Thomas Behnke - Academia.edu (original) (raw)

Papers by Thomas Behnke

We report here on qualification and calibration test results demonstrating the science performanc... more We report here on qualification and calibration test results demonstrating the science performance of the Avalanche Photodiode (APD) detector of the Ganymede Laser Altimeter (GALA, Fig. 1). Most importantly, the measures for noise reduction of the analogue receiver electronics are described. This includes proper grounding of the APD module (EXCELITAS C30654) and filtering in its vicinity and the additional measures to isolate switching noise of the analogue-to-digital convertors (ADCs) from the sensitive single-ended analogue sensor preamplifier electronics of the APD. Tests with realistic electron irradiation doses being representative for the environment of the Jovian magnetosphere and additional shielding measures have been performed in order to ensure that the dark-current noise level of the receiver does not increase significantly over the mission time.

Space Science Reviews, Feb 1, 2021

The BepiColombo Laser Altimeter (BELA) is the first European laser altimeter constructed for inte... more The BepiColombo Laser Altimeter (BELA) is the first European laser altimeter constructed for interplanetary flight. BELA uses a 50 mJ pulsed Nd:YAG laser operating at 10 Hz with a 20 cm aperture receiver to perform the ranging. The instrument also uses a digital approach for range detection and pulse analysis. The ranging accuracy is expected to be better than 2 metres and ∼20 cm in optimum conditions. With the given, only slightly elliptical, orbit, BELA should return a consistent data set for the most if not all of the planet. The instrument is required to function in an extreme environment with the thermal issues being particularly demanding. Novel solutions have been taken to resolve these issues. BELA is described in detail and its predicted performance outlined on the basis of pre-flight testing.

2022 ESA Workshop on Aerospace EMC (Aerospace EMC)

N. Schmitz, P. Palumbo, R. Jaumann, V. Della Corte, M. Zusi, J. M. Castro, M. Leese, S. Debei, D.... more N. Schmitz, P. Palumbo, R. Jaumann, V. Della Corte, M. Zusi, J. M. Castro, M. Leese, S. Debei, D. Magrin, H. Michalik, G. Cremonese, H. Hoffmann, A. Holland, L. M. Lara, B. Fiethe, E. Friso, D. Greggio, M. Herranz, A. Koncz, A. Lichopoj, I. Martinez-Navajas, E. Mazzotta Epifani, H. Michaelis, T. Behnke, R. Ragazzoni, T. Roatsch, J. Rodrigo, E. Rodriguez, P. Schipani, M. Soman, M. Zaccariotto, & the JANUS team. 1 DLR-Institute for Planetary Research, Berlin, Germany; 2 INAF-IAPS, Rome, Italy; 3 INAF-OAC, Naples, Italy; 4 IAA-CSIC, Granada, Spain; 5 CEI-Open University, Milton Keynes, UK; 6 CISAS, University of Padova, Padova, Italy, 7 INAF-OAPd, Padova Italy; 8 IDA, Technical University of Braunschweig, Germany; 9 DIST, Parthenope University, Napoli, Italy.

Advances in Space Research, 2021

Astrophysics and Space Science Library, 1998

The OCA Schmidt telescope is a classical Schmidt telescope, 90cm aperture, 1.50 meter mirror and ... more The OCA Schmidt telescope is a classical Schmidt telescope, 90cm aperture, 1.50 meter mirror and 3.14 meters focal length. It was put into operation in 1978, at a time when astronomical CCDs were in their infancy, and has been designed as a photographic telescope. It has been used for a variety of projects, involving photographic plates, and later photographic films. Intended mostly as a technological development, a small CCD camera was installed inside one of our plate holders has been done in 1992. Thereafter, the development of larger CCD cameras for our telescope has been motivated by the need to survey large area of sky in order to discover Near Earth Asteroids. Since 1995, this effort is a collaborative effort between our team and DLR Berlin.

DASIA 2000- Data systems in …, 2000

Electrical subsystem of the high resolution stereo camera for Mars Express. Uwe Schoenfeldt, Joac... more Electrical subsystem of the high resolution stereo camera for Mars Express. Uwe Schoenfeldt, Joachim Krieger, Thomas Behnke DASIA 2000-Data systems in aerospace, 77-82, 2000. The High Resolution Stereo Camera (HRSC ...

