Thanks to Doug for pointing out this LPSC update:

Mars Express: Probing the Depths
ftp://ftp.lpi.usra.edu/pub/outgoing/lpsc2006/full102.pdf

Another good article:

Martian Ice: Wide and Deep
http://skyandtelescope.com/news/article_1695_1.asp

"More recently, a shift in Mars Express's orbit has allowed MARSIS to probe the planet's south pole. There the buried ice extends down to 3½ kilometers (2 miles) under the cap in some places. Water ice appears quite transparent at radar wavelengths, and the ease with which MARSIS's signal penetrates the polar terrain suggests that the ice is relatively pure. "There's at most only a few percent of impurities," team coleader Jeffrey Plaut (Jet Propulsion Laboratory) told planetary scientists meeting in Houston this week.

Potentially more exciting is MARSIS's discovery that huge quantities of ice may underlie a large plain beyond the southern cap called Dorsa Argentea, which covers 3 million square kilometers, about 2% of the planet's surface. Geologists originally thought Dorsa Argentea was a volcanic plain, but James W. Head III (Brown University) and others recently realized that a broad ice sheet must lie beneath its dusty surface. Plaut reported that MARSIS has found multiple layers stacked beneath Dorsa Argentea to depths of up to 500 meters — and if they’re all ice, they represent a reservoir large enough to cover the entire planet with water to a depth of about 10 meters (30 feet)."

While that's great news, I think the comment about covering the whole planet to a depth of 10 meters is a bit misleading. They just took the 500m depth of the deposit and multiplied it by the 2% of the Martian surface that it covers - that gives 10m. If you melted the whole Dorsa Argentea deposit, taking the actual relief of the Martian surface into account, you'd wind up with something like image #9 on Magnus Lundstedt's Water Oceans on Mars page.

Bart

Also:

Big New Reservoir of Water Ice Suspected Under Mars
http://www.newscientistspace.com/article/d...under-mars.html

Serioius props to Magnus for having a relevant model to put some PR science to the test at just the right time.
Also excellent point Bart by the way - excellent use of the material on hand.

Regardless of how much of the surface may be theoretically covered by any melted ice, there is apparently a lot of subsurface ice, both "wide and deep" as New Scientist puts it, a very significant finding... I look forward to MRO's studies.

'Hourglass'-shaped crater - new video and perspectives

This video and accompanying images, taken by the High Resolution Stereo Camera
(HRSC) on board ESA's Mars Express spacecraft, show an unusual flow deposit on
the floors of two adjacent impact craters in the eastern Hellas Planitia region,
indicating possible glacial processes.

Full story at:

http://www.esa.int/SPECIALS/Mars_Express/SEM618NVGJE_0.html

The business about there being lots of ice under Dorsa Argentea is something important that they really did manage to keep under wraps until the actual LPSC conference -- there's not a whisper about it in any of the abstracts.

Mariner 7 saw a ragged semi-circular scarp in the south Polar region that I believe corresponds to a degraded and mostly buried impact basin. MOLA data shows it rather well. I wonder if the deepest 3.5 km thicknesses inferred for the dusty ice deposits penetrated by MARSIS are in layered deposits superimposed on the depressed region corresponding to this basin?

I haven't seen this mentioned on the forum yet - there was very interresting MARSIS lecture by Dr. Jeffrey Plaut, co-PI of MARSIS. link

I just received the new ESA Bulletin and it is mentioned that "The MARSIS radar has made significant discoveries during the last nighttime season; they will be published shortly"
Let's hope we'll be on the front-row when the discoveries are published. I'm not aware that we have an ESA equivalent of Dr. Stern in our midst but it is never too late of course
Peter

Time has passed... we now write 16th Oct as the day when a new trickle of info is published:

http://www.esa.int/SPECIALS/Mars_Express/SEMADOV74TE_0.html

So there is plenty of water for the heated swimming pools when we colonise the place.

I can appreciate the artistic enhancement that is added in many of these Mars Express images, but that image of Vastitas Borealis is just plain weird looking. Does anyone know if this is an overlay of a MARSIS image? Or just some over-zealous image retouching?

http://www.esa.int/SPECIALS/Mars_Express/SEMADOV74TE_0.html

News from OMEGA:
Did I read "geyser"?...

Yes, you did...now let's see ME and/or MRO prove it!

It's actually Deuteronilus Mensae, not Vasitas Borealis. It is is a very nice oblique 3D rendering of a HRSC imaging showing plastic material flowing out of a circular degression away from the viewing point and then to the left. Lots of features suggest ice-like behaviour - an apparent bergsrund where the material laps up against the edge of the circular feature, apparent crevasses, media flow ridges, and zones of stagnation (which even have scattered craters, suggesting that in some areas the plastic material is quite old).

So it is has nothing to do with MARSIS, there is no overlay, and there certainly has not been any retouching.

Jon

I think you and Dan are talking at cross purposes. You're describing Deutronilus Mensae but he seems to be referring to the fourth image on that page showing Vasitas Borealis, which has a large circle of blueish white material, identified as ice, in the center of the crater.

In any event, I agree with you that there isn't any retouching. The colors look artificial but Mars is stranger than we expect.

Steve

Ah, silly me. That was the only strange looking image (for me) on the page so I assumed that was the one meant.

The fourth image is perhaps the most famous, popular, and beautiful HRSC image yet. It shows a dome like deposit of white ice on an unnamed crater floor. The feature has been observed by MOC also, although none of those images have quite the same aesthetic appeal. It is perhaps the southernmost surface exposure of water ice in the Martian north polar region. I love the frost on the crater rim as well. No retouching, and I think the colour is great.

