NASA has studied options to safely deorbit the space station
NASA is asking US companies to design a $1 billion space tug to crash the International Space Station back to Earth. According to NASA, the station will be deorbited in a controlled manner to ensure avoidance of populated areas on Earth. The station's safe deorbit is the shared responsibility of the five space agencies -- including NASA, CSA (Canadian Space Agency), (ESA) European Space Agency, JAXA (Japan Aerospace Exploration Agency), and the State Space Corporation Roscosmos -- that have operated it since 1998.
The space agency has studied options to safely deorbit the space station, including the option of using up to three Rosocomos Progress spacecraft at the end of station operations. These efforts indicated that a new or modified spacecraft is needed to provide more robust capabilities for deorbit. NASA has engaged with U.S. industry and is proceeding with plans to procure a spacecraft (U.S. Deorbit Vehicle) that will perform the final, safe, deorbit maneuver of the space station, NASA said in a release.
NASA said, "The USDV is focused on the final deorbit activity. It will be a new spacecraft design or modification to an existing spacecraft that must function on its first flight and have sufficient redundancy and anomaly recovery capability to continue the critical deorbit burn."
According to ABC News, the call for designs was initiated on September 20, with proposals due no later than November 17.
NASA Associate Administrator for Space Operations Kathy Lueders in a press conference in March said the vehicle's cost estimate "was a little short of about $1 billion".
USDV proposals are due on November 17, Space.com reported. The International Space Station Program has maintained a continuous human presence aboard the microgravity laboratory for more than 22 years with assembly missions starting in 1998. Throughout the years, NASA and its international partners have worked together to operate, maintain, and upgrade parts of the station.
NASA examined several options for decommissioning of the International Space Station, including disassembly and return to Earth, boosting to a higher orbit, natural orbital decay with random re-entry, and controlled targeted re-entry to a remote ocean area, the space agency said in a release.
The space agency explained how it plans to deorbit the ISS. It explained that the primary objective during space station deorbit operations is the responsible re-entry of the space station's structure into an unpopulated area in the ocean. The chosen approach for safe decommissioning is a combination of natural orbital decay, intentionally lowering the altitude of the station likely using current propulsive elements, and then execution of a re-entry maneuver for final targeting and to control the debris footprint. This final manoeuvre is expected to require a new or modified spacecraft using a large amount of propellant.
The space station is by far the largest single structure ever built in space.
NASA has entered into a contract for commercial modules to be attached to a space station docking port with plans to later detach and has awarded three Space Act agreements for the design of free-flying commercial space stations.