This spacecraft, set to dock with the ISS in 2029, will facilitate a controlled reentry of the aging station into the Earth's atmosphere, ultimately splashing down into the ocean by 2030.

The decision to select SpaceX as the developer of the US Deorbit Vehicle is seen as a crucial step in ensuring a safe and responsible transition for the ISS at the end of its operational life. Ken Bowersox, NASA's associate administrator for Space Operations, stated that this move also supports NASA's plans for future commercial destinations and allows for continued use of space near Earth.

The primary motive behind bringing the ISS's mission to a close in 2030 is its aging infrastructure. Some components of the space station have been in use for a quarter of a century, and cracks have begun to appear, especially in the Russian segment. While the station could potentially be maintained beyond 2030, it would require a significant amount of crew time to ensure its safe operation.

In addition to retiring the ISS, NASA aims to foster a commercial economy in low-Earth orbit. To achieve this goal, the agency is collaborating with private companies to develop commercial space stations capable of accommodating NASA astronauts, as well as those from other countries and private citizens, by or before 2030. By setting a firm end date for the ISS's lifespan, NASA aims to support these commercial ventures by attracting investors.

The sheer size and mass of the ISS make an uncontrolled return to Earth an unacceptable risk. With a mass of 450 metric tons and a size equivalent to an American football field, allowing the station to reenter the Earth's atmosphere without control would pose a significant threat to human life and property. Thus, the need for a dedicated deorbit vehicle is paramount.

During the decision-making process, NASA considered various alternatives to splashing the station into a remote area of the ocean. One option involved moving the ISS into a stable parking orbit at 40,000 km above Earth, beyond geostationary orbit. However, NASA determined that this would require a significant amount of propellant, estimated to be around 900 metric tons, or the equivalent of 150 to 250 cargo supply vehicles. In contrast, deorbiting the station would only require approximately 47 m/s of delta-V.

Partial disassembly of the station before reentry was also considered but deemed too complex and risky compared to a controlled deorbit that would keep the complex intact.

While NASA's announcement did not specify which vehicle SpaceX would employ for the deorbit burn, clues can be drawn from public documents regarding the contract procurement. It is likely that NASA will select a rocket for the mission by no later than 2026, suggesting a launch date in 2029, with the deorbit vehicle being docked to the ISS one year before the planned reentry.

This contract marks an important milestone for SpaceX, solidifying its role in the future of space exploration and deorbiting technology. As the countdown to 2030 begins, NASA and its partners, including SpaceX, make significant strides towards paving the way for an exciting era of commercial space stations and continued space exploration.