Prof. Enrico Stoll Profile

Prof. Enrico Stoll

at Technische Univ Berlin

SPIE Involvement:

Author

Publications (4)

Proceedings Article | 17 October 2023 Presentation + Paper

Evaluation of orbit results on wildfire detection using a broad single-channel microbolometer sensor sensitive in the thermal infrared

Julian Bartholomäus, Philipp Werner, Enrico Stoll

Proceedings Volume 12727, 127270S (2023) https://doi.org/10.1117/12.2680895

KEYWORDS: Fire, MODIS, Imaging systems, Space operations, Infrared radiation, Equipment, Microbolometers, Forest fires, Thermography, Infrared sensors, Spacecraft, Space sensors

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Proceedings Article | 12 July 2023 Open Access

The MOONRISE-payload as proof of principle for mobile selective laser melting of lunar regolith

J. Neumann, M. Ernst, P. Taschner, J. Perwas, R. Kalms, T. Griemsmann, T. Eismann, R. Bernhard, P. Dyroey, P. Wessels, B. Grefen, J. Baasch, S. Stapperfend, S. Linke, E. Stoll, L. Overmeyer, D. Kracht, S. Kaierle

Proceedings Volume 12777, 127776E (2023) https://doi.org/10.1117/12.2691126

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Proceedings Article | 11 June 2021 Open Access

The MOONRISE: payload for mobile selective laser melting of lunar regolith

Jörg Neumann, Mathias Ernst, Patrick Taschner, Niklas Gerdes, Simon Stapperfend, Stefan Linke, Christoph Lotz, Jürgen Koch, Peter Wessels, Enrico Stoll, Ludger Overmeyer

Proceedings Volume 11852, 118526T (2021) https://doi.org/10.1117/12.2600322

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In-Situ Resource Utilization (ISRU) technologies pave the way for a sustainable colony on the Moon. Above all, the construction of structures using only the available resources is an important factor in reducing costs and logistical effort. The MOONRISE project aims to melt lunar regolith using lasers on mobile platforms for the Additive Manufacturing of structures. This process is called Mobile Selective Laser Melting (M-SLM) and has the advantage that only electrical energy and a moving system are required. In order to validate the laser melting of lunar regolith simulants on ground, a vacuum chamber was designed to host powder material at pressures of around 10-2 mbar. Laser exposure and high speed monitoring were performed through a window. Prior to finalizing the payload design, the type of laser source, appropriate spot size, power, and duration of exposure were determined by means of experimentation. For reasons of cost-efficiency, the payload development approach is to profit as much as possible from components commercial off-the-shelf (COTS), i.e. commercially available components, which have no formal space qualification. These components, e.g. built for automotive application, often withstand harsh environments or even have space heritage without the costly and long-lasting process of formal space qualification. For MOONRISE, COTS parts – partly based on space heritage - have been screened in environmental tests and selected for the payload. A detailed preliminary design review of the MOONRISE payload was conducted in 2019. The payload mainly consists of a printed circuit board (PCB) for system communication, a fiber coupled diode laser, an electrical diode driver, a beam focusing optics, and an LED illumination. For baseline operation, a laser power of typically 70W will be applied for 6s to the lunar surface at a distance of about 25cm. The LED illumination is supporting visualization of the molten regolith by external cameras. The MOONRISE payload can be accommodated to a rover or a robotic arm to ensure mobility for the melting experiments. Following that, an Engineering Model (EM) has been assembled and tested for functionality. The dimension of the payload is 1.5U CubeSat and it has a mass of about 2.5kg with further reduction potential towards flight model (FM) development. In the following steps, environmental tests, such as vibration and thermal-vacuum cycling, will be carried out with the EM. As laser melting of regolith under vacuum conditions produced dense material, tests were continued under low gravity conditions in the large-scale research device Einstein-Elevator at the Hannover Institute of Technology (HITec) of the Leibniz University Hannover (Germany), which is a further development of a classical drop tower with which experiments are carried out under conditions of microgravity [3]. It allows experiments under zero gravity conditions for about four seconds. The flight can be repeated up to 300 times per day. The Einstein-Elevator also enables adjustment of the gravity level from 0 to 5g, a feature that was used to carry out melting experiments with the EM under lunar gravitation conditions.

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Proceedings Article | 13 January 2017 Paper

Space debris: modeling and detectability

C. Wiedemann, J. Lorenz, J. Radtke, C. Kebschull, A. Horstmann, E. Stoll

Proceedings Volume 10254, 102541I (2017) https://doi.org/10.1117/12.2257479

KEYWORDS: Space telescopes, Telescopes, Particles, Sensors, Satellites, Device simulation, Computer simulations, Data modeling, Space operations, Atmospheric modeling

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High precision orbit determination is required for the detection and removal of space debris. Knowledge of the distribution of debris objects in orbit is necessary for orbit determination by active or passive sensors. The results can be used to investigate the orbits on which objects of a certain size at a certain frequency can be found. The knowledge of the orbital distribution of the objects as well as their properties in accordance with sensor performance models provide the basis for estimating the expected detection rates. Comprehensive modeling of the space debris environment is required for this. This paper provides an overview of the current state of knowledge about the space debris environment. In particular non-cataloged small objects are evaluated. Furthermore, improvements concerning the update of the current space debris model are addressed. The model of the space debris environment is based on the simulation of historical events, such as fragmentations due to explosions and collisions that actually occurred in Earth orbits. The orbital distribution of debris is simulated by propagating the orbits considering all perturbing forces up to a reference epoch. The modeled object population is compared with measured data and validated. The model provides a statistical distribution of space objects, according to their size and number. This distribution is based on the correct consideration of orbital mechanics. This allows for a realistic description of the space debris environment. Subsequently, a realistic prediction can be provided concerning the question, how many pieces of debris can be expected on certain orbits. To validate the model, a software tool has been developed which allows the simulation of the observation behavior of ground-based or space-based sensors. Thus, it is possible to compare the results of published measurement data with simulated detections. This tool can also be used for the simulation of sensor measurement campaigns. It is therefore possible to provide an estimation of the detection rates of the non-cataloged population of space debris.

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