# Akatsuki

> defunct Venus orbiter operated by JAXA

**Wikidata**: [Q416448](https://www.wikidata.org/wiki/Q416448)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Akatsuki_(spacecraft))  
**Source**: https://4ort.xyz/entity/akatsuki

## Summary
Akatsuki was a defunct Venus orbiter operated by the Japan Aerospace Exploration Agency (JAXA). Classified as a planetary probe and an orbiter specifically for Venus, its primary mission was to research the atmosphere of Venus. After its initial orbit insertion attempt failed in 2010, it successfully entered Venus orbit in 2015 and continued operations until contact was lost in April 2024, leading to its mission termination in September 2025.

## Key Facts
*   Akatsuki was launched on May 20, 2010, at 21:58:22 from Yoshinobu Launch Complex Launch Pad 1.
*   It was operated and commissioned by the Japan Aerospace Exploration Agency (JAXA).
*   The spacecraft had a launch weight of 517.6 kilograms and a dry weight of 321.3 kilograms.
*   Akatsuki is classified as a planetary probe, an orbiter (specifically for Venus), and a derelict satellite.
*   Its primary use was for research, specifically applying to the atmosphere of Venus.
*   The spacecraft measured 1.04 meters in width (spacecraft bus) and 2.12 meters in height.
*   It was powered by a photovoltaic system, generating 700 watts in Venus orbit and 480 watts in Earth orbit.
*   Akatsuki achieved Venus orbit insertion on December 7, 2015.
*   Its orbital period around Venus was 10.8 days, with an apoapsis of 370,000 kilometers and a periapsis of 10,000 kilometers.
*   Contact with Akatsuki was lost in April 2024, and its mission was officially terminated on September 18, 2025.

## FAQs
### Q: What was Akatsuki's primary mission?
A: Akatsuki's primary mission was to research the atmosphere of Venus. It was designed as a planetary probe and an orbiter specifically to study the Venusian climate.

### Q: Who operated the Akatsuki spacecraft?
A: The Akatsuki spacecraft was operated and commissioned by the Japan Aerospace Exploration Agency (JAXA). It was manufactured by NEC Space Technologies.

### Q: When was Akatsuki launched and when did it reach Venus?
A: Akatsuki was launched on May 20, 2010. After an initial failed attempt, it successfully entered orbit around Venus on December 7, 2015.

### Q: What is the current status of Akatsuki?
A: Akatsuki is currently a defunct Venus orbiter and is classified as a derelict satellite. Contact with the spacecraft was lost in April 2024, and its mission was officially terminated on September 18, 2025.

### Q: What are some other names for Akatsuki?
A: Akatsuki is also known by several aliases, including PLANET-C, Venus Climate Orbiter, PLANET C, VCO, and its native label あかつき.

## Why It Matters
Akatsuki holds significance as Japan's first dedicated mission to orbit Venus, providing crucial insights into the planet's enigmatic atmosphere. Despite an initial failure to enter orbit in 2010, JAXA's perseverance led to a successful second attempt in 2015, demonstrating remarkable engineering resilience. The probe's extended mission, lasting nearly a decade after its successful orbit insertion, allowed for long-term observations of Venus's super-rotating atmosphere, cloud dynamics, and atmospheric escape. Its data contributes to a deeper understanding of planetary climates, atmospheric evolution, and the differences between Earth and Venus, which are often considered "sister planets." As a derelict satellite, Akatsuki represents a testament to the challenges and triumphs of deep-space exploration, leaving a legacy of scientific data that continues to inform planetary science.

## Notable For
*   **Resilient Orbit Insertion**: Successfully entered Venus orbit in 2015, five years after its initial failed attempt in 2010, showcasing a remarkable recovery.
*   **Dedicated Venus Atmospheric Research**: Specifically designed to study the atmosphere of Venus, providing unique data on its super-rotation and cloud structures.
*   **Extended Operational Life**: Operated for nearly a decade in Venus orbit, far exceeding its initial mission goals after the delayed orbit insertion.
*   **Classification as Derelict Satellite**: Officially designated as a derelict satellite following the loss of signal in 2024 and subsequent mission termination.

