Dead and alive: slowly-dying Mars still holds surprises

BY RICHARD Ingham

CAMBRIDGE, England, (AFP) - Just half a lifetime ago, Mars was seen as Earth's sister, a future home-from-home, possibly also a rival -- the Red Planet, where loathsome aliens plotted invasions of our home.

Then, in the 1960s, came the hammer blow.

Blurry pictures sent back by early space probes depicted Mars as a terrifying orange desert, parched and dusty, clearly incapable of nurturing any life. The fourth rock from the Sun suddenly seemed to be just that: a rock.

Today, thanks to a flotilla of US and European space missions, yet another picture is emerging.

No one should be tempted to revive any of the verdant fantasies of sci-fi, for no sign has emerged yet of life on Mars, past or present. But the evidence now firmly states this: Mars is not dead, for it has plentiful reserves of water and maybe lingering sources of heat, too.

"It is partly a museum planet because of things that happened long ago, but it's also still an active planet," European Space Agency (ESA) scientist Gerhard Neukum told AFP at a major conference here on the Solar System.

"There's still water coming out in some places from aquifers underground... we see fog in low-lying areas in the morning and we see evidence of drainage when we go back to areas and look at them again and again."

Neukum this week presented the latest images sent back by Europe's Mars Express spacecraft, which he says suggest that the Red Planet has reserves of underground ice which have been melted by local hot sources and driven to the surface.

"Fan-shaped" deposits, characteristic of recent water flows, lie at the edge of Olympus Mons, the highest mountain on the planet.

Ice also encrusts the mountain's western scarp, on ridges between six and ten kilometers (3.75 to 6.2 miles) high, as well as polar regions, he said.

Most of Mars' volcanic activity petered out around 1.5 billion years ago, but carried on in some areas until as recently as two million years ago, Neukum said.

But the latest Mars Express images also show a million-square-kilometer (400,000-square-mile) flank of the Martian north pole that appears to be studded with up to 100 non-active volcanoes.

They do not appear to have signs of cratering or wind erosion that typically suggest ancient volcanoes.

In other words, said Neukum, they are very recent -- and, he speculates, some may even now be occasionally active.

A new NASA study says that gullies around 500 metres (yards) long are formed in some Martian locations when water pops up to the surface.

Finding water would be a godsend to any future manned mission to Mars, providing astronauts with fuel, through hydrogen, as well as the means to grow food and survive.

"The gullies may be of prime importance for human exploration," said Jennifer Heldmann of NASA Ames Research Center in California.