Based on lessons learnt with the BepiColombo Laser Altimeter (BELA) [1], electronics design impro... more Based on lessons learnt with the BepiColombo Laser Altimeter (BELA) [1], electronics design improvements have been implemented for the Ganymede Laser Altimeter (GALA), to be launched on ESA's JUICE spacecraft in 2022 [2]. Improvements include multi-point grounding and separation of “aggressor” printed circuit boards (PCBs) for the high-voltage Q-switch electronics and the pulsed high-power current source of the diode-laser pumped Nd:YAG laser from “victim” PCBs for the sensitive Si avalanche photodiode detector (APD) operating at a noise floor of about 300 fA/sqrt(Hz) in a bandwidth of 100 MHz. Most importantly, the detector amplifier has increased phase margin to avoid feedback of undamped filter resonances, and its output is digitized as differential signal very close to the APD.

This paper reports on EMC issues of the laser transmitter, the photodiode receiver, and the commu... more This paper reports on EMC issues of the laser transmitter, the photodiode receiver, and the communication port of the BepiColombo Laser Altimeter BELA during integration on ESA's Mercury Planetary Orbiter MPO. Parasitic currents originating in the active Q-switch electronics of BELA's diode-laser pumped Nd:YAG laser and from the high-power laser diode driver electronics interfered with the sensitive Si avalanche photodiode sensor operating at a noise floor of about 0.3 pA/VHz in a bandwidth of 20 MHz, and with BELA's Spacewire port, corrupting about 3% of telemetry data to the MPO memory. The problems had been eliminated by implementing multi-point grounding.

The Review of scientific instruments, 2017

This paper presents the principal considerations when designing DC-DC converters for space instru... more This paper presents the principal considerations when designing DC-DC converters for space instruments, in particular for the power converter module as part of the first European space laser altimeter: "BepiColombo Laser Altimeter" on board the European Space Agency-Japan Aerospace Exploration Agency (JAXA) mission BepiColombo. The main factors which determine the design of the DC-DC modules in space applications are printed circuit board occupation, mass, DC-DC converter efficiency, and environmental-survivability constraints. Topics included in the appropriated DC-DC converter design flow are hereby described. The topology and technology for the primary and secondary stages, input filters, transformer design, and peripheral components are discussed. Component selection and design trade-offs are described. Grounding, load and line regulation, and secondary protection circuitry (under-voltage, over-voltage, and over-current) are then introduced. Lastly, test results and ch...

Sensors, Systems, and Next-Generation Satellites XIII, 2009

The DLR Institute of Planetary Exploration has proposed a novel design for a space instrument acc... more The DLR Institute of Planetary Exploration has proposed a novel design for a space instrument accommodated on a small satellite bus (SSB) that is dedicated to the detection of inner earth objects (IEOs) from a low earth orbit (LEO). The low pointing stability of the satellite bus, the stray light and thermal environment in LEO represent the major design drivers

Special Publications, 2007

Planetary and Space Science, 2008

The Mars Express spacecraft carries the pushbroom scanner high-resolution stereo camera (HRSC) an... more The Mars Express spacecraft carries the pushbroom scanner high-resolution stereo camera (HRSC) and its added imaging subsystem super resolution channel (SRC). The SRC is equipped with its own optical system and a 1024 Â 1024 framing sensor. SRC produces snapshots with 2.3 m ground pixel size from the nominal spacecraft pericenter height of 250 km, which are typically embedded in the central part of the large HRSC scenes. The salient features of the SRC are its lightweight optics, a reliable CCD detector, and high-speed read-out electronics. The quality and effective visibility of details in the SRC images unfortunately falls short of what has been expected. In cases where thermal balance cannot be reached, artifacts, such as blurring and ''ghost features'' are observed in the images. In addition, images show large numbers of blemish pixels and are plagued by electronic noise. As a consequence, we have developed various image improving algorithms, which are discussed in this paper. While results are encouraging, further studies of image restoration by dedicated processing appear worthwhile. The SRC has obtained more than 6940 images at the time of writing (1 September 2007), which often show fascinating details in surface morphology. SRC images are highly useful for a variety of applications in planetary geology, for studies of the Mars atmosphere, and for astrometric observations of the Martian satellites. This paper will give a full account of the design philosophy, technical concept, calibration, operation, integration with HRSC, and performance, as well as science accomplishments of the SRC.