Use of a NASA Telemetry Data and Relay Satellite is seen as a second-best and expensive option. But it became inevitable following the Feb. 21 failure of the Communications and Engineering Broadcasting Test Satellite to reach geo-stationary orbit and make its inter-satellite communications link with ETS-7 possible, according to NASDA's ETS-7 project manager, Mitsushige Oda, March 24.

"After calculating the orbit of COMETS, we decided it was technically impossible to use it [for ETS-7]," he said. Oda said that the National Space Development Agency of Japan (NASDA) would pay NASA around $7.5 million.

The additional cost will be paid out under coverage provided by the Japanese insurance industry�s first foray into government space activities.

ETS-7 is a twin satellite that is designed to divide into two, fly apart and recombine in order to test remote controlled and automatic docking technologies which will be used to support Japan's international space station resupply shuttle, the H2 Transfer Vehicle. Six such maneuvers are planned from June, which will need close visual and data monitoring to prevent possible collisions.

In addition, the satellite carries a main robot arm to be used for refueling and orbital repair simulations and a series of smaller experiments by national research institutes and government agencies.

But ETS-7's mission is now endangered if a poorly operating high power antenna essential to maintain communications with the NASA satellite fails, said Oda. If the high power antenna loses further power, Oda said NASDA would have to use the satellite's lower power omni-directional antenna- which would involve up to one minute time delays for visual and technical data rerouted between NASA and NASDA communications networks.

"Using the omni-directional antenna may give us a technical challenge- I'm not saying it is impossible, but I'm not saying it is easy, either," he said.

Problems with the antenna began February 3 with the cause either in a transponder portion built by NEC Corp. of Tokyo or a cable made by ETS-7's intregrator, Tokyo-based Toshiba Corp., according to a March 18 technical assessment report released by NASDA to the Space Activities Commission.

"Toshiba is blaming NEC and is blaming Toshiba. They have been arguing a lot, but nobody really knows which part is wrong," Oda said.

Officially, the antenna output is "stable but a little bit low," according to Akihiro Fujita, Director of the Science and Technology Agency's aeronautics and space development division, March 23.

Apart from this, the report gave ETS-7 a relatively clean bill of health, with the satellite apparently recovering from a troubled start which saw a string of attitude control glitches delay the satellite's check out.

Oda said the software reprogramming since December has helped mask noise between the satellite's gyro and gateway attitude control computer, which persistently threw the satellite out of position, had done so. Despite this, another glitch occurred on March 3 when a gas jet fired after the satellites attitude control systems again miscued, but "we quickly identified and solved the problem," Oda said.

"Although the cause of the noise has not been revealed, NASDA has successfully changed ETS-7's software, so as regards attitude control, the situation has been made healthy. For the time being, technically we don't think a serious condition [with attitude control] will happen again," Fujita told Japan Space Net.

But a senior member of the Science and Technology Agency, speaking on condition of anonymity, expressed doubts that masking the noise could guarantee stability, adding the possibility of more bumps along ETS-7's rather less than smooth ride through LEO.

"The attitude control systems computers still have interface problems. The continuing noise is a problem. We can't guarantee nominal operation, it's a terrible problem. The docking experiments are a gamble." the official said.

Fujita said that in the event of ETS-7 not collecting enough data to prove Japan's automatic docking techniques, NASDA would probably redefine the H2A Transfer Vehicle flight plan to include a trial flight in 2001 which will not dock with the international space station.

A NASDA source conceded that this was a possibility.

Oda said that an integration error revealed by the March 18 report in which Toshiba misaligned the satellite's main 2 meter robot arm by 30 degrees luckily would not hinder the satellite's multiple robotics experiments.

Another member of Japan's space establishment also revealed that the Space Activities Commission had been "extremely angry" over the glitch.

"From a technical viewpoint ETS-7, will be operational from April," Oda said.