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Posted: 27 Jan 2015 09:29 PM PST
Eat your heart out, Hubble! NASA’s Dawn spacecraft is in the home stretch of its journey to Ceres and has snapped the best images yet of the dwarf planet. Grainy as they are, the new views of the 590-mile-wide world are already turning up unexpected features on the surface.
The images show significant brightness and darkness variations over the surface – particularly a bright spot gleaming in the northern hemisphere and darker spots in the southern hemisphere. While the scientists were aware of those major spots, they weren’t expecting to see quite so much texture on the surface, said Raymond, a geophysicist at the Jet Propulsion Laboratory.
Ceres is fairly warm by ice-world standards; temperatures generally range from 180 to 240 Kelvin (or minus-136 degrees Fahrenheit to minus-28 degrees Fahrenheit), Raymond said. Theoretically, the ice on Ceres’ surface should start to flow as it warms up, smoothing out any bumps such as those from impact craters. But the brightness variations across the surface make it appear very rough, she said.
Ceres was not the first stop in Dawn’s 3-billion-mile journey. The first was the protoplanet Vesta, which is vastly different from its fellow mega-asteroid, Ceres. Where Vesta is dry and lumpy, Ceres is icy and round, massive enough to have been pulled into a planet-like shape. Scientists want to find out why these two space-fossils from the early solar system ended up with such different geophysical life stories.At least with Vesta, there were meteorites linked to the asteroid that planetary scientists can study, Raymond pointed out. For Ceres, there are no such space rocks found on Earth – so the researchers have somewhat less of an idea of what to expect.
“I am excited,” Raymond said. “Just having had the wild ride at Vesta, I’m also just in awe of what’s going to happen. It’s going to be amazing.”
Posted: 27 Jan 2015 09:21 PM PST
Excerpt from wired.com
The Rosetta spacecraft has been studying comet 67P/Churyumov-Gerasimenko up close since August, collecting data of unprecedented detail and taking pictures of a starkly beautiful comet-scape. While the Philae lander has enjoyed much of the spotlight—partly thanks to its now-famous triple landing—Rosetta has been making plenty of its own discoveries.
One of the biggest came last month, when scientists found that the chemical signature of the comet’s water is nothing like that on Earth, contradicting the theory that crashing comets supplied our planet with water. Comet 67P belongs to the Jupiter family of comets, and the findings also imply that these kinds of comets were formed at a wider range of distances from the sun than previously thought, says Michael A’Hearn, a planetary scientist at the University of Maryland, College Park, and member of the Rosetta science team.
Today, scientists have published the first big set of results from Rosetta in a slew of papers in the journal Science. The results include measurements and analyses of the comet’s shape, structure, surface, and the surrounding dust and gas particles. Here are just a few of the amazing things they’ve discovered about Rosetta’s comet so far:
The surface is fantastically weird
The comet has quite the textured landscape, covered with steep cliffs, boulders, weird bumps, cracks, pits, and smooth terrain. There are fractures of all sizes, including one that’s several yards wide and stretches for more than half a mile along the comet’s neck. Researchers don’t yet know what caused these cracks. The pits have steep sides and flat bottoms, ranging in size from a few tens to hundreds of feet wide. Jets of dust shoot out from some of the pits, suggesting that the ejection of material formed these features. Another strange feature is what scientists are calling goosebumps—weird bumpy patches found particularly on steep slopes.
While other features such as pits and fractures range in sizes, all of the goosebumps are about 10 feet wide. No one knows what kind of process would make the bumps, but whatever it is could have played an important part in the comet’s formation. It may be breezy Rosetta spotted dune- and ripple-like patterns,wind tails behind rocks, and even moats surrounding rocks, suggesting that a light breeze may blow dust along the surface. Such a gentle wind would have to come from gases leaking from below.
Because of the extremely low gravity on the comet, it wouldn’t take a strong gust to blow things around. It may have formed from two separate pieces Or not. The most distinct feature of comet 67P is its odd, two-lobed shape, which resembles a duck. Although scientists have seen this lobed structure in other comets before, namely Borrelly and Hartley 2, none are as pronounced as comet 67P’s. Borrelly and Hartley 2 look more like elongated potatoes while 67P has a clearly defined head and body. The strange shape suggests the comet was once two separate pieces called cometesimals—what are now the duck’s head and body—that stuck together.
The other possibility is that erosion ate away the parts around the neck. Preliminary evidence points to the first hypothesis.
“Probably most of us on the OSIRIS team lean toward thinking it was two cometesimals,” A’Hearn said. (OSIRIS is one of Rosetta’s imaging instruments.) But the scientists won’t have conclusive evidence until they study the comet in more detail. For example, they now see layering along the neck—if erosion carved out the comet’s duck shape, they should find the same same layering pattern continuing onto the other side of the neck.
Black, with a tinge of red
Even Rosetta’s color pictures show a grayish comet, but if you were to see it in person, you would see a pitch-black chunk of dust and ice, as it reflects only six percent of incoming light. By comparison, the moon reflects 12 percent of incoming light and Earth reflects 31 percent. But comet 67P’s not completely black, as it has a hint of red. Water, water, nowhere? The comet’s covered in opaque, organic compounds. Although comet 67P is undoubtedly icy, it hardly shows any water ice on its surface at all.
