# Themis

> European Space Agency reusable launcher prototype

**Wikidata**: [Q104881005](https://www.wikidata.org/wiki/Q104881005)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Themis_programme)  
**Source**: https://4ort.xyz/entity/themis

## Summary
Themis is a European Space Agency reusable launcher prototype designed to demonstrate reusable rocket technology. It represents Europe's effort to develop cost-effective space transportation systems with a focus on sustainability and reusability.

## Key Facts
- Themis is a reusable launcher prototype developed by the European Space Agency
- It has a mass of 200 tonnes and stands 30 meters tall with a diameter of 3.5 meters
- The rocket is powered by the Prometheus engine system, featuring three engines
- Themis uses liquid methane and oxygen as its propellant, carrying 130 tonnes of fuel
- It is manufactured by ArianeGroup, a European aerospace company
- The project is part of the THEMIS programme and has satellites in the THEMIS constellation
- Themis has a maximum thrust of 980 kilonewtons
- It is named after Themis, the Greek goddess of divine law and order

## FAQs
### Q: What is the purpose of the Themis project?
A: Themis is a European Space Agency prototype designed to demonstrate reusable rocket technology. Its primary goal is to develop cost-effective and sustainable space transportation systems that can be recovered and reused after launch.

### Q: How does Themis compare to other reusable rockets like SpaceX's Falcon 9?
A: While Themis shares the reusability concept with rockets like SpaceX's Falcon 9, it represents Europe's independent approach to developing this technology. Themis is specifically focused on demonstrating a reusable upper stage rather than a complete reusable launch system.

### Q: When is Themis expected to make its first flight?
A: The source material does not provide specific dates for Themis's first flight. As a prototype, its development timeline appears to be part of ongoing European space technology development efforts.

### Q: What makes Themis unique compared to other European launch systems?
A: Themis distinguishes itself as Europe's dedicated reusable launcher prototype, focusing on liquid methane propulsion and a reusable upper stage concept. It represents a shift from Europe's traditional expendable launch systems like Ariane.

## Why It Matters
Themis matters as it represents Europe's strategic response to the growing trend of reusable launch vehicles pioneered by companies like SpaceX. By developing this prototype, the European Space Agency aims to reduce launch costs and increase competitiveness in the global space market. The project's focus on methane propulsion also aligns with broader sustainability goals in the space industry, as methane offers potential performance advantages and could be produced in situ on other celestial bodies. Themis serves as a critical stepping stone in Europe's journey toward more accessible and sustainable space transportation, potentially enabling more ambitious scientific missions and commercial space activities in the future.

## Notable For
- Being Europe's dedicated reusable launcher prototype, specifically targeting upper stage reusability
- Utilizing liquid methane and oxygen propellant, a more sustainable alternative to traditional rocket fuels
- Featuring the Prometheus engine system, designed to be more affordable and maintainable than conventional rocket engines
- Representing Europe's independent approach to reusable launch technology development
- Being part of the broader THEMIS programme which includes satellite components for space weather research

## Body
### Technical Specifications
Themis is a substantial rocket with a mass of 200 tonnes and dimensions of 30 meters in height and 3.5 meters in diameter. It is powered by the Prometheus engine system, which consists of three engines providing a maximum thrust of 980 kilonewtons. The rocket uses liquid methane and oxygen as its propellant, with a fuel capacity of 130 tonnes.

### Development and Purpose
As a prototype, Themis serves as a technology demonstrator for reusable upper stages in European launch systems. The project is managed by the European Space Agency and manufactured by ArianeGroup, a leading European aerospace company. The development of Themis reflects Europe's commitment to maintaining competitiveness in the global launch market by embracing reusability technologies.

### Program Context
Themis is part of the THEMIS programme, which includes several satellites (THEMIS-A, THEMIS-E, THEMIS-D, THEMIS-C, THEMIS-B) that form a constellation for space weather research. The rocket itself is named after Themis, the Greek goddess of divine law and order, symbolizing the structured approach to space technology development.

### Technological Approach
The project emphasizes liquid methane propulsion, which offers several advantages including potential for in-situ resource utilization on other celestial bodies. The Prometheus engine system is designed with cost-effectiveness and maintainability as key priorities, representing a different approach from traditional rocket engine design philosophies.

## Schema Markup
```json
{
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  "name": "Themis",
  "description": "European Space Agency reusable launcher prototype",
  "url": "https://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_plans_demonstration_of_a_reusable_rocket_stage/",
  "sameAs": [
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  "manufacturer": "ArianeGroup",
  "weight": {
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    "unitCode": "TNE"
  },
  "height": {
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    "value": "30",
    "unitCode": "MTR"
  },
  "width": {
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    "value": "3.5",
    "unitCode": "MTR"
  },
  "fuelType": "methane, oxygen",
  "engine": {
    "@type": "Engine",
    "name": "Prometheus",
    "numberOfEngines": 3
  },
  "thrust": {
    "@type": "QuantitativeValue",
    "value": "980",
    "unitCode": "KWT"
  }
}

## References

1. [ESA plans demonstration of a reusable rocket stage](https://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_plans_demonstration_of_a_reusable_rocket_stage/)
2. [Wie SpaceX: Wiederverwendbare Raketen und Triebwerke sollen Europäer ins All bringen | MDR.DE](https://www.mdr.de/wissen/weltall-wiederverwertbare-raketen-themis-prometheus-esa-100.html)