New data suggests Gale Crater was never filled with lake
The uncertainty of science: A new review of data from Curiosity now suggests that Gale Crater was not filled with a lake in the past — as generally believed — but instead simply had small ponds on its floor.
Previous analyses of data from Curiosity have relied heavily on a measure called the chemical index of alteration to determine how rocks were weathered over time. Joseph Michalski at the University of Hong Kong and his colleagues have suggested that because this measure was developed for use on Earth, it may not be valid in the extreme Martian climate.
Instead, they analysed the concentrations of various compounds that are expected to change based on different types of weathering over time. They found that some of the layers of rock Curiosity examined did interact with water at some point in their past, but more are likely to have formed outside of the water. “Over hundreds of metres of strata, it seems that the only layers that are demonstrably lacustrine [formed in a lake] are the lower few metres,” says Michalski. “Of the rocks visited by the rover… the fraction that is demonstrably lacustrine is something like 1 per cent.”
These rocks were mostly in the lowest few metres of sediments in the crater, suggesting the lake was not nearly as deep or extensive as we thought. “There was likely a small lake or more likely a series of small lakes in the floor of Gale crater, but these were shallow ponds,” says Michalski.
This conclusion also aligns with other recent work proposing that Gale Crater was always cold and never had running water.
None of this is proven, one way or the other, though this new conclusion would make it easier to explain Mars entire geological history. Trying to create models for Mars’ past climate that allowed large amounts of liquid water on its surface have so far been difficult at best, and have generally been unconvincing. Eliminating the need for liquid water will make explaining Mars’ geology much simpler.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: A new review of data from Curiosity now suggests that Gale Crater was not filled with a lake in the past — as generally believed — but instead simply had small ponds on its floor.
Previous analyses of data from Curiosity have relied heavily on a measure called the chemical index of alteration to determine how rocks were weathered over time. Joseph Michalski at the University of Hong Kong and his colleagues have suggested that because this measure was developed for use on Earth, it may not be valid in the extreme Martian climate.
Instead, they analysed the concentrations of various compounds that are expected to change based on different types of weathering over time. They found that some of the layers of rock Curiosity examined did interact with water at some point in their past, but more are likely to have formed outside of the water. “Over hundreds of metres of strata, it seems that the only layers that are demonstrably lacustrine [formed in a lake] are the lower few metres,” says Michalski. “Of the rocks visited by the rover… the fraction that is demonstrably lacustrine is something like 1 per cent.”
These rocks were mostly in the lowest few metres of sediments in the crater, suggesting the lake was not nearly as deep or extensive as we thought. “There was likely a small lake or more likely a series of small lakes in the floor of Gale crater, but these were shallow ponds,” says Michalski.
This conclusion also aligns with other recent work proposing that Gale Crater was always cold and never had running water.
None of this is proven, one way or the other, though this new conclusion would make it easier to explain Mars entire geological history. Trying to create models for Mars’ past climate that allowed large amounts of liquid water on its surface have so far been difficult at best, and have generally been unconvincing. Eliminating the need for liquid water will make explaining Mars’ geology much simpler.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
How much a damper will this put on search life, past or present?
The search for life will not be hindered.
Not one bit. There will always be “hopeful believers” and they will put their money (or your money) where their belief is.
As long as there is human hope, there will be a fire in the belly of all spacers to find the first extra terrestrial life.
Whether it’s on Mars, comet fragments on Mars, under the Martian ice cap, or other planets and their various moons.
Maybe the next interplanetary debris or comet that passes near earth.
Don’t be surprised if a poorly sterilized container from China declares extent life! And it’s identical to ours!
I still believe that Mars is too small and too far from the sun to have liquid water. Perhaps if it had a thicker atmosphere for a longer period of time, it had liquid water for that short time.
I believe it had a covering of ice similar to Europa and The Martian ice caps are all that’s left of the evaporated ice “above” ground.
Due to low gravity, The solar wind has blown away it’s excess atmosphere. The best evidence for this is the constant air pressure right at the threshold where water turns from a solid to a gas bypassing the liquid state.
Every time atmospheric pressure drops, sublimation takes place to maintain the air pressure balance.
Not to worry, there is still more carbon dioxide in the Martian ice caps, then there is in all of the Martian atmosphere.
“Don’t be surprised if a poorly sterilized container from China declares extent life! And it’s identical to ours!”
I believe you have just created the ultimate COVID-19 origin story.
As Robert Zubrin pointed out in his 3-part interview with Felix (mostly about Musk) last year, if we find life on Mars that’s basically identical to earthly life, plus there’s no fossil record of such life during the long ages preceding the first human expeditions, then it’ll be obvious that we brought it.
I used to not think much of panspermia. It always seemed like they couldn’t figure out how biogenesis occurred, so they kicked the can down the road to another place.
A book “A new history of life” by Peter Ward (I believe) and someone else, had some interesting points about life possibly starting on Mars. It involved lower temperatures, and a mechanism to synthesize a critical chemical; both of which would have been hard to find on the Earth of that era. Mars’s lower gravity also meant that things could get blasted off planet without getting sterilized as the late heavy bombardment waned.
So maybe, if something’s still alive on Mars- it could be very similar to Earth life. And if they did discover microbes similar to any type of Earth’s, how would you know where they originated? They could find some odd form of Archaea that could live in both places.
To repeat Zubrin’s point: look for fossils from earlier times on Mars. If the present life we find there is native, there are bound to be such.
There is a lot of debate about ancient microscopic Earth fossils, it’s very difficult to say what exactly they are, how old they are, and even sometimes if they are life.
I think ancient Mars fossils would show life existed there in the past, but not necessarily that any extant life found originated there. Especially if we find something that looks un-alien.
Max-
Good stuff!
—–
“A Princess of Mars” (1912)
Edgar Rice Burroughs
Chapter XX: “Inside the Atmosphere Factory”
https://www.erbzine.com/craft/m1pm.html#Chapter%20XX
Keep in mind the “chemical index of alteration” is based on earth processes. They may be correct, but I suspect much more data will be required until we can ‘calibrate’ such an index for Martian conditions.