06/10/2025
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The Large Space Simulator, Europe’s largest vacuum chamber, routinely reproduces space conditions on Earth to test spacecraft before they fly into orbit. The facility is complex, and the current process of training a new operator is lengthy and complicated. To make it easier, the space simulator now has a digital twin – the most realistic virtual model of the facility yet, developed for the European Space Agency (ESA) by the Spanish engineering company Empresarios Agrupados.
The Large Space Simulator (LSS), located at ESA’s Test Centre in the Netherlands, is a large chamber capable of reproducing a space-like environment. Its pumps can extract all air from the inside to create high vacuum, and liquid nitrogen circulating through thermal panels covering its walls can lower the temperature to chilly -180 °C.
“The facility is very complex, and it takes many years for people to learn how to operate it,” explains Remko Moeys, ESA’s engineer leading the digital twin project. “On top of that, we perform only about 2-3 tests per year, which offers very few occasions for a trainee to shadow and learn from an experienced operator.
“To make the process more efficient, we developed a training simulator. This ‘digital twin’ mimics the real operations of the LSS as closely as possible. Essentially, it works in a similar way to a flight simulator for pilots.”
The LSS digital twin software was developed for ESA by the Spanish engineering company Empresarios Agrupados using the simulation software ‘EcosimPro’, which the company have devised for ESA with the aim to support the aerospace industry modelling and simulation needs in several disciplines.
After almost two years of development, the training software is up and running on the monitors of the real-life LSS control room, making the experience of an operator-in-training as realistic as possible.
“In the digital twin software, a trainee sees the same things on the screen that they would see when operating the real facility, and the data is displayed in the same way as well. Everything underneath has been virtualised,” Remko clarifies.
“Let’s say I click a button in the programme to open a valve. In a real-life scenario, the computer would send a signal to the real valve and open it. In a simulated scenario, a ‘virtual valve’ opens instead. The computer calculates what would happen once it’s opened, returning the simulated data to us.
“A great advantage of our training software is that a test can be started from any point, it can be paused or stopped, and it can run faster than real-time, allowing us to skip uneventful phases that normally last hours.
“We can even introduce a failure into the test, like a valve not opening or air leaking into the vacuum chamber. This allows trainees to practice handling all kinds of potential scenarios.”
Julien Pioton, LSS operator and test engineer at the European Test Services (ETS), notes: “Training operators on a real-life facility is a long and complex process, often requiring years of hands-on experience. Moreover, operating such facilities isn’t without risk. This tool offers a safe and efficient alternative by allowing LSS operators to repeatedly practice specific test phases, build confidence, and refine their skills.”
The digital twin software will help more than just operator training. It is a powerful tool for the virtual testing of any changes to the facility before they are performed in real life, it can be used to carry out various studies such as optimising the facility’s consumption of nitrogen, rehearsing test operations in advance, or simulating abnormal operations in case of equipment failure.
Miguel Alcázar, Simulation Manager at Empresarios Agrupados, concludes: “I’m immensely proud of our team’s ability to bring this challenging project to completion in such a short time.”
“This wouldn’t be possible without the EcosimPro tools developed by Empresarios Agrupados over the past 25 years – they have become invaluable, not only for companies in space and aeronautics, but also for energy, water, and biomedicine sectors,” he adds. “I look forward to continuing our support to ESA’s future technological developments.”
About the Large Space Simulator
The Large Space Simulator (LSS), located at ESA’s Test Centre in the Netherlands, is Europe’s largest vacuum chamber. It is used for the testing of spacecraft in a space-like environment, including vacuum and extreme temperatures, before they fly into orbit.
A spacecraft under test is installed on a large robotic arm in the centre of the chamber and can be rotated with respect to a blinding beam of light produced by a set of 19 lamps, each the size of a grapefruit. This setup mimics how, when in space, the Sun-facing side of a spacecraft will heat up, while the shaded side will remain freezing cold
Exactly 50 years ago, the predecessor of the LSS – the Dynamic Test Chamber – was completed. Since then, the facility has evolved into the 15 m-high and 10 m-wide chamber we know today.
Over the past half-century, engineers have subjected countless spacecraft to the harsh conditions of space in the LSS, including the most recent EarthCARE, Smile, or the test version of Plato.