China science

How Chinese space station’s ‘modest-sized’ telescope can measure up to American giants

While many scientists believe ‘size is king’, one Chinese astronomy expert claims the smaller China Space Station Telescope (CSST) will have an advantage in researching gravitational waves, among other tasks

PUBLISHED : Wednesday, 09 March, 2016, 7:45pm
UPDATED : Monday, 12 June, 2017, 12:53pm

China faces a David and Goliath-style competition with the United States regarding its newly announced space telescope, astronomers say.

In the first official confirmation of China’s plans, Zhou Jianping, the chief designer of China’s manned space programme, revealed on Tuesday the country would install a telescope with a 2-metre mirror on its Tiangong Space Station set for launch after 2020.

Over the following decade it will survey nearly half the universe in search of dark matter, dark energy and earth-like planets, said Zhou.

But the modest size of the China Space Station Telescope (CSST) prompted some unfavourable comparisons with its giant-sized American competitors.

The James Webber Telescope, scheduled for launch in 2018, will have a 6.5-metre mirror, while Nasa is also planning the Advanced Technology Large-Aperture Space Telescope (ATLAST), which will have a whopping 10-metre mirror – five times the size of the CSST’s.

Even the Hubble Telescope, launched quarter of a century ago, sported a 2.4-metre mirror.

“In the world of telescopes, size is king. The bigger a telescope, the more it sees and the more clearly it sees,” said Kou Wen, senior engineer with the Beijing Planetarium.

He said the CSST would give astronomers another powerful tool to study the universe, but it stood little chance in a head-on competition with the American giants.

But Zhou Jianfeng, associate professor of astronomy with Tsinghua University, likened China’s telescope to the biblical character David, who according to myth defeated the giant Goliath with a sling shot.

The CSST’s field of view was 300 times that of Hubble at the same image resolution, which meant it was “300 times more efficient”, said Zhou.

That would help astronomers in tasks where speed and precision were key, such as researching gravitational waves.

Zhou said that like David, the CSST had a “slingshot” that gave it an edge.

The American telescopes operated as independent spacecraft, which meant when repairs or upgrades were needed a human crew needed to be sent. This was risky, time consuming and costly.

The Hubble Telescope, for instance, had required five shuttle flights at the cost of billions of US dollars. The economic burden forced Nasa to cancel all service missions after 2009.

But the CSST would get around the issue because it was mounted on a manned space station that would remain in orbit for decades.Components for upgrades would be carried up by the regular cargo ship visits to the station.

Zhou cautioned that putting such a telescope on a space station had not been done before due to the technical difficulties involved. Tiny shaking caused by machines or humans on the station could interfere with the telescope’s ability to take ultra-sharp images.

China was developing technology to solve the issue, Zhou said. “If it works, it will be a big innovation in space history.”