The Castalia mission to Main Belt Comet 133P/Elst-Pizarro

Abstract

We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC's activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA's highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these.

Dust-to-Gas and Refractory-to-Ice Mass Ratios of Comet 67P/Churyumov-Gerasimenko from Rosetta Observations

“…For example, two monostatic radars have been proposed to instrument the Castalia mission concept to Main Belt comet 133P/Elst-Pizzaro, proposed to ESA for the recent M5 cosmic vision round (Snodgrass et al 2018).…”

The Main Belt Comets and ice in the Solar System

“…The mission is described in detail by Snodgrass et al (2017a), but in summary this would be a rendezvous mission launched in the late 2020s, to arrive before 133P's 2035 perihelion. Its instrument complement comprises visible, NIR, and thermal IR cameras; mass spectrometers sensitive to neutral and ionised gas; a dust instrument that combines the strengths of the Rosetta GIADA and COSIMA instruments to study flux and composition of grains; a sensitive magnetometer and plasma package; and two ground-penetrating radars.…”

Small bodies science with the Twinkle space telescope

“…Castalia is a proposed ESA mission to rendezvous with the Main Belt Comet 133P/Elst-Pizarro to perform the first characterization of this intriguing population, making the first in situ measurements of the water in the asteroid belt and measuring isotope ratios as well as plasma and dust properties. 44 Although CASTAway and Castalia were not implemented by ESA, a new small bodies mission, Comet Interceptor, 45 has been accepted for ESA's F Class call for launch with Ariel in 2028. The mission aims to encounter a dynamically new comet (i.e., one that is entering the inner Solar System for the first time) as well as making solar wind measurements.…”