SpaceX Starship Developments
Starship-to-Starship Docking
SpaceX's Starship docking system, based on the flight-proven Dragon 2 design, is being developed to enable critical spacecraft connections for lunar missions. This system will allow Starship to:
- Dock with NASA's Orion spacecraft and Gateway station in lunar orbit
- Connect two Starships for in-orbit refueling operations
- Potentially link with other spacecraft following International Docking System Standards
Recent testing at NASA's Johnson Space Center validated the system's ability to perform both active and passive docking roles across over 200 scenarios. This versatile capability is essential for Starship's role in the Artemis program and future deep space exploration, enabling crew transfers, resupply missions, and the assembly of larger structures in orbit.
Settling Thrust Dynamics
SpaceX is developing techniques to manage propellant behavior during orbital refueling operations. A key challenge is controlling propellant slosh and ensuring proper settling in microgravity conditions. To address this, SpaceX plans to use "settling thrusters" to generate a small acceleration, positioning the liquid propellants at the bottom of the tanks for efficient transfer.
Key aspects being studied include:
- Propellant slosh dynamics as Starship maneuvers in space
- Required settling thrust levels to properly position propellants
- Ullage maintenance to prevent gas ingestion during transfer
- Pressure control systems to drive propellant flow
Mastering these complex fluid dynamics is crucial for enabling reliable orbital refueling, a cornerstone of SpaceX's plans for long-duration missions beyond Earth orbit.
Cryogenic Propellant Transfer
SpaceX's cryogenic propellant transfer technology is crucial for enabling long-duration space missions, including lunar landings. The company has already demonstrated intertank transfer of cryogenic propellants during Starship's third test flight in March 2024. This successful test involved transferring approximately 10 metric tons of liquid oxygen between tanks within a single Starship vehicle.
The next major milestone is a more complex ship-to-ship propellant transfer demonstration planned for 2025. This test will involve launching two Starships into low Earth orbit, with one serving as a "tanker" and the other as the recipient spacecraft. Engineers must address several challenges, including managing propellant slosh in microgravity, determining optimal settling thrust, and controlling boil-off during the transfer process.
Successful development of this technology is essential for NASA's Artemis program and SpaceX's ambitious goals of making life multi-planetary.