This is an extensive book which covers various topics related to the field of radioisotopes, like radioisotopes in environment and radioisotopes in power system space applications. The first section covers the applications of radioisotopes in environment with interesting research related to soil; water; environmental dosimetry and composition analyzer. The next section focuses on radioisotopes in power systems which generate electrical power by converting heat released from the nuclear decay of radioactive isotopes. This book will appeal to a broad spectrum of readers interested in radioisotopes.