Unit 1 Research Agencies Text I NASA Text Ⅱ ROSCOSMOS Text III CASC Unit 2 Rocket Text I HOW Rockets Work Text Ⅱ How Do Space Rockets Work Text III Repo~of a Rocket Experiment Unit 3 Space Exploration Text I A Review of Human Cognitive Performance During Long—term Spaceflight Text II The Second Space Race—a Review of Asteroid Mining Literature Unit 4 Space Station Text I Quantum Optics Experiments Using the International Space Station：a Proposal Text Ⅱ Preliminary Studies on the Development of a 3D Space Radiation Transport Model Text III A Proposal to Research the Storage Facility for Spent Nuclear Fuel at Yucca Mountain Unit 5 Space Shuttle Text I Space Shuttle Case Studies：Challenger and Columbia Text II On the Very Idea of Risk Management：Lessons from the Space Shuttle Challenger Reflerences
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