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Tiny cobbles on Mars

Tiny cobbles on Mars

Our second cool image takes us from grand galaxies, one of the universe’s largest coherent objects, to tiny cobbles on Mars. The picture to the right, taken by one of Perseverance’s close-up cameras on September 29, 2022, covers an area less than an inch across, making the largest rounded pebbles in this image only a few millimeters in size.

The rover presently sits on the floor of Jezero Crater, at the base of the delta that flowed into that crater eons ago. The data suggests that delta was created by flowing water entering a lake that filled the crater.

Did flowing water create these cobbles? These pebbles all have the look of the rounded cobble one finds either in river beds, or in glacial moraines. In both cases, the flow of the water or ice rolls the rocks along until they become rounded.

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  • pzatchok

    I would attribute the round nature to millions of years of dusty winds.

  • Col Beausabre

    pzatchok Just what I was going to post, I agree

  • Cotour

    Dusty winds? Nah.

    How do “Dusty winds” create rounded cobbles, rounded pebbles and fine sand? Winds would only produce fine sand IMO.

    Flowing water as far as I understand is the only substance that can create such an effect.

    I suspect that the first 1 billion (2 billion?) or so years on Mars was more like the earth and being bathed in water given the very familiar in many instances the topography that we can all see rather than today’s Mars which is bereft of any atmosphere of consequence.

    Where did it go?

    Over time it evaporated into space and has been absorbed underground and is frozen because Mars as a planet does not have the mass nor the atmosphere and the magnetic field to retain it.

    Mars only had just so long to retain water in a liquid form, then time ran out.

  • Andi

    One thing I’ve been wondering about – if Mars had all this water in the distant past, where did the water come from?

  • Cotour

    The same place water came from for the earth.

    Mars just cannot hold it in all three of its phases for the previously listed reasons.

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