Impact Ionisation Mass Spectrometry of Cosmic Dust Analogues I: Active Asteroids and Hydrated Minerals

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Asteroid 3200 Phaethon is an "active" asteroid, one which spectroscopically and dynamically resembles an asteroid, with no sign of surface volatiles, and yet which exhibits comet-like dust emission, generating the Geminid meteor stream.Thermal desiccation and cracking of hydrated and/or hydroxylated minerals on Phaethon has been postulated as a driver for the dust emission. However, the composition and quantity of these minerals has not been identified in dust from Phaethon and also remains poorly constrained in the general interplanetary and interstellar dust populations.The Destiny Dust Analyser (DDA) instrument (PI R. Srama, U. Stuttgart), onboard the upcoming Japanese Destiny+ spacecraft, represents a unique opportunity to measure the composition of these dusts via cation and anion impact ionisation mass spectrometry.This project will produce metal-coated, water-rich mineralogical cosmic dust analogues and electrostatically accelerate them onto laboratory impact ionisation mass spectrometers, including the DDA flight spare/laboratory models.The mass spectra produced by these grains, as well as by non-hydrated/-hydroxylated control samples, will be characterised in order to predict the mass spectra expected from naturally-occurring water-containing grains, provide calibration factors for their quantitative identification and further understand the role of impact velocity and particle mass on the generated spectra.