The Mars mystique

Whatever Curiosity uncovers about the past, it still leaves open the possibility that habitats may exist on the red planet today. Indeed, the prospect of extant life seems less far-fetched than it did in the years following the Viking results (see timeline). One of the remarkable discoveries from Odyssey is the presence of vast amounts of frozen slurry below the Martian surface, which is either ice layers tens of feet thick or a mix of ice and soil. The deposits extend from the poles deep into temperate latitudes.

The presence of the ice was confirmed in 2008 by the Phoenix Mars Lander, whose sampling scoop discovered it just beneath the surface at its landing site, informally known as Green Valley, in the north polar region. To the researchers' surprise, the lander also detected snow falling during its six-month mission.

Radar on the Mars Reconnaissance Orbiter uncovered evidence that the lower-latitude deposits may represent the remains of glaciers retreating as the planet undergoes a warming trend – part of long-term swings in the planet's average warmth tied to its tilt and orbit. Shaded by rock and soil on the surface, some of these formations are up to a half-mile thick and extend for miles. Flash melting of remnant glaciers when erosion exposes some of their ice may be responsible for relatively young-looking gullies orbiters have spotted on crater walls.

"I didn't see this one coming," Dyar says of the evidence of the hidden glaciers and their implication for changes in Mars' climate.

As for the potential biological significance of the discoveries, she points to a recently published analysis of a microbial community in Antarctica. These bacteria live in tiny brine channels that snake through a sheet of ice at least 90 feet thick that caps Lake Vida in East Antarctica. Temperatures in the microbes' briny home hover around 8 degrees F.

The team, led by Alison Murray, a microbial ecologist with the Desert Research Institute in Reno, Nev., notes that a half-mile-thick layer of permafrost beneath the surrounding landscape isolates the frozen lake from any influx of ground water from the surrounding valley. The lightless depths at which the bacteria live isolate them from any seasonal meltwater that might pond on the surface of the ice.

The team estimates that the briny ecosystem has been isolated for millenniums. The microbes appear to be thriving on residual organic and inorganic matter trapped in the system after it was isolated and frozen, as well as on hydrogen produced by chemical reactions as brine interacts with layers of sediment in the ice.

Could there be similar microbial ecosystems on Mars?

Scientists speculate that microbes represent one possible source for wisps of methane detected in Mars' atmosphere. But the detection remains controversial, and methane can come from geological as well as biological processes.

* * *

As early as 1948, Wernher von Braun, a German rocket scientist who later would head NASA's Marshall Space Flight Center in Huntsville, Ala., was already formulating serious plans for sending humans to Mars. His seminal book, "The Mars Project," envisioned a fleet of 10 spacecraft, assembled at a space station orbiting the Earth, traveling to the red planet with 70 crew members.

The space travelers would be ferried from ships orbiting Mars down to the surface in winged spacecraft, fitted with skis, that would land on one of the planet's frozen poles. They would spend 443 days on Mars before returning to Earth.

Von Braun's scheme put hard physics and rocket-fuel numbers to a vision typically the province of science fiction – a vision that many scientists and space agencies aspire to today. It's one more reason the search for water and other scientific data being sent back from the red planet is so important.

Previous

1 | 2 | 3 | 4 | 5

Next