This book contains the papers presented at both the fourth Mission Idea Contest (MIC-4) and the Deorbit Device Competition (DDC, later renamed as the Debris Mitigation Competition (DMC)) during the 4th UNISEC-Global Meeting, which followed the 7th Nano-Satellite Symposium in Kamchia, Bulgaria in October 2016. MIC-4 collected 28 papers from 17 countries around the world, with a particular emphasis to encouraging innovative exploitation of micro/nana satellites to provide useful capabilities, services or data. Among them, 11 papers were selected for publication in this volume. Facing with growing risks caused by increasing numbers of space debris, DDC/DMC was introduced for the first time in UNISEC-Global community. This may be an expression of our concerns as part of space community as well as an educational entity. Based upon this recognition, DDC/DMC received 22 papers from 15 countries across the world. Among them, this volume contains seven excellent papers.