With the number of confirmed rocky exoplanets in the habitable zone increasing steadily, their
characterisation and the search for exoplanetary biospheres is becoming an increasingly urgent issue
in astrobiology. To date, most efforts have concentrated on the study of biosignatures in
exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterising an
exoplanet (habitability, geology, presence of life etc.) by studying material ejected from the
surface during an impact event. For a given impact event, we estimate the escaping mass and assess
its subsequent collisional evolution in a circumstellar orbit ("debris disk"). We calculate the
fractional luminosity of the dust as a function of time after the impact event and study its
detectability with current and future instrumentation. We consider the possibility to constrain the
dust composition, giving information on the geology of the exoplanet or the presence of a biosphere.
Despite considerable difficulties (small dust masses, noise such as exozodiacal dust etc.), studying
dusty material ejected from an exoplanetary surface might become an interesting complement to
atmospheric studies in the future.
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