Themis completes second fuelling rehearsal

2 min read · reported by ESA

ESA’s Themis reusable rocket stage demonstrator successfully completed its second ‘wet dress rehearsal’ at Esrange Space Center in Sweden on 29 September, testing the vehicle and ground procedures under representative cryogenic conditions.

The second wet dress rehearsal allowed teams from SSC Space and Themis prime contractor ArianeGroup to rehearse operations with the demonstrator on the launch pad.

Themis is a European Space Agency (ESA) rocket prototype – a flagship European demonstrator for low-cost rocket recovery and reuse technologies. Powered by the reusable, liquid oxygen and methane-fuelled engine Prometheus, Themis is on the launch pad at the Esrange Space Center in Sweden operated by SSC Space.

The 29 September rehearsal followed a first wet dress rehearsal held in July and allowed the operators at SSC Space’s launch facility and prime contractor ArianeGroup engineers to practice countdown procedures. The rocket prototype was filled with liquid nitrogen cooled down to –200°C to test the whole system and see how it holds up under the extreme cold and highly-pressurised systems as well as checking if all systems work correctly in these conditions.

Preparing for automated ground operations

A reusable launcher needs to be secured after landing, and any remaining propellants must be recovered and stored safely before maintenance or repairs can be performed. Robotic systems have been built to allow these operations to be carried out while personnel remain at a safe distance.

Themis is designed to touchdown on land within an area of just 20 x 20 metres where robots will then locate the rocket, move to it and connect automatically to drain any remaining fuel and oxidiser.

Taking over from a traditional launch tower, the robots are designed to ensure the main connections from the launchpad to the rocket. The rehearsal also included testing some of the elements of the robotic ground operations planned for Themis.

Themis will run on liquid methane and oxygen, but for this rehearsal liquid nitrogen was used for safety. It has similar properties in terms of cryogenic temperature and density but is not flammable nor explosive.

Themis, the first European reusable main stage’s full-scale demonstrator, was developed by ESA’s future Space Transportation preparation programme, with ArianeGroup as prime contractor and multiple European industrial partners. Once completed, Themis was taken forward by the Horizon Europe project SALTO – funded by the European Commission – for the launch campaign. The SALTO project is part of the EU Space Research and Innovation Work Programme and managed by the EU executive agency HaDEA , bringing together 25 consortium partners from 12 European Union countries.

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Published by the European Space Agency. View the original →