I AM extremely nervous about commenting at all, in any way on anything written by such a stellar scientist of high repute.

It is intriguing to consider the aspects of later water and accelerated development of intelligent life and technology.

The article mentions a major asteroid impact. Yes, when planetary scientists studied the Argyre Basin on Mars, they saw evidence for the LHB’s intensity. The basin resulted from a giant impact on Mars between 3.8 and 3.9 billion years ago. Evidence showed that this impact raised Mars’ surface temperature by several hundred degrees, causing a runaway loss of water vapor. It led to thinking that this event permanently transformed Mars into a cold, dry planet.

Also, thinking that far back, and of magnetic fields, Mars’ dynamo shut down 4.0–4.1 billion years ago and has never restarted since then. [Robert J. Lillis et al., “Time History of the Martian Dynamo from Crater Magnetic Field Analysis,” Journal of Geophysical Research: Planets 118, no. 7 (July 2013): 1488–1511, doi:10.1002/jgre.20105; G. Schubert, C. T. Russell, and W. B. Moore, “Timing of the Martian Dynamo,” Nature 408 (December 7, 2000): 666–67, doi:10.1038.35047163.] Furthermore, the lower a planet’s atmospheric pressure, the more rapid its rate of water loss and the greater its radiation dose at the planet’s surface. While the shutdown of Mars’ dynamo might not have been immediately detrimental to possible life, the long-term effects of the dynamo shutdown would have been permanently catastrophic and would guarantee the loss of almost all, but not all of Mars’s surface water, early on. At least considering this factor (magnetic field), which also has implications regarding solar wind and cosmic radiation.

Past research has also indicated that at about 4 billion years ago, when Mars was about 560 million years old, there was likely a warm, wet episode. However, it has been thought that it ended abruptly with an event called the carbonate catastrophe. Liquid water reacts with carbon dioxide to form carbonic acid. As this acid inevitably rained on Mars, it would have produced carbonates, which leach greenhouse gases, water vapor, and carbon dioxide from the atmosphere. Such leaching would have swiftly transformed Mars into a dry, cold wasteland despite the continued brightening of the Sun. Again, maybe this is just old information?

Yes, the new research regarding water's notable existence later is downright exciting. Looking at the original article (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021AV000534), it is rather convincing to consider a new dating for water factors. How does the chlorite salts figure in abiosis? And, a highly accelerated pace of life from one-celled to high technology calls for some angle with a virtual warp speed evolution, which is already hard to be happy with in a many-billion-year scheme.

I agree that material from impacts on Mars could have (and can) raised Martian soil into space, some landing on Earth (a well-known and established effect between planets/moons). And maybe that affected the chemistry on Earth. But the reverse is also true, and we could easily find remains of early Earth life in current Martial soil that was wafted up from Earth. It has been suggested that might cloud our assessment of life on Mars if we find certain molecules relating to life.

All this is commented/inquired about here by someone "light years" behind the prowess of the writer of this article. And, I'm sure you, as the writer, are well-aware of probably everything I mentioned. I just had curious questions.