China’s the world’s largest single radio dish telescope, is now fully operational

China’s Five-hundred-meter Aperture Spherical Radio Telescope, known as FAST, is the world’s most sensitive listening device.

The single-dish radio telescope is made of 4,450 individual panels that scan the sky, detecting the universe’s whispers and shouts. It’s cradled in a natural Earth depression the size of 30 soccer fields.

It has more than twice the collecting area of the world’s previous largest radio telescope, the 305-meter dish in Arecibo, Puerto Rico. With construction completed in 2016, FAST has undergone rigorous testing and has one more hurdle before it’s considered fully operational.

At the end of September, the $171 million USD (1.2 billion CNY) project will undergo the final review process in China, called the National Construction Acceptance.

In this final national review, FAST must demonstrate that it meets its initial specifications.

Those specifications were first laid out in the telescope’s design proposal in 2008. The NAOC says that in a review carried out earlier in 2019, FAST already that is as sensitive, if not more, than the original design spec.

Once we pass this review, FAST becomes an accepted telescope for exploring the Universe, said JIANG Peng, FAST’s chief engineer and deputy director of FAST Operation and Development Center, NAOC. Fast has been open to Chinese astronomers since April 2019. After the National Construction Acceptance, it will be open to astronomers across the world.

Both LI and Jiang emphasize international collaboration when it comes to using FAST. As LI said in a press release, Our hope for FAST is an open-sky policy, with the goal of advancing the work of humanity.

Though FAST was wholly funded by the government of China, other organizations like Australia’s Commonwealth Scientific and Industrial Research Organization collaborated on the project.

But while LI and Jiang are in favor of granting access to international scientists (they’ve both worked with the Arecibo telescope and with radio telescopes in Australia,) it’s not yet clear how that will play out. Usage decisions will be up to the government of China.

Radio telescopes have been around since about 1937, when amateur astronomer Grote Reber built one in his backyard in Illinois. It was a 9 meter parabola, and it’s considered the beginning of radio astronomy.

Now radio telescopes are enormous installations. Some are monolithic like FAST and Arecibo, while some are collections of individual dishes covering a large area, like the Very Large Array in New Mexico, which has 28 separate 25 meter dishes.

A pulsar is formed when a giant star collapses into a rotating neutron star. As it rotates, the neutron star emits a beam of intense radiation. That beam can’t be seen visually, but radio telescopes like FAST can listen for it. By monitoring the pulsar with a powerful radio telescope like FAST, astronomers can also learn about other phenomena like gravitational waves.

Fast Radio Bursts are transient pulses of radio waves that last anywhere from a fraction of a millisecond to several milliseconds. Many FRBs have been detected, even three that repeat.

But so far, their exact origin is a mystery, though they seem to be from outside the Milky Way. Though their signals are faint once they reach Earth, they are extremely energetic; much more than pulsars. FAST will hopefully advance our understanding of FRBs.

These observations could improve our understanding of high-energy physics, star evolution, and galaxy evolution.

FAST has been operating scientifically for a while now, even though it hasn’t passed its final review. Scientists working with it have already discovered 130 new pulsar candidates, and 93 of those have been confirmed with other radio telescopes.

These are great results, especially when compared with the Arecibo facility, which has discovered 200 pulsars since 1968.

In fact, FAST’s power and sensitivity has been producing other results, too. On August 29th, it detected more than a few dozen bursts from FRB 121102, which is the first repeating FRB source ever discovered. Other major radio telescopes around the world have been monitoring FRB 121102 since it was first discovered in 2012, but FAST is the first telescope to detect so many bursts in such a small amount of time.

FAST’s science team is analyzing data from those detections and they hope to shed some light on the origin of FRBs.

FAST astronomers will also use its power to look for hydrogen out there in space. Hydrogen is both the most plentiful and the oldest chemical element. “We’re going to discover curious emissions,” JIANG said. These observations could improve our understanding of high-energy physics, star evolution, and galaxy evolution.

FAST will also perform two sky surveys which will take about five years. It’ll take another ten years just to analyze all that data. Still, as JIANG says, there’s room for flexibility in the telescope’s operational schedule, to pursue any surprises that come up.

There’s already been one submission process for scientists hoping to use FAST to pursue their own research. In that process, FAST received 133 proposals involving over 500 scientists. In the future, we can expect to see a constant flow of scientific papers based on FAST data.

Sources / Further Reading: Universe today

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