Will Curiosity find new clues to ancient Martian habitability, or perhaps even life, at Hematite Ridge?

Hematite ridge, as seen from near Curiosity's landing site, a few kilometres away. Credit: NASA / JPL-Caltech / annotated by A. Fraeman
Hematite Ridge, as seen from near Curiosity’s landing site, a few kilometres away. Click on image for larger version. Credit: NASA / JPL-Caltech / annotated by A. Fraeman

As the Curiosity rover gets ever closer to its major destination of Mount Sharp, there is an interesting feature there which has become a priority target, one which may help scientists to further study the past habitability of this area, or even provide possible clues to life itself.

Hematite Ridge as it has been nicknamed, is a long, low ridge running along the base of Mount Sharp. It is about 5-10 metres (16-33 feet) tall, 200 metres (600 feet) wide and 6.5 kilometres (4 miles) long. From data provided by the Mars Reconnaissance Orbiter spacecraft, the ridge has been found to have a coating of hematite on top. Why is this significant? Hematite is an iron mineral which forms in water. In that aspect, its discovery here isn’t too surprising, as it has been found elsewhere on the planet before and Curiosity has already provided a flood of evidence that this area was once underwater, with swift-moving streams or rivers. That water was also neutral and non-acidic; it would have been quite safe for people to drink or microbes to swim around in.

Overhead view of Hematite ridge and surrounding terrain. Click image for larger version. Credit: NASA / JPL-Caltech
Overhead view of Hematite Ridge and surrounding terrain. Click on image for larger version. Credit: NASA / JPL-Caltech

There are two main scenarios in which scientists think the hematite here could have formed, both involving chemical processes connected to the sedimentary layers in Mount Sharp. Either chemical precipitation within the rocks caused by underground water which became exposed to an oxidizing environment, or weathering by water which was neutral or slightly acidic. On Earth, both of these processes have one thing in common; as noted by the scientists involved, “Both scenarios indicate that this ridge was a site of past active iron oxidation. Iron oxidation that occurs at chemical interfaces almost exclusively involves microorganisms.”

Interesting; it would be premature to say that microorganisms must have been involved in forming the hematite formed here on Mars as well, but the possibility is an enticing one. At the very least, this formation should provide an additional glimpse at what the habitable conditions were like here millions or billions of years ago. Curiosity is not a life-detection mission specifically, but it is considered possible that it could still discover clues relating to past life, if it ever existed, in a less direct manner.

It will be several more months still before the rover gets close to Hematite Ridge, but the studies it does there should be quite interesting and the close-up views of the nearby mountain, canyons, mesas and buttes, spectacular.

Paul Scott Anderson is a freelance space writer with a life-long passion for space exploration and astronomy. He currently writes for The Spaceflight Group, AmericaSpace and Examiner.com. His own blog The Meridiani Journal is a chronicle of planetary exploration.
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