Themis programme

The Themis programme is an ongoing European Space Agency programme carried by prime contractor ArianeGroup, aiming to develop a prototype reusable rocket first stage and plans to conduct demonstration flights. The prototype rockets will also be called Themis. As of 2025, two prototypes are being developed: Themis 1-Engine Hop (T1H) and Themis 1-Engine Evolution (T1E). Later, a three-engine variant (T3) will be built. ^{[1] [2]}

Themis is expected to provide valuable information on the economic value of reusability for the European government space program and develop technologies for potential use on future European launch vehicles. ^{[3] [ non-primary source needed ]} Themis will be powered by the ESA's Prometheus rocket engine. ^[3] Eventually, lessons learned with Themis' development will pave the way for developing the European reusable launcher Ariane Next, which should first fly in the 2030s. ^[4]

Themis is distinct from a similar project CALLISTO under development by CNES, DLR, and JAXA.

Background

Two possible landing sites have been mentioned in discussions surrounding the project: ^[5]

• The former Diamant launch complex, which will be used for the flight testing phase; ^[6]
• The Ariane 5 launch complex, which will become available after the transition from the Ariane 5 to Ariane 6.

The estimated program timeline, as of December 2020 ^[update] , was as follows: ^[7]

• 2020: Basic stage testing, composed of tank filling and ground support equipment tests. ^[8]
• 2021: Prometheus engine testing
• 2022: Low-altitude hop tests (short flights up from and down to the launch site)
• 2023: Initial flight test
• 2023–2024: Loop tests (repeated flights of the reusable demonstration vehicle)
• 2025: Full flight envelope test

Suborbital flight tests were slated to begin as early as 2023 at Europe's Spaceport in Kourou, French Guiana, but have been delayed. ^[5]

Timeline

• On 15 December 2020, ESA signed a contract worth €33 million with ArianeGroup in France for the "Themis Initial Phase". This first phase of the Themis programme involves development of the flight vehicle technologies and test bench and static fire demonstrations in Vernon, France. It also includes the preparation of the ground segment^{[ clarification needed ]} at the Esrange Space Center in Kiruna, Sweden, for the first hop tests and any associated flight vehicle modifications. ^{[5] [ non-primary source needed ]}
• In December 2021, ESA completed a series of tanking tests on the steel propellant tanks for Themis. ^[9]

• On 22 June 2023, the first hot-fire test of the Prometheus engine, as a part of the Themis first stage demonstrator, was successfully conducted in Vernon, France. ^[10]
• Landing leg testing began in July 2024. ^[11]
• In November 2024, ESA has awarded a contract to ArianeGroup to build a second Themis demonstrator (T1E) ^[12] and announced that testing of the Themis main systems has been completed and the assembly of the first demonstrator was underway. ^[13]
• In December 2024, ArianeGroup has brought the main elements of Themis (T1H) together for the first time during a full-fit check in Les Mureaux, France. ^[1]

See also

• List of European Space Agency programmes and missions

• Future Launchers Preparatory Programme  – European Space Agency rocket development projects
• CALLISTO  – Type of reusable rocket
• Prometheus (rocket engine)  – Methalox spacecraft propulsion system
• Ariane Next  – Orbital recoverable launch vehicle of the European company ArianeGroup
• SpaceX reusable launch system development program
• Miura 5  – European orbital recoverable rocket of the company PLD Space

References

1. Parsonson, Andrew (2024-12-17). "Themis Reusable Rocket Takes Shape as ArianeGroup Completes Fit Check". European Spaceflight. Retrieved 2025-03-14.
2. "Themis demonstrations". www.esa.int. Retrieved 2025-03-15.
3. "Prometheus to power future launchers". ESA . 14 December 2017. Retrieved 15 December 2020.
4. Patureau de Mirand, Antoine (July 2019). Ariane Next, a vision for a reusable cost efficient European rocket (PDF). 8th European Conference for Aeronautics and Space Sciences. doi:10.13009/EUCASS2019-949 . Retrieved 18 August 2021.
5. "ESA plans demonstration of a reusable rocket stage". ESA . 15 December 2020. Retrieved 24 September 2021.
6. "Diamant in the rough – in Kourou, the old launch complex gets a facelift for Themis". ArianeGroup . 24 September 2021. Retrieved 24 September 2021.
7. Payer, Markus (30 November 2020). "ArianeWorks on European reusable rocket prototype Themis". SpaceWatch.Global. Retrieved 15 December 2020.
8. "CNES, ArianeGroup Move Forward on Themis Reusable Rocket Project". Parabolic Arc. 26 February 2021. Retrieved 24 September 2021.
9. Beil, Adrian (2021-12-08). "Themis tanking test marks milestone in ESA's path to reusability". NASASpaceFlight.com. Retrieved 2025-03-14.
10. Richards, Bella (2023-06-23). "Themis, Prometheus complete first hot-fire tests in France". NASASpaceFlight.com. Retrieved 2023-10-23.
11. Parsonson, Andrew (2024-07-29). "MT Aerospace Begins Testing Themis Landing Leg". European Spaceflight. Retrieved 2024-08-02.
12. Parsonson, Andrew (2024-11-21). "ESA Awards Another €230M to ArianeGroup for Themis Demonstrator". European Spaceflight. Retrieved 2025-03-14.
13. Parsonson, Andrew (2024-11-07). "ESA Shares Rare Update on Themis Reusable Booster Demonstrator". European Spaceflight. Retrieved 2025-03-14.

External links

• ESA Themis website