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Ancient river systems on Mars seen in unparalleled detail:
A high-resolution satellite has captured detailed images of a rocky Martian cliff face revealing that it was formed by rivers more than 3.7 billion years ago. That is roughly the same time that life was starting to begin on Earth.
[...] The team examined images [...] taken by NASA's High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter spacecraft. The images were taken inside the enormous Hellas impact crater in the southern Martian hemisphere, one of the largest impact craters in the solar system.
A 200-metre-thick stack of layered rocks are visible within the cliff walls, shown in enough detail that Joel and his colleagues could be sure they are sedimentary rocks, formed by running water. The rivers would have continuously shifted their gullies, creating sandbanks.
Journal Reference:
Francesco Salese et al. "Sustained fluvial deposition recorded in Mars' Noachian stratigraphic record", Nature Communications (2020). DOI: 10.1038/s41467-020-15622-0
The presence of sedimentary rock indicates the long-term presence of water and boosts the chances that life evolved there.
(Score: 5, Interesting) by deimtee on Wednesday May 06 2020, @07:30PM (2 children)
Doesn't seem likely. It take high pressure to make liquid CO2, usually it just sublimes.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by PiMuNu on Thursday May 07 2020, @12:40PM (1 child)
I found a couple of references, one ancient:
https://edition.cnn.com/2000/TECH/space/08/04/white.mars/index.html [cnn.com]
and one fairly oblique:
https://www.nasa.gov/mission_pages/mars/images/pia09031.html#.XrQAmvl7mV4 [nasa.gov]
I guess the lack of stuff on the internet means that the CO2 theory has fallen away..
As a sceptic - the martian environment is, literally, alien, and so I always hesitate when we get "it looks a bit like hydrological feature on earth" becomes "it *is* hydrological feature", which is essentially the content of TFA.
(Score: 2) by deimtee on Friday May 08 2020, @11:43PM
Thinking about it, I have vague recollections of reading a theory about it. You need a layer of CO2 that gets buried by dust/sand. Later on, conditions change and the CO2 warms up enough to sublime and the resulting gas is enough to creat a fluidised bed out of the overlaying dust/sand. I don't know if it's feasible, but it would give flow-like features.
If you cough while drinking cheap red wine it really cleans out your sinuses.