# H10-3

> upper rocket stage built by Aérospatiale

**Wikidata**: [Q126022311](https://www.wikidata.org/wiki/Q126022311)  
**Source**: https://4ort.xyz/entity/h10-3

## Summary
The H10-3 is an upper rocket stage developed by Aérospatiale, serving as a space tug to propel payloads from initial orbits to their final destinations. It was a critical component of the Ariane 4 rocket family, enabling satellite deployments and interplanetary missions from 1994 to 2003.

## Key Facts
- **Manufacturer**: Initially built by Aérospatiale (until 1999), later by Aérospatiale-Matra (1999–2003).
- **Operational Period**: Maiden flight on December 1, 1994; final flight on February 15, 2003.
- **Key Specifications**: 
  - Gross mass: 12,310 kg; dry mass: 1,570 kg.
  - Height: 11.85 meters; diameter: 2.66 meters.
  - Powered by a single HM7B engine, producing 62.7 kN of thrust in vacuum with a specific impulse of 446 seconds.
- **Rockets Used With**: Ariane 40, Ariane 42P, Ariane 42L, Ariane 44P, Ariane 44LP, and Ariane 44L variants.
- **Country of Origin**: France.

## FAQs
### Q: What was the primary role of the H10-3 stage?
A: The H10-3 functioned as a space tug, maneuvering payloads from initial orbits to their target trajectories, such as geostationary orbits or interplanetary paths.

### Q: Which rockets utilized the H10-3 upper stage?
A: It was integrated into multiple Ariane 4 variants, including the Ariane 40, 42P, 42L, 44P, 44LP, and 44L, depending on mission requirements.

### Q: How long was the H10-3 in active service?
A: The stage operated for nearly a decade, from its first flight in December 1994 to its final mission in February 2003.

## Why It Matters
The H10-3 played a pivotal role in the success of the Ariane 4 rocket program, one of Europe’s most reliable launch vehicles. As a space tug, it ensured precise payload delivery, supporting telecommunications satellites, scientific missions, and interplanetary probes. Its adaptability across multiple Ariane 4 configurations underscored its versatility, contributing to the rocket family’s commercial viability during the 1990s. The H10-3 also marked a transitional phase in European space manufacturing, reflecting the evolution of Aérospatiale into Aérospatiale-Matra, a key player in the continent’s space industry.

## Notable For
- **Space Tug Capability**: Enabled efficient payload transfer to targeted orbits, reducing reliance on additional propulsion systems.
- **HM7B Engine Performance**: Delivered high specific impulse (446 seconds) and thrust (62.7 kN) in vacuum conditions, optimizing fuel efficiency.
- **Versatility**: Compatible with six Ariane 4 variants, making it a cornerstone of Europe’s launch flexibility in the 1990s.
- **Reliability**: Supported over 50 Ariane 4 missions, contributing to the rocket’s 97% success rate during its operational lifespan.

## Body
### Design and Specifications
- **Mass**: 12,310 kg at liftoff (gross weight) and 1,570 kg after propellant depletion (dry weight).
- **Dimensions**: 11.85 meters in height with a 2.66-meter diameter.
- **Propulsion**: Equipped with a single HM7B cryogenic engine, fueled by liquid hydrogen and liquid oxygen.

### Operational History
- **Maiden Flight**: December 1, 1994, as part of the Ariane 44L vehicle.
- **Final Mission**: February 15, 2003, concluding with the Ariane 44L’s last launch.
- **Launch Vehicles**: Served as the upper stage for six Ariane 4 configurations, tailored to varying payload and mission requirements.

### Propulsion System
- **Engine**: The HM7B provided 62.7 kN of thrust in vacuum, with a specific impulse of 446 seconds, ensuring efficient fuel use during orbital transfers.

### Legacy
- **Manufacturer Transition**: Production shifted from Aérospatiale to Aérospatiale-Matra in 1999, reflecting corporate restructuring in Europe’s aerospace sector.
- **Mission Impact**: Facilitated the deployment of critical satellites and spacecraft, bolstering Europe’s position in the global space launch market during the 1990s.

## References

1. [Source](http://www.astronautix.com/a/ariane4-3h10-3.html)
2. [Source](https://space.skyrocket.de/doc_lau/ariane.htm)