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Test Tanks Fueled for ESA’s Themis Reusable First Stage

By Doug Messier
Parabolic Arc
December 2, 2021
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ESA is taking the first steps towards the in-flight demonstration of a prototype reusable rocket first stage called Themis from 2023 onwards. (Credit: ArianeGroup)

VERNON, France (ESA PR) — Recently completed tests of two propellant tanks set a first technological milestone in the ESA reusability roadmap towards the demonstration of a reusable first stage vehicle called Themis.

Through the Themis programme, ESA aims to assess the economic value of reusability for Europe while investing in new technologies for potential use in ESA’s future fleet of launch vehicles.

Control room during live Themis tanking tests. (Credit: ArianeGroup)

The Themis experimental approach promotes learning by hardware testing. This Agile methodology focuses on activities of greatest value and works to short timescales.

To accelerate development, technologies are being tested early in the development cycle. As part of this, prime contractor ArianeGroup recently performed six tests in Vernon, France, to validate the fluidic and electrical processes and sequences for the correct operation of two test propellant tanks. During these tests the tanks were filled then drained of cryogenic propellants.

Themis test tanks during cryogenic filling and draining tests. (Credit: ArianeGroup)

This initial phase of the Themis project involves the preparation of the flight vehicle technologies alongside firing demonstrations of its reusable Prometheus engine. It also includes the preparation of the ground segment at the Esrange Space Center in Kiruna, Sweden, for the first hop-test flights and any associated refurbishment of the vehicle between flights.

The fluidic and electrical operations of these test cryogenic tanks and ground equipment have been validated ahead of time to de-risk hot firing tests with the Prometheus engine under integration on the same test bench.

Thermal camera view of tanks during cryogenic tests. (Credit: ArianeGroup)

“This is an exciting time. In the next step for Themis, we will combine two key building blocks for the future of space transportation systems in Europe. Both are developed within ESA’s Future Launchers Preparatory Programme. Themis, ESA’s flagship reusable first stage vehicle and Prometheus, its next-generation low-cost reusable engine,” said Yann Tincelin, Space Transportation Systems Project Engineer at ESA.

Prometheus is an ultra-low-cost engine built extensively through additive layer manufacturing. This has reduced the estimated cost of production by a factor of ten compared to Ariane 5’s core stage Vulcain engine. It features variable thrust and multiple ignitions and is therefore suitable for core and upper rocket stages.

Themis launch (Credit: CNES-REAL DREAM)

The fuel used for Prometheus is liquid oxygen–methane which is highly efficient, allows standardisation and operational simplicity. Methane propellant is also widely available and easy to handle which will minimise ground operations before and after flight. 

Prometheus technologies are likely to be incorporated in improvements made to rocket engines currently in operation.

European industry steps ahead

In parallel to the ongoing activities for ground hot firing tests, Themis flight demonstrators are also under preparation. A European ecosystem of industry partners is forging ahead to develop and manufacture components.

Themis reusable rocket roadmap (Credit: CNES-REAL DREAM)

Flight version steel cryogenic tanks are being manufactured. Low-cost optimised thrust vector actuation systems for Prometheus are being designed. The landing legs system has entered its final design stage before manufacture. All these enabling building blocks will come together for integration on the Themis flight demonstrator for low-altitude hop-tests in Kiruna, Sweden.

Meanwhile, the final design of ‘Launch complex 3’ at Kiruna Esrange Space Center has been reviewed by the Swedish Space Center and ArianeGroup, to prepare for the first Themis hop-tests in Sweden in 2023.

This incremental progress is built on early evaluation at each intermediate step with focus first on technical de-risking of Prometheus integration into a fully operational stage, then on flights increasingly representative of operational launch vehicles.

The final steps will be flights from Europe’s Spaceport in French Guiana in 2025 to demonstrate ascent to high altitude, reentry, landing, refurbishment and reuse, with an integrated Themis demonstrator equipped with three Prometheus engines and all the required subsystems for enabling stage recovery.

7 responses to “Test Tanks Fueled for ESA’s Themis Reusable First Stage”

  1. Malatrope says:

    Glad to see Elon Musk’s methods and designs catching on!

    • ThomasLMatula says:

      If you are going to copy, copy from the leader.

    • Nick H says:

      Beck took quite a few shots at SpaceX in the video. He was suggesting kinda the opposite of what you are.

    • StarshipsForever says:

      I see nothing of the sort here. This is a very big step in many ways away from SpaceX in design. Just the fact that the shape and materials is a big difference right there to begin with. The fairing being a part of the first stage that returns with it is another big step away from what anyone is doing. And then there’s the fixed landing legs that also act like strakes.

      Ironically, it seems that aspects of Neutron are more similar to New Glenn than to F9 or Starship/Super Heavy. No grid fins, just wedge-shaped steering fins and the strake-like legs look more like the strakes on NG than anything else.

      • Malatrope says:

        Mainly I was referencing the hardware-rich development cycle. But as long as we’re comparing differences, Musk wouldn’t have used strakes as they are unnecessary. So are landing legs. The fairing is unimportant because SS will have a cargo door also. Neutron isn’t landing the 2nd stage. The grid fins are more effective than the steering fins. I will admit that carrying the 2nd stage as “cargo” is an interesting notion, but of course both SS and Falcon can RLS. Neutron is “fat” to hit more air on return, whereas SS simply turns 90 degrees to expose the greatest cross-section.

        The more competitors the merrier, in my opinion. But the push to lower costs came solely because Musk proved they could be drastically reduced with Falcon 9. The next ten years are going to see a lot of companies that got started by orbiting beer-cooler-size payloads suddenly realizing they have to carry more or become obsolute. Beck realizes this, and is planning accordingly. I consider both Beck and Musk as far-thinking people.

        For the record, I have RKLB stock, in it for the long haul.

  2. schmoe says:

    Peter Beck presented Rocket Lab’s Neutron update today. It will be powered by a very similar engine to the Prometheus: Rocket Lab’s Archimedes engine is in the same thrust class and also a methalox gas-generator.

    Race is on to see which one flies first. 😀

  3. _MBB says:

    to prepare for the first Themis hop-tests in Sweden in 2023.

    According to the image, the hop tests were supposed to start in 2022. So they are already a year behind.

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