NASDA's ETS-VII, comprising of two joined satellites named "Chaser" and "Target" were successfully launched in November 1997 into 550km orbit. After a series of performance tests, the first unmanned docking test of the satellite was carried out by NASDA on July 7th 1998.

Mitsubishi Electric designed and developed the Rendezvous Docking (RVD) system on ETS-VII, including its operating and commanding facilities at ground tracking station. The system required sensor technology to accurately locate the position of the two satellites and to guide satellite to its destination on time. It was also necessary to be able to freely control satellite attitude and position. While developing the system, Mitsubishi Electric built the Rendezvous Docking Operation Test System (RDOTS) on ground to simulate the movement of satellite in space, and to test the sensors and navigation control.

On July 7th at 7:09 a.m. Japan time, the command for separation was transmitted from NASDA's tracking station in Tsukuba. Receiving the command, "Chaser" activated its docking system, and released "Target." The proximity sensor control guided and maintained "Target" at the range of 2 meters from "Chaser" for approximately 15 minutes. At command," Target" approached "Chaser" at 1cm/sec., using thruster engine to guide itself to point of capture. The two satellites rejoined at 7:27 a.m., making it the first successful unmanned docking of satellites in space. NASDA will carry out another docking test on August 7, taking the two satellites to the distance of 500m, which will be followed by another test taking them 9 km apart.

The success of Mitsubishi Electric's docking system on ETS-VII grounded the path for a more efficient and reliable system for the H- II Transfer Vehicle (HTV). The HTV is NASDA's unmanned satellite planned for launch in 2000 which will transport equipment and supplies to the international space station. The HTV is currently under development by Japanese rocket and satellite companies including Mitsubishi Electric.