Originally due for launch today by the sixth flight of the H2 -Japan�s first locally developed rocket, the rocket�s primary payload is Engineering Test Satellite-VII's. ETS-7 will conduct a series of automatic docking experiments to develop the skills needed to support a wide variety of activities on the Space Station.

ETS-7 will split into a 2480 kg main "chaser" bus and a square panel-shaped 410 kg "target" satellite. The two satellites will separate to distances ranging from 2 meters to 9 kilometers, then recombine. On a secondary level the satellite will also be used as a platform for performing several simple robot arm tests moving square blocks about on a panel.

Already considered technically and logistically difficult, the docking missions have had to be completely rescheduled following on going problems with the 2-ton Communications and Broadcasting Engineering Test Satellite (COMETS) that has yet to be launched. COMETS was to provide communications support as a feeder satellite, according to NASDA's ETS-7 program manager, Mitsushige Oda.

"If everything goes smoothly we'll now start in May. If not we'll have to start in June. ETS-7's orbit is not sun-synchronous and we can't get enough power to run the trials for two weeks every 50 days, and one of those periods falls in June," he said.

Extra pressure comes from insurance limitations and the costs of using NASA's TDRS-W and TDRS F7, the latter during STS missions, which are seen as less than ideal temporary replacements. Cover, currently "under negotiation" with a consortium of insurers lead by Tokyo Fire and Marine Insurance Company Ltd. only extends six months into the mission for the robot portion of the flight. Oda refused to say how much NASDA was paying for TDRS, usage of which was agreed only late in the summer, but he called it "very expensive."

"The budget has already been submitted, so we'll have to deal with the extra costs with the money we have, we'll have to manage," he said. Oda said that using TDRS posed some technical challenges integrating TDRS for the robot portion, but the mission would be placed in considerable difficulties if COMETS faced any further postponements, or failed. COMETS is currently scheduled for a January or February launch.

"The rendezvous docking experiments are based on using COMETS. If we have to use one of the TRDSs, we'll have to rewrite everything, and rewriting software entails risks," he said.

"It will be extremely difficult to complete the docking maneuvers using TDRS because of the 6-8 second time delays involved," but Toshiba and NASDA were already proceeding with contingency plans to cope, said Yoshio Toriyama, senior manager of Toshiba's spacecraft systems engineering dept., November 10.

The trials will help, but not be vital for Japan to develop the Hope Transfer Vehicle, an unmanned supply pod mounted on top of a H2A rocket which will supply the Japanese Experiment Module on the international space station, according to Oda.

"The success of ETS-7 will be good for the Hope Transfer Vehicle. Theory is going to be put into practice. But the supply vehicle will have its own test flight.

The supply vehicle is currently in conceptual design phase and is currently slated for a test launch in 2001.

But Mitsubishi Electric Corporation and Mitsubishi Heavy Industries, who look the most likely candidates to build the supply vessels' hardware regard the docking technologies as vital to the development of that program, said Mitsubishi Electric's ETS-7 program manager, Hiroshi Koyama. Mitsubishi Electric is responsible for designing much of the docking subsystems.

"Japan has no technologies for docking and this [ETS-7] is essential to our national development program," said Ryuichi Sekita, deputy director of that agency's space policy division, November 11. The mission is seen within Japan as a key test of NASDA's satellite building capability following the spate of failures that have plagued NASDA. In June this year the Advanced Earth Observing Satellite finally failed after a multitude of problems with apogee raising, its international sensor payload, and the collapse of its solar paddle. In 1994 ETS-7�s predecessor, ETS-6, couldn't reach proper orbit after its apogee engine failed, sabotaging the satellite's communications mission.

On top of everything else, integrating Japan's first twin satellite posed a "major challenge" for Toshiba, according to Toriyama, pushing the company and Japanese satellite development into new territory. "ETS-7 requires simultaneous operational technology, complicated communication links, integration of seven on-board computers and a development program that didn�t include engineering models for at least half of the satellite components," he said.

"We are walking a tightrope," said Mitsugi Chiba, director of the Science and Technology's space policy division, November 11, who said failure of any of the satellite's non-experimental components could cause a major policy review on satellite construction and further delays and costs for NASDA which can hardly afford them.

"If another failure occurs then it's very critical. The public will lose confidence in Japan�s reputation for reliability and it'll become a political problem," Sekita said. Further, more is at stake as the mission is the first launch of a major foreign satellite, NASA's Tropical Rainfall Measuring Mission satellite.

"The experiments will be very difficult. We don't need a complete success, just enough information to flight qualify the basic technologies. However if the satellite fails then the Hope Transfer Vehicle program will have to be delayed," he said.

Sekita also said that budget would be found for a small bus mission demonstration satellite-based back up mission as orbital docking capabilities was a high priority policy goal and, in any case, Japan was reluctant to rely or pay for supply missions hosted by STS or Soyuz missions.

Aside from docking experiments ETS-7, will carry a complex series of robot experiments. On the primary level a 2 meter, 140 kg Toshiba-built robot arm will conduct floating object recapture and simulated refueling experiments which the contractor sees as an essential step in its plans to build platform-mounted satellite-servicing robots, said Yoshio Toriyama.

"The arm builds on the legacy of the [recent STS-flown] Manipulator Flight Demonstration arm and the [Japanese Experiment Module's] remote manipulator system from which we will develop our orbital service vehicle," he said.

That platform is now in conceptual design stage, according to Koji Ito, chief specialist of Toshiba's space programs division.,

On a secondary level ETS-7 also mounts a Fujitsu Ltd advanced robotics hand sponsored by the Ministry of International Trade and Industry, an NEC Corp antenna assembly mechanism for the Communication Research Laboratory and a truss structure handling experiment built by Shimizu Corp for the National Aerospace Laboratory.

For NEC, the integration of four of the satellite's subsystems were important for NEC�s moves to commercialize its satellite technology, as well as providing crucial building blocks for the national program under NASDA, according to Shinjiro Otani, assistant general manager of NEC's space systems division.

The camera system, which is also being used on COMETS and the Institute of Space and Astronautical Sciences asteroid-sample-return mission MUSES-C, could become a NASDA monitoring standard. NASDA is considering onboard visual monitoring systems for some satellites following the collapse of the paddle of the Advanced Earth Observing Satellite. In communications, NEC supplied transponders which could conduct simultaneous inter-satellite and satellite ground links which NEC expects to be useful for future LEO constellations.

Otani said that the rendezvous radar, through which ETS-7 will largely be able to mate and disengage, will be vital for the H2A Transfer Vehicle's successful maneuvering. More importantly, the optical portion of the radar, now being redeveloped for inter-satellite laser communications for NASDA's OICETS satellite, was also a vital technology for large LEO satellite constellations such as Teledesic for which NEC was bidding on the inter-satellite subsystems component of Teledesic, he said.