Japanese navigation constellation set to expand with H-IIA launch
Japan is set to launch its third H-IIA rocket in 2017. The two-stage booster, the workhorse vehicle for the Japanese space agency, will send to space Michibiki-2, the second satellite in the country’s regional navigation system.
Liftoff is currently scheduled for 8:17 p.m. EDT on May 31 (00:17 GMT June 1) from the Tanegashima Space Center in Japan. As of May 30, Michibiki-2 has been encapsulated inside the fairing of the 174-foot (53-meter) tall rocket. The weather for the area at launch time is expected to have partly cloudy skies with a five percent chance of precipitation. The temperature will be around 74 degrees Fahrenheit (23 degrees Celsius).
Michibiki-2 is part of the Quasi-Zenith Satellite System (QZSS), which is a regional navigation system that operates from inclined, elliptical geosynchronous orbits known as “figure-eight” Tundra orbits. Four satellites are planned for this constellation and will broadcast GPS-interoperable and augmentation signals in addition to QZSS signals. Three will operate in Tundra orbits, while one will be in a geostationary orbit (GEO).
The Japan Aerospace Exploration Agency (JAXA) is building the system to increase the accuracy of navigation devices in the country. Currently, these devices utilize the U.S.-built GPS system. However, according to JAXA, because there is a small number of satellites in Japan’s field of view, services have not always been offered in a stable way.
Once Michibiki-2, as well as Michibiki-4 in 2018, is launched, the system will become operational. Importantly, it can be used with the GPS system to augment their signals to increase accuracy. According to JAXA, eight or more visible satellites are ideal. There are currently five to seven GPS satellites regularly visible. With the fully operating QZSS, that would allow for eight to 10 visible satellites.
While Michibiki-2 will be the second satellite in the system to be launched, it will actually be the first of Phase 2, which will demonstrate the full system capability. Phase 1 involved sending Michibiki-1 into space back in 2010 as a technology demonstrator. However, it will be part of the primary three-satellite constellation along with Michibiki-2 and 4. Michibiki-3, when it launches, will augment the system from GEO.
According to JAXA, satellite signals from one or two satellites can be obstructed in urban areas and more mountainous regions, which includes most of Japan, so the agency will ultimately expand the number of QZSS satellites to seven.
Michibiki-2 has a mass of about 8,800 pounds (4,000 kilograms). It will operate in an orbit that is 20,268 miles (32,618 kilometers) by 24,202 miles (38,950 kilometers) and inclined by 41 degrees. It was built by Mitsubishi Electric.
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a blog about the International Space Station, called Orbital Velocity.