Atmospheric entry of fluffy cometary particles under early Earth's conditions

Yann Brouet (1) , Jérémie Lasue (2) , Anny Chantal Levasseur-Regourd (3) , Pierre Encrenaz (4)

1 Physikalisches Institut [Bern]
2 IRAP - Institut de recherche en astrophysique et planétologie
3 PLANETO - LATMOS
4 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique

At the epoch of the Late Heavy Bombardment (LHB), the delivery of complex organic compounds on Earth, necessary for the apparition of life, was likely favored by the fluffy structure of the interplanetary dust of cometary origin (e.g. Lasue et al. , 2007). We have used Direct Simulation Monte Carlo (DSMC) methods (Bird, 1994) to simulate the entry of compact spherical particles and fractal aggregates of spherical grains (representative of fluffy cometary particles found in the interplanetary dust cloud), with a fractal dimension of 2.31, under early Earth’s conditions. We performed 2-D calculations at the onset of particle ablation. Particle size varies from 2 mm to 100 μm. Several entry speed have been tested: 12 km/s (prograde orbit), 30 km/s and 71.5 km/s (retrograde orbit). Results show significant differences between compact and irregular particles in terms of temperature distribution.

Mots clés: Monte Carlo method; ablation; cometary fluffy particles; organic matter; early Earth's atmosphere

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]

Yann Brouet, Jérémie Lasue, Anny Chantal Levasseur-Regourd, Pierre Encrenaz. Atmospheric entry of fluffy cometary particles under early Earth's conditions. ISSOL and Bioastronomy Joint International Conference (Origins 2011), Jul 2011, Montpellier, France. . ⟨hal-01432603⟩