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See detailDevelopment of a Decision Support System for Incorporating Risk Assessments during the System Design of Microsatellites
Pandi Perumal, Raja UL

Doctoral thesis (2021)

The primary purpose of this research is to develop a decision support system for the early design of an optimal and reliable satellite while making the overall conceptual design process more efficient ... [more ▼]

The primary purpose of this research is to develop a decision support system for the early design of an optimal and reliable satellite while making the overall conceptual design process more efficient. Generally, a satellite design process begins with a mission definition followed by the functional design of the satellite system. Beyond this, the design goes through several iterations and eventually results in a detailed satellite system design. Only then does it make sense to feed in the piece-part information to estimate the reliability of the entire satellite system. Predicted reliability from this bottom-up method may sometimes be markedly lower than the requirements. In such case, the maturity of the design is brought down, and mitigation strategies need to be implemented to meet the reliability requirements. Consequently, introducing new or redundant parts as a mitigation approach can violate the previously satisfied requirements such as mass, power and cost. Furthermore, additional design iterations are needed until all the requirements are met. Therefore, this design approach is expensive, inefficient, and can be avoided if reliability is considered from the early design phase. However, the challenge is to simultaneously perform reliability analysis and system design as they are entirely different engineering disciplines. In this research, a decision support system: DESIRA is developed to bridge the gap between these two engineering disciplines and incorporate reliability assessments during the early design phase, thus resulting in a truly optimal satellite design. With its unique features such as Reliability Allocation, Reliability Growth, Multidisciplinary Design Optimization and Reliability-Based Multidisciplinary Design Optimization, DESIRA effectively aids the system design at each maturity level. [less ▲]

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See detailAtmospheric Re-entry Energy Storage (ARES)- A Novel concept for utilizing atmospheric re-entry energy
Pandi Perumal, Raja UL; Abbud-Madrid, Angel; Voos, Holger UL

in Proceedings of the Conference GLEX 2021 (2021, June 18)

As the aspirational goal of Mars settlement starts to slowly materialize, it is apparent that its viability hinges on the utilization of its energy and material resources. Although Mars has a thinner ... [more ▼]

As the aspirational goal of Mars settlement starts to slowly materialize, it is apparent that its viability hinges on the utilization of its energy and material resources. Although Mars has a thinner atmosphere than Earth, it still exerts large amounts of heat on entry vehicles, generating temperatures around ~1500 deg C. Therefore, the entry vehicle is covered with a thick layer of ablative heat shield to protect the inside from reaching undesired temperatures. However, the temperature on the Martian surface is significantly cold. It varies between -140 deg C and 30 deg C. One of the critical challenges in developing a settlement and operating equipment on Mars is to find adequate heat sources on its surface. The envisioned heat sources are solar energy, geothermal energy, greenhouse gases and Radioisotope Thermoelectric Generators (RTG). Although solar and possibly geothermal energy are the preferred sources for their unlimited supply, they are localized and require an elaborate infrastructure. Trapping greenhouse gases also requires extensive infrastructure. RTGs require a large amount of radioactive fuel and both the equipment and fuel have to be transported from Earth. Due to its hazardous nature, disposal/reprocessing of the fuel will be challenging. Interestingly, little to no effort has been spent to study the possibility of utilizing the large heat generated during vehicle entry. This paper proposes a novel concept to collect, store and utilize the atmospheric entry heat energy using Phase Change Materials (PCMs) obtained from the Martian moons. Mars settlement architectures suggest that Phobos and Deimos can be used to set up preliminary base camps. These moons are potentially trapped C-type asteroids and have the possibility to contain rich Lithium reserves. Lithium and its alloys have a relatively high latent heat of fusion and low density, making them an ideal PCM for this application. This concept takes advantage of the undesired heat generated during atmospheric entry to melt the PCMs. A storage system would store and insulate the melted PCM as it solidifies and heat energy is released. The utilized PCM could then be reused and consumed for a variety of purposes. With current technology limitations, the heat storage system could only store the heat energy obtained using PCMs for a few hours. While the results from ongoing research could considerably increase its efficiency, PCMs could be used as a temporary energy source in landing sites where no other energy generation infrastructure is available. Alternatively, the heat generated from PCMs could be converted to electricity using thermoelectric generators. [less ▲]

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See detailComparison of Multidisciplinary Design Optimization Architectures for the design of Distributed Space Systems
Pandi Perumal, Raja UL; Voos, Holger UL; Dalla Vedova, Florio et al

in Pandi Perumal, Raja; Voos, Holger; Dalla Vedova, Florio (Eds.) et al Proceedings of the 71st International Astronautical Congress 2020 (2020, October)

Advancement in satellite technology, and the ability to mass-produce cost-effective small satellites has created a compelling interest in Distributed Space System (DSS), such as Low Earth Orbit (LEO ... [more ▼]

Advancement in satellite technology, and the ability to mass-produce cost-effective small satellites has created a compelling interest in Distributed Space System (DSS), such as Low Earth Orbit (LEO) satellite constellations. Optimization of DSS is a complex Multidisciplinary Design Optimization (MDO) problem involving a large number of variables and coupling relations. This paper focuses on comparing three different MDO architectures for a DSS design problem. Initially, an overview of the constellation model, the subsystems model, and the coupling relationships between the subsystems and the constellation are provided. The modelling of the subsystems and the constellation configuration are carried out in OpenMDAO. Later, three monolithic MDO architectures, namely, Individual Discipline Feasible (IDF), Simultaneous Analysis and Design (SAND) and Multidisciplinary Feasible (MDF) are compared by implementing them to the developed DSS model. The results indicate IDF outperforms the rest of the architectures for the conceptual design of DSS. The optimum objective function obtained by IDF is 1% lower than SAND and 7% lower than MDF. While the functional evaluation required for IDF is 50% lower than SAND and 90% lower than MDF. [less ▲]

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