Editorial: Next generation of materials for space applications

Reza Hedayati^1*Malgorzata Holynska²T. John Tharakan³Antonio Mattia Grande⁴Paramjit Kour⁵Syafiqah Nur Azrie Safri⁶

• ¹KN Toosi University of Technology, Tehran, Iran
• ²European Space Agency, Paris, France
• ³Liquid Propulsion Systems Centre, Valiamala, India
• ⁴Politecnico di Milano, Milan, Italy
• ⁵University of Jammu, Jammu, India
• ⁶Universiti Putra Malaysia, Serdang, Malaysia

longer delivery times, and they propose suggestions for developing technologies to realize a sustainable human presence in space.The review article by Pernigoni and Grande [4] provides an overview of the most significant innovations in the field of materials for space applications, along with the related advantages and challenges. After introducing the main environmental factors in space and their possible risks and effects on materials, the authors proceed with the description of novel materials for space applications, subdivided into polymers, metals, semiconductors, composites, and mixtures. Innovations in manufacturing techniques and in-situ resource utilization are also briefly.Gupta et al. [5] explore the feasibility of using Microbially Induced Calcite Precipitation (MICP) to repair damaged sintered lunar bricks. Their systematic approach reveals that while initial damage significantly compromises the mechanical properties of these bricks, subsequent repairs using MICP-based slurry results in a meaningful recovery of their compressive strength.Instead of heavy metal, Tarikuzzaman et al. [6] propose the wasted human hair for being used as building material in space due to its high tensile strength and its availability in any long-term mission. They measure the concrete workability, compressive strength, and porosity for a series of different cement compositions. Increased workability and porosity for increasing hair concentrations is observed. Compressive strength slightly decreases with increased hair concentration.Due to good thermal conductivity and thermal shock resistance, ultra-high temperature ceramics such as zirconium diboride (ZrB2) have been investigated as promising materials to be used in reusable thermal protection systems. Meanwhile, radiation exposure in space can pose risks of degrading such material properties, especially over a prolonged mission duration. In another interesting paper, Rønning and Tang [7] study the interaction of electron radiation-which can be found in the outer Van Allen belt, with ZrB2. They investigated the response of thermo-optical properties of ZrB2 to increasing electron radiation fluences. The ZrB2 samples were characterized by their microstructure, thermal conductivity, coefficient of thermal expansion (CTE), emittance, absorptivity, and surface roughness before and after irradiation.