## Body

### Overview
Akatsuki is a defunct Venus orbiter operated by the Japan Aerospace Exploration Agency (JAXA). It is classified as a planetary probe and an orbiter, specifically designed for Venus. The spacecraft is also known by several aliases, including PLANET-C, Venus Climate Orbiter, PLANET C, プラネットC, 第24号科学衛星, VCO, 晓号金星探测器, 黎明号, 晓号, and أكاتسوكي (مركبة فضائية). Its native label is あかつき. The manufacturer of Akatsuki was NEC Space Technologies.

### Mission Details
Akatsuki's primary use was for research, specifically focusing on the atmosphere of Venus.
A significant event in its mission was its rocket launch on May 20, 2010, at 21:58:22 from Yoshinobu Launch Complex Launch Pad 1. The launch vehicle used was an H-IIA, specifically H-IIA-17.
An initial planetary flyby of Venus occurred on December 7, 2010, at 00:00.
The spacecraft successfully performed an orbit insertion around Venus on December 7, 2015, at 00:00.
The mission experienced a loss of signal in April 2024.
The mission termination was officially set for September 18, 2025.

### Technical Specifications
*   **Mass**:
    *   Launch weight: 517.6 kilograms
    *   Dry weight: 321.3 kilograms
*   **Dimensions**:
    *   Width (spacecraft bus): 1.04 meters
    *   Width (photovoltaic system): 5.062 meters
    *   Height: 2.12 meters
    *   Length: 2.101 meters
*   **Power**: Powered by a photovoltaic system. It generated 700 watts in orbit of Venus and 480 watts in orbit of Earth.
*   **Orbital Parameters (around Venus)**:
    *   Parent astronomical body: Venus
    *   Apoapsis: 370,000 kilometers
    *   Periapsis: 10,000 kilometers
    *   Orbital period: 10.8 days
    *   Orbital inclination: 3 degrees
    *   Orbital eccentricity: 0.95
    *   Semi-major axis of an orbit: 190,000 kilometers
*   **Service Life**: 13.9 years.

### Status
Akatsuki is classified as a derelict satellite, meaning it is an artificial satellite that has been abandoned, neglected, decommissioned, or has become nonfunctional but remains in orbit. Contact with Akatsuki was lost in April 2024, and its mission was formally terminated on September 18, 2025.

### Identifiers & Links
*   **SCN**: 36576
*   **NAIF ID**: -5
*   **COSPAR ID**: 2010-020D
*   **NSSDCA ID**: 2010-020D
*   **Websites**:
    *   http://akatsuki.isas.jaxa.jp/ (Japanese)
    *   http://akatsuki.isas.jaxa.jp/en/ (English)
    *   https://global.jaxa.jp/projects/sas/planet_c/ (English)
*   **Twitter**: Akatsuki_JAXA (Started April 16, 2010). As of February 7, 2023, it had 68,916 followers.
*   **Wikipedia Title**: Akatsuki (spacecraft)
*   **Commons Category**: Akatsuki (spacecraft)
*   **Freebase ID**: /m/05xmxw
*   **Encyclopædia Britannica Online ID**: topic/Akatsuki
*   **Encyclopedia of China (third edition) ID**: 507415 (拂晓号), 568576 (黎明号)
*   **Yle Topic ID**: 18-317777
*   **Huijiwiki Article ID**: sat:晓号 (1376)
*   **Sitelink Count**: 36

## References

1. Jonathan's Space Report
2. [Source](https://global.jaxa.jp/projects/sas/planet_c/)
3. [Source](https://www.nec.com/en/global/techrep/journal/g11/n01/pdf/110110.pdf)
4. Freebase Data Dumps. 2013
5. [Source](https://pds.nasa.gov/ds-view/pds/viewMissionProfile.jsp?MISSION_NAME=VENUS%20CLIMATE%20ORBITER)
6. [Source](https://www.planetary.org/articles/2802)
7. [Source](https://www.isas.jaxa.jp/topics/003749.html)
8. [Source](https://www.space.com/jaxa-loses-contact-akatsuki-venus-probe)
9. [Venus Climate Orbiter “AKATSUKI” Operation Completed. Japan Aerospace Exploration Agency. 2025](https://global.jaxa.jp/press/2025/09/20250918-2_e.html)
10. [Source](https://twitter.com/Akatsuki_JAXA)
11. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)