Most Mars meteorites found on Earth may have been blasted here from a single impact on Mars around 3 million years ago.
This is a great scientific detective story. It has a lot of uncertainties, should definitely be taken with a grain of salt, but is nonetheless very convincing.
A zircon crystal found in western Australia has been dated as the oldest known piece of the Earth’s crust.
Orbital images from Mars Reconnaissance Orbiter have confirmed that the mysterious rock that appeared near Opportunity was not ejecta from a nearby meteorite impact.
The scientists theorized that there was a very remote chance that a nearby impact has thrown the rock into place, but the images show nothing nearby. Moreover, if there had been an impact we probably would have seen more rocks raining down all around. The images are further confirmation that the rock was kicked up by the rover itself as it rolled along.
Scientists produce the first global geologic map of Jupiter’s moon Ganymede.
A very useful start to the geological study of the solar system’s largest moon.
The geological history of Venus: What’s known, not known, and unknown.
This is a very clearly written overview by James Head, one of the world’s preeminent planetary geologists, of what has been learned about the geology of Earth’s sister planet, the planet of a million volcanoes. Key quote:
Many features on Venus (folded mountain belts, rift zones, tesserae) were like Earth, but there were few signs of Earth-like plate tectonics, so that Venus seemed to have a single lithospheric plate that was losing heat conductively and advectively. But the cratering record presented a conundrum. First, the average age of the surface was <20% of the total age of the planet, and second, the average was not a combination of very old and very young surfaces, such as Earth’s continents and ocean basins. Third, the lack of variability in crater density, and of a spectrum of crater degradation, meant that all geological units might be about the same age. This implied that the observed surface of Venus must have been produced in the past hundreds of millions of years, possibly catastrophically, with very little volcanic or tectonic resurfacing since then! Suddenly, Venus was not like Earth, nor like the Moon, Mars, or Mercury.
Some scientists even believe that Venus was essentially resurfaced in a massive volcanic event about a half billion years ago. Others disagree. Meanwhile, the European probe Venus Express has gotten hints that volcanic activity is still going on.
As Head concludes, it has been 20 years since the last spacecraft arrived at Venus to do geological research. It is time to return.
Photos taken 33 years ago by a photographer who died in the Mt. St. Helens eruption have been discovered and developed.
Reid Blackburn took the photographs in April 1980 during a flight over the simmering volcano. When he got back to The Columbian studio, Blackburn set that roll of film aside. It was never developed. On May 18, 1980 — about five weeks later — Blackburn died in the volcanic blast that obliterated the mountain peak.
Those unprocessed black-and-white images spent the next three decades coiled inside that film canister. The Columbian’s photo assistant Linda Lutes recently discovered the roll in a studio storage box, and it was finally developed.
A White Christmas on Mars.
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.
More news from Curiosity: Gale Crater held at least one lake in the past, and that lake existed for longer and more recently than expected.
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.
Seismic data now suggests that a volcano is beginning to stir far beneath the Antarctica icecap.
The article can’t resist noting how a really big eruption could melt a lot of ice and change the climate, neither of which is very likely.
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.
