Blockchain is a promising and emerging technology that can have immense potential to provide decentralized trust, data security and integrity, traceability, transparency, visibility, and auditability across various areas in the aerospace and defense industries. In this survey, we study how blockchain features, platforms, and architectures can be leveraged to reshape and revolutionize modern aerospace and defense ecosystems and applications. We also provide discussion into key blockchain complementary architectural technologies such as Oracles, IPFS, and Filecoin. Furthermore, we discuss key opportunities and roles for blockchain in aerospace and military applications. We investigate such opportunities by illustrating multiple use case scenarios including battlefield operations management, border protection, swarm assistance for rescue operations, logistics and supply chain management. Moreover, we compare the existing blockchain platforms to analyze their suitability and applicability for aerospace and defense applications. Finally, we identify and discuss several open issues and challenges for the widespread adoption of blockchain in the aerospace and defense industry. These include latency, privacy, regulation and law, large data traffic, smart contract security, and interoperability.