Almost, but not quite… the Opportunity rover is now driving to another area on the hillside where it is currently located, after attempting to reach a difficult rock target. The rover wasn’t quite able to get close enough to the target to conduct further studies, after driving on the steepest slope ever encountered by any rover so far, on Knudsen Ridge.
Was there ever life on Mars? That is one of the longest-running and most debated questions in planetary science, and while there have been tantalizing clues, solid evidence has been elusive. Now there is a new piece to add to the puzzle, which may be one of the most interesting yet. As first reported on Smithsonian.com, odd formations composed of silica seen by the Spirit rover, nicknamed “cauliflower” for their shapes, may have been produced by microbes, new research suggests. They are very similar to some silica formations on Earth which are found in hydrothermal environments and are known to have formed with the help of microscopic organisms.
The various rover and lander missions on Mars have provided unprecedented glimpses into the planet’s past, including geological history and environmental conditions. In many ways, ancient Mars was similar to Earth, with abundant water and volcanic activity. Now, new research has revealed that there was also another related Earth-like phenomenon: acid fog.
The Spirit rover may have finished its journey a long time ago, but there is still plenty of data to go through and analyze, and continued study of that data has provided more evidence for one of the rover’s most significant findings: ancient hot springs in this area inside Gusev crater. Hot springs, as on Earth, would also have provided a potentially habitable environment for any Martian microorganisms, as well as being ideal for preserving fossils of such organisms if they existed.
The idea that Mars used to be a “water world” and sort of like a smaller version of Earth in many ways is now pretty much accepted among planetary scientists; the debate continues however as to just how wet it was and for how long. The answer would have direct implications for the possibility of life ever having started there.
Two more pieces of the puzzle now suggest, or reinforce the notion, that Mars was indeed a much wetter place than the cold, dry desert we see today.
First, new findings regarding a discovery made by the Spirit rover a few years ago indicate that water was much more abundant and the atmosphere was probably at least twenty times thicker than it is now, which would have allowed surface water to exist.
The evidence comes from a rock fragment found embedded in volcanic sediment, known on Earth as a bomb sag since the sediment visibly “sags” below the rock as a result of the rock penetrating the sediment from the impact (after being ejected during a volcanic eruption).
Josef Dufek, an Assistant Professor at Georgia Tech University, has been studying the Martian bomb sag to see what it can tell us about conditions on Mars millions or billions of years ago. His findings were just published in the journal Geophysical Research Letters.
He re-created the bomb sag’s characteristics in the laboratory, to determine the conditions present when it originally formed. Using dry, damp and saturated sand beds to replicate the sediments, he found that only the saturated sand beds produced similar results to what is seen on Mars, indicating that the Martian soil was likely very wet when the bomb sag formed.
“Our study is consistent with growing research that early Mars was at least a transiently watery world with a much denser atmosphere than we see today,” said Dufek. “We were only able to study one bomb sag at one location on the Red Planet. We hope to do future tests on other samples based on observations by the next rover, Curiosity.”
Elsewhere on Mars, the Mars Express orbiter has taken new images of ancient water-carved channels in the Acidalia Planitia region, a huge basin in the northern lowlands. Like others on the planet, they show “dendritic” drainage patterns, typically formed by runoff of water from rain or melting snow.
While there is still no consensus on how long the watery period lasted on Mars, to what extent or whether it was a warm or colder environment, it seems certain that water did play a large role in shaping the terrain of the Red Planet early in its history. But then Mars somehow lost most of its water, while Earth continued to maintain its rivers, lakes and oceans. How that change occurred can teach us more about how Mars evolved as well as our own planet’s geological and biological history.
This article was first published on Examiner.com.
Two milestone but bittersweet announcements today from NASA… first, the formal end of mission for the Mars rover Spirit, after no communication for almost a year now, despite many repeated attempts. Spirit had gone into winter hibernation as in previous years, but this time, after being stuck in a deep sand trap for so long, with dwindling power, apparently wasn’t able to come out of it’s sleep this time. But for a mission initially designed to last three months, Spirit last about seven years! The other rover, Opportunity, however, continues to make its way across the Meridiani plains, and is now getting close to the huge Endeavour crater, which we’ve been eagerly waiting for, for a long time now…
On a positive note though, there was also announced today a new deep-space mission to launch in 2016 called Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) which will bring samples back to Earth from asteroid 1999 RQ36. As well as providing new information on the history of asteroids and the solar system, it will also help pave the way for a future manned mission to an asteroid, as directed by President Obama, before going to Mars.
Two more pieces of the water-on-Mars puzzle in the last few days… the Mars rover Spirit has found new evidence of liquid water having trickled down into the soil in the relatively recent past, while the Mars Reconnaissance Orbiter has found an old volcanic cone which would have been warm and wet even after most of Mars had already started to change to the cold, dry place we see today.
When Spirit became stuck in the sand last year, the wheels churned up the soil during extraction attempts, which turned out to be a blessing in disguise. The revealed layers below the surface indicated that small amounts of water, perhaps from frost or snow, trickled down into the soil, likely sometime within the last few hundreds of thousands of years (recently, geologically-speaking) and on an on-going basis. See also the published paper here.
Meanwhile, the deposits of hydrated silica on an old volcanic cone in Nili Patera, photographed by the Mars Reconnaissance Orbiter, are thought to be the best evidence yet for ancient hydrothermal vents (fumaroles or hot springs). On Earth, such places are prime areas of habitability for microbes. They would also have been habitable places on Mars, but were they actually inhabited? The deposits are similar to ones found at hydrothermal vents in Iceland. The Mars rover Spirit had also previously found similar deposits directly in the soil (another tie-in to the other findings discussed above), evidence that fumaroles or hot springs were once present at its landing site.
According to a new paper published in Nature Geoscience, large deposits of carbonates have been found buried about six kilometres (four miles) below the surface of Leighton crater (exposed by the original impact), near the huge shield volcano in the Syrtis Major region. Small deposits have been found before on the surface, including recently by the rover Spirit, but much larger amounts would be additional evidence of a warmer, wetter ancient Mars, with a thicker atmosphere of carbon dioxide. Notably, carbonates are formed in non-acidic (alkaline) liquid water. So this finding would again reinforce the idea of ancient lakes, seas or oceans on the surface. But were those waters cold or warm? What about those icebergs? It seems like every time another piece of the puzzle is found, it just raises more questions…