104 Aerospace Engineering: The Use of a Thermal Protection System
Basic understanding of heat transfer (conduction, convection, radiation), knowledge of Newton's Laws of Motion
In this workshop, we will learn about the evolution of spacecraft designs and strategies to manage the heating experienced during atmospheric entry. For example, we will learn about the two categories of TPS materials: reusable systems and ablative systems. Reusable TPS are suitable for low heat flux conditions, such as a return from Low Earth Orbit (~7.5 km/s). However, ablative TPS is the only option for high-heat flux entries, such as Lunar or Martian returns (~11 km/s and ~13 km/s, respectively). These ablative TPS are designed to decompose during an atmospheric entry, thereby protecting the spacecraft from the harsh aerothermal environment. Ablative TPS systems are characterized by different densities, materials, and architectures, depending on the mission's specific needs. One successful class of ablative TPS often utilized by NASA missions is lightweight carbon phenolic ablators, which consist of a carbon fiber substrate impregnated with a phenolic resin. Phenolic Impregnated Carbon Ablator (PICA) is one material in this class, which uses a rigid carbon fiber substrate, and was successfully flown on the NASA Mars Science Laboratory (MSL) and Stardust missions. We will learn the fundamental physical laws that govern the ablation process and provide cooling to the spacecraft. Due to restrictions in mass loading, optimization of heat shielding and mass of TPS materials are necessities, and accommodating spares is impractical. We will learn how NASA engineers design and test the heat shields to minimize the group and maximize safety.
【Sample research topics】
What are the differences in flight conditions between the Space Shuttle and a space capsule?
What consequences does this have for thermal protection system design? What are the main innovations in thermal protection systems in the last 20 years?
How can new additive manufacturing tools be used to make spacecraft? What kind of sensors can we use to monitor the thermal protection materials in flight? What are the critical safety challenges for planetary exploration?