Tokyo — For the past quarter of a century, Japan's No. 2 automaker, Nissan Motors, has been quietly turning out space and military rockets. So quietly, that many of the company's own staff were hardly aware of the activity.
There was no secrecy involved - ''It was simply that we only contribute a miserly 0.4 percent to the company's annual turnover,'' explains Kazuo Shibata, general manager of the Aeronautical and Space Division.
Mr. Shibata, however, has recently been inundated with visitors, particularly Japanese reporters, after a company announcement it planned a stronger emphasis in future on its nonautomotive activities. (Nissan turns out almost 3 million cars and trucks a year.)
''Top executives have told us they would like to see our annual sales turnover increase tenfold over the next few years,'' the division chief explains.
Nissan's space and defense activities are handled from a Tokyo factory that once belonged to the Nakajima Aircraft Company. Between 1914 and the end of World War II the company turned out almost 30,000 bombers and fighters for the Imperial Army.
Now half of this division's annual output goes to the military. The rest involves satellites and rockets for scientific research.
The company is now playing a leading role in developing the solid-fueled N-series rockets which Japan plans to use to launch practical satellites in the next few years. The satellites would be for such purposes as weather observation , communications, broadcasting, geological studies, and scientific experiments.
The automaker is in charge of developing the rocket motors and many of the metal structural parts, and has a joint venture with another company producing rocket fuel. For the defense forces, it has been making surface-to-surface rockets and air-to-air rockets.
Now Nissan is steadily moving into the missile field. Under American license it is making motors and parts for the US-developed Hawk and Sparrow missile systems now used by the Japanese military.
Now the thrust of research and development allows Nissan to produce future guided missiles from start to finish, Shibata says.
Although there is a strict government ban on the export of any type of military-related equipment, Nissan would still like to export some of its other products, like the strictly scientific rockets.
Says the Nissan executive: ''We have been approached many times by foreign companies proposing various projects, including joint manufacturing. But nothing has been accomplished so far, because the attitude of the Foreign Ministry and Ministry of International Trade and Industry is not favorable to us.
''A number of our space scientists, too, want very much to see Japanese-developed rockets exported. But the government is very severe.''
For the time being, therefore, Nissan must concentrate on building up domestic sales. For the past three years these have hovered around the $52 million mark, but a 30 percent increase is the target for fiscal 1982.
Shibata says: ''Nissan considers this division a must in contributing to national defense and security. It's not the scale of sales that is the most important, therefore, but the consideration that this might create a better corporate image.''