (a proxy for the jets) and how varying factors impact these properties, we can better understand the Martian climate and winds. Computers just aren’t good enough to do the required task, but the fans spotted for orbit are easily spotted by the human eye. The Planet Four and Planet Four: Terrains projects are on-going online citizne science proejects collaborating with over 150,000 people around the world. Volunteers map the dark seasonal fans and other surface features carved during by the carbon dioxide gas jets.