Despite a spectacularly successful series of measurements on and above the surface of Mars, European and American scientists are as baffled as ever about the fate of liquid water on the Red Planet, writes Leo Enright
Indeed, a month after these latest international investigations began, the search for liquid water on Mars appears to have taken one step forward, then two large steps back as the experts struggle to make sense of a treasure-trove of pictures and measurements from what remains a hostile and seemingly bone-dry world.
Expectations were raised last month when Europe's triumphant Mars Express team announced that their spaceship - safely in orbit - had sent back stunning pictures and a measurement of water molecules at the South Pole of Mars.
This last finding was not a surprise, since it has been known for decades that water is frozen at the Martian poles (it would have been a sensation if it were not detected), however European Space Agency officials considered the detection an important milestone on the way to mapping water abundances across the entire planet to depths of many metres.
The announcement was also important for the agency after media attention concentrated on the loss of a small British-build lander called Beagle-2, which had been added to the main European mission very late in the project's planning. Senior American space agency officials were privately astonished at the tone of European media reporting around an unsurprising confirmation of frozen water at Mars, however they emphasised the enormous power of the Mars Express suite of scientific instruments to contribute important new information in the months ahead.
Meanwhile, back on Mars, the planet continued to throw up surprises. Almost two weeks after arriving on Mars, the US Mars Exploration Rover called Spirit began its main mission as the first robotic field geologist ever to work on the surface of another planet. It started to bring to bear a powerful complement of US and European instruments to analyse the soil and rocks around its landing site in the middle of Gusev Crater, a basin the size of Munster that many scientists believe may once have contained a deep lake.
The first target of Spirit's attention was a small rock the size of a rugby ball which scientists had nicknamed Adirondack. On minute examination, Adirondack proved to be exactly what it seemed: a rock.
"If I were to hit it with my geologist's hammer," said Dr Ray Arvidson of Washington University in St Louis, "my hammer would ring like a bell and my arm would be sore for a week."
Adirondack appears to be indistinguishable from countless volcanic rocks that are to be found across Ireland and around the world. It is a basalt.
"That rock could be an Antrim basalt," said geologist Dr Paul Lyle at the University of Ulster's Jordanstown campus. "The mineral analysis done by the rover shows it to be similar to the basalts of the Giant's Causeway and of the Cavehill Mountain overlooking Belfast."
The bad news for water-seeking scientists is that basalt does not form in water.
"It is probably the most common igneous (volcanic) rock on Earth," explained Dr Lyle, who recently published a guide to North of Ireland geology that includes 10 excursions across Ulster from Donegal to Co Down.
"The only connection between basalt and water is that extensive basalt eruptions would also be sending out large amounts of water vapour. The question is where that water vapour went on Mars."
On the other side of the planet Mars, at the second Mars Exploration rover landing site, Opportunity is completing its second week on the surface but has only begun its detailed analysis. Yet already it has presented scientists with a baffling series of apparently contradictory findings.
Opportunity has landed inside a 22-meter-wide crater in the heart of a region of Mars that has offered tantalising hints of a geology that might have been driven by water.
In every direction, its instruments see the telltale signs of rusty iron - a crystalline mineral called hematite that, like basalt, is commonplace in Ireland and around the world.
Scientists speculate that the hematite might have formed during an era when water flowed freely on Mars - but the findings of their robot geologist have so far confounded them.
Instead of finding evidence for water, Opportunity's German-build rock analyser has found basalt again. This time the volcanic rock is in the form of finely ground sand, and close-up pictures beamed back this week show a surface like many beaches in Ireland.
Microscopic glass beads in the Martian sand only serve to confirm a volcanic origin, since experts think they may have formed in a red-hot fountain of lava spewed onto the surface eons ago.
It is all a very long way from images of Mars as an ancient Elysium that might once have been a land of flowing rivers the length of Europe and lakes the size of Munster.
But it is early days yet. This year's US and European exploration of Mars has only just begun. Dr Steven Squires of Cornell University, who is principal scientist for the Mars rovers, said the latest evidence relates to only two microscopic patches of ground on a planet with the same land area as Earth
"We haven't given up," he said. "Remember that we only have to find one rock!"