Figure 1. Illustration of Hayabusa2 - MASCOT is stored in the left side face (Image credit: JAXA)
Figure 2. (Left) Illustration of MASCOT separating from Hayabusa2, (Right) Illustration of MASCOT landed on Ryugu (Image credit: JAXA)
Figure 3. Optical window for infrared detector
An optical window for infrared detectors from Optical Coatings Japan was used for the small asteroid lander "MASCOT" that was mounted on the Hayabusa2.
The mission of Hayabusa2 was to explore the asteroid Ryugu and bring samples back to Earth. This is expected to help unravel the mysteries of the origin of the water on Earth and the origin of the organic matter that became the raw material for life. The return of the sample to Earth was successfully achieved in December 2020 and Hayabusa2 set off from Earth once again.
The small asteroid lander MASCOT (Mobile Asteroid Surface Scout) was the equipment that was mounted on Hayabusa2 to go on the journey to Ryugu and conduct scientific observations of the surface materials and physical properties.
"MASCOT" is a small asteroid lander developed by DLR (the German Aerospace Center) and CNES (the French National Centre for Space Studies).
It separated from Hayabusa2 on October 3, 2018 and landed on the asteroid Ryugu after free falling for six minutes. MASCOT measured 30 x 30 x 20 cm (cuboid) and weighed about 10 kg. It moved autonomously on Ryugu and conducted observations at multiple locations for about 17 hours.
An infrared spectroscopy microscope called "MicrOmega" was mounted on the bottom face of MASCOT and was used to investigate the types and physical properties of the minerals on the surface with infrared light ranging from 0.9 μm to 3.5 μm. MicrOmega used an infrared detector manufactured by LYNRED (https://lynred.com/), and an optical window manufactured by our company was used on that detector.
Our optical windows have excellent thermal cycle durability and an AR coating that suppresses reflectance in a broad range from 0.9 μm to 3.5 μm, which contributed to the imaging of the surface of Ryugu. The optical windows manufactured by Optical Coatings Japan are available for any wavelength band and have features such as excellent thermal durability, high light transmission, and high resistance to light. They can also be metallized for package sealing on the outer periphery, including on the side faces. They are used in a wide range of sectors such as space, atmospheric measurement, and security.