- Lunar Impactor Finds Clear Evidence of Water Ice on Moon
- New Brain Cells May Knock Out Old Memories
- Comet Hunter’s Last Look at Earth Is Haunting
- Underwater Glider Hunts, Records Cryptic Whales
Posted: 13 Nov 2009 10:29 AM PST
There is water on the moon, NASA confirmed today, and lots of it.
In the first look at results from the LCROSS mission, which sent a probe crashing into the Cabeus crater near the moon's south pole, NASA's main investigator said their instruments clearly detected water, despite the underwhelming plume.
Within the field of view of their instruments, the team measured approximately 220 pounds or about 26 gallons of water. Next, the team will try to understand how the compounds they saw in the plume relate to what's actually embedded in the lunar regolith at the bottom of the permanently shadowed crater.
"We need to take all the information — the amount of ejecta, the size of the crater — and reconstruct the entire event and understand how it all fits back into the ground," Colaprete said at a NASA Ames press conference.
For about a decade, lunar scientists have known the moon contained a lot of hydrogen, thanks to the Lunar Prospector mission, but it wasn't entirely clear what form that hydrogen was stored in. Now, the LCROSS observations provide a handy explanation for the hydrogen: It's bound with oxygen to form water.
"[Chandrayaan] could not see into the shadowed craters. Their observation is entirely unique and complimentary. We looked inside the shadowed craters. The amounts and flavors could be distinctly different," Colaprete said. "They saw water bound and adsorbed in grains. We saw, potentially, real crystalline water ice."
Combined with the various confirmations of water ice on Mars, it's becoming clear that water — at least in ice form — is present throughout our solar system.
Astronomers are gaining a new appreciation for celestial bodies that once seemed rather staid.
"[LCROSS] is painting a really surprising new picture of the moon. This is not your father's moon," said Greg Delory of the University of California, Berkeley. "Rather than a dead and unchanging world, it could be a dynamic and interesting one."
Delory, who is not on the LCROSS team, also called the discovery "exciting and extraordinary," saying lunar science could now move on to other fascinating questions.
"What's equally important is what we do next," Delory said. "Where did the water come from? How long has it been there? What kind of processes are involved in putting it there and removing it and destroying it?"
There are all kinds of sources for the water, Delory said. It could come from comets, the solar wind, the moon itself or even the Earth.
"Now that we know that water is there we can begin in earnest to go to the next set of questions," he said.
And answering them could tell us a lot about the solar system and its planetary bodies' relationship to water, which is necessary to all forms of life we know.
Colaprete may have another surprise in waiting, hinting that they glimpsed other interesting compounds in the plume that arose from Cabeus crater.
"This goes beyond the water, there's a lot of stuff that came out of there," Colaprete said, before saying he didn't want to say "too much beyond" that.
Delory was equally excited but circumspect saying, "I'm sure the LCROSS team is going to reveal new and exciting discoveries as they continue to analyze their data."
So, while the first LCROSS surprise — the wimpy plume — was disappointing, perhaps the next one the mission delivers will be happy.
Posted: 12 Nov 2009 02:44 PM PST
Old memories may get the boot from new brain cells.
A new rodent study shows that newborn neurons destabilize established connections among existing brain cells in the hippocampus, a part of the brain involved in learning and memory. Clearing old memories from the hippocampus makes way for new learning, researchers from Japan suggest in the November 13 Cell.
Other researchers had proposed the idea that neurogenesis, the birth of new neurons, could disrupt existing memories, but the Cell paper is the first to show evidence supporting the idea, says Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto.
Scientists have known that memories first form in the hippocampus and are later transferred to long-term storage in other parts of the brain. For some amount of time the memory resides both in the hippocampus and elsewhere in the brain. What's not been known is how, after a few months or years, the memory is gradually cleared from the hippocampus.
Researchers have also debated the role of neurogenesis in learning and memory. The hippocampus is one of only two places in the adult brain where scientists know that new neurons form. On the basis of previous studies, many researchers think new neurons stabilize memory circuits or are somehow otherwise necessary to form new memories.
The new study suggests the opposite: Newborn neurons weaken or disrupt connections that encode old memories in the hippocampus.
