End of an era for space-exploring antenna in Japan

TOKYO: Having handled communications for Japan’s space exploration efforts for over 30 years, including with the asteroid probe Hayabusa, the 64-meter (about 209 foot) diameter giant antenna at the Japan Aerospace Exploration Agency (JAXA)’s Usuda Deep Space Centre in Saku, Nagano Prefecture, is to be retired from front-line service.

Construction on a new antenna will begin this spring, with the handover set for three years’ time. Those involved say they will miss the country’s largest antenna, which detected Hayabusa after its signal was lost, and supported its return to Earth in 2010.

Plans for the current antenna were conceived in 1979. As Japan was considering its involvement in the international study of Halley’s Comet, which was due to near Earth in 1986, an opportunity was recognised to build a communications antenna that could be used for Japan’s space exploration well into the future.

Those responsible for construction – led by Tomonao Hayashi, now 88 and a professor emeritus at the University of Tokyo – chose Usuda (now Saku) from a list of 10 candidate locations for its high elevation, low rainfall and distance from urban areas and aircraft flight paths.

For the antenna at U sud a, J AX A adopted a new design earlier than the US National Aeronautics and Space Administration (Nasa) did. The design increased the precision of signal receptions and the antenna immediately exhibited its great power in the international study of Halley’s Comet. The ability of its giant dish to receive even faint signals from probes several hundred millions of km away saved Japan’s space exploration from crisis on many occasions.

When communications with Hayabusa were interrupted in 2005 and recovery seemed hopeless, the antenna picked up a weak signal from the probe six weeks later. In 2010, it also detected radio waves from the missing probe Akatsuki after it had failed to enter orbit around Venus, and then ensured the success of another attempt in December last year.

Chief of the deep space centre, Zenichi Yamamoto, 57, said it was “thanks to our predecessors building a giant antenna even before Japan’s space exploration had begun in earnest.”

Usuda became known to astronomy fans as a “star city,” drawing about 5,000 visitors a year. However, having well exceeded its intended lifespan of 15 years, JAXA decided to begin operating from fiscal 2019 a new, slightly smaller but higher-powered antenna.

The future of the current antenna is uncertain. JAXA wants to keep it in reserve, but in the event of a malfunction there is no guarantee that repairs will be possible. Amid calls from residents not to demolish the antenna, a proposal to retain it as a radio telescope for astronomical observation is also being considered.

“More than anything, I am delighted that the antenna came to be loved by local residents,” Hayashi said. “Keep using it while it still can be used.”

More than anything, I am delighted that the antenna came to be loved by local residents. Keep using it while it still can be used.

– Tomonao Hayashi, professor emeritus at the University of Tokyo

— Yomiuri Shimbun photo Standing in front of the giant antenna that will be retired in three years in Saku, Nagano Prefecture, Japan, head of the center Zenichi Yamamoto says, “Without this, we could not have had a second chance with the Venus probe Akatsuki.”