Orateur
Description
Pluto’s tenuous atmosphere is mainly composed of molecular nitrogen N2 and methane CH4, with 515 ± 40 ppm of carbon monoxide CO (Lellouch et al., 2017, Young et al., 2018). This atmosphere is the place of a complex photochemistry producing aerosols that surround Pluto as several thin haze layers extending at more than 350 km of altitude (Cheng et al., 2017, Gladstone et al., 2016, Stern et al., 2015, Young et al., 2018). These aerosols can deeply affect Pluto’s atmospheric chemistry and climate. For instance, the aerosols can deplete from the atmosphere small hydrocarbons to form more complex molecules (Luspay-Kuti et al., 2017). They can also serve as cloud condensation nuclei (Lavvas et al., 2016, Luspay-Kuti et al., 2017) or cool the atmosphere by absorbing solar radiations (Zhang et al., 2017).
Laboratory simulation is one way to support these hypotheses and constraint the formation pathways, the chemical composition or the physical properties of Pluto’s aerosols. Thus, we produced analogues of Pluto’s aerosols, using the PAMPRE experimental setup (Szopa et al., 2006) developed at LATMOS (Guyancourt, France). As the CH4 mixing ratio strongly varies all along the atmospheric column (Young et al., 2018), different types of analogues were synthesized, in variable proportions of N2 and CH4, with 500 ppm of CO; the idea being to mimic aerosols formed at different altitudes in Pluto’s atmosphere.
The chemical composition of these analogues was inferred from infrared spectroscopy, high-resolution mass spectrometry and elemental composition analyses. Their optical constants (refractive indices and absorption coefficients) were determined by spectroscopic ellipsometry.
| Field | Planetology (incuding small bodies and exoplanets) |
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