Japan’s Mitsubishi Heavy Industries will launch an H-IIA (H-2A) rocket Tuesday (local time) carrying the country’s QZSS-4 navigation satellite. The rocket is expected to depart from the Tanegashima Space Centre at 07:01 local time (22:01 UTC on Monday).
QZSS-4, which will be known as Michibiki No.4 once in orbit, is the fourth member of the Quasi-Zenith Satellite System (QZSS), a constellation of satellites which Japan is launching to improve the accuracy of satellite navigation in its densely-populated cities.
QZSS broadcasts additional signals compatible with the US Air Force’s Global Positioning System (GPS), providing additional points of reference that a QZSS-enabled receiver can use to triangulate its position.
GPS, as well as its Russian and European counterparts GLONASS and Galileo, use constellations of satellites in medium Earth orbit. Each satellite carries highly-accurate atomic clocks and broadcasts signals that encode the exact time of transmission.
A receiver can use these signals to calculate the distance to the satellite from the difference in time between the signal being transmitted and received. By computing the distance to several satellites – whose positions are known from their orbit ephemeris – the receiver can triangulate its position.
A receiver must be able to pick ...