STIX Attenuator Mechanism

Almatech Contribution

In the frame of ESA Solar Orbiter scientific mission, Almatech has been selected to design, develop and test the Attenuator Mechanism (ATM) part of the STIX instrumentDetector Electronic Module (DEM). The ATM is an X-Ray moveable attenuator, consisting of thin layers of aluminium moving in front of the X-Ray detectors.

The main design drivers were the mass budget <200g, the accelerations in the motors up to 300g, the high reliability needed (>0.999) and the weight distribution in order to ensure minimal exported forces (<0.1N) during the mechanism movement.

Almatech has so far successfully met all the requirements mentioned above, including a design concept allowing 2 stable positions without the need of a locking mechanism, improving the reliability of the ATM.

“The attenuator mechanism is a perfect example of a space mechanism with a smart lightweight design that fulfilled all the requirements. We managed to optimize even more its performances by running numerical simulations of the different parts in motion, that was pretty cool. Looking at all the work done, and at the exceptional interest raised by the whole space mechanism community during its presentation at the ESMATS 2015, we are looking forward to the last reward: its first operation in space!”

Dr Marco Lai

Almatech Principal Engineer

About the mission

Solar Orbiter is a Science mission of jointly developed between ESA and NASA, that was selected as the first medium (M)-class mission of ESA’s Cosmic Vision  programme for launch in 2019. Solar Orbiter’s goal is to address the central question of Heliophysics: how does the Sun create and control the heliosphere? Solar Orbiter is designed to identify the origins and causes of the solar wind, the heliospheric magnetic field, the solar energetic particles, the transient interplanetary disturbances, and the Sun’s magnetic field.

About the payload

The Spectrometer/Telescope for Imaging X-rays (STIX) instrument will image in X-rays the extremely hot Plasma heated to tens of millions of degrees and the high-energy electrons accelerated to nearly the speed of light that are emitted during a solar flare.

The Solar Orbiter mission (Credit ESA)

mass budget

maximum exported forces

minimum reliability


Presented at the 16th European Space Mechanisms & Tribology Symposium , 2015