Free Astronomy Magazine March-April 2021

MARCH-APRIL 2021 MARS ROVERS probable meteorite impact and is made up of gravel and pebbles ce- mented together in a sandy matrix, a formation that geologists call a sedimentary conglomerate. where researchers had, for the first time, the absolute certainty that water flowed on Mars in the distant past. Hottah is a slab of rock that rose from the ground following a R emains of an ancient Martian stream, at the Link site. The sharp shape of some rocks is indicative of the direction of water flow. The sce- nario is marked by the erosion of the most exposed fractured parts, which show an abundant pouring of gravel. Below, a comparison between an enlargement of the Link bed with the bed of a terrestrial stream. The conglomerate sediments, the type of cementation, the smoothing of the gravel and the erosion of the matrix are virtually identical. [NASA/JPL- Caltech/MSSS and PSI] The characteristics of gravel and pebbles are completely similar to those of gravel and pebbles mod- eled and transported by homolo- gous terrestrial waterways, so much