The Minor Planet Physical Properties Catalogue: Connection with the Virtual European Solar and Planetary Access of EUROPLANET and the big data challenge for planetary science

摘要

<p><strong>Introduction</strong></p> <p>The small bodies (also known as minor planets) in our solar system are usually discovered by telescopic surveys. The results of these observations are organised by the Minor Planet Center (MPC), which determines orbits from the astrometric observations of the surveys. As of May 15, 2022, the MPC has an orbit database of 1,193,635 minor planets. However, the MPC data do not tell us what a minor body actually is, as they not contain physical properties such as albedo, diameter, volume, shape, composition, mass, bulk density, period of rotation and direction in the sky of the axis of rotation. Asteroids have very diverse values of these physical properties, whose knowledge is important for scientific studies of our solar system and its origin, planetary formation and evolution, space exploration, and planetary defence.</p> <p>The physical properties of small bodies are spread across many publications, several websites (e.g. the NASA planetary data service) and archives. Many compositionally diagnostic spectra are also presented in a series of publications, but their source files are not necessarily public. This poses a fundamental problem to our ability to massively exploit the physical properties of minor bodies. Moreover, the values ​​of these physical parameters are extremely heterogeneous, obtained by several different groups, project teams and telescopic surveys, and even individual researchers, using different techniques. For example, thermal models are used to interpret observations in the mid-infrared (between 3.5 and 100 μm) from space and from the ground for the measurement of diameters and albedos. However, other techniques such as radar or the measurement of stellar occultation times provide measurements of diameters.</p> <p> </p> <p><strong>A centre of minor planets’ physical properties<span class="Apple-converted-space"> </span></strong></p> <p>The Minor Planet Physical Properties Catalogue, or MP3C for short, collects and organises in a single place and makes available to the community values of physical properties of asteroids and other small bodies of our solar system. The MP3C is designed for very heterogeneous and big amount data: as of March 2022 it contains 3,710,587 measured properties, all of which are fully referenced to their published sources. The MP3C offers two main interfaces to explore the data (Figs. 1 and 2), namely (i) a web portal (mp3c.oca.eu) that allows to perform extraction of physical properties values on the basis of a single or list of minor bodies identifiers (names, numbers), but also on ranges of physical and dynamical properties; (ii) a data server offering a Table Access Protocol (TAP), which is defined and compatible with the standards of the Virtual Observatory (VO). The data server is accessible at https://dachs.oca.eu. MP3C is registered as service of the Virtual Observatory and therefore searchable and accessible using Virtual Observatory tools such as TOPCAT (Fig. 2). Using TOPCAT and/or the TAP, a human or robotic user can perform queries in a standardised database language (ADQL). MP3C contains sizes, albedos, absolute magnitudes, masses and rotational period, along with osculating and proper orbital elements of 1,169,632 minor bodies. At the time of writing we are also implementing in the MP3C table of spectral classes, colours, rotation vector orientation, and later reflectance spectra of minor planets.</p> <p> </p> <p><strong>Interface with the Virtual European Solar and Planetary Access of EUROPLANET</strong&gt