The towering 3-D features of Martian canyons and highlands are about to stand out like never before, thanks to data from a high-resolution camera on the Mars Express orbiter.
These data, collected by the camera on the European Space Agency's Mars Express, are allowing scientists to create so-called Digital Terrain Models (DTMs) to look around the Martian surface from different directions and angles, as opposed to the usual bird's-eye view from above provided by previous Mars orbiter cameras. The new data sets have now been released on the Internet, the European Space Agency announced this week.
"Understanding the topography of Mars is essential to understanding its geology," said Gerhard Neukum, HRSC lead scientist at Freie Universität (FU) in Berlin, Germany.
Creating the data for such digital models requires spacecraft to study the same Martian feature at least twice, each time from a different angle. Most previous efforts to do this have involved spacecraft making two orbital passes over features.
The Mars Express High Resolution Stereo Camera (HRSC) only needs one overhead pass to capture images of a feature from three different angles — on approach, directly underneath and receding into the distance. The camera also obtains altitude measurements for its high-resolution images.
All that data is processed by the German Space Agency (DLR) and FU Berlin for several years before digital models of the Martian surface can start to emerge. Now researchers are selecting the best data to "stitch them together" and develop digital models on a "global scale," Fred Jansen, Mars Express senior manager, told SPACE.com.
The newly released DTMs allow researchers to instantly gauge the slope of hillsides or the height of cliffs, as well as the altitude and slope of lava flows or desert plains.
"This data is essential for understanding how water or lava flowed across Mars," Neukum said.
It also helps planetary scientists better interpret Martian data from other instruments and missions, such as the Mars Advanced Radar for Subsurface and Ionosphere Sounding.
"Once we know where the surface is, we can correctly interpret the radar echoes we get from below it," said Angelo Rossi, HRSC scientist.
Lower orbits of Mars Express allow for more detailed pictures. The Mars Express mission will continue collecting such data until at least 2009.
See Mars in 3-D
Mars Water Was Very Salty
BOSTON - If there was life in surface water on Mars early on, it might have enjoyed a very buoyant, salty ride, if it could thrive in such a hostile environment at all, new research suggests.
Minerals in sedimentary rocks found at Mars' Meridiani Planum by NASA's Opportunity rover suggest they formed in extremely salty water even saltier than the oceans on Earth, said Andrew Knoll of Harvard University, who is part of a team of scientists taking a closer look at the geological data collected by the Mars Exploration Rovers mission.
Water was definitely present at least for short periods of time at Meridiani Planum, he said, but no one has known how habitable it might have been nor whether it was around long enough for life to take hold and endure.
So Knoll and his colleagues looked at data that reveal the chemistry of the salts in the rocks there as a gauge of the salinity of the ancient water. That allowed the scientists to estimate how salty the brines were at the time the minerals were deposited.
"The punchline is it was really salty," Knoll told a gathering of reporters here at the annual meeting of the American Association for the Advancement of Science, "salty enough that only a handful of terrestrial organisms would have a ghost of chance of surviving there when conditions were at their best."
Constrains the possibilities
There are a couple dozen organisms on Earth that can tolerate the salinity levels determined by Knoll and his team to have been present when the Meridiani Planum rocks were deposited, he said.
The research, to be presented today in detail to scientists as well, is currently under review at a top research journal, Knoll said.
Knoll and his colleagues also have found several different classes of minerals that reveal how little the rocks at Meridiani Planum were altered since they were exposed to the elements, he said. Water at this location was "rare and transient," according to the research, detailed in an online paper in the Journal of Geophysical Research — Planets.
The best era during which to look for evidence of martian life would be in Mars' earliest history, Knoll said, that is, during the first 500 million to 600 million years, before the Meridiani Planum rocks were deposited.
The new findings bring scientists no closer to determining whether there was ever microbial life on Mars, but they do "constrain our thinking about life on Mars," Knoll said, painting a picture of an environment that is very "forbidding" for life.
Double whammy
Previously, Mars mission data have revealed that liquid water at Meridiani Planum was very acidic.
"So it is doubly bad if it's acidic and salty," Knoll said.
"I'm not sure the effects are necessarily additive, but certainly there are limits to the physiological ways that microorganisms can adapt to tolerate acidity," he said. "There are also limits to ways that they can adapt to tolerate highly saline environments and those are completely different physiological systems. In a sense, it makes it harder to adapt that there are two biochemical systems that would need adapting."
Scientists are more optimistic that life might have had a chance on Mars in its early history compared to later on. In earlier times, Mars' environment was probably wetter, less oxidizing (a condition that is challenging for most life) and less acidic, but "that doesn't mean it was terrific. It just wasn't as bad as it got later," Knoll said.
Meanwhile, Mars scientists and mission engineers gathered at the AAAS meeting today also looked forward to the May 25 arrival of NASA's Phoenix Lander at Mars' north pole and discussed work on the Mars Science Laboratory (MSL) mission, set to launch in September 2009. MSL will carry a new rover to Mars that is far more complex and sophisticated, and five times heavier, than each of the MER rovers on the red planet now. The MER rovers are learning more about the habitability of the planet in the distant past, said Richard Cook, MER project manager.
Instruments on MSL will focus on detecting organic material at the planet and collecting more precise data on the minerals at Mars.
As for the MER rovers, Spirit is hunkered down for winter, parked on a north-facing slope and serving as a weather station to monitor a nearby dune field. And Opportunity is descending down the wall of Victoria Crater, investigating its finely layered rock stacks, made mostly of sulphate salts, said Steve Squyres of Cornell University, head of the science team for the MER mission.
The rovers nearly died last summer during intense dust storms on Mars that nearly stole all their ability to gather power, but they again outperformed expectations and endured. In fact, it looks good for them to be operational when Phoenix arrives in late spring.
Eagle guards Melbourne landmark
Staff at a Melbourne landmark have resorted to unusual methods to try to prevent damage to their building - a wedge-tailed eagle called Zorro.
They hope Zorro's presence on the roof of the city's Arts Centre will scare away white cockatoos that have been attacking its iconic tower.
The flocks of cockatoos have been pecking at the tiny lights that illuminate the 163-metre spire.
So far they have caused more than US$63,000 (£32,000) worth of damage.
Zorro will also be joined by a peregrine falcon named Bibi and the two birds will be brought to the building every day for the next six weeks as a trial.
"Cockatoos are part of their prey, so it's a natural solution," Arts Centre spokesman Jeremy Vincent told the French news agency AFP.
"The cockatoos aren't hurt, because the predators are tethered to the building, but their presence on the building acts as a deterrent."
A handler will also be present to monitor Bibi and Zorro while they are on the roof of the Arts Centre.
So far the two birds of prey were keeping the cockatoos away, Mr Vincent said, but they were also attracting groups of tourists.
Cockatoos are parrot-like birds known for their destructive habits.
