The International Space Station is hailed as one of the most complex engineering, scientific, and collaborative human achievements in modern history. It was launched 20 years ago by two old Cold War rivals and has since been the center of life for six astronauts. Now, the station is nearing the end of its lifespan and will eventually crash back to Earth, landing in the remote Pacific Ocean away from populated areas. NASA is now asking US companies to design a $1 billion space tug to help crash the station back to Earth in a controlled manner.

The agency requests funding for the project in its 2024 budget request, released last week. “NASA is asking for designs for a United States Deorbit Vehicle (USDV) to perform final ISS orbit shaping and reentry burns,” the space agency wrote in the document. NASA SAID THAT the USDV would be able to rendezvous, dock, and perform ISS attitude control and translation maneuvers. It will also be able to provide refueling for the ISS for the final time.

According to the request, it will take up to five years to develop the USDV. The agency hopes to prepare it for the ISS’s deorbit, scheduled for 2031. At that point, the station will be lowered from its current orbit by three Russian Progress cargo vehicles then brought down for a controlled reentry into Earth’s atmosphere. This is to ensure the station doesn’t hit any functioning satellites and avoid contaminating Earth’s surface.

While the ISS is in operation, its safety and security are the responsibility of five international space agencies — including NASA, CSA (Canadian Space Agency), (ESA) European Space Agency, JAXA (Japan Aerospace Exploration Agency), and the State Space Corporation Roscosmos. The ISS is the largest space station ever built and resides 250 miles above Earth. The USDV will need to be able to maneuver the space station to lower it from its current orbit, but it will not be able to provide the necessary thrust for an escape from low Earth orbit. Other methods of escaping the planet’s gravitational pull have been considered, but they would require new hardware and large amounts of fuel.

The USDV will be the first to use Hall Effect Thrusters, which generate electric power by converting electrical current into magnetic fields. The concept is similar to the spacecraft Dawn and Hayabusa 2 thrusters. Several companies, including Thales Alenia and the Polytechnic University of Turin, are working on possible designs for the USDV. The ISS partners will make the final decision, who must decide if the project should go ahead before the station’s deorbit is planned for 2030. NASA could begin requesting USDV designs in 2022 if the plan is approved. The space station will be disassembled in a controlled manner to ensure it avoids any populated areas on Earth, then slammed into the Pacific Ocean at Point Nemo, known as the “space cemetery” for its frequent reentry targets of space debris.