Evidence of water flowing on our most similar neighbor
by Alex Stone
Pictures taken by the camera on NASA's Mars Global Surveyor suggest that rivulets of liquid water were flowing on the Red Planet within the past few years and may still be flowing today, welling up from beneath the Martian surface and streaming down gullies along the sloping walls of impact craters.
Two craters in particular caught the attention of NASA scientists. Both are in the planet's southern hemisphere, and both looked unremarkable at first glance. That changed when the Surveyor team reimaged the craters over several years and spotted two brightly streaked gullies with branched endings—a hallmark of flowing water—that were not visible in earlier pictures. The researchers speculate that the streaks formed when water bubbled up from a subsurface reservoir and ran down the gullies, leaving behind a pale-toned trail of sedimentation that is seen in the Surveyor snapshots as a bright line against a darker background. "We reimaged it several times at different sun angles to be sure it wasn't just a trick of different illumination conditions," says Ken Edgett, a member of the research team that made the discovery. More than just a geologic curiosity, finding water on Mars has major implications for the search for life, because the presence of H2O greatly increases the odds that living organisms once thrived on the planet, and perhaps still inhabit it today. "We didn't expect this to happen in our lifetime, let alone our 10-year mission," Edgett says.
But is the liquid flowing down these gullies really water? Probably, say experts at NASA's Jet Propulsion Laboratory, but more evidence is needed to seal the case. "You can never be certain from orbit," Edgett says. "But this is the best evidence yet of liquid water being present on Mars right now."
Sunday, March 11, 2007
Neutrinos of the Sea
Scientists hope to find rare high-energy particles in the sea.
by Kathy A. Svitil
Giorgio Gratta, a physicist at Stanford University, is going fishing for high-energy neutrinos, ghostly subatomic particles that bombard Earth from unknown objects in deep space. These particles can interact with water, emitting a shudder of light, albeit under such rare circumstances that just a few of them strike each square mile of ocean each year.
But neutrinos can also heat the water, generating acoustic waves. The Navy's Atlantic Undersea Test and Evaluation Center, a 100-square-mile hydrophone array used to track ships and weapons during undersea naval exercises, could pick up these tiny vibrations. "You can put hydrophones in the water and listen to the neutrinos," Gratta says.
During the past several months, Gratta and his students have begun collecting data from seven of the array's 52 hydrophones. He is using computer software to filter out noise from wind, surf, ship engines, snapping shrimp, and echolocating dolphins. "Things look good," he says.
Next he hopes to plug into the rest of the hydrophones, start tallying the neutrinos, and begin to zero in on the strange, energetic objects that emit them.
by Kathy A. Svitil
Giorgio Gratta, a physicist at Stanford University, is going fishing for high-energy neutrinos, ghostly subatomic particles that bombard Earth from unknown objects in deep space. These particles can interact with water, emitting a shudder of light, albeit under such rare circumstances that just a few of them strike each square mile of ocean each year.
But neutrinos can also heat the water, generating acoustic waves. The Navy's Atlantic Undersea Test and Evaluation Center, a 100-square-mile hydrophone array used to track ships and weapons during undersea naval exercises, could pick up these tiny vibrations. "You can put hydrophones in the water and listen to the neutrinos," Gratta says.
During the past several months, Gratta and his students have begun collecting data from seven of the array's 52 hydrophones. He is using computer software to filter out noise from wind, surf, ship engines, snapping shrimp, and echolocating dolphins. "Things look good," he says.
Next he hopes to plug into the rest of the hydrophones, start tallying the neutrinos, and begin to zero in on the strange, energetic objects that emit them.
The Titanic's Revenge
Butterfly effect breaks up the world's biggest icebergby
by Jeffrey Winters
The largest icebergs usually hug the Antarctic coast for decades before wandering into deep ocean water, where they melt and fall to pieces. To listen for clues about how such icebergs eventually break apart, geophysicists Douglas MacAyeal of the University of Chicago and Emile Okal of Northwestern University planted seismographs on the surface of iceberg B15A, a 71-mile-long block of ice with the distinction of being the world's largest free-floating object. Their recording turned up the sounds of the iceberg being battered to bits against the Antarctic shore over a couple days in October 2005. The big surprise came when the researchers tracked down the origin of that battering.
