The Spaceborne Imaging Spectrometer DESIS: Mission summary and potential for scientific developments

Abstract

The DLR Earth Sensing Imaging Spectrometer (DESIS) is a spaceborne instrument installed and operated on the International Space Station (ISS). The German Aerospace Center (DLR) has developed the instrument and the full pre-processing chain up to L2A, while the US company Teledyne Brown Engineering (TBE) provided the Multi-User System for Earth Sensing (MUSES) platform and the infrastructure for operations and data tasking. DESIS is equipped with an on-board calibration unit and a rotating pointing mirror (POI). The POI can change the line of sight in the forward/backward direction (independently of the MUSES orientation), allowing the observation of the same area with different pointing angles within an overflight. About four years after the mission’s kick-off, the DESIS spectrometer was integrated into MUSES in August 2018, marking the start of the commissioning phase. The DESIS on-orbit functional tests were successful, and the DLR-built processing chain installed at DLR for scientific users and at Amazon Web Service for commercial users started to generate operational L1B, L1C and L2A DESIS products. In October 2019 the operational phase started the distribution of the data to scientific and commercial users. Since then, the instrument performance has been constantly evaluated. In a continuous monitoring process, the data quality is controlled and, if necessary, the calibration algorithms and tables are adjusted. This is essential for the later data application by scientists. In particular, the monitoring approaches emphasize the need for high and consistent data quality over long time periods. In autumn 2021, the first DESIS user workshop demonstrated the widespread use of DESIS data for topics like water and terrestrial resource monitoring, biodiversity and forest management. This presentation will give an overview of the DESIS mission, data quality, data access, and provides examples and perspectives on the scientific exploitation of the mission. The contribution for the CHIME mission is presented exemplarily for the CHIME test sites that are constantly observed by DESIS since 2020. DESIS data acquisition opportunities rely on the non-sun-synchronous ISS orbit, resulting in observation and illumination conditions difficult to reproduce. On the other hand, DESIS time series contain images of different day times, sensor incident angles as well as sun zenith angles and thus, can open up new opportunities for the monitoring of Earth system processes that have a daily variability such as photosynthesis. Finally, DESIS multitemporal data stacks can be an essential data base for algorithm and operational processor developments that shall be able to handle massive data amounts. The DESIS data archive is open for such research and developments and thus, is a valuable imaging spectroscopy data source.