SpaceX will employ a highly advanced capsule to deorbit the International Space Station (ISS) when its mission concludes.
On Wednesday, NASA and SpaceX revealed their plan to safely decommission the ISS by guiding it to reenter Earth’s atmosphere, aiming for it to disintegrate and what remains to plunge into the ocean around early 2031, marking the station’s 32nd year. NASA ruled out alternative options like disassembling the station or transferring ownership.
NASA awarded SpaceX an $843 million contract for this task, involving the largest structure ever constructed in space.
Reasons for Deorbiting the ISS
The ISS is aging. Initiated by Russia and the U.S. in late 1998, it became operational in 2000. Subsequent contributions from Europe, Japan, and Canada expanded it to the size of a football field, weighing almost 1 million pounds (430,000 kilograms). NASA anticipates the station will remain functional until at least 2030. By then, private companies are expected to launch their own space stations, with NASA transitioning to a customer role. This shift, already applied to cargo and crew missions, allows NASA to concentrate on lunar and Martian exploration. If commercial stations are not ready by 2030, NASA might extend the ISS’s operational life to ensure continuous scientific research.
Challenges of Returning the ISS to Earth
Dismantling the ISS and returning its parts to Earth was considered but deemed impractical and hazardous. The ISS was not designed for disassembly in orbit, and the process would be costly and risky for astronauts. No current spacecraft can accommodate the station’s large components. Boosting the ISS to a higher orbit was also dismissed due to logistical complexities and the risk of creating space debris.
Deorbiting Process
To keep the ISS in its orbit, visiting spacecraft regularly boost it to about 260 miles (420 kilometers) high. Without these boosts, the ISS would gradually descend uncontrollably. To ensure a safe reentry over a remote area of the South Pacific or Indian Ocean, a spacecraft will be launched to dock with the ISS and guide it to a specific reentry path. NASA expects some parts, ranging from the size of a microwave oven to a car, to survive reentry and fall within a narrow debris field of 1,200 miles (2,000 kilometers) long. Initially, NASA considered using three Russian supply ships but opted for a more robust spacecraft, leading to SpaceX securing the contract in June for the deorbit vehicle.
Design of the Deorbit Spacecraft
SpaceX will modify its Dragon capsule, known for transporting supplies and astronauts to the ISS, to handle the deorbit task. The upgraded Dragon will feature a larger trunk with 46 engines and over 35,000 pounds (16,000 kilograms) of fuel. According to SpaceX’s Sarah Walker, the main challenge will be to design a spacecraft powerful enough to guide the ISS while withstanding atmospheric drag during descent. The capsule will need a particularly powerful rocket to reach orbit. It will be launched 1.5 years before the ISS’s planned deorbit. Astronauts will remain on board during the initial phase of the descent, vacating six months before the final maneuver. Once the ISS descends to about 137 miles (220 kilometers), the Dragon capsule will complete the deorbit in four days.
Previous Deorbit Experiences
NASA’s first space station, Skylab, fell to Earth in 1979, with debris landing in Australia and the Pacific. Efforts to control Skylab’s descent or boost its orbit with the space shuttle failed as the shuttle was not ready in time. Ground controllers managed a controlled descent aimed at the Indian Ocean, though some debris reached Western Australia. Russia deorbited its Mir station in 2001 and previously several Salyut stations, gaining more experience with space station reentries.
Preservation of ISS Artifacts
NASA plans to retrieve small items from the ISS for museum displays, such as the ship’s bell, logs, and panels with patches. These items will be returned via SpaceX supply ships in the final years of the ISS’s operation. Ken Bowersox of NASA expressed a desire to save larger items, but practicality dictates a single, controlled deorbit is the most feasible solution.
