The European Space Agency’s (ESA) PLATO space telescope has successfully concluded a crucial pre-launch testing campaign. These tests were conducted under conditions designed to precisely mimic the harsh environment of outer space.
The rigorous testing took place within the Large Space Simulator (LSS) at ESA’s ESTEC facility in the Netherlands. This facility boasts Europe’s largest vacuum cryogenic chamber, capable of recreating the extreme vacuum and temperatures that spacecraft encounter in orbit.
PLATO, an acronym for PLAnetary Transits and Oscillations of stars, is a mission dedicated to the search for Earth-like planets orbiting Sun-like stars. Its sophisticated design features 26 highly sensitive telescope units. These instruments are capable of detecting minute changes in a star’s brightness, indicating the transit of a planet across its face. The data gathered during this testing phase will undergo thorough analysis in the coming months. Assuming no significant issues arise, the mission’s launch is tentatively scheduled for January 2027, aboard an Ariane 6 rocket.
How the Tests Were Conducted
To perform the tests, the PLATO satellite was placed inside a sealed chamber. The air was evacuated to create a vacuum, achieving a pressure one billion times lower than Earth’s atmosphere. Simultaneously, liquid nitrogen circulated through the chamber walls to drastically reduce the temperature, while a system of heaters simulated the Sun’s thermal impact on the satellite’s panels and thermal shield. This type of verification is essential to confirm that all onboard systems will function reliably under actual space conditions.
During the testing, engineers simulated various operational scenarios. In the initial phase, the side of the satellite designated to face the Sun reached approximately 150°C, with all systems fully operational. Concurrently, the telescope units, shielded from direct solar exposure, were maintained at temperatures between -70°C and -90°C.
Subsequently, the entire satellite was subjected to extreme cold. In this scenario, internal heating systems were activated to prevent the instruments from dropping below their operational temperature limits. These checks are vital to ensure the satellite can perform effectively in both nominal and challenging thermal environments.
Maintaining precise temperature control for the 26 telescopes was a critical aspect of the testing. The accuracy of their focus is highly dependent on minute thermal variations. Therefore, the tests specifically evaluated the satellite’s ability to sustain stable and controlled conditions over time.
The 26 Telescopes and Italian Contribution
The 26 ultra-precise camera units are PLATO’s primary scientific instruments. They are designed to measure brightness variations as low as 80 parts per million, a level of accuracy essential for detecting Earth-sized planets. Even minor inaccuracies could render the detection of these subtle signals impossible.
These critical components were developed by a European consortium of research institutions from Italy, Switzerland, and Sweden. The project was coordinated by Roberto Ragazzoni at the Astronomical Observatory of Padua and is currently headed by the president of INAF (Istituto Nazionale di Astrofisica). Funding for the development of the telescope’s optical units comes from the Italian Space Agency (ASI), the Swiss Space Office, and the Swedish Space Agency. The design of the 26 cameras is an INAF endeavor, with Leonardo responsible for their manufacturing.
With the completion of the tests in the Large Space Simulator, the work continues with the analysis of the collected data. This information will be instrumental in refining models that describe the behavior of the satellite and its cameras. If all proceeds according to plan, PLATO will be ready for its launch in early 2027.
