Space instrument gets good vibrations in major step for solar wind mission

A cutting-edge x-ray telescope has shaken off a test that put it through the rigours of being launched into space, in a major milestone for a mission to study the effects of the solar wind.

The Soft X-ray Imager (SXI) Instrument, developed at Space Park Leicester by University of Leicester scientists and engineers for the upcoming SMILE mission, has completed its vibration test campaign of the flight model instrument - a critical milestone on the path to delivery.

SMILE (the Solar wind Magnetosphere Ionosphere Link Explorer) is the first major collaborative science mission between the European Space Agency and the Chinese Academy of Sciences and is due for launch in 2025. SMILE will study how the solar wind interacts with the Earth’s magnetic environment.

The SXI is led by Dr Steven Sembay at the University of Leicester, supported by funding from the UK Space Agency, and leverages decades of experience in space science at the University of Leicester. It is a wide-field X-ray telescope that uses micropore optics to spectrally map the location, shape, and motion of Earth's magnetospheric boundaries.

The Assembly, Integration and Test (AIT) Team at the University of Leicester successfully integrated space-flight subsystems to complete the SXI Telescope within a purpose-built cleanroom at Space Park Leicester. Upon the completion of the Telescope build, it was subjected to the harsh environments expected during launch of the SMILE spacecraft to ensure the hardware will successfully survive the launch and remain operational once in space.

The vibration testing was performed at the Science and Technology Facilities Council’s (STFC) RAL Space, supported by a dedicated team of RAL Space test engineers. The test was designed and led by University of Leicester, and was supported by a team of University of Leicester and ESA personnel on-site.

The SXI Telescope vibration test was a significant challenge due to the complexity relating to the size of the instrument (0.7 x 0.35 x 0.85 m), its high centre of mass, complex eigen modes and sensitive components such as the detectors and optical elements of the telescope mirror. The SXI focusses X-rays using an array specialised glass plates called Micropore Optics (MPOs). These MPOs are extremely delicate thin, curved glass plates, only 1.2 mm thick, containing millions of square holes.

Steven Sembay, SMILE SXI Principal Investigator, said: “The University of Leicester has the technical expertise to design and build optical assemblies of MPOs into structures that can survive the rigours of launching into space. SXI will be the third instrument launched into space using such optics built at here at the University of Leicester.  Demonstrating these optics will successfully survive the launch of the spacecraft was a key goal of the test campaign.

Parthil Patel, SMILE Lead Mechanical Engineer at University of Leicester, said: “It is an especially significant achievement to complete SXI Telescope’s Vibration test given the number of critical regions that have to be precisely monitored and assessed during testing. The completion of the Vibration test means the flight SXI Telescope has been subjected to the harshest loads it will see during its lifetime and it has successfully survived that. The success of this test is a huge testament to the skill and commitment of the team involved across a large collaboration in designing, analysing, building and testing what is a very complex Instrument.”

David Rippington, Principal Dynamic Test Engineer at RAL Space, said: "We see a wide range of space instrumentation come through our facilities, and it's been great to add the SXI to the list of exciting projects our teams have helped ready for space. The vibration test campaign was complex in nature using force limiting and accelerometers to control and provide notching to protect the hardware. The completion of this phase is a great milestone for the Leicester team – congratulations to those involved.

“Now that we’ve proven that the instrument can survive launch, we need to ensure it will survive the harsh conditions of space when it gets there. The SXI is now in the very capable hands of our colleagues in the thermal vacuum test team, where it will undergo further tests for this purpose. Fingers crossed for another successful campaign!”

Following the completion of the Vibration test, the Telescope will now be subjected to the extreme thermal environment it is expected to see during its orbit by performing Thermal Cycling and Thermal Balance tests to further demonstrate that SXI Telescope will successfully operate during its orbit.