QZS-5

QZS-5 was the second of three Michibiki satellites to be launched to expand QZSS to a seven-satellite constellation. In 2017, Michibiki's four-satellite constellation was established, and with it there are at a minimum two Michibiki satellites (one in QZO and one in GEO) constantly visible from Japan. Satellite navigation requires at least four satellites to be visible, so users need to receive signals from QZSS and other global navigation satellite system (GNSS) at the same time.^[3] In its seven-satellite constellation, four Michibiki satellites (one in QZO, two in GEO, and one in quasi-geostationary orbit (QGEO)) will be constantly visible from Japan, thus eliminating the system's dependancy on other GNSS. QZS-5 was to join QZS-2 and 4, QZS-1R in Quasi Zenith Orbit.

QZS-5 was manufactured by Mitsubishi Electric (MELCO), and its positioning mission payload was manufactured by NEC.^[4] QZS-5 had an intended design life of 15 years.^[2] Like QZS-6 and QZS-7, the satellite had a Precise Ranging Payload (PRP) consisting of Inter-satellite ranging (ISR) and satellite/ground bi-directional ranging. PRP enabled the satellite to achieve a precise positioning measurement compared to previous Michibiki satellites. The Japan Aerospace Exploration Agency's Advanced Satellite Navigation System (ASNAV) project is responsible for Michibiki's PRP.^[5] For ISR, QZS-5 was to be the source of the signals. QZS-6 and QZS-7 were to receive QZS-5's signal to measure the distance between them.^[6]

QZS-5 was launched aboard an H3-22S rocket on 22 December 2025. An anomaly occurred during the second-stage burn that led to a premature engine cutoff and the subsequent loss of the QZS-5 satellite.^[7][8]