Temperature profile validation data for a numerical thermophysical study of asteroid 1998 KY26

Background This dataset includes information necessary to reproduce the figures used in the numerical thermophysical study of the near-Earth asteroid 1998 KY26, target of the Hayabusa2 extended mission. This study was conducted to determine the extent of presence of volatiles within the asteroid by comparing the temperatures of shape model nodes to the sublimation threshold of water in vacuum: 110 K. Shape model node temperatures are computed using a thermophysical finite element model (TPFEM), which iteratively solves the 3D heat conduction equation. Due to uncertainty in current observations of 1998 KY26, this study varied the asteroid's spin pole orientation (measured in terms of ecliptic longitude and latitude), size (measured as equivalent diameter), thermal conductivity, Bond albedo, and specific heat capacity input parameters for TPFEM to see how changes in these parameters impacted the asteroid's bulk average temperature. These parameters were varied in isolation over 13 tests, with the first test designated as the "base case" due to it containing only intermediate values. In each TPFEM simulation, the asteroid's heliocentric position is fixed, so each test is comprised of 20 positional cases, each corresponding to an 18° true anomaly arc, to examine the impact of the asteroid's orbit on long-term temperature trends. TPFEM parameter Units Base case value Minimum value Maximum value Ecliptic longitude (λ) ° 36 30 45 Ecliptic latitude (β) ° -44 -60 -30 Equivalent diameter m 11 9 13 Thermal conductivity W/m*K 5.403 4.863 5.943 Bond albedo 0.300 0.245 0.355 Specific heat capacity J/kg*K 670.6 502.9 838.2 The data included here is a subset of what was gathered during the 1998 KY26 study, specifically being the necessary information to reconstruct the reference figures that have also been provided. In the "CaseNodeTemps" figure, MATLAB heatmap patches are shown for select positions in the asteroid's orbit for the base case configuration. In the "TempVariation" figure, node temperatures are averaged across all positional cases for select tests and sorted into 30 bins ordered by distance from the shape model origin. The mean, 1-σ region, maximum, and minimum values for each bin are plotted. Dataset Interpretation Each row in the CaseNodeTemps tables corresponds to a node ID. The first three columns in the table are the positional components of the node, and the fourth column contains the temperature of the node. A shape model faces file is also provided, which shows how nodes are grouped into triangular surface facets. Table label True anomaly Notes A 0° Periapsis B 90° C 144° Position of coldest recorded surface node (169.104 K) D 180° Apoapsis E 270° F 306° Position of hottest recorded surface node (313.908 K) The following table presents the variation performed corresponding to each letter in the TempVariation series. Not all TPFEM parameter tests are included in the reference image, as their differences from the base case are small. Table label Parameter varied Bulk average temperature (K) A None (base case) 225.737 B Spin pole orientation: (λ,β) = (45°,-60°) 225.489 C Spin pole orientation: (λ,β) = (30°,-30°) 225.583 D Spin pole orientation: (λ,β) = (45°,-30°) 225.609 E Bond albedo: 0.245 229.848 F Bond albedo: 0.355 221.433 Script Usage Two MATLAB scripts are included: "createCaseNodeTempsFig.m" and "createTempVariationFig.m", which have names corresponding to the figure title they are used to create. If placed in the same directory as all six lettered tables of the corresponding category, the scripts are configured to automatically print their respective figures. These outputs should be identical to the reference figures. Note that "createCaseNodeTempsFig.m" also requires "Faces1998KY26.csv" as an input (placed in the same directory as all other inputs).