TOKYO >> The Japan Aerospace Exploration Agency (JAXA) will start developing a new high-efficiency radar system in 2018 to monitor space debris as small as about 4 inches, as part of its efforts to avoid collisions between debris and artificial satellites, according to sources.

JAXA plans to begin full-scale operation of the radar as early as 2023 in cooperation with another radar system separately designed by the Defense Ministry, sources said.

The agency currently uses a radar system deployed in Okayama Prefecture to monitor space debris that travels over Japan in low Earth orbit at an altitude of several hundred to 1,243 miles. However, the current system only covers debris that is 5 feet across or larger. The majority of space debris is about 4 inches.

JAXA is to build the new radar system adjacent to the existing one. The agency aims to achieve 200 times the detection capability of the current radar, by significantly increasing the output of electric waves cast onto space debris and utilizing a processing technology for special signals.

If data analysis suggests the possibility of collisions between space debris and JAXA’s 10 satellites operating in low orbit, the agency will use the system to change the satellites’ orbit from the ground by remote control.

The Defense Ministry is also preparing to install a radar system in Yamaguchi Prefecture to monitor space debris in stationary orbit at an altitude of about 22,370 miles. Satellites traveling in stationary orbit include communication and meteorological satellites that are important for activities of the Self-Defense Forces.

The number of pieces of space debris — including broken pieces of artificial satellites and wreckage from rockets — has been increasing yearly with the progress of each country’s space development.

About 20,000 space debris particles that are 4 inches or larger are mainly in low orbit.

In 2009, a U.S. satellite collided with a defunct Russian satellite, sending the U.S. satellite out of control. In 2011, space debris narrowly missed the International Space Station.