Mars was hot then cold then hot again. Could life have really survived there?

[Admin]

Scientists may have figured out how Mars hung onto its surface liquid water in its ancient history via alternating periods of hot and cold. But what would the impact have been on habitability?

Mars was hot then cold then hot again. Could life have really survived there? : Read more

 

[wwyarb]

Scientists may have figured out how Mars hung onto its surface liquid water in its ancient history via alternating periods of hot and cold. But what would the impact have been on habitability?

Mars was hot then cold then hot again. Could life have really survived there? : Read more

Hydrogen bond with carbon to form carbon dioxide?? I don't understand. Methane, perhaps?

 

[billslugg]

"Scientists had previously theorized that Mars was able to hold on to its liquid water without it freezing despite its distance from the sun thanks to an excess of hydrogen in its atmosphere.

This element, the universe's lightest, would bond with carbon atoms to form carbon dioxide in the Martian atmosphere. "

My interpretation is that the dust storms put lots of water at the top of the atmosphere where energetic ions disassociate it. The hydrogen escapes to space, leaving an atmosphere rich in oxygen which joins with carbon monoxide to make CO2.

Yes, hydrogen has something to do with it, but not in the way the article says. Basically at a loss here.

 

[Gary Brown]

The Harvard original luckily doesn't claim that bonding H to CO makes CO2 !

Explaining persistent hydrogen in Mars’ atmosphere

New insight into Red Planet’s hot again, cold again history

seas.harvard.edu

 

[George²]

Hydrogen bond with carbon to form carbon dioxide?? I don't understand. Methane, perhaps?

Ultraviolet rays dissociate water into hydrogen peroxide and oxygen. This facilitates the binding of carbon into methane molecules and the burning of some of the carbon to carbon dioxide. The processes leave behind a positive number of free hydrogen, which saturates and eventually leaves the atmosphere.
This is also the reason for the loss of water on Mars. Yes, there is still some water there in the form of ice, but nothing like the original amounts.

 

[Torbjorn Larsson]

The most interesting find is that they can explain the absence of carbonates under a CO2 atmosphere, because the climate that would induce that was so temporary.

Hydrogen bond with carbon to form carbon dioxide?? I don't understand. Methane, perhaps?

It's a bad article, I suggest Evan Gough's at Universe Today instead ("How Hydrogen Kept Early Mars Warm"). But in turn I don't understand why you did not read the paper that contains the information. It's already in the abstract:

We find that H2 outgassing from crustal hydration and oxidation, supplemented by transient volcanic activity, could have generated sufficient H2 fluxes to transiently foster warm, humid climates. We estimate that Mars experienced episodic warm periods of an integrated duration of ~40 million years, with each event lasting ≥105 years, consistent with the formation timescale of valley networks. Declining atmospheric CO2 via surface oxidant sinks or variations in the planet’s axial tilt could have led to abrupt shifts in the planet’s redox state and transition to a CO-dominated atmosphere and cold climate.

So water was leaking out and oxidized by minerals to release H2. Together with CO2 it heated the climate. The CO2-CO, water and climate cycling is more complex:

It was a temporary mechanism:

Our model also suggests crustal hydration could not have warmed the climate for longer than a cumulative total time of ~2–4 × 107 years (depending on the atmospheric pressure, corresponding to about 10% of the Noachian period), unless the present-day water inventory contained in the ice and the crust13 is underestimated. Therefore, our results imply only a few major warming events (~1 to 100 events, each of 105–4 × 107 years in duration).