Tag: geology

Data from Messenger now shows that as Mercury cooled it shrunk far more than earlier data had indicated.

9:17 am

Data from Messenger now shows that as Mercury cooled it shrunk far more than earlier data had indicated.

A new census of these ridges, called lobate scarps, has found more of them, with steeper faces, than ever before. The discovery suggests that Mercury shrank by far more than the previous estimate of 2-3 kilometres, says Paul Byrne, a planetary scientist at the Carnegie Institution for Science in Washington DC. He presented the results today at a meeting of the American Geophysical Union in San Francisco, California.

The finding helps explain how Mercury’s huge metallic core cooled off over time. It may also finally reconcile theoretical scientists, who had predicted a lot of shrinkage, with observers who had not found evidence of that — until now. “We are resolving a four-decades-old conflict here,” Byrne told the meeting.

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Curiosity has succeeded in dating the age of one of its rock samples, the first time this has ever been done remotely on another planet.

12:33 pm

Curiosity has succeeded in dating the age of one of its rock samples, the first time this has ever been done remotely on another planet.

The second rock Curiosity drilled for a sample on Mars, which scientists nicknamed “Cumberland,” is the first ever to be dated from an analysis of its mineral ingredients while it sits on another planet. A report by Kenneth Farley of the California Institute of Technology in Pasadena, and co-authors, estimates the age of Cumberland at 3.86 billion to 4.56 billion years old. This is in the range of earlier estimates for rocks in Gale Crater, where Curiosity is working.

This is significant engineering and scientific news. In the past the only way to date the rocks on another world was to bring them back to Earth. This was how the moon’s geology was dated. On Mars, dating has only been done by crater counting, comparing those counts with those on the Moon, and then making a vague guess. To have the ability to date rocks remotely means that geologists can begin to sort out the timeline of Mars’s geology without having to bring back samples.

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New data suggesting the presence of granite on Mars also suggests that the planet is more geologically complex than previously believed.

9:17 am

The uncertainty of science: New data suggesting the presence of granite on Mars also suggests that the planet is more geologically complex than previously believed.

In my years of science writing, I can’t count the number of times I’ve written the phrase “more complex than previously believed.” For some reason, modern scientists seem to always assume that things will be simple, with one straight-forward answer. From gamma ray bursts to supernovae to planetary formation to whatever, the first example found and the first theory developed from that first example has repeatedly been expected to explain everything.

But that’s not how things work. Instead, the closer scientists have looked, the more complex and interesting things have always become. Many different things can cause gamma ray bursts. Supernovae come in many types. Solar systems don’t have to resemble ours. Everything is always more complex than you first believe.

Scientists would get things wrong less often if they simply kept this thought in mind, at all times.

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Geologists have determined that the magma reservoir under Yellowstone is much bigger than previously thought.

9:25 am

The uncertainty of science: Geologists have determined that the magma reservoir under Yellowstone is much bigger than previously thought.

Jamie Farrell, a postdoctoral researcher at the University of Utah, mapped the underlying magma reservoir by analysing data from more than 4,500 earthquakes. Seismic waves travel more slowly through molten rock than through solid rock, and seismometers can detect those changes.

The images show that the reservoir resembles a 4,000-cubic-kilometre underground sponge, with 6–8% of it filled with molten rock. It underlies most of the Yellowstone caldera and extends a little beyond it to the northeast.

The geologists also noted that the threat from a huge volcanic eruption is less of a concern than that of earthquakes.

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Asteroid 2012 DA14 might experience seismic activity when it zips pass the Earth tomorrow.

2:57 pm

Asteroid 2012 DA14 might experience seismic activity, an asteroid quake, when it zips pass the Earth tomorrow.

[MIT scientist Richard] Binzel imagines what an astronaut floating alongside such an asteroid might see: “The surface could slowly sway or rock by a few centimeters. Other things to look for would be puffs of asteroid-dust rising from the surface and gentle avalanches on the steepest slopes of craters.” In rare cases, “rubble pile” asteroids might break apart during the encounter and then re-form as Earth recedes into the distance.

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Want to learn something of the geology of the Grand Canyon?

2:10 pm

Want to learn something of the geology of the Grand Canyon? The Geological Society of America has just published a special volume of papers, with the introductory and afterword [pdf] chapters available online.

Those two chapters provide a very good layman’s summary of the geological state-of-the-art of the Grand Canyon. Very worthwhile reading if you plan to hike down in the near future.

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The press lets Curiosity get the better of them

10:46 pm

The big news is out. Today the eagerly awaited press conference at the American Geophysical Society meeting in San Francisco on the recent results from the Mars rover Curiosity was finally held. The announced results had been hyped like crazy when rumors began to spread a few weeks ago that Curiosity had discovered something truly spectacular.

Well, here are some of the headlines heralding the results.
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Changes in the levels of sulphur dioxide since Venus Express arrived in orbit around Venus in 2006 now suggest strongly that the spacecraft has detected volcanic activity on the planet.

