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Wednesday, 31 December 2008

Space news for the end of the year, 2008

Today:

  1. Gamma-Ray Evidence Suggests Ancient Mars Had Oceans
  2. Mysterious Source of High-Energy Cosmic Radiation Discovered
  3. 'Firefly' to scout Earth's puzzling gamma blasts
  4. Hopes rise for liquid water on Saturn moon
Most of them are short but very exciting, like the last one for example. Enjoy!

Gamma-Ray Evidence Suggests Ancient Mars Had Oceans

(PhysOrg.com) -- An international team of scientists who analyzed data from the Gamma Ray Spectrometer onboard NASA's Mars Odyssey reports new evidence for the controversial idea that oceans once covered about a third of ancient Mars.
"We compared Gamma Ray Spectrometer data on potassium, thorium and iron above and below a shoreline believed to mark an ancient ocean that covered a third of Mars' surface, and an inner shoreline believed to mark a younger, smaller ocean," said University of Arizona planetary geologist James M. Dohm, who led the international investigation.

Mars Odyssey's GRS, or Gamma Ray Spectrometer, led by William Boynton of UA's Lunar and Planetary Laboratory, has the unique ability to detect elements buried as much as 1/3 meter, or 13 inches, below the surface by the gamma rays they emit. That capability led to GRS' dramatic 2002 discovery of water-ice near the surface throughout much of high-latitude Mars.

Results from Mars Odyssey and other spacecraft suggest that past watery conditions likely leached, transported and concentrated such elements as potassium, thorium and iron, Dohm said. "The regions below and above the two shoreline boundaries are like cookie cutouts that can be compared to the regions above the boundaries, as well as the total region."

The younger, inner shoreline is evidence that an ocean about 10 times the size of the Mediterranean Sea, or about the size of North America, existed on the northern plains of Mars a few billion years ago. The larger, more ancient shoreline that covered a third of Mars held an ocean about 20 times the size of the Mediterranean, the researchers estimate.

Scientists studying spacecraft images have a hard time confirming "shoreline" landforms, the researchers said, because Mars shorelines would look different from Earth's shorelines. Earth's coastal shorelines are largely a direct result of powerful tides caused by gravitational interaction between Earth and the moon, but Mars lacks a sizable moon. Another difference is that lakes or seas on Mars could have formed largely from giant debris flows and liquefied sediments. Still another difference is that Mars oceans may have been ice-covered, which would prevent wave action.source

My comment: Isn't it lovely how Mars turns from Red Planet to Blue Planet in our understanding? Can you imagine the planet with its oceans flowing. And if two planets in our Solar System have oceans, imagine how many more outside it have them.

Mysterious Source of High-Energy Cosmic Radiation Discovered

(PhysOrg.com) -- Scientists announced Wednesday the discovery of a previously unidentified nearby source of high-energy cosmic rays. The finding was made with a NASA-funded balloon-borne instrument high over Antarctica.

Researchers from the Advanced Thin Ionization Calorimeter (ATIC) collaboration, led by scientists at Louisiana State University, Baton Rouge, published the results in the Nov. 20 issue of the journal Nature. The new results show an unexpected surplus of cosmic ray electrons at very high energy -- 300-800 billion electron volts -- that must come from a previously unidentified source or from the annihilation of very exotic theoretical particles used to explain dark matter.

"This electron excess cannot be explained by the standard model of cosmic ray origin," said John P. Wefel, ATIC project principal investigator and a professor at Louisiana State. "There must be another source relatively near us that is producing these additional particles."

According to the research, this source would need to be within about 3,000 light years of the sun. It could be an exotic object such as a pulsar, mini-quasar, supernova remnant or an intermediate mass black hole.

"Cosmic ray electrons lose energy during their journey through the galaxy," said Jim Adams, ATIC research lead at NASA's Marshall Space Flight Center in Huntsville, Ala. "These losses increase with the energy of the electrons. At the energies measured by our instrument, these energy losses suppress the flow of particles from distant sources, which helps nearby sources stand out."

The scientists point out, however, that there are few such objects close to our solar system.