By measuring ocean swells of different wavelengths, the duo traced the destructive turbulence to a storm in the Gulf of Alaska that, a few days earlier, had kicked up 40-foot-high seas. Like the proverbial butterfly that flapped its wings in Beijing and caused a hurricane halfway around the world, the Alaskan storm's waves spread out across the Pacific Ocean and broke apart an iceberg more than 8,000 miles away. "It was jaw dropping," says MacAyeal.
If global warming leads to an increase in monster storms, MacAyeal adds, then the entire Antarctic ice skirt could be in jeopardy: Larger sea swells could pulverize its huge icebergs and floating ice shelves. The ice skirt plays a critical role in keeping the land-based Antarctic ice cap in place. Destroy the floating ice and the ice cap (which holds enough water to raise sea levels by 200 feet) would collapse unimpeded into the sea.
by Jeffrey Winters
The largest icebergs usually hug the Antarctic coast for decades before wandering into deep ocean water, where they melt and fall to pieces. To listen for clues about how such icebergs eventually break apart, geophysicists Douglas MacAyeal of the University of Chicago and Emile Okal of Northwestern University planted seismographs on the surface of iceberg B15A, a 71-mile-long block of ice with the distinction of being the world's largest free-floating object. Their recording turned up the sounds of the iceberg being battered to bits against the Antarctic shore over a couple days in October 2005. The big surprise came when the researchers tracked down the origin of that battering.
By measuring ocean swells of different wavelengths, the duo traced the destructive turbulence to a storm in the Gulf of Alaska that, a few days earlier, had kicked up 40-foot-high seas. Like the proverbial butterfly that flapped its wings in Beijing and caused a hurricane halfway around the world, the Alaskan storm's waves spread out across the Pacific Ocean and broke apart an iceberg more than 8,000 miles away. "It was jaw dropping," says MacAyeal.
If global warming leads to an increase in monster storms, MacAyeal adds, then the entire Antarctic ice skirt could be in jeopardy: Larger sea swells could pulverize its huge icebergs and floating ice shelves. The ice skirt plays a critical role in keeping the land-based Antarctic ice cap in place. Destroy the floating ice and the ice cap (which holds enough water to raise sea levels by 200 feet) would collapse unimpeded into the sea.
Whatever Happened to... Project Blue Book?
The government gave up on alien tall tales.
by Stephen Ornes
From 1948 until 1969, the U.S. government collected about 80,000 pages of first-hand reports—including descriptions, drawings, and diagrams—on more than 12,000 sightings of UFOs.
Begun as Project Sign, it was quickly renamed Project Grudge, then Project Blue Book in early 1952. The new moniker, inspired by the blue books college students use to take written exams, was supposed to indicate the seriousness with which the study was being undertaken.
With 1,500 reports, 1952 was also the year with the most sightings. All in all, 701 remain "unidentified" to this day. The rest were attributed to a variety of sources, including bright planets, auroras, aircraft, searchlights, and birds. Project Blue Book was shut down in 1969 after a rigorous study led by the physicist Edward Condon concluded that UFO sightings all had mundane, nonthreatening explanations.
Since that time, the U.S. government no longer investigates claims of "flying saucers"—a term that dates back to the first widely reported UFO sighting by an American businessman in 1947. Independent groups of civilians still maintain that the government intentionally withholds information about UFO sightings, both past and present.
by Stephen Ornes
From 1948 until 1969, the U.S. government collected about 80,000 pages of first-hand reports—including descriptions, drawings, and diagrams—on more than 12,000 sightings of UFOs.
Begun as Project Sign, it was quickly renamed Project Grudge, then Project Blue Book in early 1952. The new moniker, inspired by the blue books college students use to take written exams, was supposed to indicate the seriousness with which the study was being undertaken.
With 1,500 reports, 1952 was also the year with the most sightings. All in all, 701 remain "unidentified" to this day. The rest were attributed to a variety of sources, including bright planets, auroras, aircraft, searchlights, and birds. Project Blue Book was shut down in 1969 after a rigorous study led by the physicist Edward Condon concluded that UFO sightings all had mundane, nonthreatening explanations.
Since that time, the U.S. government no longer investigates claims of "flying saucers"—a term that dates back to the first widely reported UFO sighting by an American businessman in 1947. Independent groups of civilians still maintain that the government intentionally withholds information about UFO sightings, both past and present.
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