Jon

Some information about what MARSIS is doing and not doing.

"And liquid water? Do we have answers to where it might be?

MARSIS data inversion on the south pole has found compatibility with water dielectric constant. According to the geologist opinion in many areas at medium latitude could be possible to find subsurface water traces."


Exciting stuff! I wonder what depth are the medium latitude water deposits expected?

142 days until phoenix launches.... and counting. It'll be nice to put some "ground truth" to MARSIS results on the poles.

More on the ice deposits at the Southern Hemisphere..
I read that in the next edition of Science a team of German scientist will report on the presence of a massive 1.6 million cubic km of almost pure water ice at the South pole of Mars. If that lot melts, Mars would be covered in 11 m water.
Anyone with access to Science who can add to this rather brief announcement?

JPL has a press release up on its site: "Mars' South Pole Ice Deep and Wide".

It wasn't clear to me on a hasty comparison with last year's announcements how much of this is really news.

It looks as though the hypothetical depth if the ice was melted rendered liquid has been increased from ten feet to eleven feet.

TTT

Edit: As subsequent posts pointed out, that should be from ten to eleven meters.

Last year's announcement included speculation that if held true, then melting would cover the planet 10 meters in water. This new announcement is very different in that it is not only confirmation of what they once thought MIGHT be true, but also additional ice has now been found and confirmed.

Then it was speculation on quantity; now it is fact.

This is just ice in the South Polar area. I wonder how much additional ice is at the North Pole.

ESA's news release.

With so much water now positively identified it may be time to change our mindset about Mars.
Where the research started tentatively with "Follow the Water" it seems appropriate to start thinking in terms of "Mars Water Missions".
Both EU and USA are developing new Flagship missions and, with all respect, why travel to Jupiter & beyond for water when it is relatively speaking at our doorstep on Mars?

Not so long ago there was also a mention of Methane being detected on Mars. Whilst this may still be a "whiff" in scientific terms, i.e. not so firm as this confirmation of the presence of water, I would say that the combination of these two gives a very clear steer if not an overwhelming case for developing Detecting Life (or LIfe-artifact) studies on Mars.

Or on the right path aren't we?...

You're joking of course.(?) Studying the global sea of Europa is a whole nuther ballgame.

One of the things this gets me thinking about is what would have happened, historically, when a major impact hit one of these polar ice sheets. Many tens of km of water ice could be vaporized, and H2O ice is on the order of 100,000 times denser than the current martian atmosphere. Some CO2 would be released as well. It seems like a big impact could have doubled the martian atmosphere whereas a truly colossal basin-creating impact could create a martian atmosphere more comparable to Earth's in extent. That H2O would probably end up deposited globally as an ice layer of cm (?), then sublimate away in the equatorial regions and gradually end up poleward. This would be create a limited catastrophic water cycle that may have "turned" just a few times in martian history.

All this great news about the ice deposits is a great testament to the operations people who got MARSIS working. The ESA web site details some of the long delays in getting those weird MARSIS booms deployed, and the problems they had when they finally did it. The good news took many frustrating years of patience.

Let's hope this is a big help to the Phoenix team. I hope their search starts as well as this European mission did:
http://www.youtube.com/watch?v=ryd9udbh6X8

-don

Although this is great news with significant implications, MARSIS still has a lot of work to do. Since it has been determined that only about 4% of the original water on Mars could have been lost to space, that leaves 95% missing. This particular discovery only finds about 10% of that missing water. Let's assume that the North Polar region has a similar amount of ice locked up underneath. That means 75% of the original water on Mars is still missing. Perhaps the reservoirs found closer to the equator make up a few percentages. Now that means 70% of the water is missing. Where is it?

My guess is that there are additional HUGE reservoirs underground over a variety of areas on Mars. MARSIS should be able to find some of them. That means it still needs to do a survey over the entire planet. With the core of Mars being much cooler than Earth, water could easily have penetrated underground MUCH deeper. The question is: how deep?

Water that's essentially frozen, or combined as hydrate in rocks like the Meridiani and Gusev evaporite and salt deposits is probably widely distributed on Mars, but harder than <deleted> to detect directly. One of the things that Marsis is looking for but I suspect is not seeing is a transition between the cryo-lithosphere <frozen megaregolith> and a mid-crustal water-table, kept warm by geo-<aero->thermal heat flow. I think the overall suspician pre-mission is that it wouild be too deep and too attenuated by iron-rich rock absorption of the radiowaves to be detected.

Future missions might carry a super-Marsis payload... more complex antennas giving a more directional vertical beam, much more radiated power.. more antenna/receiver sensitivity.... Not trivial. Longer wavelengths might help probe deeper., but at the expense of horiffically long antenna, difficulty with even the nighttime atmosphere, and lower vertical resolution.

Would a global network of seismometers be able to detect a Martian hydrosphere? (And how much would it cost?)

I'm sure a careful search of the data would eventually reveal one if it were present. A network of seismometers is absolutely necessary on Mars. I'm sure that it will happen within the next 30 years, if not much sooner.

Finding a Martian hydrosphere is important, but would be one of the least interesting things that researchers would be looking for. The internal structure of Mars is likely to be very different than Earth's. And industry would be extremely interested in commercially viable resources that they could easily exploit. Seisometers could reveal an incredible amount that is hidden underneath the surface of Mars. Much of the detailed work might have to wait for actual human presence; but if it can be done robotically sooner, then the effort would be well worth it.

Astrobiology magazine has an informative interview with Jeff Plaut, the co-Principal investigator of the MARSIS radar instrument.