Closer to sky, Chile’s ALMA Observatory spots secrets of universe

Parched, sun-beaten, windswept and barren, the Atacama Desert in northern Chile is definitely inhospitable to any human. A global scientific community, however, braves the punishing reality.

As conditions there are ideal for stargazing, scientists have joined hands in building one of the world’s highest astronomical observatories: the Atacama Large Millimeter/submillimeter Array (ALMA) telescope.

Situated more than 5,000 meters above sea level on the Chajnantor Plateau, the ALMA consists of 66 individual antennas pointing skyward to capture millimeter and submillimeter radio waves, turning the unnoticed corner into eyes of the Earth.

“Strictly speaking, the ALMA is an interferometer,” ALMA visitor coordinator Danilo Vidal told Xinhua. “That is a combination of many antennas whose objective is to simulate one major telescope.”

The ALMA is a joint project among the European Southern Observatory, the U.S. National Science Foundation, and the National Institutes of Natural Sciences of Japan, all in cooperation with Chile.

It is “unique in its class and additionally a giant of its kind,” as it simulates a telescope with up to 16 km in diameter, Vidal added. “The bigger the diameter, the better the resolution of the equipment, so it’s more powerful. So the more we open up this telescope, the better.”

While Vidal and his colleagues work in an environment that is fully oxygenated and held to the highest safety standards, stepping outside in the harsh desert is a different story.

Due to the high altitude, fierce wind, and intense ultraviolet radiation there, employees are urged to use an oxygen tank, wear clothes that cover the entire body, and be careful not to exert themselves.

This extremely arid zone is perfect for receiving cosmic waves, said Dario Hernandez, an electrical engineer who has worked on the antenna maintenance team for seven years.

“Signals are so low” in frequency that they would be difficult to be detected in other places, but “because we are in a drier place, we have less atmosphere” to interfere with the reception, Hernandez said.

Signals captured by the antennas would be digitized and sent via fiber optic cables to one of the fastest supercomputers around the world. It has more than 134 million processors and, more importantly, can operate at an extremely high elevation.

“As there has never existed a tool of this nature, with this capacity, all observation that the ALMA does is historic,” Vidal said.

According to Richard Simon, a scientist at the observatory, one of the ALMA’s greatest achievements was capturing detailed images of the formation site of a giant planetary system in 2014.

The image shows a series of brilliant concentric rings separated by dark gaps, where scientists believe planets could form.

On Wednesday, astronomers in different countries announced that they had captured the first ever image of a black hole, thanks to the Event Horizon Telescope (EHT), an Earth-sized virtual telescope network linking eight telescopes around the globe.

The ALMA helped to guarantee high-quality calibration of the data from the other telescopes, leading to the EHT’s fantastic images, according to ALMA Director Sean Dougherty.

Although each antenna weighs more than 100 tons, they are sufficiently solid to withstand being relocated without their mechanisms suffering damage.

Moving them around the desert plateau is “analogous to changing lenses on a camera, and that’s what we do all year,” said Vidal. “This is what many scientists dream about.”