A large number of the valley networks scarring the surface of Mars were carved by water melting beneath glacial ice, not by free-flowing rivers as previously thought ... The findings effectively throw cold water on the dominant “warm and wet ancient Mars” hypothesis, which postulates that rivers, rainfall and oceans once existed on the red planet. ...
The similarity between many Martian valleys and the subglacial channels on Devon Island in the Canadian Arctic motivated the authors to conduct their comparative study. ... In total, the researchers analyzed more than 10,000 Martian valleys, using a novel algorithm to infer their underlying erosion processes. ...
Valley Formation on Early Mars by Subglacial and Fluvial Erosion ~ Anna Grau Galofre, A. Mark Jellinek, Gordon R. Osinski
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
Postby BDanielMayfield » Tue Aug 04, 2020 12:49 am
This makes a great deal of sense. When considering the Faint Young Sun Problem, it has been even harder to explain abundant liquid water on early Mars than a warm early Earth. At 50% farther from the Sun than Earth, Mars only receives 1/1.5^2 or 44.4% of Earth's solar energy.
There still likely was a vast Martian ocean in its Northern hemisphere, but most of it was probably always frozen.
Bruce
Just as zero is not equal to infinity, everything coming from nothing is illogical.
BDanielMayfield wrote: ↑Tue Aug 04, 2020 12:49 am
This makes a great deal of sense. When considering the Faint Young Sun Problem, it has been even harder to explain abundant liquid water on early Mars than a warm early Earth. At 50% farther from the Sun than Earth, Mars only receives 1/1.5^2 or 44.4% of Earth's solar energy.
There still likely was a vast Martian ocean in its Northern hemisphere, but most of it was probably always frozen.
These environments would also support better survival conditions for possible ancient life on Mars. A sheet of ice would lend more protection and stability of underlying water, as well as providing shelter from solar radiation in the absence of a magnetic field—something Mars once had, but which disappeared billions of years ago.
BDanielMayfield wrote: ↑Tue Aug 04, 2020 12:49 am
This makes a great deal of sense. When considering the Faint Young Sun Problem, it has been even harder to explain abundant liquid water on early Mars than a warm early Earth. At 50% farther from the Sun than Earth, Mars only receives 1/1.5^2 or 44.4% of Earth's solar energy.
There still likely was a vast Martian ocean in its Northern hemisphere, but most of it was probably always frozen.
Exactly, Bruce. So "warm and wet Mars" probably never existed.
Hamlet: V, i
--------------------------------------------------------------------------------------
First Gravedigger: [Throws up another skull]
HAMLET: There's another: why may not that be the skull of a
lawyer? Where be his quiddities now, his quillets,
his cases, his tenures, and his tricks? why does he
suffer this rude knave now to knock him about the
sconce with a dirty shovel, and will not tell him of
his action of battery? Hum! This fellow might be
in's time a great buyer of land, with his statutes,
his recognizances, his fines, his double vouchers,
his recoveries: is this the fine of his fines, and
the recovery of his recoveries, to have his fine
pate full of fine dirt? will his vouchers vouch him
no more of his purchases, and double ones too, than
the length and breadth of a pair of indentures? The
very conveyances of his lands will hardly lie in
this box; and must the inheritor himself have no more, ha?
Where be Mars's Moraines now, his Drumlins, his Roches moutonnées, his Alluvial stratification, his Glacial deposits, his Loess deposits, his Glacial valleys, his cirques, his arêtes, his and pyramidal peaks? (The very conveyances of his lands will hardly lie in these posts.)
Does that mean that you believe that Mars really was warm and wet in the past, with exposed rivers happily burbling and surging (or just rolling along, like old man river Mississippi) over the Martian plains?
So Percival Lowell was "half right" about the rivers of Mars after all?
Ann wrote: ↑Wed Aug 05, 2020 5:10 am
Funny, Art, and a good point.
Does that mean that you believe that Mars really was warm and wet in the past, with exposed rivers happily burbling and surging (or just rolling along, like old man river Mississippi) over the Martian plains? So Percival Lowell was "half right" about the rivers of Mars after all?
