Image of a channel between putative lakes from the Context Camera (CTX) onboard NASA’s Mars Reconnaissance Orbiter (MRO).
Modern Mars is frigid and dry, but new evidence suggests that in some locations on the equator there may have been lakes as recently as 3 billion years ago.
Researchers from Imperial College London and University College London studied images from the context camera (CTX) on NASA’s Mars Reconnaissance Orbiter (MRO) of several flat-floored depressions in Ares Vallis, near the martian equator.
Previously these depressions were thought to be due to the collapse of the surface as ground ice sublimated directly to gas, but CTX images reveal small channels connecting the depressions, suggesting that water flowed between them. Similar features can be found in “thermokarst” landscapes in Alaska and elsewhere, where permafrost is melting to create lakes and streams.
To determine the age of the features, the scientists counted more than 35,000 craters in the area. Assuming that the current surface was continuously exposed to impacts from space since it was emplaced, the density of craters points to an age of roughly three billion years.
Previously, it was thought that Mars dried up between 4 and 3.8 billion years ago, but if the cratering age from this study is correct, these new results suggest at least brief periods later in martian history when lakes could exist.
The lead author, Dr Nicholas Warner, from the Department of Earth Science and Engineering at Imperial College London, said: “Most of the research on Mars has focused on its early history and the recent past. Scientists had largely overlooked the Hesperian Epoch as it was thought that Mars was then a frozen wasteland. Excitingly, our study now shows that this middle period in Mars’ history was much more dynamic than we previously thought.”
It is not clear how long-lived the lakes were, but Warner and colleagues suggest that they may have served as oases for life in an otherwise inhospitable world. They also suggest that these lakes would be an interesting landing site for future robotic missions.
What’s the next step? The researchers plan to study other equatorial areas, including the mouth of Ares Vallis and Chryse Planitia to see how widespread the putative lakes were.
So, um, do these potentially “long-lived” lakes and perhaps open flowing waters have implications for atmospheric models?
I assume the Hesperian epoch would remain, as it is “marked by the formation of extensive lava plains” and the Noachian is defined (?) by “many large impact craters” [Wikipedia]. The mineralogical Siderikan epoch may or may not move over a bit, from 3.5 Ga to 3, depending on atmosphere conditions. (“With the end of volcanism and the absence of liquid water, the most notable geological process has been the oxidation of the iron-rich rocks … “.)
But if there were life, if only dragged up into ice-covered waters that remained under low pressure by dust covers as ice persist over time yet today on Mars, and at times transported under openly (?) to other waters, it may be that our then life-bearing seas looked upon other life-bearing waters. Those were times to live in!
Eventually I think we will find that during the most extreme planetary dust storms on Mars, suspended particles act as abrasive elements causing continued erosion on the surface. The suspended particulates, in a fluidic state, then RESEMBLES water erosion.
Alternately, we might find that during planetary dust storms, surface temperatures rise high enough for liquid water (albeit salt saturated) to form and ALSO cause some of the observed erosion.
Planetary dust storms occur during Mars closest approach to Sol and may also occur due to volcanic eruption, meteor impact or even tribo electric bombardment associated with CME’s. Should it be that some or all of these factors coincide, then how high might surface temperatures go?
Another factor to consider would be Mars polar inclination shifting as it processes through ‘recent’ geologic time.
Torbjorn Larsson OM
Try: Topic C in this abstract: http://www.case.edu/cse/eche/ESA2008_Proceedings/F2.pdf
Or: http://www.iop.org/EJ/article/1367-2630/5/1/370/nj3170.html
Or: http://physics.ksc.nasa.gov/Publications/Results%20of%20Mission-Ready%20Triboelectric%20Device-Final.pdf
(This for a device to determine charge state on the Martian surface)
Or: http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3122.pdf
Given the extremely low temperatures, pressures and atmospheric moisture content combined with dust particle size and lower gravity, tribo electric forces may play a far greater role in Martian weather than has been previously assumed?
Your statement, “under general conditions abrasion tends to flatten out topography” – Consider what fluids/water does to earthly terrains. Yes there are flattened areas where water has pooled AND then there are places like the Grand Canyon, where obviously gravity and elevation plays a role in the effects of abrasive fluids.
The transference of electrical charge from a CME to ground are obvious when observing melted power lines and exploded transformers here on Earth. Perhaps those same charges are not as evident on Mars? Then again, as the rover’s have spun their wheels into alternately charged substrates, charges have built up on their frames causing motors to drop out and memory circuits to be interrupted. That is to say, alternating charge within surface dust deposits are a distinct possibility dependent upon electric current present at the time of deposition.
Tribo electric stimulation by injection of CME energies are an artifact of particulate levitation via field interactions.
Aqua, I’m disappointed, you don’t live up to your name. 😉
But we can test your dusty hypothesis. Meridiani Planum, that Opportunity travels on, has been so scoured by abrasion to loose some ~ 1 km of material, or so Wikipedia claims. Does it look like fluvial features? No, it is flat.
Not surprisingly, as under general conditions abrasion tends to flatten out topography. [Funny how friction ‘dissipates’ entropy from macroscale to microscale, always.] Dust abrasion fails a test.
But we need to be fair and test the water hypothesis too. We now know that water has been influential in forming Mars, both from spectroscopic analysis of minerals from orbit and from direct finds from Opportunity, Spirit and Phoenix. Fluvial formation passes at least one test.
Btw, your alternative ways of triggering dust storms doesn’t trigger any memories. 😀 Are there evidence for those?
As for CMEs, I doubt ejection sputtering would give triboelectricity. As preferentially neutrals are sputtered. (And there are plenty of electrons to displace charge with anyway. Coronal mass ejections are likely neutral on average, no reason they would loose presumed ambipolarity, so no charge addition there either.) AFAIU triboelectricity occur when larger chunk of materials loose electrons from frictional processes.
Nor would a CME reach Mars surface what I know of, the induced ionospheric pause is way up in the atmospheric column. (But I could be mistaken, this isn’t my cup of tea!)
Aqua, I have no idea what you are talking about. Nothing makes sense in your scientific explanation.
Smells like pseudoscience.
Oops.. I forgot CO2