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Tennis-Court-Sized Antennas Launched into Orbit (December 21, 2006)

An image of the ETS-VIII in orbit (Courtesy of JAXA)

On the afternoon of December 18, 2006, the Japan Aerospace Exploration Agency (JAXA) launched the Engineering Test Satellite KIKU No. 8 (ETS-VIII) , Japan's biggest satellite to date. The satellite was loaded with two record-large antennas, each as big as a tennis court. Once in orbit, the antennas will unfurl like umbrellas, and experiments will be conducted with them. If successful, the tests will pave the way for direct communications between the satellite and portable terminals the size of mobile phones.

Opening the Antennas
KIKU No. 8 is a geostationary satellite that is 7.3 meters tall, 3.7 meters long, 4.6 meters wide, and weighs 5.8 tons. It is the eighth in a series of satellites that first went into orbit in 1975. Designed primarily for communications tests that link the satellites with earth, the KIKU were developed by JAXA jointly with the National Institute of Information and Communications Technology (NICT) and Nippon Telegraph and Telephone Corporation (NTT) with a budget of approximately ¥50 billion ($43.4 million at 115 yen to the dollar).

Unfolding the antenna (trial) (Courtesy of JAXA)

KIKU No. 8 was loaded with two antennas, each measuring 19 meters by 17 meters and spanning an area about the size of a tennis court when open. One antenna will be used for transmission and the other for reception. They are the largest in the world and far bigger than the satellite antennas used today, which at most are 10 meters long. The antennas were folded during the satellite's launch and opened a week later with a spring mechanism.

Trying Experimental Stage
The process of opening the antennas in space is extraordinarily difficult because of differences in the gravity acting on them on Earth and in space. The massive size of the antennas ruled out trial experiments on the ground before the launch, and JAXA instead sent into space smaller antennas twice and conducted experiments on them. The first time, the antenna failed to open properly, but the second time success was achieved just in time for the actual launch.

A computer-generated image of the ETS-VIII (Courtesy of JAXA)

Once the satellite goes into orbit and the antennas are unfurled, JAXA will start conducting tests on direct communications between the satellite and portable terminals sometime in April 2007, in the goal of making it possible to obtain information on areas where ground communications equipment has been damaged by disasters. Advances in satellite communications technologies are expected to be instrumental in enhancing emergency vehicle services during crises, speeding up rescue operations, and improving people's lives in many other ways.

Copyright (c) 2006 Web Japan. Edited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.