# Himawari 4

> Japanese meteorological satellite launched in 1989

**Wikidata**: [Q11276484](https://www.wikidata.org/wiki/Q11276484)  
**Source**: https://4ort.xyz/entity/himawari-4

## Summary
Himawari 4 is a Japanese meteorological satellite launched in 1989 as part of the Himawari series. It was a spin-stabilized weather satellite designed to monitor weather and climate, operating in geostationary orbit. The satellite was decommissioned in 2000 after serving for over a decade.

## Key Facts
- Launched on September 5, 1989, at 19:11 UTC from the Osaki Launch Complex.
- Part of the Himawari series of Japanese meteorological satellites.
- Operated by the Japan Meteorological Agency and the National Space Development Agency.
- Massed 725 kg at launch and 325 kg at service entry.
- Dimensions: 345.1 cm in height and 214.6 cm in diameter.
- Launched using the H-I rocket (H-20(F) variant).
- Manufactured by Hughes Aircraft Company (United States).
- Spin-stabilized satellite with a geostationary orbit.
- Decommissioned in February 2000, classified as a derelict satellite.
- Preceded by Himawari 3 and succeeded by Himawari 5.

## FAQs
### Q: What was Himawari 4's primary purpose?
A: Himawari 4 was a weather satellite designed to monitor weather and climate, providing data for Japan's meteorological agency.

### Q: How long did Himawari 4 operate?
A: The satellite was operational from December 1989 to June 1995 before being decommissioned in February 2000.

### Q: What type of orbit did Himawari 4 use?
A: Himawari 4 operated in a geostationary orbit, allowing it to remain stationary relative to Earth's surface.

### Q: Who built Himawari 4?
A: The satellite was manufactured by Hughes Aircraft Company (United States) and launched by Japan.

### Q: What was unique about Himawari 4's stabilization?
A: Himawari 4 used spin stabilization, a method where the satellite rotates to maintain its orientation in space.

## Why It Matters
Himawari 4 was part of Japan's early efforts to establish a reliable weather monitoring system in space. As a spin-stabilized satellite, it demonstrated an innovative approach to maintaining stability without complex attitude control systems. The satellite contributed to Japan's meteorological capabilities, providing critical data for weather forecasting and climate research. Its decommissioning marked the end of an era for the Himawari series, which later evolved into more advanced satellites like Himawari 8 and 9. The satellite's role in early space-based weather observation highlights Japan's growing expertise in satellite technology and its commitment to environmental monitoring.

## Notable For
- First Japanese meteorological satellite in the Himawari series.
- Pioneered spin stabilization for weather satellites.
- Operated in geostationary orbit for over a decade.
- Developed by Hughes Aircraft Company, showcasing international collaboration.
- Precursor to later, more advanced Himawari satellites.

## Body
### Launch and Design
Himawari 4 was launched on September 5, 1989, using the H-I rocket (H-20(F) variant) from the Osaki Launch Complex. The satellite was spin-stabilized, meaning it relied on rotation to maintain its orientation in space. This design choice simplified the satellite's structure and reduced the need for complex attitude control systems. The satellite had a launch mass of 725 kg and a service entry mass of 325 kg. Its dimensions were 345.1 cm in height and 214.6 cm in diameter, typical for geostationary weather satellites of the era.

### Operational Period
Himawari 4 entered service in December 1989 and remained operational until June 1995. It was decommissioned in February 2000, transitioning to a derelict satellite status. During its operational life, it provided valuable weather and climate data to the Japan Meteorological Agency and the National Space Development Agency. The satellite's geostationary orbit allowed it to continuously monitor weather patterns over Japan and the surrounding region.

### Technological Significance
Himawari 4 was built by Hughes Aircraft Company, reflecting the international collaboration in early space programs. The satellite's spin-stabilized design was a technological innovation for the time, demonstrating that reliable weather monitoring could be achieved with simpler systems. The satellite's decommissioning marked the end of an era for the Himawari series, which later evolved into more advanced models like Himawari 8 and 9.

### Legacy
Himawari 4's legacy lies in its role as a foundational satellite in Japan's meteorological satellite program. It contributed to the development of Japan's space-based weather monitoring capabilities and set the stage for future advancements in the field. The satellite's decommissioning in 2000 signified the transition to newer, more sophisticated satellites, ensuring continued progress in weather observation and forecasting.

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## References

1. [Source](https://space.skyrocket.de/doc_sdat/gms-2.htm)
2. Jonathan's Space Report
3. [Source](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-070A)
4. [Source](https://www.jaxa.jp/projects/sat/gms/index_j.html)