The Instrument Design of the DLR Earth Sensing Imaging Spectrometer (DESIS).

Whether for identification and characterization of materials or for monitoring of the environment, space-based hyperspectral instruments are very useful. Hyperspectral instruments measure several dozens up to hundreds of spectral bands. These data help to reconstruct the spectral properties like reflectance or emission of Earth surface or the absorption of the atmosphere, and to identify constituents on land, water, and in the atmosphere. There are a lot of possible applications, from vegetation and water quality up to greenhouse gas monitoring. But the actual number of hyperspectral space-based missions or hyperspectral space-based data is limited. This will be changed in the next years by different missions. The German Aerospace Center (DLR) Earth Sensing Imaging Spectrometer (DESIS) is one of the new currently existing space-based hyperspectral instruments, launched in 2018 and ready to reduce the gap of space-born hyperspectral data. The instrument is operating onboard the International Space Station, using the Multi-User System for Earth Sensing (MUSES) platform. The instrument has 235 spectral bands in the wavelength range from visible (400 nm) to near-infrared (1000 nm), which results in a 2.5 nm spectral sampling distance and a ground sampling distance of 30 m from 400 km orbit of the International Space Station. In this article, the design of the instrument will be described.

Ultraviolet imaging spectroscopy shows an active saturnian system.

Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms peaks at 4 x 10(34). Saturn's aurora brightens in response to solar-wind forcing, and the auroral spectrum resembles Jupiter's. Phoebe's surface shows variable water-ice content, and the data indicate it originated in the outer solar system. Saturn's rings also show variable water abundance, with the purest ice in the outermost A ring. This radial variation is consistent with initially pure water ice bombarded by meteors, but smaller radial structures may indicate collisional transport and recent renewal events in the past 10(7) to 10(8) years.