Pluto’s ice: 97% nitrogen, 3% methane

More results from the press conference going on right now at the 42nd meeting of the AAS Division for Planetary Sciences:

Pluto’s surface ice is made up of 97% nitrogen, 3% methane, while the surface of the Kuiper Belt object Eris (which is larger than Pluto) is even more rich in methane, with a make up of 90% nitrogen and 10% methane. Both measurements go down to a depth of about 10 inches. To see the abstract for this result, go here.

The wind-blown dunes of Mars

The HiRise Camera on Mars Reconnaissance Orbiter has released some wonderful new pictures, showing what are called barchan dunes on Mars.

Barchans are crescent-shaped, with the horns of the crescents pointing downwind. One barchan is visible in the upper part of the image, with the Southeast (lower right) horns longer than the other. This trend, along with the position of the steep face of the dune on the South side, indicates that the predominant winds which formed the dunes came from the North.

There are a lot more great images on the websites above.

Wind-blown dunes

Life in the Chilean mine

A very detailed update on the trapped Chilean miners, now expected to be rescured in early November. Two key quotes:

The miners are sleeping on cots that were sent down in pieces and reassembled, and each can look forward every weekend to eight minutes each of video chat time with his family using compact cameras and a phone that was disassembled to fit through the hole.

And:

Their routine starts with breakfast – hot coffee or tea with milk and a ham-and-cheese sandwich. Then lots of labor: Removing the loose rock that drops through the bore holes as they are being widened into escape tunnels; cleaning up their trash and emptying the toilet; and attending to the capsules known as “palomas” – Spanish for carrier pigeons – that are lowered to them with supplies.

The miners must quickly remove the contents – food, clean clothes, medicine, family letters and other supplies – and send back up material such as dirty clothes, rolled up like sausages to fit. Each trip down takes 12 to 15 minutes, then four minutes for unloading and five minutes to pull them back up. At least three miners are constantly stationed at the bore hole for this work.

The crumbling cliffs of Mars

Among the new images posted last week by the HiRise camera on Mars Reconnaissance Orbiter is a picture showing the layered and looping ridgelines within Galle Crater. A close-up of these ridgelines revealed the precarious nature of those crumbling cliff tops.

Below is a low resolution version of the image, with a high resolution cropped inset below that, showing a close-up of the most interesting looking area. In the inset you can see that the top of the cliff has separated away. It almost looks as if several large pieces are about to break off. You can also see that the top of the cliff to the north is made up of hanging rocks that appear to almost float in the air. They too look as if they are about to break off.

What makes this even more intriguing is that there are no boulder piles at the bottom of any cliff. All we can see on the valley floor is a pattern of polygonal fractures, possibly “due to ground ice, or regional tectonic stresses.” If large pieces of these ridge lines are breaking off periodically, as they surely appear to be doing, where has the debris gone?

Martian cliffs

crumbling cliffs

Something is recycling the methane on Mars

Research results posted today [pdf] at the European Planetary Science Congress show that the methane in Mars’s atmosphere is seasonally variable and far more short-lived than predicted, disappearing in less than a year. Some process, therefore, must be both using it and replenishing it. On Earth, that’s almost always done by some form of life process. Key quote by one of the scientists, from the press release:

“Only small amounts of methane are present in the martian atmosphere, coming from very localised sources. We’ve looked at changes in concentrations of the gas and found that there are seasonal and also annual variations. The source of the methane could be geological activity or it could be biological ­ we can’t tell at this point.”

The image below shows the three regions (in yellow) where the methane is concentrated.

Mars methane locations

Avalanches on Mars

Saturday’s weekly dump of publications from the American Geophysical Union also included a paper that showed visual proof of avalanches on Mars! In this case, the location is Russell Crater, “a large crater in the southern hemisphere that exposes a large dune field in its center.” The avalanches occur because a frost layer made up of dry ice and a little bit of frozen water builds up on the crest of the dunes. When that frost melts, dark streaks about three to six feet wide and about 150 feet long appear, flowing downhill. The scientists believe these are avalanches made up of “a mixing of sand, dust, and unstable CO2 gas.”

wide shot of before and after
Before and after shots of the dark streaks flowing down the dune.

close-up, before and after
Close-ups of the streaks, before and after.

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