FAST: China officially opens world’s largest radio telescope

27 Sep 2016


China has given a new dimension to the search for extra-terrestrial life, or ETs – and the scientific and lay world is equally excited.

The largest radio telescope in the world officially opened on Sunday, according to China's official Xinhua News.

The Five-hundred-meter Aperture Spherical Telescope, or FAST, is named after its diameter, which, at 500 metres, is 195 metres wider than the second-largest telescope of its kind, the Arecibo Observatory in Puerto Rico.

Xinhua reports the telescope cost $180 million and 8,000 people were displaced from their homes to create the necessary 3-mile radius of radio silence around the facility. It will be used for "observation of pulsars as well as exploration of interstellar molecules and interstellar communication signals."

Pulsars are imploded cores of stars slightly larger than the sun, which emit radiation that can be detected from Earth, if your telescope is sensitive enough. A researcher with China's National Astronomical Observation, Qian Lei, told Xinhua the new telescope is so sensitive, in a test it detected radio waves from a pulsar 1,351 light-years away.

The telescope, comprised of 4,450 panels, is nestled in a natural crater in the remote Pingtang county in China's southern Guizhou province. Green hillsides of karst formations, dissolved and eroded over eons, envelope the wok-shaped dish. It is the ideal environment for a radio telescope, according to The New York Times. The karst serve as a natural barrier against earthly radio noise and wind that could drown out whispers from space. The Arecibo Observatory in Puerto Rico, was built into a similar environment.

Like radio telescopes in other parts of the world, FAST will study interstellar molecules related to how galaxies evolve. For example, this summer a team using data from the Very Large Array, a collection of radio antennas in the New Mexico desert, picked up what scientists describe as "faint radio emission from atomic hydrogen ... in a galaxy nearly 5 billion light-years from Earth." In the paper describing their findings, the team writes that the "next generation of radio telescopes", like FAST, will build on their findings about how gases behave in galaxies.

As for FAST's final use, studying interstellar communication signals, it could be more simply referred to as searching for intelligent extra-terrestrial life. "In theory, if there is civilization in outer space, the radio signal it sends will be similar to the signal we can receive when a pulsar ... is approaching us," Qian told Chinese state media.

About 984 feet, or 300 meters, wide, the Arecibo Observatory was used by Joseph Taylor, an astronomer at Princeton University, in his discovery of indirect proof of gravitational waves, which earned him a Nobel Prize in 1993.

FAST has double the sensitivity of its Puerto Rican counterpart, and five to 10 times the surveying speed, according to Xinhua. Yet, both telescopes more or less operate the same way: They detect electromagnetic radiation in the cosmos.

''This is light with a wavelength a million times or so longer than our eyes can detect,'' writes Elias Brinks, an astronomer at the University of Hertfordshire, in a contribution to US News and World Report. ''Not surprisingly, the sky at these long wavelengths looks vastly different, which is exactly why observations at radio wavelengths reveal information that is not accessible with optical telescopes.''

The resolution of the images will appear much worse than how we see the world with our own eyes. But the sheer size of FAST will allow it to collect vast amounts of signals from even the deepest reaches of space.

"A radio telescope is like a sensitive ear, listening to tell meaningful radio messages from white noise in the universe.'' Nan Rendong, chief scientist of the FAST project with the National Astronomical Observatories, Chinese Academy of Sciences, told Xinhua when the construction of FAST was completed in July. ''It is like identifying the sound of cicadas in a thunderstorm."

FAST is optimized to detect neutral hydrogen, ''the most abundant element in the universe, and raw materials from which stars are formed,'' writes Dr Brinks.

''FAST will be able to make a complete census down to much lower levels of the hydrogen content of the local universe than has been possible so far,'' he says. ''How much hydrogen is found, where and in what kind of agglomerations, will have direct consequences for how scientists think the universe evolved from its earliest phase and how galaxies formed and have continued to grow with time.''

The telescope is also expected to discover thousands of pulsars, according to Xinhua. Pulsars can serve as ''high-precision clocks'' to reveal gravitational waves from black holes or even the Big Bang, offering a window into the beginnings of the universe.

China also hopes to use the telescope to search for signs of alien life. The telescope could detect extraterrestrial signals sent to Earth, intentionally or accidentally. This search has proven fruitless in the six decades the world has sought out extra-terrestrial life. But FAST marks a significant investment in this search. The $180-million price of the project (which some have reported sounds modest) is much more than the "shoestring" this quest has operated on, as Pete Spotts reported for The Christian Science Monitor in July 2015.

The results of that search aren't expected to come soon, as scientists must calibrate the telescope over the next three years. But, FAST also represents a shift in the types of investments China has made.

''Chinese science is often seen as serving the country's economic and military expansion, seeking ruthlessly practical dividends,'' wrote Chris Buckley and Adam Wu for The New York Times. ''But the telescope shows the government in Beijing is also willing to spend heavily to propel China high into the big leagues in research that offers few direct payoffs, apart from knowledge and prestige.''

Communication could go both ways. In 1974, the Arecibo radio telescope sent a signal deep into space with a graphic containing, among other things, images of "the Arecibo telescope, our solar system, DNA, a stick figure of a human, and some of the biochemicals of earthly life", according to the SETI institute, a scientific organization devoted to the search for extra-terrestrial life.

In an interview with the BBC, the deputy project manager for the new Chinese telescope, Peng Bo, said the project was exciting for Chinese scientists. "For many years, we have had to go outside of China to make observations - and now we have the largest telescope," he said.

The FAST telescope – which spans 1,640-feet, and whose combined area is equal to almost 450 basketball courts – shows China's growing ambition to be a science and space superpower. But the country has also emphasized the importance of collaborating with the international scientific community in its quest to understand the stars and, perhaps, discover other galactic inhabitants.

China's investment in space exploration is not limited to earth-based telescopes. Although it is not one of the countries that helps run the International Space Station, China launches its own rockets carrying satellites. Earlier this month, China launched Tiangong-2, its second space lab, shortly before its first space lab fell back to earth.

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