QZS-5

QZS-5

Artist's rendering of QZS-5 in orbit
Mission type	Navigation
Operator	CAO
COSPAR ID	2025-308A
SATCAT no.	67231
Website	https://qzss.go.jp/
Spacecraft properties
Spacecraft type	QZS Block III-Q [1]
Bus	DS2000
Manufacturer	Mitsubishi Electric
Launch mass	4.8t
Dry mass	2.0t
Payload mass	647kg [2]
Power	6.7kW
Start of mission
Launch date	22 December 2025, 01:51:00 (2025-12-22UTC01:51Z)  UTC
Rocket	H3-22S
Launch site	Tanegashima, LA-Y2
Contractor	JAXA
Orbital parameters
Reference system	Geocentric
Regime	Medium Earth orbit
QZSS ←  QZS-6 QZS-7  →

QZS-5 (Michibiki No.5) was a Japanese navigation satellite lost during launch. It was intended to form part of the Quasi-Zenith Satellite System (QZSS). QZS-5 was to be deployed to a quasi-zenith orbit (QZO).

Satellite

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 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]

Launch

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]}

Comparison of QZS-5, 6, and 7

Comparison of QZS-5, 6, and 7 ^{[2] [1]}

Schematics of satellite	QZS-5	QZS-6	QZS-7
Design life (after launch)	15 years
Launch date	22 December 2025	2 February 2025	February 2026
Orbit	QZO	GEO	QGEO
Rocket	H3-22S
Mass (dry/launch)	1.8t/4.8t	1.9t/4.9t	2.0t/5.0t
Block type	III-Q	III-G	III-G
Payload electricity consumption	2.4kW	2.7kW	3.0kW
Position, Navigation, and Timing (PNT)	L1-C/A (L1-C/B), L1C, L5
Precise Point Positioning (PPP)	L6
Position Technology Verification Service (PTV)	—	L1Sb, L5S
L-band antenna type	Patch antenna
Precise Ranging Payload (PRP)	Inter-satellite ranging (ISR), satellite/ground bi-directional ranging
Message Communication Payload (MCP)	—		S-band (MCP developed by MELCO)
Secondary Payload	—	SĀCHI

References

1. "Constellation Information". Cabinet Office . Retrieved 2025-12-09.
2. "Establishing A Seven Satellite Constellation for Quasi-Zenith Satellite System in order to Realize High Precision Positioning Society" (PDF) (in Japanese). Mitsubishi Electric. 2021. Retrieved 2025-12-09.
3. Hayashi, Kimiyo (December 6, 2024). "準天頂衛星「みちびき」7機体制へ—「マイハザードマップ」を作る中学生の期待". DSPACE (in Japanese). Retrieved 2025-12-09.
4. "「みちびき」7機体制で、GPSの日本単独運用を目指す 高精度な測位サービスを支えるNECの技術と人" (in Japanese). NEC . Retrieved 2025-12-09.
5. "高精度測位システム（ASNAV）". JAXA . Retrieved 2025-12-09.
6. Watanabe, Hibiki (December 9, 2024). "準天頂衛星システムみちびき6号機機体公開". Space Authors Club (in Japanese). Retrieved 2025-12-09.
7. "JAXA | H3ロケット8号機の打上げ失敗及び対策本部の設置". JAXA | 宇宙航空研究開発機構 (in Japanese). Retrieved 2025-12-22.
8. Jones, Andrew (22 December 2025). "Japan's H3 suffers second-stage anomaly, QZS-5 satellite lost". SpaceNews.

External links

• Special website of launch (in Japanese)
• Michibiki seven-satellite constellation special website (in Japanese)