The DLR Earth Sensing Imaging Spectrometer (DESIS) is a space-based hyperspectral instrument developed by Deutsches Zentrum für Luft- und Raumfahrt (DLR). The optical system of the spectrometer was fabricated and prealigned by the Fraunhofer-Institut für Angewandte Optik und Feinmechanik (IOF).
The paper describes the manufacturing, integration, and testing of this optical system. It was realized as an all reflective system using metal-based mirrors and a modular, so-called snap-together approach, which allows to simplify the integration of optical systems considerably. Measured r.m.s. wavefront errors of the complete system are in the range of 63 nm to 120 nm, which is compliant with the instrument’s requirements.
The DLR Earth Sensing Imaging Spectrometer (DESIS) is a new space-based hyperspectral sensor developed and operated by a collaboration between the German Aerospace Center (DLR) and Teledyne Brown Engineering (TBE). DESIS will provide hyperspectral data in the visible to near-infrared range with high resolution and near-global coverage. TBE provides the platform and infrastructure for the operation on the International Space Station (ISS), DLR has developed the instrument. This paper gives an overview of the design of the DESIS instrument together with results from the optical on-ground calibration. In-flight calibration, stability of dark signal and rolling vs. global shutter analysis will be presented.
The DLR Earth Sensing Imaging Spectrometer (DESIS) is a new space-based hyperspectral instrument developed by DLR and operated under collaboration between the German Aerospace Center (DLR) and Teledyne Brown Engineering (TBE). DESIS will be mounted on the International Space Station on the MUSES platform in 2018 and will provide hyperspectral Earth Observation in the wavelength range from visible to near-infrared with high resolution and near global coverage. TBE provides the platform and infrastructure on the ISS. DLR developed the instrument, while the optical system was fabricated and pre-aligned by the Fraunhofer Institut fur Angewandte Optik und Feinmechanik (IOF). This paper presents the on-ground adjustment, focusing and calibration approach for DESIS done at the optical lab of the Institut fur Optische Sensorsysteme (DLR). The optical lab set-up will be described in detail. Selected calibration results like detector Modulation Transfer Function (MTF) and linearity, optics MTF and wave front, focus position, smile and keystone measurement, instrument spatial and spectral MTF, and absolute radiometric calibration will be presented. The spectral and radiometric in- ight calibration approach of the DESIS calibration unit (CAL) based on stabilized Light Emitting Diode (LED) arrays will be demonstrated. In addition, the innovative pointing unit (POI) in front of the instrument and its pointing accuracy will be introduced. Finally imaging quality and accuracy of the sensor calibration will be evaluated with respect to foreseen applications.
Rosetta is one of the cornerstone missions of the European Space Agency for having a rendezvous with the comet 67P/Churyumov-Gerasimenko in 2014. The imaging instrument on board the satellite is OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System), a cooperation among several European institutes, which consists of two cameras: a Narrow (NAC) and a Wide Angle Camera (WAC).
The WAC optical design is an innovative one: it adopts an all reflecting, unvignetted and unobstructed two mirror configuration which allows to cover a 12° × 12° field of view with an F/5.6 aperture and gives a nominal contrast ratio of about 10–4.
The flight model of this camera has been successfully integrated and tested in our laboratories, and finally has been integrated on the satellite which is now waiting to be launched in February 2004.
In this paper we are going to describe the optical characteristics of the camera, and to summarize the results so far obtained with the preliminary calibration data. The analysis of the optical performance of this model shows a good agreement between theoretical performance and experimental results.
Direct optical communication links might offer a solution for the increasing demand of transmission capacity in satellite missions. Although direct space-to-ground links suffer from limited availability due to cloud coverage, the achievable data rates can be higher by orders of magnitude compared to traditional RF communication systems.
In 2017 the new hyperspectral DLR Earth Sensing Imaging Spectrometer (DESIS) will be integrated in the Multi-User-System for Earth Sensing (MUSES) platform  installed on the International Space Station (ISS).
The Sentinel-4 payload is a multi-spectral camera system, designed to monitor atmospheric conditions over Europe from a geostationary orbit. The German Aerospace Center, DLR Berlin, conducted the verification campaign of the Focal Plane Subsystem (FPS) during the second half of 2016. The FPS consists, of two Focal Plane Assemblies (FPAs), two Front End Electronics (FEEs), one Front End Support Electronic (FSE) and one Instrument Control Unit (ICU). The FPAs are designed for two spectral ranges: UV-VIS (305 nm - 500 nm) and NIR (750 nm - 775 nm). In this publication, we will present in detail the set-up of the verification campaign of the Sentinel-4 Qualification Model (QM). This set up will also be used for the upcoming Flight Model (FM) verification, planned for early 2018. The FPAs have to be operated at 215 K ± 5 K, making it necessary to exploit a thermal vacuum chamber (TVC) for the test accomplishment. The test campaign consists mainly of radiometric tests. This publication focuses on the challenge to remotely illuminate both Sentinel-4 detectors as well as a reference detector homogeneously over a distance of approximately 1 m from outside the TVC. Selected test analyses and results will be presented.