Analysis of the energy storage and thermal control subsystems of the Mars Science Laboratory rover

Interplanetary travel has always fascinated the human mind, specifically the exploration of new environments to understand their habitability and whether they have hosted life in the past or present. The main purpose of the following paper is to provide an overview of a mission to the planet Mars. Initially, an overview of the possible forms of energy, thanks to which a spacecraft can be powered, is shown, and subsequently, the production of energy using Radioisotope Thermoelectric Generators (RTGs) is focused on, since for interplanetary missions and deep space missions far from the Sun, it is not efficient to design a power system based on solar energy due to the weakness of solar radiation. Several missions have been implemented using a radionuclide power system such as: Cassini, New Horizons, Galileo, Ulysses, LES-8/9, Voyager 1 and 2, MSL/Curiosity, Perseverance, etc. The MMRTG has several advantages such as: 1) their power production that does not depend on the spacecraft orientation and shadowing; 2) they guarantee independence of distance from the Sun; 3) they provide low power levels, but for a long period of time, and are not susceptible to radiation damage. The main disadvantages are: 1) they affect the radiation environment of the spacecraft; 2) they are an interference source for plasma diagnostic equipment; 3) the installation of the radioactive source requires careful handling procedures due to the risk of radiation. The two most used radionuclides are discussed in more detail below, with their respective half-life and specific powers: Plutonium-238 and Americium-24. In Chapter 4, the ten scientific instruments work in synergy to acquire information on the geology, atmosphere, environmental conditions and potential biosignatures on Mars. The power consumption of each instrument and the range of operating temperatures is focused on in detail to subsequently carry out a sizing of the batteries and the thermal control system. Chapter 5 explains why NASA JPL chose exactly one electrochemical cell in a specific configuration to enable the rover to power payloads even in the most power demanding situation. The study arrives at the solution proposed by NASA JPL, with all parameters within the mission requirements, but with a small variation in the number of strings in parallel, due to the consideration of a higher power consumption. In the last part of the paper, thanks to the study of the operational temperature ranges of each instrument in chapter 4, the thermal control system is sized, trying to determine the necessary flow rate to keep the rover avionics within the allowed temperature limits.