# COMETS

> Japanese communications demonstration satellite

**Wikidata**: [Q48621](https://www.wikidata.org/wiki/Q48621)  
**Source**: https://4ort.xyz/entity/comets

## Summary
COMETS (Communications and Broadcasting Engineering Test Satellite) was a Japanese communications demonstration satellite launched in 1998. It was designed to test experimental technologies in telecommunications and was operated by the National Space Development Agency, with support from the Communications Research Laboratory. The mission ended in 1999 after a launch failure that prevented it from reaching its intended geostationary orbit.

## Key Facts
- **Type**: Communications satellite and technology demonstration spacecraft
- **Mass**: 3,900 kilograms
- **Operator**: National Space Development Agency (Japan)
- **Launch Date**: February 21, 1998, at 07:55 UTC
- **Launch Vehicle**: H-II-5F rocket
- **Launch Site**: Yoshinobu Launch Complex Launch Pad 1 (Japan)
- **Orbit**: Initially intended for a geostationary transfer orbit but failed to achieve it
- **Decommissioning**: August 6, 1999
- **Aliases**: Kakehashi, Communication Engineering Test Satellite
- **Country of Origin**: Japan

## FAQs
### Q: What was the purpose of the COMETS satellite?
A: COMETS was a Japanese communications demonstration satellite designed to test experimental technologies in telecommunications. It was operated by the National Space Development Agency and supported by the Communications Research Laboratory.

### Q: Why did the COMETS mission fail?
A: The COMETS mission ended in 1999 due to a launch failure that prevented the satellite from reaching its intended geostationary transfer orbit.

### Q: Who operated the COMETS satellite?
A: The COMETS satellite was operated by the National Space Development Agency of Japan, with support from the Communications Research Laboratory.

### Q: What was the launch date of COMETS?
A: COMETS was launched on February 21, 1998, at 07:55 UTC from the Yoshinobu Launch Complex Launch Pad 1 in Japan.

### Q: What was the mass of the COMETS satellite?
A: The COMETS satellite had a mass of 3,900 kilograms.

## Why It Matters
COMETS played a crucial role in advancing Japanese satellite communications technology. As a technology demonstration spacecraft, it tested experimental telecommunications systems, contributing to the development of future satellite-based communication networks. Despite its early decommissioning due to a launch failure, COMETS provided valuable insights into satellite operations and design, influencing subsequent missions in the field. Its mission highlighted the challenges and complexities of achieving stable geostationary orbits, which remain critical for modern communications satellites.

## Notable For
- **First Japanese Communications Demonstration Satellite**: COMETS was one of the first Japanese satellites dedicated to testing telecommunications technologies.
- **Technology Testing**: It demonstrated experimental systems for satellite-based communication, which were later adopted in operational satellites.
- **Launch Failure**: The mission ended prematurely due to a failure to reach the intended orbit, providing lessons for future launches.
- **Collaboration**: The project involved collaboration between the National Space Development Agency and the Communications Research Laboratory, showcasing joint efforts in space technology.

## Body
### Overview
COMETS (Communications and Broadcasting Engineering Test Satellite) was a Japanese satellite launched on February 21, 1998, aboard an H-II-5F rocket. It was developed to serve as a communications demonstration spacecraft, testing experimental technologies in telecommunications. The satellite was operated by the National Space Development Agency, with support from the Communications Research Laboratory.

### Mission Details
- **Primary Objective**: To demonstrate and test new telecommunications technologies in a space environment.
- **Orbit**: Initially intended for a geostationary transfer orbit, but the mission failed to achieve this due to a launch anomaly.
- **Decommissioning**: The satellite was decommissioned on August 6, 1999, marking the end of its operational life.

### Technical Specifications
- **Mass**: 3,900 kilograms.
- **Launch Vehicle**: H-II-5F, a variant of the H-II rocket family.
- **Launch Site**: Yoshinobu Launch Complex Launch Pad 1 in Japan.

### Significance
COMETS contributed to the advancement of satellite communications technology in Japan. Its mission provided valuable data on the performance of experimental systems in space, influencing future satellite designs. The launch failure, however, highlighted the challenges of achieving precise orbital positioning, which remains a critical factor in satellite operations.

### Legacy
Despite its early decommissioning, COMETS remains a notable example of Japan's efforts to innovate in space communications. Its technologies and lessons learned continue to inform current and future satellite missions.

## References

1. [Source](https://space.skyrocket.de/doc_sdat/comets.htm)
2. Jonathan's Space Report