This paper discusses the challenges and perspectives of cryogenic propellant management for crewed deep space exploration. Liquid hydrogen and liquid methane, along with liquid oxygen as an oxidizer, are the most promising propellants due to their high specific impulse and ability to be produced in situ. To extend the duration of space missions, cryogenic propellants must be stored and refueled from on-orbit depots. The paper reviews reference missions, architectures, and technology demonstrators, highlighting the main operations required for cryogenic storage and transfer. It emphasizes the need for advancements in physical knowledge to address gaps in current understanding, particularly in areas such as conditioning, storage, maneuvers, and transfer. The review also discusses the importance of cryogenic fluid management (CFM) technologies, including propellant depots, and the challenges associated with microgravity conditions. The paper concludes by outlining the scientific and technological challenges that need to be overcome to enable sustainable deep space exploration.This paper discusses the challenges and perspectives of cryogenic propellant management for crewed deep space exploration. Liquid hydrogen and liquid methane, along with liquid oxygen as an oxidizer, are the most promising propellants due to their high specific impulse and ability to be produced in situ. To extend the duration of space missions, cryogenic propellants must be stored and refueled from on-orbit depots. The paper reviews reference missions, architectures, and technology demonstrators, highlighting the main operations required for cryogenic storage and transfer. It emphasizes the need for advancements in physical knowledge to address gaps in current understanding, particularly in areas such as conditioning, storage, maneuvers, and transfer. The review also discusses the importance of cryogenic fluid management (CFM) technologies, including propellant depots, and the challenges associated with microgravity conditions. The paper concludes by outlining the scientific and technological challenges that need to be overcome to enable sustainable deep space exploration.