Rosetta Spacecraft

Rosetta Spacecraft On Its Way To Meet Asteroid Steins

ScienceDaily (Aug. 29, 2008) — ESA’s Rosetta spacecraft will make a historic encounter with asteroid (2867) Steins on 5 September 2008. The doors of ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany, will be open to the media as of 18:00 on 5 September to follow the fly-by events. Read more

Rosetta
Organization	European Space Agency
Major contractors	European Space Agency
Mission type	Comet Orbiter/Lander
Flyby of	Earth, Mars, 2867 Šteins, 21 Lutetia
Satellite of	67P/Churyumov-Gerasimenko
Launch date	March 2, 2004 at 07:17 UTC
Launch vehicle	Ariane 5
Decay	N/A
Webpage	ESA-Rosetta

Rosetta is a European Space Agency-led robotic spacecraft mission launched in 2004 intended to study the comet 67P/Churyumov-Gerasimenko. Rosetta consists of two main elements: the Rosetta space probe and the Philae lander. The spacecraft will also flyby and examine two asteroids on its way to the comet.

The probe is named after the Rosetta Stone, as it is hoped the mission will help unlock the secrets of how our solar system looked before planets formed. The lander is named after the Nile island Philae where an obelisk was found that helped decipher the Rosetta Stone.

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How Do Galaxies Grow?

How Do Galaxies Grow? Massive Galaxies Caught In The Act Of Merging

ScienceDaily (Aug. 26, 2008) — Astronomers have caught multiple massive galaxies in the act of merging about 4 billion years ago. This discovery, made possible by combining the power of the best ground- and space-based telescopes, uniquely supports the favoured theory of how galaxies form.

How do galaxies form? The most widely accepted answer to this fundamental question is the model of 'hierarchical formation', a step-wise process in which small galaxies merge to build larger ones. One can think of the galaxies forming in a similar way to how streams merge to form rivers, and how these rivers, in turn, merge to form an even larger river. This theoretical model predicts that massive galaxies grow through many merging events in their lifetime. But when did their cosmological growth spurts finish? When did the most massive galaxies get most of their mass?

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Cattle shown to align north-south

By Elizabeth Mitchell
Science reporter, BBC News

Cattle (J Cerveny)
Cattle partake in some directional grazing

Have you ever noticed that herds of grazing animals all face the same way?

Images from Google Earth have confirmed that cattle tend to align their bodies in a north-south direction.

Wild deer also display this behaviour - a phenomenon that has apparently gone unnoticed by herdsmen and hunters for thousands of years.

In the Proceedings for the National Academy of Sciences, scientists say the Earth's magnetic fields may influence the behaviour of these animals.

The Earth can be viewed as a huge magnet, with magnetic north and south situated close to the geographical poles.

Many species - including birds and salmon - are known to use the Earth's magnetic fields in migration, rather like a natural GPS.

A few studies have shown that some mammals - including bats - also use a "magnetic compass" to help their sense of direction.

Dr Sabine Begall, from the University of Duisburg-Essen, Germany, has mainly studied the magnetic sense of mole rats - African animals that live in underground tunnels.

"We were wondering if larger animals also have this magnetic sense," she told BBC News.

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NASA Images Show Gamma Ray Bursts Across Milky Way

This all-sky view from Fermi reveals bright gamma ray emissions in the plane of the Milky Way, center, and in bright pulsars and super-massive black holes. (Nasa/u.s. Department Of Energy/international Large Array Telescope Team)

By Sindya N. Bhanoo

Washington Post Staff Writer
Wednesday, August 27, 2008; Page A03

NASA researchers yesterday released images collected by a new telescope studying high-energy gamma rays. A combined image from 95 hours of the telescope's initial observations showed bursts of gamma rays glowing across the plane of the Milky Way.

The Gamma-Ray Large Area Space Telescope, renamed Fermi, was launched in June and is off to a promising start, NASA scientists said.

"I like to call it our extreme machine," said Jon Morse, the director of astrophysics for NASA. "It will help us crack the mysteries of these enormously powerful emissions."

Gamma rays are powerful light rays invisible to the naked eye. Because Earth's atmosphere absorbs gamma rays, they can be studied only from the outskirts of the universe.

Fermi is gathering data on gamma rays that originate near black holes and high-energy stars called pulsars.

Though much remains unknown, bursts of gamma rays are thought to be emitted from particles coming out of black holes and pulsars, said Peter Michelson, a Stanford physicist and a principal investigator for the mission.

"We don't yet understand the mechanism for how the particles that emit the gamma rays are accelerated," Michelson said. "We're not even sure what the nature of the particles are."

The study is a follow-up on work done by the Energetic Gamma-Ray Experiment Telescope, a mission that studied gamma rays from 1991 to 2000.

Fermi's technology allowed scientists to compile in days what took the first mission one year to do, said Steve Ritz, one of the project's scientists.

The telescope was renamed Fermi yesterday, after Italian physicist Enrico Fermi, because he is "today regarded as one of the top scientists of the 20th century," Ritz said.

The scientists hope that in the five to 10 years that it is in orbit, Fermi will be as remarkable as its namesake.

"This powerful space observatory will explore the most extreme of environments for us," Morse said.

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Mystery Of Young Stars Near Black Holes

Until now, scientists have puzzled over how stars could form around a black hole, since molecular clouds - the normal birth places of stars - would be ripped apart by the black hole's immense gravitational pull.

However, the new study by Professor Ian Bonnell (St Andrews) and Dr Ken Rice (Edinburgh) found that stars appear to form from an elliptical-shaped disc, the remnant of a giant gas cloud torn apart as it encounters a black hole.

The discovery of hundreds of young stars, of high masses and making oval-shaped orbits around a black hole three million times more massive than the sun, and at the centre of our Galaxy, is described as one of the most exciting recent discoveries in astrophysics.

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Cell Self-destruction for the Greater Common Good

Random molecular processes during cell division allow some cells to engage in a self-destructive act to generate a greater common good, thereby improving the situation of the surviving siblings

Normally, salmonellae grow poorly in the intestine because they are not competitive with other bacteria of the gut. However, this dynamic changes if salmonellae induce an in-flammatory response, namely diarrhoea, which suppresses the other bacteria. The in-flammation is triggered by salmonellae penetrating into the intestinal tissues. Once in-side, salmonellae is killed by the immune system. This in turn creates a conflict: salmonellae are either suppressed by the other bacteria in the gut, or die while trying to eliminate these competitors.

In recent years it has been recognized that such random processes in a cell can have a large influence on individual cells. The work by the ETH Zurich researchers reveals a new biological explanation for this phenomenon. Prof. Ackermann says, "Random processes could promote job-sharing in many different types of organisms." Many bacteria manufacture substances which are toxic to their hosts but which are only released into the host environment if the bacteria sacrifice themselves - if this is the sole method to get the toxin out of the cell. This is why every cell makes a decision: toxin and death or no toxin.


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Black holes and the formation of stars

Now Ian Bonnell, an astronomer at the University of St Andrews in Scotland, and William Ken Rice of the University of Edinburgh have created a computer simulation that offers a possible explanation for how the stars could have formed. They detailed their model in the Aug. 22 issue of the journal Science.

In their model, a giant gas cloud plunges in toward the black hole. As it gets close, much of the cloud is ripped apart by the black hole's gravity, though some portion of it survives because of the turbulence of the gas in the cloud.

This remnant forms an oval disk of gas orbiting around the black hole, gravitationally bound but beyond the range within which it would be sucked in. Variations in the density of the material in the disk then cause it to condense into stars and break up, leaving the stars in an oval orbit around the black hole where the disk used to be.

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