NASA is planning a controlled deorbit of the International Space Station (ISS), with the process set to begin in 2028 and conclude with its fiery re-entry into Earth's atmosphere in 2030. The agency has allocated approximately $1 billion for this complex operation, which aims to guide the 450,000-kilogram (992,000-pound) station into a remote, uninhabited region of the Pacific Ocean known as Point Nemo.
Recent events, including a near-emergency evacuation of astronauts due to a 'worsening' leak, have underscored concerns about the ISS's aging infrastructure and the risks associated with its continued operation. The station, which orbits at an altitude of 250 miles (400 km) and travels at 17,500 mph (28,000 km/h), requires constant propulsion to maintain its orbit. However, NASA plans to cease these orbital boosts starting in 2028, allowing the ISS to gradually descend.
A natural, uncontrolled re-entry poses significant risks, as large portions of the station could survive atmospheric burn-up and impact populated areas. Space debris experts estimate that several hundred objects could reach the ground, necessitating a controlled descent to mitigate potential casualties. The internationally agreed-upon 'casualty risk limit' for spacecraft re-entries is one in 10,000. Given the ISS's massive scale, an uncontrolled descent would far exceed this threshold.
To achieve a controlled re-entry, NASA awarded SpaceX a contract worth just under $1 billion to develop a 'tugboat' vehicle. This will be a modified version of the company's Crew Dragon capsule, equipped with enhanced propulsion and propellant capabilities to push the ISS out of orbit. The mission involves docking the modified Dragon with the ISS, performing a series of orbital maneuvers over several months to shape its descent, and ultimately initiating a final burn to send it towards Earth.
The final human crew is expected to depart the ISS in mid-2029, with operations ceasing by the end of that year. The deorbit vehicle will then dock with the now uncrewed station. After a period of orbit shaping burns, the final re-entry burn will occur when the ISS is approximately 175 miles (280 km) above Earth. The ISS and the deorbit vehicle are projected to hit the atmosphere at approximately 17,000 mph.
While most of the station is expected to disintegrate due to friction, NASA estimates that between 40 to 100 tons of denser material could potentially survive the re-entry. The controlled descent into Point Nemo, located in the South Pacific, is the safest option, minimizing the danger to populated landmasses. A historical precedent for uncontrolled re-entry concerns NASA's 1979 Skylab mission, which scattered debris over Western Australia.
The ISS, a collaborative project involving NASA, Russia, the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), and the Canadian Space Agency (CSA), has been continuously inhabited since November 2000. It serves as a vital microgravity laboratory for scientific research across various disciplines. NASA alone spends approximately $3 billion annually on the ISS program, with international partners contributing substantial funding. The end of the ISS's operational life is part of a broader transition in space exploration, with partners like Russia planning their own orbital platforms and private companies like Axiom Space developing commercial modules. International efforts are also underway for future orbital endeavors, including lunar and Martian bases.