COLORADO SPRINGS, Colo. — Japan, which just committed more than $500 million to expand a satellite system to enhance GPS signals over its territory, is eyeing a new constellation of spacecraft for regional maritime surveillance, according to a government official.

Tomotaka Inoue, deputy counselor in Japan’s Cabinet-level Office of National Space Policy, said the country has experienced a number of maritime territorial incursions and is unable to keep watch over its home waters via terrestrial means.

The proposed constellation would be developed in cooperation with the Association of Southeast Asian Nations (ASEAN), a collection of countries including Indonesia with large swaths of territorial waters.

The proposed ASEAN Disaster Monitoring Constellation is still in the discussion phase, Inoue said in a brief interview following a presentation here at the 29th National Space Symposium. The satellites would be smaller and cover wider territory at lower spatial resolutions than Japan’s Information Gathering Satellites for military reconnaissance, now in orbit.

Disaster monitoring has emerged as a Japanese priority following passage of a 2008 law that overhauled Japan’s space policy. In addition to permitting Japan to deploy military space systems, the law, which was updated in January, redirects Japanese space development away from technology-focused projects to those with practical applications and economic benefits.

In his address to the conference, Inoue outlined a number of priority investment areas for Japan’s $3 billion-per-year space program: positioning, navigation and timing; remote sensing, including military reconnaissance and weather; communications; and launch vehicles.

In the first category, Japan has put its money where its mouth is, recently awarding Mitsubishi Electric Corp. of Tokyo a $539 million contract to expand the number of satellites in its Quasi-Zenith Satellite System (QZSS) from the current one that is on orbit to four. Inoue said plans call for eventually having seven satellites in the QZSS system, a regional overlay that enhances the accuracy of signals from the U.S. GPS satellite constellation.

Military space also is a priority given recent developments involving North Korea, Inoue said. The Information Gathering Satellite program was hatched in the late 1990s to keep tabs on North Korea, for example.

Inoue said Japan cooperates with the United States on a number of military space-related activities, including missile defense, QZSS and the Information Gathering Satellite system. Space situational awareness, which refers to the ability to detect and track objects in Earth orbit, is the next area of cooperation, he said.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...