El Dorado

The Spirit rover has just arrived at the large expanse of dark sands of El Dorado on the southeastern side of Husband Hill. The rippling, textured dunes look like waves, almost surreal.

Image credit: NASA/JPL

Phyllosilicates and Early Mars

The OMEGA team (ESA) has published a new article on the phyllosilicates / clay minerals found by Mars Express in Nature. Abstract and article here.

Meridiani Debate Continued

More articles covering the on-going debate, from ASU, Geotimes and Astrobiology Magazine.

Methane Problems

A new methane article by Vladimir Krasnopolsky from the Catholic University of America has been published in Icarus. The last sentence of the abstract is interesting and sure to be controversial (as usual):

"The overall results strengthen the biogenic origin of martian methane and its low variability."

Abstract and article here.

The Great Meridiani Debate

Acidic water, volcanoes or impacts? The debate is on! Updates regarding this today from Nature, Nature, CU, New Scientist and Space.com.

The Space.com article includes comments from Squyres (who it says was not contacted prior to the article being published):

"Squyres said a deeper understanding of the situation came when Opportunity examined Endurance Crater, where observations were made of 25 vertical feet of rock outcrops. Those results were published just a month ago, after the two Nature papers had been submitted. Knauth, McCollom and Hynek "hadn't seen that stuff when they wrote their papers," Squyres said. The nature of the layering and grain sizes deeper inside Endurance Crater "is absolutely incompatible with a volcanic or impact origin," Squyres said. It is "completely compatible" with the idea of windblown material, and the upper meter or so "shows evidence for deposition of water. The chemistry varies with depth in a way that requires that subsurface liquid water interacted with the rocks after they were deposited." Squyres emphasized that his team has always thought the water was mostly underground, occasionally creating small surface lakes that evaporated quickly. Squyres also stressed that nobody has done anything other than good science with the data available. "It's always good to have alternative hypotheses," he said. "In the end, the best ideas win. It forces everybody to go back and sharpen their arguments. All of this is a good thing."

The MER team's own comprehensive findings have been published in several articles in
Earth and Planetary Science Letters. As per the usual process in peer-reviewed journals, the articles must be purchased, although the abstracts are available for free. One of the articles is available for free however, 'An Astrobiological Perspective on Meridiani Planum' (PDF).

Note: This is sure to be a long-running and intense debate. Also, regardless though of whether the CU team are correct or not regarding the acidic sulphate deposits in these scenarios, the earlier clay deposits found by Mars Express are still another matter...

More on Martian Water and Clays

Additional evidence for previous non-acidic liquid water and the resulting phyllosilicates / clay minerals continues to come in, from both Mars Express in orbit and Spirit on the ground.

More information here and here.

Dry Ice Storms at Martian Poles?

New evidence suggests that large storms, similar to thunderstorms on Earth, but made of dry ice (carbon dioxide crystals) may form frequently over Mars' poles.

Special Effects Images: Opportunity

More great special effects images, this time from Opportunity.

Image credit: NASA/JPL

Update - UA Researchers Show Liquid Water Can Exist on Mars' Surface

The AGU abstract for the previously posted report on brines being able to exist on the Martian surface is now online.

Glacial Microbes and Martian Methane

Living, methane-producing microbes have been discovered for the first time deep underground in glacial ice in Greenland. The finding may provide clues as to the possible origin of at least some of Mars' methane.

More information here and here.

Auroras on Mars

Hundreds of auroras, similar to Earth's (aka the northern lights), have been seen in Mars' atmosphere by Mars Global Surveyor and Mars Express.

More on Buried Craters, Ice and Clays

Another good report from Geotimes concerning the buried crater, ice deposits and clay minerals found by Mars Express.

More information here.

Two Kinds of Martian Water

Jean-Pierre Bibring, principal investigator for Omega on Mars Express, sums it up nicely in this new BBC News article:

"Crucially, these are not the sulphate minerals seen by the US Mars rovers but a different class of hydrated minerals, known as phyllosilicates - more familiarly called clay minerals. In Bibring's opinion, it is far more likely that ExoMars will find evidence of life laid down in these rocks than if it were to look at the sulphates documented by the US vehicles. "Phyllosilicates trace the moment when liquid water was perennial and persistent - something not necessary to make sulphates. To make clay minerals requires long-standing bodies of water and [for life to form] you need that - at least with the experience we have from Earth." This puts Marwth Vallis and other clay locations - such as Arabia Terra, Terra Meridiani, Syrtis Major, and Nili Fossae - high on the list of possible ExoMars targets. And it pushes down the list the sulphate locations such Meridiani Planum and Gusev Crater currently being inspected by the US Mars rovers. Their sulphates were formed in acidic conditions - a challenging environment for any lifeform to evolve.

It is a point echoed last week by US rover scientist Dr Andrew Knoll of Harvard University. He observed: "Life that had evolved in other places or earlier times on Mars, if any did, might adapt to Meridiani conditions, but the kind of chemical reactions we think were important to giving rise to life on Earth simply could not have happened at Meridiani." Jean-Pierre Bibring says the instruments on ExoMars should be equipped to look for large carbon molecules in amongst the clays of Marwth Vallis as a possible signature of past life."

Note: Re my contention about making the critical distinction between the clay minerals and sulphates, both part of Mars' water story, I'm glad to see at least BBC News and a handful of others are showing both sides of the equation. Daily Planet on Discovery Channel here in Canada ran a piece yesterday on the new ice findings by Mars Express, which was good (and I like DP), but no mention yet of the clay mineral findings.

The Complex History of Water on Mars - Rover Update, Part 2

Part two of Steve Squyres' podcast rover update is now online! Podcast here and transcript here.

The Complex History of Water on Mars - Rover Update, Part 1

In part one of a two-part podcast rover update, Steve Squyres outlines the lastest updated findings by Opportunity regarding past water at Meridiani, how the conditions were highly salty and acidic, with a fluctuating groundwater table which periodically came to the surface but was primarily underground. Podcast here and transcript here.

More information here.

Note: It is important, imperative even, to view Opportunity's findings in context of the new ones from Mars Express this week. Yes, the geological age shown by Opportunity was salty and acidic (re the sulphate bedrock), but it also seems that, in the previous time period, as shown by Mars Express (including in Meridiani) and outlined by ESA, the water was non or less acidic and stably present (as well as abundant), whether still mostly as groundwater and aquifers or ? Something happened, as the ESA team put it, to cause the water to become more acidic later on, some kind of global climatic change.

The phyllosilicates / clay minerals found by Mars Express are one of the key findings of any mission. A lot of the media and science media coverage this week so far covers the new MER findings, but not the Mars Express findings (or often much briefer), re the phyllosilicates in particular.

Hopefully Opportunity can look at deeper layers such as in Victoria crater; people may now assume that the sulphates represent the entire history here, but if the Mars Express team is correct, then it is only one part of a longer and more varied story.

A Pile 'O Cobbles

An interesting looking mound of dark material, seemingly more of the dark "cobbles" all over this area around Erebus crater, as seen in this pancam view just taken by Opportunity on sol 658. Detailed results of analysis of some of the cobbles done previously is still pending, altough Steve Squyres previously mentioned back on August 17 that they are Martian objects of unique composition (not meteorite fragments as per one hypothesis). So what are they, and why are these ones all piled up like that?

Image credit: NASA/JPL