Browsing by Author "Killian, Matthias"
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Item Integrated EVA Thermal Simulations using TherMoS and V-SUIT(46th International Conference on Environmental Systems, 2016-07-10) Cusick, Andrew; Killian, Matthias; Olthoff, ClaasTwo dynamic simulation tools have been developed at the Technical University of Munich in the past years: The Thermal Moon Simulator (TherMoS) and the dynamic portable life support system (PLSS) simulation Virtual Space Suit (V‑SUIT). Development of TherMoS and V‑SUIT started in 2009 and 2011, respectively. Both tools are MATLAB®-based and spin-offs from the Virtual Habitat (V-HAB) project. V-SUIT aims to dynamically simulate space suit portable life support systems and both their interaction with a detailed and dynamic human model, as well as the dynamic external environment of a space suit moving on a planetary surface. TherMoS was initially developed to enable the dynamic thermal simulation of moving objects on the lunar surface in general. To achieve this, a thermal model of the lunar surface is created including three-dimensional features like craters and boulders. For the use with V-SUIT, TherMoS provides information about heat transfer between the space suit and its environment. This paper describes the process of connecting V‑SUIT and TherMoS to each other. Interfaces between both simulation tools allow TherMoS to transfer information about radiation exchange factors and boundary nodes to V-SUIT. In turn, V‑SUIT performs the overall thermal calculations in combination with the PLSS simulation. Thermal calculations for the radiative heat transfer performed by TherMoS are validated against results from ESATAN-TMS thermal modeling software using a correlated model. Once all interfaces were established, a model of a generic spacesuit was created and run through several dynamic simulation scenarios. Results show the effects of the dynamic thermal environment propagating through the different layers of the models, from the suit exterior via the suit layers to the inside where the interactions with the suit gas flow and the astronaut are modeled.Item Lunar Traverse Planning with Integrated Thermal Simulation(2020 International Conference on Environmental Systems, 2020-07-31) Killian, MatthiasIn the near future, solar-powered rovers are expected to explore the poles of the Moon. The simulation tool Thermal Moon Simulator for Exploration (TherMoS X), currently under development at the Chair of Astronautics at the Technical University of Munich, is now able to optimize traverses of a rover on the lunar surface. As a novelty, TherMoS X simulates the full energy state of the rover including its thermal state. The updated thermal model of the Moon determines temperatures of the surface of the Moon, which show a Pearson correlation coefficient of 0.955 if compared to Diviner. Analyses in this paper focus on a solar-powered rover with a rechargeable battery and power consumption simulated in specific domains. A thermal model of the rover including a resistive heating element completes the simulation approach. An adapted version of the optimization algorithm A* determines near-optimal solutions of traverses along waypoints while simulating the energy state of the rover. Traverse optimization is carried out at two different sites in the south polar region of the Moon with a precise terrain model of co-registered data from LOLA. The investigated areas are 30 km by 30 km. Results show that in both scenarios a rechargeable battery is required to find a traverse that is navigable under the given boundary conditions. At one site, the traverse with the lowest battery capacity possible differs significantly from the ones that result from optimization with the classic approach A* where the energy state of the rover is neglected. Total distance is slightly longer by 18.1 % but the battery capacity is 86 % less than the one needed to follow the shortest traverse determined by the original A* algorithm. At the other site, no difference in traverses occurs mainly because waypoints are positioned close by and illumination conditions are benign.Item Mars Rovers - Limits of Passive Thermal Design(47th International Conference on Environmental Systems, 2017-07-16) Gscheidle, Christian; Killian, MatthiasRovers of successful missions to Mars made use of active and passive thermal control options. However, in order to survive the night, all of them relied on a heat source such as electrical energy stored in batteries or from radioactive decay. In this paper, we want to find an optimum point for a minimalistic rover design such as Mars Exploration Rovers that relies mainly on passive thermal control but might also include a small heat source, either RHU or electrical. A thermal model consisting of ten nodes allows varying the size of the rover in the range from Sojourner up to the size of MSL rover. We calculate the heat exchange of the internal components with the environment for each size of the rover and compare the influence of parameters such as body volume and insulation. Due to the different mechanisms of heat transfer, namely convection, conduction, and radiation, the ratio between heat loss and available solar energy on solar cells increases with the size of a rover necessitating usage of RTG (as in MSL rover) for heating or better insulation of the inner components. Investigated worst case cold environmental conditions include latitudes from 0°N to 40°S with wind speeds ranging from 0 m s-1 up to 15 m s-1Item Thermal Environment for the Lunar Volatile Prospector Mission(47th International Conference on Environmental Systems, 2017-07-16) Killian, Matthias; Fisackerly, RichardThe ESA mission concept Lunar Volatiles Prospector intends to send a rover to the south pole of the Moon for scientific exploration. Investigation of permanently shadowed regions (PSR) is one of the main objectives of the mission in the search for and analysis of volatiles. An instrument onboard a rover with a mobile range of about 50 km shall determine the distribution of water and other volatiles on a local scale. Previous analyses, which considered additional requirements on waypoints and scientific return, revealed a preference for the Shoemaker and Faustini crater region. On addition to mission constraints such as visibility to earth for communication purposes, available light for recharging batteries etc., the thermal environment plays a significant role for the success of a mission to this region. Lunar surface temperatures in the polar region vary between 25 K and 300 K for the targeted period in the year 2022. In this paper, a traverse is characterized regarding the thermal environment and corresponding heat fluxes of the rover. ESATAN-TMS was used in order to calculate radiative heat transfer and to solve the model. With analyses from this paper, dynamic thermal requirements can be established for a potential rover. In addition, thermal calculations from this paper shall be the baseline for future optimization of the traverse together with scientific requirements for a best scientific return as well as mitigating requirements for the design of the rover.Item Traverse Planning on the Lunar Surface – Benefits from Thermal Modeling(45th International Conference on Environmental Systems, 2015-07-12) Killian, Matthias; Hager, Philipp B.Classic traverse optimization methods focus on energy demands for driving only. The subject of this work is to identify potential for future traverse optimizations in lunar environments by combining thermal modeling with classic optimization methods related to locomotion energy. For this purpose five different traverses are investigated that share the same starting and final point on two sides of a lunar crater. For the simulations presented in this paper, an in-house developed lunar specific thermal preprocessor creates the lunar scenery, the moving sample object, and its traverses in a geometrical and nodal representation. The commercial software package ESATAN-TMS performs the thermal calculations afterwards, starting with ray tracing and finishing with solving the entire nodal network. Rovers can profit from traverse optimization by increasing the mission lifetime or the exploration area because of power savings in the thermal control subsystem. The analysis of all simulated traverses focuses on energetic aspects: energy needed for locomotion, energy needed for thermal control, and possible energy acquired by solar cells. Traverses differ in their distance between two points, the period in shadow and the terrain slope in the same artificial lunar setting. In order to estimate the influence of thermal design, the five traverses were analyzed with three different rover configurations. Results show that energy savings ranging from 32 % to 83 % are possible compared to the shortest traverse, dependent on the rover configuration and the traverse. A longer travel time has to be taken into account for such energy savings.