As the International Space Station (ISS) approaches the end of its operational life, NASA and SpaceX have outlined a comprehensive plan to safely deorbit the massive structure.
This ambitious endeavor will ensure a controlled reentry, minimizing risks to populated areas and allowing for a smooth transition to future space habitats.
The Need for Deorbiting the ISS
Launched in 1998, the ISS has been a symbol of international cooperation and scientific achievement. The station has supported countless scientific experiments and technological advancements over the decades. However, after more than 30 years in orbit, the ISS is showing signs of aging.
Components and systems that have operated far beyond their intended lifespans are becoming increasingly difficult and expensive to maintain. By 2030, the ISS is expected to reach the end of its service life, necessitating a plan for its safe deorbit. This move is also aligned with NASA’s broader strategy to transition low Earth orbit operations to private companies, allowing the agency to focus on deep space missions to the Moon and Mars.
Developing the Deorbit Strategy
NASA awarded SpaceX an $843 million contract to develop a deorbit vehicle based on its Dragon spacecraft. The selected vehicle, known as the United States Deorbit Vehicle (USDV), will be a heavily modified version of the Dragon capsule. The USDV will feature a larger trunk section equipped with additional thrusters and propellant tanks, enhancing its capability to safely guide the ISS through a controlled reentry.
According to Sarah Walker, director of Dragon mission management at SpaceX, the enhanced trunk will be twice as long as the standard Dragon trunk and will include 46 Draco thrusters. Walker described the vehicle, noting, “It’s almost a spacecraft in and of itself.” These modifications are essential to manage the significant tugs and forces the vehicle will encounter as it lowers the ISS’s orbit and brings it into a controlled descent.
Ensuring Safe Reentry
Ensuring a controlled and safe reentry for the ISS is a complex task. The space station currently orbits at an altitude of approximately 400 kilometers. Without periodic boosts from visiting spacecraft, the station would naturally descend, eventually reentering the Earth’s atmosphere in an uncontrolled manner.
To avoid this scenario, NASA and SpaceX plan to use the USDV to gradually lower the station’s orbit to about 330 kilometers over six months. This gradual descent will be carefully monitored to ensure precision and safety. The final phase of the deorbit operation will involve the USDV guiding the ISS into a specific reentry corridor over a remote section of the South Pacific or Indian Ocean, ensuring that any surviving debris lands safely away from populated areas.
Technical Specifications of the USDV
The USDV is designed to handle the unique challenges of deorbiting the ISS. With a mass of more than 30,000 kilograms, including 16,000 kilograms of propellant, the USDV will be significantly larger and more powerful than the current Dragon spacecraft. The vehicle will need a powerful rocket for launch, potentially heavier than the Falcon 9 used for standard Dragon missions.
This enhanced vehicle will include a robust propulsion system to manage the precise deorbit maneuvers. The USDV will be launched to the ISS approximately 1.5 years before the planned reentry. After docking with the station and completing a thorough checkout, it will begin the controlled descent process. This timeline ensures that all systems are fully operational and that there is ample time to address any unexpected issues.
Transitioning to Commercial Space Stations
NASA’s plan to deorbit the ISS is part of a broader strategy to transition low Earth orbit operations to private companies. By fostering the development of commercial space stations, NASA aims to create a sustainable space economy where multiple entities operate and maintain orbital habitats.
This transition will allow NASA to focus its resources and expertise on deep space exploration, including missions to the Moon and Mars. The successful deorbit of the ISS will mark a significant milestone in this transition, demonstrating the viability of commercial partnerships and the capability of private companies to handle complex space operations. This shift is expected to drive innovation and reduce costs, benefiting the entire space industry.