Kaoru Inokuchi, a neuroscientist at the University of Toyama in Japan, and his colleagues used radiation and some genetic tricks to block neurogenesis in rats and mice that had been trained to fear getting a mild electric shock when placed in a particular cage. Control animals, with normal neurogenesis, eventually were able to bypass their hippocampi and retrieve the fear memory directly from long-term storage. But animals in which neurogenesis had been blocked still depended on the hippocampus to recall the fear memory, the researchers found.
Running on an exercise wheel, which boosts neurogenesis, also sped the rate at which old memories were cleared from the hippocampus.
But that doesn't mean new neurons aren't necessary to teach old brains new tricks, says Inokuchi.
"Our findings do not necessarily deny the important role of neurogenesis in memory acquisition," Inokuchi says. "Hippocampal neurogenesis could have both of these roles, in erasing old memories and acquiring new memories."
Essentially, the new neurons may aid formation of new memories by keeping the hippocampus from filling up with old ones.
Frankland adds, "This is about as novel as it gets in the field of neurogenesis and memory. It pretty much represents an entirely new framework that other researchers will chip away at for years to come."
Image: Hippocampal neuron/NIH
Posted: 12 Nov 2009 01:51 PM PST
This gorgeous image of a blue arc of the Earth against the blackness of space was captured by the Rosetta spacecraft as it swung by our planet.
To gather up the necessary energy to reach the comet out past Mars' orbit, Rosetta needed three swings past Earth. This is its third and final flyby. It will reach the comet in early 2014.
Unlike the most famous pictures of Earth, which show most of the blue marble, this photo presents a planet in darkness, just the South Pole awash in light.
Image: ESA. High-resolution image of planet Earth from Rosetta.
Posted: 12 Nov 2009 01:21 PM PST
The mysterious beaked whale is the target of a new undersea glider trying to track the deep-diving mammals by their high-frequency clicks and squeals.
A Seaglider unmanned underwater vehicle with an underwater microphone began patrolling the coast of Hawaii on October 27 and will finish up its initial mission on November 17. By then, it will have collected half a terabyte of data.
By applying software that automatically picks up beaked whale sounds from the rest of the sounds of the ocean, the researchers hope to gain a deeper understanding of how these rare whales live.
Sound recording of orca whale squeals and clicks from a Seaglider test run in the Puget Sound. It's been slowed down for human ears.
"They live far off shore, and they are not very obvious. When they surface, they are only up for a second or so and they are hard to see," said Dave Mellinger, a marine scientist at Oregon State University who focuses on the automatic detection of whales from acoustic signals. "They are pretty cryptic. That makes them good acoustic candidates."
The Seaglider is one of a host of new acoustic tracking tools that are helping scientists better understand the behavior of deep sea whales. Using autonomous underwater gliders, hydrophones, and sophisticated algorithms, they are a key tool in the race to map where whales live while whales are still living. For example, dedicated-listening buoys help protect right whales near Cape Cod while providing valuable scientific data.
The beaked whale appears to be particularly sensitive to the powerful sonar used by the world's naval fleets. Over the past decade, dozens of these rare whales have died in a series of incidents that seem linked to naval exercises, even if it's hard to prove the connection.
The carcasses that wash up on shore are consistent with the hypothesis that the whales respond to the sonar by surfacing too quickly, inducing the bends (.pdf). Nitrogen, and other gases that had been dissolved into the liquids inside their bodies by the high-pressure at depth, transform back into gas as the pressure is released. If they rise too fast, the amount of gas overwhelms the body's natural systems for expelling it, causing bubbles to form in the bloodstream and tissues.
The only sure way to make sure that the whales aren't injured by military sonar use is to ensure that there aren't any whales in the area when the naval soundings occur. But that would require figuring out how to find and track the whales, which has proven difficult. It's a big ocean and the high-frequency noises they make don't carry in the water like the bass calls of a blue whale or humpback.
The U.S. Office of Naval Research, though, has been pouring money into learning more about the whales. Mellinger's project received $1.5 million.
"We've been focusing on beaked whales because of the conservation implications of being able to find them," Mellinger said.
A single glider can't provide the breadth of monitoring they would need, but it's possible fleets of gliders could.
The next step for Mellinger and his teammates could be to integrate and calibrate their data with information from U.S. Navy hydrophone arrays. Most of the Navy's systems can't record the high frequencies used by the beaked whales to locate their small squid prey, but some are sensitive enough to use.
"What we'd like to do is track a beaked whale using the Navy hydrophones and have a glider operating nearby," he said. "We're hoping to do that next year."
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