arXiv subjects

Simon Porter

Publications and source records attributed to Simon Porter.

8 recordsLinked to original sources

arXiv2026

Kilometre-scale Jovian moon characterized for a potential JUICE flyby

Jupiter's irregular satellites are thought to be relics of early Solar System planetesimals. However, their small sizes, large distances from Earth and close angular proximity to Jupiter make them difficult to characterize remotely. Here we report multi-instrument observations of kilometre-sized Kallichore, the only irregular moon of Jupiter amenable to a close flyby by ESA's Jupiter Icy Moons Explorer (JUICE), whose astrometric and physical properties were still poorly constrained. We used Hubble photometry and astrometry, followed by a ground-based, multi-site stellar occultation campaign and astrometric and photometric observations with the 10.4-m Gran Telescopio Canarias. We reduced Kallichore's orbital uncertainty by up to approximately 80% and determined its shape: an elongated object with a minimum semi-axis ratio of a/b = 1.53 +/- 0.10, an area-equivalent diameter of 3.8 (+2.3/-0.3) km and a dark surface with a geometric albedo of 3.7% (+0.7/-2.2). No close companions were detected. These new constraints provide a viable pathway towards a JUICE flyby once the spacecraft arrives in the Jupiter system in 2031.

astro-ph.EP↗

arXiv2025

Tracking the Activity of the Interstellar Object 3I/ATLAS through its Perihelion

In order to facilitate interplanetary spacecraft observationsof 3I/ATLAS, we have monitored and predicted the optical properties of its coma using both ground and space-based observations. Here, we describe how the data from space-based solar coronagraphs and the PUNCH mission enabled tracking of 3I/ATLAS's optical magnitude throughout its entire perihelion passage, including the period between October 8 and 30, 2025, when it was not visible from Earth.

astro-ph.EP↗

arXiv2024

Beyond Point Masses. I. New Non-Keplerian Modeling Tools Applied to Trans-Neptunian Triple (47171) Lempo

Many details of the formation and evolution of the solar system are best inferred by understanding the orbital and physical properties of small bodies in the solar system. For example, small body binaries are particularly valuable for measuring masses. By extending the models of small body binaries beyond point masses, new information about the shape and spin orientation becomes available. This is particularly informative for Trans-Neptunian multiples (two or more components) where shapes and spin orientations are poorly understood. Going beyond point masses requires modeling tools that no longer assume fixed Keplerian orbits. To this end, we have developed a new n-quadrupole integrator SPINNY (SPIN+N-bodY) and pair it with a Bayesian parameter inference tool MultiMoon, both of which are publicly available. We describe these tools and how they can be used to learn more about solar system small body multiple systems. We then apply them to the unique Trans-Neptunian hierarchical triple system (47171) Lempo, finding a three-point-mass solution for the first time. This solution has two surprises: unequal densities of the inner components and a dynamical configuration apparently unstable on the age of the solar system.

astro-ph.EP↗

arXiv2021

Measuring Research Information Citizenship Across ORCID Practice

Over the past 10 years stakeholders across the scholarly communications community have invested significantly not only to increase the adoption of ORCID adoption by researchers, but also to build the the broader infrastructures that are needed both to support ORCID and to benefit from it. These parallel efforts have fostered the emergence of "research information citizenry", which comprises, but is not limited to, researchers, publishers, funders, and institutions. This paper takes a scientometric approach to investigating how effectively ORCID roles and responsibilities within this citizenry have been adopted. Focusing specifically on researchers, publishers, and funders, ORCID behaviours are measured against the approximated research world represented by the Dimensions dataset.

cs.DL↗

arXiv2020

Captured Small Solar System Bodies in the Ice Giant Region

This white paper advocates for the inclusion of small, captured Outer Solar system objects, found in the Ice Giant region in the next Decadal Survey. These objects include the Trojans and Irregular satellite populations of Uranus and Neptune. The captured small bodies provide vital clues as to the formation of our Solar system. They have unique dynamical situations, which any model of Solar system formation needs to explain. The major issue is that so few of these objects have been discovered, with very little information known about them. The purpose of this document is to prioritize further discovery and characterization of these objects. This will require the use of NASA and NSF facilities over the 2023 2032 decade, including additional support for analysis. This is in preparation for potential future insitu missions in the following decades.

astro-ph.IM↗

arXiv2014

On the Roles of Escape Erosion and the Relaxation of Craters on Pluto

Pluto and its satellites will be the most distant objects ever reconnoitered when NASA's New Horizons spacecraft conducts its intensive flyby of this system in 2015. The size-frequency distribution (SFD) of craters on the surfaces in the Pluto system have long been expected to provide a useful measure of the size distribution of Kuiper Belt Objects (KBOs) down to much smaller size scales than presently observed. However, currently predicted escape rates of Pluto's atmosphere suggest that of order one-half to several kilometers of nitrogen ice has been removed from Pluto's surface over geologic time. Because this range of depths is comparable to or greater than most expected crater depths on Pluto, one might expect that many craters on Pluto's surface may have been removed or degraded by this process, biasing the observed crater SFD relative to the production-function crater SFD. Further, if Pluto's surface volatile layer is comparable to or deeper than crater depths, and if the viscosity of this layer surface ice is low like the viscosity of pure N2 ice at Pluto's measured 35 K surface temperature (or as low as the viscosity of CH4 ice at warmer but plausible temperatures on isolated pure-CH4 surfaces on Pluto), then craters on Pluto may also have significantly viscously relaxed, also potentially biasing the observed crater SFD and surface crater retention age. Here we make a first exploration of how these processes can affect the displayed cratering record on Pluto. We find that Pluto's surface may appear to be younger owing to these effects than it actually is. We also find that by comparing Pluto's cratering record to Charon's, it may be possible to estimate the total loss depth of material from Pluto's surface over geologic time, and therefore to estimate Pluto's time-averaged escape rate.

astro-ph.EP↗

arXiv2014

Ejecta Transfer in the Pluto System

The small satellites of the Pluto system (Styx, Nix, Kerberos, and Hydra) have very low surface escape velocities, and impacts should therefore eject a large amount of material from their surfaces. We show that most of this material then escapes from the Pluto system, though a significant fraction collects on the surfaces of Pluto and Charon. The velocity at which the dust is ejected from the surfaces of the small satellites strongly determines which object it is likely to hit, and where on the surfaces of Pluto and Charon it is most likely to impact. We also show that the presence of an atmosphere around Pluto eliminates most particle size effects and increases the number of dust impacts on Pluto. In total, Pluto and Charon may have accumulated several centimeters of small-satellite dust on their surfaces, which could be observed by the New Horizons spacecraft.

astro-ph.EP↗

arXiv2012

KCTF Evolution of Trans-Neptunian Binaries: Connecting Formation to Observation

Recent observational surveys of trans-neptunian binary (TNB) systems have dramatically increased the number of known mutual orbits. Our Kozai Cycle Tidal Friction (KCTF) simulations of synthetic trans-neptunian binaries show that tidal dissipation in these systems can completely reshape their original orbits. Specifically, solar torques should have dramatically accelerated the semimajor axis decay and circularization timescales of primordial (or recently excited) TNBs. As a result, our initially random distribution of TNBs in our simulations evolved to have a large population of tight circular orbits. This tight circular population appears for a range of TNO physical properties, though a strong gravitational quadrupole can prevent some from fully circularizing. We introduce a stability parameter to predict the effectiveness of KCTF on a TNB orbit, and show that a number of known TNBs must have a large gravitational quadrupole to be stable.

astro-ph.EP↗