Which isn’t too surprising, as comets Tempel 1 and Hartley 2 didn’t have much ice on their surfaces either, A’Hearn says. Rosetta has yet to see sunlight reach every side of the comet yet, so there may still be some icy patches hidden from view. But, researchers do see the comet spraying water vapor into space, which means water ice likely lies just beneath the surface. The ice doesn’t have to be more than a centimeter deep to be invisible from the infrared instruments that detect the ice. Indeed, the data from Philae’s first bounce suggested that there’s a hard layer of ice beneath 4 to 8 inches of dust.
This duck floats
If you could find a big enough pond, that is. Like other known comets, the density of comet 67P is about half that of water ice. Initial measurements reveal that it’s also very porous—as much as 80 percent of it may be empty space. Rosetta has found depressions, which may have formed when the surface collapsed over particularly porous material underneath.
Different from every angleAs the comet nears the sun, it heats up, and ices and other volatile chemicals sublimate, spraying gases into space. So far, the most prominent gases that have been ejected are water vapor, carbon dioxide, and carbon monoxide. They spew out in different amounts from different parts of the comet. In particular, a lot of the water has been observed gushing out from the neck.
The comet will continue to get more active as it reaches its closest approach to the sun in mid-August. It will burst with stronger jets of gas and dust, and maybe even blast off chunks of itself. If the comet is this interesting now, A’Hearn says, just wait until it gets to its nearest point to the sun, when it’s just 1.29 times farther from the sun than Earth is.
Posted: 27 Jan 2015 09:10 PM PST
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Posted: 27 Jan 2015 08:47 PM PST
72-year old Jure Sterk left Tauranga, New Zealand, in December 2007 on his sailboat 'Lunatic Piran'. His boat may have been small, but his ambition was large - a non-stop circumnavigation. However his story had not begun there, and was already a testament both to the sailor's doggedness and his love of the sea.
He had actually left Europe three years before - on the 5th September 2004 - in an effort to circumnavigate without making landfall. Each time he experienced problems with the boat and was obliged to enter ports for repairs.
However, finally he set sail to the East from New Zealand and his plan was reportedly to sail via Cape Horn, north around the Azores, back around Cape of Good Hope, around Tasmania, across the Southern Ocean, around the bottom of New Zealand and back to Tauranga.
In the beginning of this year Jure was on his last leg to New Zealand.
He had kept contact with amateur radio enthusiasts, but was last reported in early January 2009.
On April 30, the RV Roger Revelle, out of San Diego, CA, USA was enroute from Durban, South Africa to Freemantle/Perth, Australia on an oceanographic research cruise and was at Latitude 32-18.0S, Longitude 091-07.0E,, when the 2nd mate sighted the drifting boat.
While steaming at 12 knots toward our next station, the ship unexpectedly stopped several miles before the station. We were wondering what the occasion was, did someone hook a tuna finally? I was in the lab running nutrient samples when my lab partner from the other watch came in and said that we had found a sailboat with no one on board.
I went out on deck and there she was, just drifting along. Her mainsail was set but it was in tatters. She had a white hull with white sails. To my mind she was quite small, maybe 30 feet? She was floating high in the water, certainly she was watertight and not sinking. Her hull was very heavily fouled with marine growth; it was obvious she had been out here for a long time.
There was a fishing pole rigged over the side although no line in the water. There was a line over the side trailing aft. Her hatch from the cockpit into the cabin was open but everything seemed in order, no water in the cockpit or obviously in the cabin. Her name was partially visible on her stern, 'Lunatic Pirate', but no home port or nationality.
She was a very sad, melancholy looking craft.
What happened to leave her drifting out here, alone. Where was her crew? Did they abandon her, thinking she was in trouble? Did they get knocked overboard by the boom? Slip and fall overboard and weren't able to swim fast enough to catch her again?
The first mate said that he could see a log book in the cabin so a Jacob's ladder was put over the side and someone went onboard and retrieved the log book and several other items. The last entry in the log book was from January, 2009, she may have been drifting out here since then?
Interestingly, there were several large fish swimming about the boat, anything floating in the sea seems to attract them. I was told there were two mahi-mahi and one wahoo. I saw one fish, no idea what it was.
I am sure the idea of pirates went through a lot of minds, certainly it occurred to me.
I went on deck after we were underway again and I saw her off the stern, it was so sad, just watching her 'sail' away, all alone again.
Enough to make me cry. I didn't take a picture of that, I think I'm glad.
However, the story is not ended, and the mystery may have been cleared by another cruising sailor, Peter, on his yacht Coconut, who was sailing in the Indian Ocean.
'I was sailing my small yacht 1000 miles behind Juri (also heading East)and had daily radio conversations with him.
'The plan on the day of his accident was to get in his dinghy and clean his rudder and trim tab as the fouling had reduced his speed to 2-3knots. His forestay was broken some time previous and his main had been reduced in size as it was torn.
'His plan was to get some more speed and to clean up his steering system. The weather on the day I lost radio contact was as good as it gets down there and he had been waiting for that break in the weather.