7:46 am

Changes in the levels of sulphur dioxide (SO2) since Venus Express arrived in orbit around Venus in 2006 now suggest strongly that the spacecraft has detected volcanic activity on the planet.

The SPICAV data show that the concentration of SO2 above the main cloud deck increased slightly to about 1000 parts per billion by volume (ppbv) between 2006 and 2007, but then steadily decreased over the next five years, reaching only 100 ppbv by 2012. This is very reminiscent of a pattern observed by Pioneer Venus during the 1980s, the only other multi-year dataset of SO2 measurements.

One of best explanations for these changes is a volcanic eruption back in 2006, which would have inserted a great deal of SO2 into the upper atmosphere. Since then, ultraviolet radiation from the sun has steadily destroyed it.

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An Italian court has convicted seven earthquake scientists of manslaughter for their failure to properly warn the public prior to the L’Aquila earthquake.

1:22 pm

An Italian court has convicted seven earthquake scientists of manslaughter for their failure to properly warn the public prior to the L’Aquila earthquake.

The court also sentenced the men to six years in prison, which is two years more than the prosecutor recommended.

The more I have read about this case, the less I have been in sympathy with the scientists. While it is absurd to expect any scientist to be able to precise predict the occurrence of an earthquake, in this case some of the individuals convicted had issued statements that actually go against basic earthquake science in order to give the public a false sense of safety. They claimed that the increased level of seismic activity suggested a reduction in the risk of an earthquake, when all research actually indicates the exact opposite.

Some additional details here.

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Scientists have found the source of the water on the Moon and Mercury: the solar wind.

8:48 am

Scientists have found the source of the water on the Moon and Mercury: the solar wind. Key paragraph:

“We found that the ‘water’ component, the hydroxyl, in the lunar regolith is mostly from solar wind implantation of protons, which locally combined with oxygen to form hydroxyls that moved into the interior of glasses by impact melting,” said Zhang, the James R. O’Neil Collegiate Professor of Geological Sciences. “Lunar regolith is everywhere on the lunar surface, and glasses make up about half of lunar regolith. So our work shows that the ‘water’ component, the hydroxyl, is widespread in lunar materials, although not in the form of ice or liquid water that can easily be used in a future manned lunar base.” [emphasis mine]

Though this result would explain the detection of hydrogen on the lunar surface and would also mean that this hydrogen is far less useful for future colonists than previously hoped, it doesn’t eliminate the possibility that there is ice in the permanently shadowed craters near the lunar poles that came from other as yet unknown sources.

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The first results from the two GRAIL space probes have revealed the Moon has a much thinner crust than previously believed.

6:01 pm

The uncertainty of science: The first results from the two GRAIL space probes have revealed that the Moon has a much thinner crust than previously believed.

These preliminary results have also found that the Moon’s surface topography closely matched the variations in the gravitational field, and that there appears no evidence in the gravitational field of the giant ancient impact basins that scientists have for decades assumed were there, based on surface evidence. This last result is especially surprising, and will force an almost complete rewrite of the Moon’s geological history.

Interestingly, these results are only peripherally related to GRAIL’s main research goal, which was to map the Moon’s deep structure and core. I suspect there are even more surprises coming when this data gets released.

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Mars’ clay minerals might have been formed by volcanic processes, not standing liquid water as generally believed.

9:37 am

The uncertainty of science: Mars’ clay minerals might have been formed by volcanic processes, not standing liquid water as generally believed, according to a new study.

Data collected by orbiting spacecraft show Mars’ clay minerals may instead trace their origin to water-rich volcanic magma, similar to how clays formed on the Mururoa atoll in French Polynesia and in the Parana basin in Brazil. That process doesn’t need standing bodies of liquid water. “The infrared spectra we got in the lab (on Mururoa clays) using a reflected beam are astonishingly similar to that obtained on Mars by the orbiters,” lead researcher Alain Meunier, with the University of Poitiers in France, wrote in an email to Discovery News. The team also points out that some of the Mars meteorites recovered on Earth do not have a chemistry history that supports standing liquid water.

If correct, this alternative explanation would mean that Mars was not that wet in the past, and would have been far less likely of ever having sustained life.

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Images from Curiosity have spotted some unexpected geology in Gale Crater.

9:03 am

Images from Curiosity have spotted some unexpected geology in Gale Crater.

A mosaic of high-definition images of Mount Sharp, the central peak dominating the landing site at Gale Crater, reveals tilted strata never before seen on Mars. The strata dip downwards at an angle close to that of the slope of the foothills of the 18,000-ft. tall mountain within which they are formed.

“The cool thing is the cameras have discovered something we were unaware of,” says mission chief scientist John Grotzinger. “This thing jumped out at us as being very different to what we expected,” he adds. Lying in the low-lying foothills beyond the dune field between the rover and the base of Mount Sharp, the inclined layers are a “spectacular feature” that could not be seen from orbit.

I think there are two reasons these tilted layers are puzzling scientists.
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