Blockchain technology concerns the decentralized distribution of information over a network via a shared immutable database. This paper explores present and future applications of Blockchain for Space and Space for Blockchain, providing deep examination and review of substantive technical content. We propose new opportunities including: space-based data feeds for decentralized oracle networks and the trustless execution of smart contracts by and for space, the distributed ledger as a next generation of Transparency and Confidence Building Measures (TCBMs) and for the enhancement of global cybersecurity, and their integration into existing legal, insurance, and economic frameworks.