LLANO DE CHAJNANTOR, Chile – Earth’s largest radio telescope is growing more powerful by the day on this remote plateau high above Chile’s Atacama desert, where visitors often feel like they’re planting the first human footprints on the red crust of Mars.
The 16,400-foot altitude, thin air and mercurial climate here can be unbearable. Visitors must breathe oxygen from a tank just to keep from fainting. Winds reach 62 mph and temperatures drop to 10 below zero.
But for astronomers, it’s paradise.
The lack of humidity, low interference from other radio signals and closeness to the upper atmosphere make this the perfect spot for the Atacama Large Millimeter/submillimeter Array, or ALMA, which is on track to be completed in March.
So far, 43 of the 66 radio antennas have been set up and point skyward like 100-ton white mushrooms. Linked as a single giant telescope, they pick up wavelengths of light longer than anything visible to the human eye, and combine the signals in a process called interferometry, which gives ALMA a diameter of 9.9 miles.
The result is unprecedented resolution and sensitivity – fully assembled, its vision will be up to 10 times sharper than NASA’s Hubble Space Telescope.
“What surprises me is what is being observed. Until now, we haven’t had such a capable observatory. We’ve never been able to observe with such resolution, such accuracy,” says David Rabanus, ALMA’s instrument group manager.
900 teams compete
More than 900 teams of astronomers competed last year to be among the first to use the array, and scientists from around the world are already taking turns at the joysticks.
They’re looking for clues about the dawn of the cosmos – from the coldest gases and dust where galaxies are formed and stars are born, to the energy produced by the Big Bang. So-called birthing clouds of cold gases and debris can look like ink stains with other telescopes, but ALMA can show their detailed structures.
ALMA also reaches farther beyond Earth’s nitrogen-blue skies than any other radio telescope and has already captured images different from anything seen before by visible-light and infrared telescopes. After a 2003 groundbreaking, scientific operations began last year with a quarter of ALMA’s final capacity.
Seeing in three dimensions made possible the recent discovery of a spiral structure surrounding R Sculptoris, providing new insights about how dying red giant stars implode and send off raw material that will later form into other stars. Those results were published in the scientific journal Nature.
ALMA has even been able to detect sugar molecules in the gas surrounding a star about 400 light-years away, proving the existence of life’s building blocks there.
Jointly funded and managed by the United States, Canada, the European Union, Japan and Taiwan, the $1.5 billion project is an engineering triumph that launches Chile, already home to some of the world’s largest optical telescopes, to the forefront of ground-based space exploration.
“We’re talking about the United Nations of astronomy joined for a billion-dollar adventure. Scientists are like kids playing with very expensive toys, and these ones are technological developments that could change the world,” said Jose Maza, a University of Chile astronomy professor.
Going to extremes
At ALMA, scientists and researchers are willing to go to extremes to catch a glimpse of the universe through those eyes.
As many as 500 people at a time live at 9,500 feet above sea level in shipping containers modified as trailers. Their shifts can last 12 hours daily for eight straight days.
Inside ALMA’s control room, German astronomer Rainer Mauersberger had no idea he had put his orange sweater on backward. He was thinking about the formation of galaxies, hoping perhaps to spot a black hole.
“This project has to do with the origin of our life and our future,” Mauersberger explained as he sat near a long table full of Halloween masks, used by the scientists to share a light moment or a laugh to break up the long days and nights of stargazing.
“It’s about how can we predict our future climates, the evolution of the earth, the sun, our species,” he said. “We know more about our universe, our culture, than we ever dreamt of 100 years ago.”
