Why did Mars dry out?

[Eldorado]

“People have put forward different ideas, but we’re not sure what caused the climate to change so dramatically,” said University of Chicago geophysical scientist Edwin Kite. “We’d really like to understand, especially because it’s the only planet we definitely know changed from habitable to uninhabitable.”

Kite is the first author of a new research study that examines the tracks of Martian rivers to see what they can reveal about the history of the planet’s water and atmosphere.

Many scientists had previously assumed that losing carbon dioxide from the atmosphere, which helped to keep Mars warm, caused the trouble. But the new research findings, published on May 25, 2022, in the journal Science Advances, suggest that the change was caused by the loss of some other important ingredient that maintained the planet warm enough for running water.

https://scitechdaily.com/why-did-mars-dry-out-mystery-deepens-as-new-study-points-to-unusual-answers/

[+Hammerclaw]

With no magnetosphere to deflect it, the solar wind eroded the atmosphere away over billions of years. The natural heat generated by radioactive elements in it's mantle dissipated over time, slowly chilling the planet and locking much of the atmosphere away into ice.

[Abramelin]

From the article:

"Mars once ran red with rivers. The telltale tracks of past rivers, streams, and lakes are still visible today all over the planet. But about three billion years ago, they all dried up—and no one knows why."

By means of what measurement did they determine that date of about 3 billion years ago?

[jethrofloyd]

1 hour ago, Abramelin said:

By means of what measurement did they determine that date of about 3 billion years ago?

I'm by no means an expert, but I believe the scientists can roughly determine it based on the spectral photographs, and erosion of the Mars surface .

''The cratered highlands of Mars have many river valleys that formed in a water-rich environment about 4.5 to 3.7 billion years ago. Erosion since then has been slow, leaving these very old features preserved. Later, massive outflows of groundwater formed flood channels tens to hundreds of kilometers wide and perhaps over 1,000 kilometers (620 miles) long.''

[+Hammerclaw]

1 hour ago, Abramelin said:

From the article:

"Mars once ran red with rivers. The telltale tracks of past rivers, streams, and lakes are still visible today all over the planet. But about three billion years ago, they all dried up—and no one knows why."

By means of what measurement did they determine that date of about 3 billion years ago?

By scientific methods developed over centuries, empirical observation and contemporary methods.

Surface Geology of Mars – Planetary Sciences, Inc. (planetary-science.org)

 

[Abramelin]

15 minutes ago, jethrofloyd said:

 

''The cratered highlands of Mars have many river valleys that formed in a water-rich environment about 4.5 to 3.7 billion years ago.

So if I combine that with the 3 billion years of my quote, it took about 1 billion years for Mars to dry out.

[jethrofloyd]

7 minutes ago, Abramelin said:

So if I combine that with the 3 billion years of my quote, it took about 1 billion years for Mars to dry out.

Yes, it took about 1 billion years for poor planet Mars to dry out. But, 1 billion years is not a short time.The Earth is 4.5 billion years old.

[Abramelin]

28 minutes ago, jethrofloyd said:

Yes, it took about 1 billion years for poor planet Mars to dry out. But, 1 billion years is not a short time.The Earth is 4.5 billion years old.

I have read somewhere, a long time ago, that Mars may have had liquid water and rivers as 'recent' as a couple of hundred millions of years ago. But you know it: can't find it anymore.

Well, there's always Wiki;

https://en.m.wikipedia.org/wiki/Water_on_Mars

Recently updated and very detailed; worth the read.