Japan’s Mitsubishi Heavy Industries will launch an H-IIA rocket Saturday, carrying the third spacecraft for the country’s Quasi-Zenith Satellite System of GPS augmentation satellites. The H-IIA is scheduled to lift off from the Tanegashima Space Centre with QZS-3 at 13:40 local time (04:40 UTC).
The QZS-3 satellite, which after launch will be named Michibiki No.3, will be placed into geosynchronous transfer orbit by Saturday’s launch. It is part of a constellation of spacecraft intended to improve the accuracy of satellite navigation in built-up areas. The Quasi-Zenith Satellite System (QZSS) will initially consist of four satellites, broadcasting additional signals compatible with the US Global Positioning System (GPS).
A GPS receiver determines its position by using precise timing signals from a constellation of at least twenty-four satellites in Medium Earth orbit. The time signals are used to calculate the distance to each satellite, allowing a receiver to triangulate its position. In order to achieve a precise location, at least four satellites must be visible to the receiver.
QZSS is designed to help Japanese users overcome a shortcoming of the GPS constellation which causes receivers to become less accurate in cities where large numbers of tall buildings form urban canyons. Buildings ...