# ALOS-4

> Japanese synthetic-aperture radar satellite

**Wikidata**: [Q22131682](https://www.wikidata.org/wiki/Q22131682)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/ALOS-4)  
**Source**: https://4ort.xyz/entity/alos-4

## Summary
ALOS-4 (Advanced Land Observing Satellite 4), also known as Daichi-4, is a Japanese synthetic-aperture radar (SAR) satellite operated by the Japan Aerospace Exploration Agency (JAXA). Launched on July 1, 2024, it succeeds the lost ALOS-3 satellite and is designed to observe the Earth's surface using L-band radar while also tracking maritime vessels via an automatic identification system (AIS).

## Key Facts
- **Launch Date:** July 1, 2024, at 03:06:00 UTC.
- **Launch Vehicle:** H3 Launch Vehicle (flight H3-F3).
- **Operator:** Japan Aerospace Exploration Agency (JAXA).
- **Manufacturer:** Mitsubishi Electric.
- **Mass:** 2,990 kg (launch weight).
- **Orbit:** Sun-synchronous orbit.
- **Design Life:** 7 years.
- **Instruments:** Phased Array L-band Synthetic Aperture Radar (PALSAR) and a satellite automatic identification system (AIS).
- **Predecessor:** ALOS-3 (destroyed in a launch failure).
- **Identifiers:** COSPAR ID 2024-123A; NSSDCA ID 2024-123A; SCN 60182.

## FAQs
### Q: What is the primary function of ALOS-4?
A: ALOS-4 is a synthetic-aperture radar satellite designed for Earth observation. It also functions as an AIS satellite, capable of tracking maritime vessels.

### Q: When was ALOS-4 launched?
A: ALOS-4 was successfully launched on July 1, 2024, from the Yoshinobu Launch Complex Launch Pad 2.

### Q: How does ALOS-4 relate to ALOS-3?
A: ALOS-4 follows ALOS-3, which was a Japanese satellite destroyed in a launch failure.

### Q: What rocket was used to launch ALOS-4?
A: The satellite was launched using the Japanese H3 Launch Vehicle, specifically configuration H3-F3.

## Why It Matters
ALOS-4 represents a critical step in Japan's ongoing commitment to space-based Earth observation and disaster management. Following the destruction of its predecessor, ALOS-3, the successful deployment of ALOS-4 on July 1, 2024, restores and advances the country's capability to monitor the Earth's surface. The satellite is significant because it combines two distinct but complementary technologies: a high-performance Phased Array L-band Synthetic Aperture Radar (PALSAR) and a satellite automatic identification system (AIS).

The inclusion of L-band SAR allows the satellite to image the Earth's surface through clouds and regardless of weather conditions, which is vital for monitoring disasters such as earthquakes, floods, and landslides. Simultaneously, the AIS receiver enables the satellite to track ships across the ocean, enhancing maritime safety and security. Manufactured by Mitsubishi Electric and weighing nearly 3 tons, ALOS-4 is a substantial piece of infrastructure with a design life of 7 years, ensuring long-term data collection for both environmental monitoring and maritime situational awareness.

## Notable For
- **Dual Capability:** It is distinct for operating as both a synthetic-aperture radar satellite and an AIS satellite simultaneously.
- **Restoration of Capability:** It successfully restores the "Daichi" (Land Observing) series after the loss of ALOS-3.
- **H3 Rocket Payload:** It is a notable payload for the H3 Launch Vehicle (flight H3-F3), Japan's flagship expendable launch system.
- **High Power Capacity:** The spacecraft is powered by two solar arrays generating 5,200 watts of power, supporting its advanced radar systems.

## Body
### Mission Overview
ALOS-4, known natively as "陸域観測技術衛星4号" (Land Observing Technology Satellite No. 4), is an artificial satellite developed by Japan. It falls under the class of synthetic aperture radar satellites and AIS satellites. The mission follows the timeline of the ALOS series, specifically succeeding ALOS-3.

### Technical Specifications
The satellite has a total launch mass of 2,990 kilograms. It is designed to operate in a Sun-synchronous orbit for a service life of 7 years. To power its onboard systems and radar instruments, ALOS-4 utilizes a spacecraft solar array system consisting of 2 panels with a combined generation capacity of 5,200 watts.

### Scientific Instruments
The payload includes two primary systems:
1.  **Phased Array L-band Synthetic Aperture Radar (PALSAR):** The primary instrument for high-resolution surface imaging.
2.  **Satellite Automatic Identification System:** An instrument designed to track maritime vessels.

### Launch Details
ALOS-4 was launched on July 1, 2024. The launch took place at the Yoshinobu Launch Complex Launch Pad 2. The launch vehicle was the H3 Launch Vehicle, specifically the H3-F3 variant. The launch contractor was Mitsubishi Heavy Industries. The satellite was assigned the COSPAR ID 2024-123A upon successful deployment.

## Schema Markup
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  "name": "ALOS-4",
  "description": "Japanese synthetic-aperture radar satellite and AIS satellite operated by JAXA.",
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## References

1. [Source](https://space.skyrocket.de/doc_sdat/alos-4.htm)
2. [Source](https://www.eoportal.org/satellite-missions/alos-4)
3. [Source](https://www.satnavi.jaxa.jp/ja/project/alos-4/)
4. SATCAT
5. [Source](https://nextspaceflight.com/launches/details/2554)
6. Jonathan's Space Report
7. [Source](https://space.oscar.wmo.int/satellites/view/alos_4_daichi_4)