The most powerful spacecraft ever sent to Mars has begun revealing new clues to the red planet's changing environment, including more hints of past water flow. Scientists hope the U.S. space agency's Mars Reconnaissance Orbiter will detect whether liquid water still exists there.
The first images from the satellite are test pictures taken in late September and early this month to help scientists calibrate their instruments. But a Mars researcher at the U.S. space agency NASA, Steve Saunders, says the pictures offer a preview of spectacular shots yet to come.
"We have another new Mars," said Steve Saunders. "Every time we go to Mars with a new set of instruments, we have a different planet."
The Mars Reconnaissance Orbiter has five times better resolution over more area than satellites currently circling the planet. It can see things smaller than one meter across, thanks to extremely sharp cameras and an altitude 20 percent lower than its predecessors - about 300 kilometers.
Another NASA Mars scientist, Richard Zurek, calls the detail of the first images incredible.
"You're seeing information that is comparable or even better than what you would see flying over the surface of the Earth from a commercial airliner," said Richard Zurek.
NASA says the orbiter is seeing details in the shapes and layers of icy ground near Mars' north pole. An instrument peering at a vast valley in the region named Chasma Boreale has seen layers that vary in amounts of ice and dust. Johns Hopkins University researcher Scott Murchie says this suggests that climate cycles have occurred relatively recently.
"So what this is telling us is that at the north polar cap over the last 100,000, or so years, there has been a really dynamic history of change in climate that is recorded in the layers of ice, much like the way we would determine Earth's climate change by going back and looking at a core of ice in Greenland," said Scott Murchie.
At another valley called Mawrth Vallis, much lower in latitude, the Mars Reconnaissance Orbiter has been able to detect differences in clays spotted previously by the European Space Agency's Mars Express satellite. Murchie says some are rich in iron and others contain aluminum.
"Clay is really significant geologically because for it to form, the rocks have to have been soaking for a really long period of time in water," he said. "Differences in the mineralogy tell us something about how the environment might have been different from place to place."
Murchie says the areas rich in clay show some of the best evidence for conditions possibly favorable to life on ancient Mars.
University of Arizona geologist Alfred McEwen points to other new evidence of water at a small crater in the red planet's southern hemisphere. He describes a system of gullies that weave in and out as if they are braided.
"That tells us water flowed in this area," explained Alfred McEwen. "And that was geologically recent. So we are confirming previous results in much greater detail. Water does flow on the surface of Mars in the current geologic epoch."
The big question is whether water is seeping on the surface of Mars today. McEwen says there is no evidence yet, but researchers will continue to monitor surface changes over time with the new U.S. orbiter and the other U.S. and European spacecraft already circling to see if they can detect present water flows.
Richard Zurek adds that scientists do not even know when and for how long it flowed in the past.
"How persistent has it been, and does it come in a single episode or multiple episodes? I think that what we're seeing that as we see more detail, that history can be quite complex," he said. "Ultimately we're looking to see finer slices in time of the evolution of Mars."
The scientists say that many questions about Mars cannot be answered from above, but will require more rovers like the current pair named Spirit and Opportunity. What the Mars Reconnaissance Orbiter can do is gather enough data to suggest where future surface robots should be sent.