Since it was completed in 2008, scientists have been using the Telescope Array cosmic ray observatory it to study incredibly tiny particles coming at us from space with enormous energy. They are billions of times more powerful than anything we can create on Earth. The mystery is: What awesomely violent process is launching them?
"Well, that's the billion dollar question. These particles are extremely rare. But when they do hit us, they hit us with an enormous bang."
–Prof. Pierre Sokolsky
"These particles are streaming towards us. It's like looking down the barrel of a gun," said professor Pierre Sokolsky, dean of the University of Utah's College of Science. The University of Utah is one of more than 30 research institutions around the world that are involved in the desert-based project.
At a glance, it doesn't look like one of the world's largest scientific instruments. Most of the individual components, each about the size of a billiard table, are isolated by themselves in a vast desert west of Delta. More than 500 of the so-called "scintillation detectors" are spread across 300 square miles.
There are also three huge observatory buildings containing a total of 38 telescopes. Their segmented mirrors are aimed at the sky, looking for ultra-high-energy cosmic rays. The high-energy particles are distinct from low- energy cosmic rays that originate in our own Sun. Low- energy cosmic rays pass through our bodies by the thousands every day. Ultra-high-energy cosmic rays originate in much more distant and mysterious parts of the universe. They are relatively rare and typically collide with air molecules in the outer fringes of Earth's atmosphere, disintegrating them into a shower of sub- atomic particles. The Telescope Array is designed to detect those showers.
The 507 scintillation detectors capture traces of the particles as they spread across the desert. The mirrored telescopes are only used at night because they're looking for a cone-shaped glow of light streaking down through the atmosphere.
"We're looking for very faint light, essentially a hundred-watt light bulb moving at the speed of light," said professor John Matthews, project manager of the Telescope Array.
On Main Street in Delta, the University of Utah has now opened the Millard County Cosmic Ray Visitor Center. It gives members of the public a chance to get up to speed on one of the universe's most baffling mysteries. Something in space is launching in the incredibly small particles with astounding levels of energy. The ultra-high energy cosmic rays are essentially single protons, each one packing the punch of a World Series fastball. But where, exactly, is the cosmic pitcher's mound?
"Well, that's the billion dollar question," Sokolsky said. "These particles are extremely rare. But when they do hit us, they hit us with an enormous bang."
The particles hit the Earth's atmosphere from every direction and scientists say they must be launched by some extraordinarily violent process in the Universe. The best guess now is that the cosmic rays originate in what's known as an Active Galactic Nucleus, Matthews said, "which has a black hole at the center, and it's basically sucking in galaxies. Some of those particles shoot out and maybe some of them are getting here to us."
Sokolsky said the effort to understand these awesome centers of energy in the Universe may go on for years. He said the knowledge that might come from that has an unknown potential for practical applications, but as a pure question of science, human curiosity makes it an exciting project.
"It's the mystery. It's the chase," said Sokolsky.
The visitor center will generally be open weekdays, 10:30 a.m. to 2:30 p.m. Displays will provide lots of information to visitors, but no final answer.
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