A Martian river canyon?
Click for full image.
Today’s cool image highlights the biggest mystery of Mars that has baffled scientists since the first good pictures of its surface were taken in the early 1970s by the Mariner 9 orbiter. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a very small segment of the 400-mile-long meandering canyon on Mars called Nigal Vallis. From the Wikipedia page:
The western half of Nirgal Vallis is a branched system, but the eastern half is a tightly sinuous, deeply entrenched valley. Nirgal Vallis ends at Uzboi Vallis. Tributaries are very short and end in steep-walled valley heads, often called “amphitheater-headed valleys.”
We can see one of those short tributaries on the image’s left edge. The overview maps below provide a wider view of this entire canyon.
The white rectangle on the overview map to the right marks the area covered by today’s full image. The red rectangle south of Valles Marineris and north of Argyre Basin on the global map below shows the area covered by the overview map to the right.
What formed this canyon? Our Earth-eyes immediately assume that water carved it, and based on Earth geology, scientists have theorized that water did the carving in a catastrophic flood.
Water from Nirgal Vallis contributed to a great flood that went through the rim of Holden Crater [to the east and downstream from this picture] and helped form a lake in the crater. It’s estimated that Nirgal Vallis had a discharge of 4800 cubic meters/second. Water from Nirgal Vallis was inbounded in Uzboi Vallis because the rim of Holden Crater blocked the flow. At a certain point the stored water broke through the rim of Holden and created a lake 200–250 m deep. Water with a depth of at least 50 m entered Holden at a rate that 5-10 times the discharge of the Mississippi River. Terraces and the presence of large rocks (tens of meters across) support these high discharge rates.
The problem with this theory of a catastrophic flood is that no scientist has yet produced a good model that would allow liquid water to flow on Mars, now or ever in the past. The visible geological evidence says there was a flood of water, but the conditions on Mars say such liquid water could never have flowed. The Martian atmosphere was always either too cold or thin.
Note also the location of Nirgal Vallis on the global map:
This long canyon is located in the dry equatorial regions inside 30 degrees latitude, as are many of the other canyons that suggest catastrophic floods (Valles Marineris and Kasei Valles). Was that equatorial region of Mars once very wet? If so, where did all of its water come from? Some scientists theorize that the heat of the volcanoes to the west released the water from underground aquifers, but that is a theory. And if this water once existed, where did it go? Was it transported to higher latitudes during the many climate cycles of Mars, caused by shifts of its obliquity, or rotational tilt? Or was it lost to space over time because Mars’ weak gravity could not hold it?
Questions, questions, questions. The biggest geological mystery of Mars is that we presently have only scratched the surface of its complex history. We have a lot of tantalizing data, but none of it is sufficient to answer some of the most basic questions.
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
Click for full image.
Today’s cool image highlights the biggest mystery of Mars that has baffled scientists since the first good pictures of its surface were taken in the early 1970s by the Mariner 9 orbiter. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a very small segment of the 400-mile-long meandering canyon on Mars called Nigal Vallis. From the Wikipedia page:
The western half of Nirgal Vallis is a branched system, but the eastern half is a tightly sinuous, deeply entrenched valley. Nirgal Vallis ends at Uzboi Vallis. Tributaries are very short and end in steep-walled valley heads, often called “amphitheater-headed valleys.”
We can see one of those short tributaries on the image’s left edge. The overview maps below provide a wider view of this entire canyon.
The white rectangle on the overview map to the right marks the area covered by today’s full image. The red rectangle south of Valles Marineris and north of Argyre Basin on the global map below shows the area covered by the overview map to the right.
What formed this canyon? Our Earth-eyes immediately assume that water carved it, and based on Earth geology, scientists have theorized that water did the carving in a catastrophic flood.
Water from Nirgal Vallis contributed to a great flood that went through the rim of Holden Crater [to the east and downstream from this picture] and helped form a lake in the crater. It’s estimated that Nirgal Vallis had a discharge of 4800 cubic meters/second. Water from Nirgal Vallis was inbounded in Uzboi Vallis because the rim of Holden Crater blocked the flow. At a certain point the stored water broke through the rim of Holden and created a lake 200–250 m deep. Water with a depth of at least 50 m entered Holden at a rate that 5-10 times the discharge of the Mississippi River. Terraces and the presence of large rocks (tens of meters across) support these high discharge rates.
The problem with this theory of a catastrophic flood is that no scientist has yet produced a good model that would allow liquid water to flow on Mars, now or ever in the past. The visible geological evidence says there was a flood of water, but the conditions on Mars say such liquid water could never have flowed. The Martian atmosphere was always either too cold or thin.
