December 30, 2021 updates Posted on December 30, 2021 by Doug Loss Knocking on the Stars: The Philosophical Implications of the Search for Extraterrestrial Intelligence http://clusty.ast.villanova.edu/aprsa/files/mortensen_final.pdf A Review on Human Interplanetary Exploration Challenges https://arc.aiaa.org/doi/10.2514/6.2022-2585 The Economics of Interstellar Flight https://arxiv.org/abs/2112.13911 Spin-orbit coupling for close-in planets https://arxiv.org/abs/2112.14335 Composition of super-Earths, super-Mercuries, and their host stars https://arxiv.org/abs/2112.14512