Undersea neutrino observatory to be second-largest human structure


December 19, 2011

Visualized: the height of a KM3NeT detection unit

Visualized: the height of a KM3NeT detection unit

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An audacious project to construct a vast infrastructure housing a neutrino observatory at the bottom of the Mediterranean Sea is being undertaken by a consortium of 40 institutes and universities from ten European countries. The consortium claims that KM3NeT, as it is known, will "open a new window on the Universe," as its "several" cubic kilometer observatory detects high-energy neutrinos from violent sources in outer space such as gamma-ray bursts, colliding stars and supernovae.

A property of neutrinos that makes their observation compelling to physicists is their lack of charge. This makes them immune to electromagnetic forces that may influence or interfere with alternative means of observation, such as photons and cosmic rays. Neutrinos are therefore ideal for observing the Universe at very great distances.

That neutrinos interact only very weakly with matter necessitates a detector in the order of a billion kg (2.2 billion lb), hence the requirement for such a large volume of seawater. A cubed array of optical modules is deployed, which detect light given off by muons which are emitted as neutrinos interact with the sea.

Though yet to begin construction, the KM3NeT project stands on the shoulders of the decade-long research projects known as ANTARES, NEMO and NESTOR. ANTARES is presently the largest neutrino observatory in the northern hemisphere, though KM3NeT will claim that title upon completion. For now, the University of Wisconsin's IceCube Neutrino Observatory, completed last December, is the largest in the world and will work together with the completed KM3NeT, effectively forming a global neutrino observatory with a view of the whole sky.

A new opportunity afforded by KM3NeT will be the ability to look for high-energy neutrinos from the Galactic Center (which is barely visible to the IceCube) where a supermassive black hole is thought to exist. Scrutiny of neutrinos from the Galactic Center by KM3NeT may assist with the identification of dark matter by looking for the neutrinos produced by neutralino annihilation, neutralinos being thought to accumulate in the centers of very large objects in space.

Giorgio Riccobene told Popsci that on the scale of human constructions, it will be second only to the Great Wall of China. In addition to the neutrino observatory, KM3NeT will house equipment for monitoring the deep-sea environment, including (according to Popsci) the recording of whale song and the observation of bioluminescent organisms.

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life. All articles by James Holloway

I am tired of the assertion that the Great Wall is the largest human construction, or the only one visible from space. Four thousand square miles of Holland (the quarter of the country that would be sea without human intervention) is surely bigger by volume, and naked-eye visible from further away. This makes KM3NeT third.


freaky, i am scared.

Martin Siry

It reminds me of the Tower of Babel.

Adrian Akau

Geometeer, I think the point is that the Great Wall and the Pyramids were marvels created by the ancient world. Your marvel of keeping the sea at bay is a modern marvel, but it was done with modern machinery and engineering. The Hoover Dam was also such an engineering feat. The area of land that it made arable was considerable too.


All right Geometeer. Yours is bigger.

Anyway, back to the point, it seems that the scientific community is full on searching for WIMPs (to prove the theories of dark matter and super symmetry) by observing for example the annihilations of neutralinos. Very nice.

Is there a plan as to the whereabouts of the site ?


Riccobene\'s \"on the scale of human constructions, it will be second only to the Great Wall of China\" said nothing about date -- and date can hardly be the point, since KM3NeT will be \"done with modern machinery and engineering\". As to whether Holland was, the first stage was in the sixteenth and seventeenth centuries, which pumped dry many lakes for agriculture, with windmills. In the nineteenth century, they pumped more, by steam. Where does \"modern\" begin?

Facebook User

I thought the IceCube could see the galactic center just fine, since neutrinos are hardly affected by the whole earth mass.


I hate to ask an obvious question, but, how would this structure affect and/or be affected by, submarines? In peacetime, or during warfare? Will it be strong enough to pierce the hull of a nuclear submarine? \"It couldn\'t happen here [there, or anywhere]\" is not a comforting assurance. Neither is, \"We\'ll post it off limits on the charts\".

Myron J. Poltroonian

Labels like \"modern\" and \"natural\" are subjective and carry no objective meaning, making them useless for communicating ideas. I suggest that the first person to use their mind to survive was employing the most potent tool possible. Their technological development at that point is irrelevant.

Too bad this enterprise is not built for profit. It would be better and cheaper. The less public projects the better, no matter how grand they seem.


Where the detector is placed is dependent upon what type of Nutreno is to be observed, what advantage is there to having a detector in a busy shipping lane full of plankton, silt debris and sonic disturbance over the current methods of using glaciers in the Antarctic and solvent tanks in salt mines ?.

Looks cheaper with a large number of detector towers mainly by people who do not understand the expense of working in such an extreme environment for a long time. In 1901 Marconi\'s first antenna at Poldhu was destroyed by storms, a very similar structure to this one. One pressure wave from a distant landslide would do horrible things to the instrument. To get a quick repair job done it is a far cry from erecting 2 masts and a long copper cable.


I agree with k2backhoe; what will this reveal to us that Ice Cube (for which I built components) wont? And do we really need several more tons of man-made junk polluting an ecosystem for such a tiny scientific outcome?

Peter Wright
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