Curiosity Finds Strong Evidence of Ancient Lake on Mars

Mount Sharp – a mountain on Mars and the primary target of NASA’s Mars rover Curiosity – was built by sediments deposited in a large lake bed over tens of millions of years, says rover science team.
Read More »

http://www.sci-news.com/space/science-curiosity-ancient-lake-mars-02328.html

I approve.

dv said:

I approve.

I don’t approve. The key feature that led to the selection of Gale crater as the landing site for Curiosity is that it sits on the junction between the highlands and lowlands. That means that whatever massive event created the lowlands could have led to temporary peculiarities in the region of Gale Crater, in particular the strange shape of Mount Sharp.

All the rocks found by Curiosity are igneous in origin, mostly basalt. And this suggests that Mt Sharp is a shield volcano similar to Hawaii. Although Curiosity has definitely found alluvial deposits, these are alluvial fans created by rapid collapse of the crater rim. There is no sign of hydraulic rounding of crater-bottom sediments except in those alluvial fans.

Apart from that, the pressure of Mars atmosphere is too low to support liquid water for any substantial period of time.

Am writing this before reading link, so my opinions are subject to change.

Have looked at the link.

“This view from the Mast Camera on board Curiosity shows an example of cross-bedding from water passing over a loose bed of sediment. The cross-bedding – evident as layers at angles to each other – reflects formation and passage of waves of sand, one on top of the other. These are known as ripples, or dunes. The direction of migration of these small ripples and dunes was toward the southeast. That direction is toward Mount Sharp and away from the area where Curiosity found evidence of delta deposits where a stream entered a lake.”

Hmm, cross bedding is typically associated with water, so they could be right. It’s not normally a feature of lava flows, but it can also be created by wind-blown sediments. The flow direction seems to be towards Mt Sharp, which argues against a water-based origin. The crater itself is clearly the result of asteroid impact, erosive forces are nowhere near strong enough to have created the crater by erosion of lake sediments.

I’d be far happier with the lake picture if they could show that the bonding between sand grains was due to evaporites, salts that were left behind when the water evaporated. Curiosity has the spectroscopic tools to check this.

mollwollfumble said:

I’d be far happier with the lake picture if they could show that the bonding between sand grains was due to evaporites, salts that were left behind when the water evaporated. Curiosity has the spectroscopic tools to check this.

One could imagine that if the tools were aboard then they are there for that purpose?