ESA Shares Rare Update on Themis Reusable Booster Demonstrator

ESA has provided a rare update on ArianeGroup’s progress in developing the agency’s Themis reusable booster demonstrator.

The European Space Agency has provided a rare update on the progress of its Themis reusable booster demonstrator project.

Themis was initially a CNES project that was first announced in early 2018. In November 2019, during the ESA ministerial-level council meeting, member states agreed to fund the development of Themis with ArianeGroup as the project’s prime contractor. In December 2020, ArianeGroup received an initial €33 million in funding for the project. At the time, the first low-altitude hop test was expected to take place in 2022.

In a 6 November update, ESA shared several details on the progress toward an initial Themis hop test, which is currently scheduled to take place in 2025.

According to ESA, testing of the Themis main systems has been completed and the assembly of the demonstrator is now in full swing. The single Prometheus engine and its associated thrust vector actuation system have been installed onto the demonstrator’s engine bay.

The Prometheus engine for ESA’s Themis reusable booster demonstrator has been successfully installed.
A Prometheus engine being installed on the Themis reusable booster demonstrator | Credit: ArianeGroup

The initial low-altitude hop test, which will take place from Esrange Space Centre in Sweden, will only require a single Prometheus engine, which will fire continuously for the duration of each test. Higher altitude tests, which will be conducted from the Guiana Space Centre, will require three Prometheus engines.

With the demonstrator’s engine installed, work is now being done to install the avionics systems including the onboard computers, power distribution hardware, batteries, and cable harness. The stainless-steel propellant tanks have been cleaned following testing in Vernon and are now ready to be installed onto the demonstrator’s main structures.

Work on the demonstrator is being done in the old Ariane 5 assembly building at the ArianeGroup Les Mureaux facility near Paris. Once assembly is complete, it will be transported by truck over 3,000 kilometres to the Esrange Space Centre.

At Esrange, work is also in full swing as the team finalizes the electric and fluidic ground support equipment, including fuel lines, rocket stands, flares for burning off unused fuel, and propellant tanks. ESA is also outfitting the Themis mission control centre in a dedicated ESA building at the facility.

Following the initial low-altitude tests in Sweden, which are projected to last no more than twelve months, testing will move to the Guiana Space Centre in French Guiana. These tests will be conducted from a new facility being built on the grounds of the old Diamant launch site.

Andrew Parsonson
Andrew Parsonson has been reporting on space and spaceflight for over five years. He has contributed to SpaceNews and, most recently, the daily Payload newsletter. In late 2021 he launched European Spaceflight as a way to promote the continent's excellence in space.