Mars' water may have come from ancient asteroid impacts

Nov 24, 2022
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I think there is ample evidence that Mars had rivers and water in the past. It seems that it was a world similar to ours in ancient times. Water erosion is evident and I do wonder what else we will find there.

Does water always have to come from an asteroid? Why could it not develop on the planet naturally?

This is actually my very first post, so I'm just feeling my way here.

Karl
 
I note some words of caution in the article here.

"However, the Red Planet's old surface also complicates the history of that water. Mars' once plentiful water has, over billions of years, mostly leaked into space. NASA's MAVEN (Mars Atmosphere and Volatile Evolution) ventured to Mars in 2014 to measure the current rate of atmospheric loss. But estimates of historical water loss to space have to date been based on the D/H ratio of water in Mars' mantle. In Mars' atmosphere, water molecules are blasted by ultraviolet radiation from the sun, which breaks them apart into their component atoms of oxygen and hydrogen or deuterium. Because deuterium is heavier than regular hydrogen, it doesn't escape into space as quickly, so the proportion of deuterium on Mars relative to regular hydrogen increases over history. If one knows the D/H ratio that Mars' water started off with, then one can calculate the amount of water lost to space. However, carbonaceous chondrites have a different, higher D/H ratio compared to Mars' mantle, so therefore using only the mantle D/H measurement to calculate water loss will skew the result, making it seem as though more water has escaped than really has. This leads to a problem, since scientists have an estimate for how much water all told has made it to Mars. If less water has escaped over history, then there must be more water still lurking somewhere on Mars besides that which is locked up in the polar ice deposits. "There must be a reservoir of water that we don't see," Bizzarro said. "People have hypothesized that this reservoir could reside in the crust in the form of hydrated minerals — i.e., clays — or buried ice deposits."

Here is a report about Earth getting water from meteorites that is a new report too.

Winchcombe meteorite bolsters Earth water theory, https://www.bbc.com/news/science-environment-63631563

ref - The Winchcombe meteorite, a unique and pristine witness from the outer solar system, 16-Nov-2022. "Abstract Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth’s water."

How Martian meteorites stack up against the analysis done for the Winchcombe meteorite remains an open question in my judgment. On Earth we have plenty of water to sample and compare, what about Mars today? Also, how many meteorites are required to create an ocean on Mars and Earth's water supply? How long did it take to deliver the total number of meteorites to Mars and Earth to create our water supply here and what is claimed about Mars, say 4 billion years ago? Remember too, Mars and Earth would be orbiting the Faint Young Sun, nothing like our Sun today using the meteorite age paradigm and stellar evolution model for the Sun.
 

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