An alternative explanation is that the surplus of high energy electrons might result from the annihilation of very exotic particles put forward to explain dark matter.

The 4,300-pound ATIC experiment was designed to be carried to an altitude of about 124,000 feet above Antarctica using a helium-filled balloon about as large as the interior of the New Orleans Superdome. The goal was to study cosmic rays that otherwise would be absorbed into the atmosphere. source


ВръзкаMy comment: I wouldn't go for the dark energy explanation, simply because it's way too easy. It's just another name for the unknown. If you ask me, this should have a very physical explanation and I wonder what it might be.

'Firefly' to scout Earth's puzzling gamma blasts

Nov. 24, 2008

When space shuttle astronauts dispatched NASA's Compton Gamma Ray Telescope into orbit in 1991, scientists figured they would learn more about supernovas, black holes and other phenomena that blast off high-energy rays.

They never expected to uncover gamma ray flashes coming from Earth itself.

"Occasionally they saw these very strange events," said NASA's Doug Rowland, with the Goddard Space Flight Center in Greenbelt, Md. "They were very short, relatively weak compared to supernova events and they seemed to be coming from the Earth.

Other than manmade nuclear explosions there had been no known sources of terrestrial gamma rays, Rowland said.

Follow-up studies confirmed the discovery and left scientists scrambling for an explanation. A new mission, called Firefly, is being developed to test the leading theory: terrestrial gamma ray flashes are caused by lightning.

"So far there's just circumstantial evidence," Rowland told Discovery News.

The idea is that strong electrical fields over lightning are producing ions and electrons out of neutral gas and blasting them into space. The flashes last for just a fraction of a second, but they are very strong — up to 30 times more powerful than a cosmic ray.

The research is not just an academic curiousity. Allan Weatherwax, a Firefly co-investigator with New York's Siena College, points out that high energy electrons associated with the flashes could be a source of the charged particles that end up impacting spacecraft and satellites orbiting Earth.

The science instruments will be incorporated into a football-sized spacecraft known as CubeSat and launched as a secondary payload in 2010 or 2011. Firefly will cost about $1 million for a three-year mission.

Firefly is being designed to simultaneously track lightning strikes and gamma ray flashes to determine what relationship, if any, exists, and what types of lightning trigger the bursts.

© 2008 Discovery Channel source

My comment: I think it's very unlikely that those gamma emissions come from lightening. Obviously lightening is very high voltage, but still, I don't think it can produce such a rush of particles to be seen from the space. I think it's something more fancy, like aliens for example. If they used something to travel trough space, it is likely that it will involves exotic particles. Sure, it sounds little crazy, but why not? We have a Blue Mars, the possibility of intelligent extra-terrestrials grows with every new research we make.

Hopes rise for liquid water on Saturn moon

ET Nov. 26, 2008

WASHINGTON - Astronomers looking at the spectacular supersonic plumes of gas and dust shooting off one of Saturn's moons say there are strong hints of liquid water, a key building block of life.

Their research, appearing in Thursday's issue of the journal Nature, adds to the growing push to explore further the moon Enceladus as one of the solar system's most compelling places for potential life.

Using images from NASA's Cassini probe, astronomers had already figured that the mysterious plumes shooting from Enceladus' icy terrain contain water vapor. New calculations suggesting the gas and dust spew at speeds faster-than-sound make the case for liquid, said study lead author Candice Hansen of NASA's Jet Propulsion Lab in California. Her team calculated the plumes travel more than 1,360 mph.

Other planetary scientists, such as Andrew Ingersoll at the California Institute of Technology, said the research is good, but that it is possible to achieve such speeds with ice particles and at cooler temperatures. So Hansen hasn't proven her case yet, he and other scientists said.

Europa, a moon of Jupiter, may have a liquid ocean beneath its frozen surface. But Enceladus, thought responsible for producing one of Saturn's rings, is more accessible, Hansen said. source

My comment: Well, I can't say much here. It makes sense to have water on those moons, because their planets are big, they emit heat, they have tidal force and they protect them from flying bombs. It's just the obvious place for water and for life.

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