Modes of ejecta emplacement at Martian craters from laboratory experiments of an expanding vortex ring interacting with a particle layer

A Suzuki (1) , I Kumagai (2) , Y Nagata (3) , K Kurita (1) , Olivier S. Barnouin-Jha (4)

1 Shinshu University [Nagano]
2 IPGP - Institut de Physique du Globe de Paris
3 TUAT - Department of Applied Physics [Tokyo]
4 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]

Ejecta morphologies of many Martian craters indicate fluidized emplacement which differs from ballistic emplacement in dry, airless environments. Double Layered Ejecta craters possess particularly interesting ejecta morphologies: two lobes and radial lineations on their surface, which probably result from gas-dominated radial flow during the emplacement. To examine how a radial flow interacts with surface particles to generate some of the observed morphologies on Mars, we have conducted water tank experiments in which a vortex ring encounters a particle layer. The threshold of particle motion and three interaction modes are described by two dimensionless numbers: particle Shields' parameter and particle Reynolds number. Our results show that gas-dominated flows are possible during cratering and could be used to constrain the ancient Martian environment from observations.

Domaines: Planète et Univers [physics]

A Suzuki, I Kumagai, Y Nagata, K Kurita, Olivier S. Barnouin-Jha. Modes of ejecta emplacement at Martian craters from laboratory experiments of an expanding vortex ring interacting with a particle layer. Geophysical Research Letters, 2007, 34 (5), pp.L05203. ⟨10.1029/2006GL028372⟩. ⟨insu-01270088⟩