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Mini-EUSO experiment
Science objectives of Mini-EUSO experiment
Mini-EUSO Flight model
Mini-EUSO Flight model during final vibration tests (Torrita di Siena).
The front Fresnel lens of Mini-EUSO
The front Fresnel lens of Mini-EUSO. The blue checkered structure behind is the focal surface. In the top left and bottom right corners are present the Visible and Near Infrared cameras
Mini-euso FM
Mini-euso FM during night-sky observations
One of the Nomex pouches and subsequent return to Earth
One of the Nomex pouches containing the Solid State Drives for data storage and subsequent return to Earth
Mini-EUSO (Engineering Model)
Mini-EUSO (Engineering Model) during night sky observation.
Left: the PDM unit of EUSO-TA. Center Mini-EUSO FM during assembly. Right: Mini-EUSO EM
Left: the PDM unit of EUSO-TA. Center Mini-EUSO FM during assembly. Right: Mini-EUSO EM

The Mini-EUSO (Multiwavelength Imaging New Instrument for the Extreme Universe Space Observatory), telescope is designed to perform observations of the UV light emission from Earth. It has been located in front of the UV transparent window in the Zvezda Russian module in the ISS since the launch in August 2019, looking at our planet in nadir mode.

The Mini-EUSO instrument (37 * 37 * 62 cm3) comprises a telescope with a large (40 degrees) field of view,  based on an optical system which employs two Fresnel lenses (25 cm of diameter) for increased light collection. The UV light is then focused onto a 2304-pixel multi-anode photomultiplier focal surface (Photo-Detector-Module or PDM) similar to those flown in EUSO-Balloon, EUSO-SPB1  and EUSO-TA. Observations are complemented in the visible and Near Infrared range by two ancillary cameras and a number of UV sensors.

The main Mini-EUSO objectives are the study of atmospheric phenomena, like Transient Luminous Events (TLEs), meteors and meteoroides, the search for Strange Quark Matter (SQM) and the detection of some cosmic ray showers. Furthermore, Mini-EUSO could represent the first step in a roadmap of potential debris removal via laser ablation.

With Mini-EUSO – for the first time – create a dynamic map of nocturnal emissions of ultraviolet in the earth. These measurements are completed by a Near Infrared and a visible camera.

With this detector we can – for the first time – create a dynamic map of nocturnal emissions of ultraviolet in the Earth’s atmosphere, studying phenomena of terrestrial and astrophysical origin.

In detail, we can study several transient phenomena such as: a) marine bioluminescence and of the ‘milky sea’ phenomenon, generated by plankton, b) detection and study of meteorite, c) Search for quark strange matter. This hypothetical new state of matter could exist in   quarks stars or at the center of neutron stars and reach the Earth in the form of interstellar meteorites. Due to their high density, these fragments of nuclear strange matter would appear as interstellar (220 km/s) meteorites that burn for a long time in the atmosphere and with spectral emissions different from the classical meteorites d) Search for Ultra-high-energy cosmic rays.

Scheme of Mini-EUSO detector
Scheme of Mini-EUSO detector for observations from the inside of the ISS. Dimensions are 37 cm37 cm62 cm (with 25cm diameter lenses). The instrument will be placed in the nadir UV transparent window of the International Space Station.
Astronaut Paolo Nespoli
Astronaut Paolo Nespoli with RIKEN manufactured lens for MINI-EUSO.  
Mini-EUSO engineering model during assembly
Mini-EUSO engineering model during assembly. In the center of the picture it is possible to see the 36 Multi-anode photomultiplier (2304 pixel) focal surface with readout electronics.