Note also the location of Nirgal Vallis on the global map:
This long canyon is located in the dry equatorial regions inside 30 degrees latitude, as are many of the other canyons that suggest catastrophic floods (Valles Marineris and Kasei Valles). Was that equatorial region of Mars once very wet? If so, where did all of its water come from? Some scientists theorize that the heat of the volcanoes to the west released the water from underground aquifers, but that is a theory. And if this water once existed, where did it go? Was it transported to higher latitudes during the many climate cycles of Mars, caused by shifts of its obliquity, or rotational tilt? Or was it lost to space over time because Mars’ weak gravity could not hold it?
Questions, questions, questions. The biggest geological mystery of Mars is that we presently have only scratched the surface of its complex history. We have a lot of tantalizing data, but none of it is sufficient to answer some of the most basic questions.
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
A lot of the craters outside the river bed also have a teardrop shaped pattern behind them, all aligned in the same direction. As far as where can the water go, I’ve thought about planetary geology a bit over the years. When a planet first forms, it is really hot and most water should vaporize, outgas and wind up in the proto atmosphere. As the planet’s surface cools, the water will condense and form a layer on top. Over time, I would expect a lot of this water to be absorbed back down into the interior rocks like a giant sponge. The rest lost to space in the case of Mars as it randomly sublimates from the frozen surface. I would expect there to be a lot of water containing rocks deep into the Martian surface.
Ryan Lawson: Entertaining theory about planetary formation. Please tell me exactly which planet under what conditions this might apply? Mars? Venus? Earth? Ganymede? Some exoplanets? I also assume you have gathered in great detail the exact conditions that existed during formation, right?
Kansas Joe McCoy and Memphis Minnie
“When the Levee Breaks” (1929)
https://youtu.be/swhEa8vuP6U
3:14
@Robert
This is just an idea that comes from work experience in two fields, coal power industry and polymer industry. Both materials are moisture dependent for processing, as in we need them dry or things don’t work out so well. Polymers, in many cases, will rapidly reabsorb moisture so handling is a time critical issue. A lump of coal absorbs slower than powdered coal (surface area dependent). Rocks should generally behave the same way over a longer timeframe ie outgas water vapor when heated, absorb water when cooled. There would also be a maximum saturation point for different minerals. We see on earth volcanoes releasing a lot of water vapor. I imagine some of that remained trapped from planetary formation, but more of it seems to come from shallow volcanoes that are continental crust material rather than deep volcanoes. Deep volcanoes tend to ooze while shallow volcanoes tend to explode from excess gases.
So I would expect this behavior to apply to any large rocky body to some degree unless it is completely deep frozen where water might accumulate on the surface through accretion and then just stay there or occasionally sublimate away.
I have no answers as to why there’s huge river channels that flow nowhere.
Like a puzzle, I keep reminding myself the variables that govern Mars. 1/3 the gravity of earth, that makes it fluffy. Literally has porous voids in the crust of the planet that would not be compressed as dense as earth.
When the enormous cloud of gas from a supernova came up the local chimney and engulfed our solar system for a few hundred years… it would have added a considerable amount of ocean and nitrogen atmosphere to earth (also causing the Ice Age as the sun went dark)
At the same time, adding ices (water, ammonia, methane, and every element that was contained in the stellar remanent) freezing to the surface of moons in the outer solar system, like Europa. (Preserved frozen history of our solar system waiting for core samples to be performed)
Mars is also cold.
Was it once covered with ice in the same event? Is the ice caps all that’s left over of a once ice covered world? Are the riverbeds that go nowhere actually once filled with water compressing the soil underneath like one long lake as the water sunk into the soil or evaporated away in the low air pressure?
I do not know, but the air around Mars is being blown away by the solar wind… It is not a coincidence that the air pressure is exactly the same amount where water boils in low temperatures. As the air pressure goes down, water will boil and bring the pressure back up to maintain the balance. Thus, the air pressure remains constant as it slowly replenished as it’s blown away. (There is twice as much atmosphere frozen to the pole’s then there is surrounding Mars)
I am thinking it is likely that’s a surface of Mars is saturated with liquid, there’s much evidence frozen in time of glaciers, of possible mud volcanoes (especially north east of Helena basin), and meteor impacts that went splat. (The equator, being the warmest, will boil off first, making it the driest)
Chemical reactions will be different because the lack of oxygen. The red soil has absorbed everything available. The pH of the soil will be unusual in the extreme, full of peroxide and ionized particles. Colonists on the surface will need to wash off or decontaminate before entering any livable space.