NASA and SpaceX Unveil Plans for ISS Deorbit Vehicle

NASA and SpaceX have shared new details about their collaborative effort to develop a U.S. Deorbit Vehicle, a spacecraft based on SpaceX’s Dragon, designed to safely deorbit the International Space Station (ISS).

This development marks a significant step in preparing for the end of the ISS’s operational life in 2030, as NASA transitions to commercially owned space destinations.

During a recent teleconference, key figures from NASA and SpaceX discussed the vehicle’s design and the deorbit strategy. Participants included:

• Ken Bowersox, Associate Administrator for NASA’s Space Operations Mission Directorate;
• Dana Weigel, Manager of NASA’s International Space Station Program;
• Sarah Walker, Director of Dragon Mission Management at SpaceX.

Vehicle design and capabilities

The Deorbit Vehicle will be based on SpaceX’s Dragon spacecraft, but about half of the vehicle will feature a new design. According to Weigel, early considerations involved using three Roscosmos Progress vehicles for deorbiting the ISS. However, the Roscosmos segment wasn’t designed to control three Progress vehicles simultaneously, leading to the current Dragon-based approach.

Walker explained that the Deorbit version of Dragon would require substantial enhancements, including approximately six times the usable propellant and three to four times the power generation and storage compared to the current Dragon model. The enhanced design will start with the Cargo Dragon version, featuring an improved trunk section to host propellant tanks, engines, avionics, power generation, and thermal hardware tailored for the deorbit mission.

The vehicle will be equipped with 46 Draco engines, with 22 to 26 firing simultaneously to provide about 10,000 Newtons of thrust during the final burn. This setup will ensure controlled and effective deorbiting of the ISS, according to SpaceX and the Agency.

With 6x more propellant and 4x the power of today’s Dragon spacecraft, SpaceX was selected to design and develop the U.S. Deorbit Vehicle for a precise, controlled deorbit of the @Space_Station https://t.co/GgtuplTwqQ pic.twitter.com/E23sS7CE4U

— SpaceX (@SpaceX) July 17, 2024

Notably, the Deorbit Vehicle will be docked to the Node 2 forward port of the ISS about a year and a half before the planned reentry. Weigel noted that the vehicle will be delivered by SpaceX, with NASA responsible for procuring launch services through its Launch Service Program.

SpaceX intends to compete for this launch contract, with “a couple of different configurations across the Falcon product line” that could support the mission, said Sarah Walker.

Deorbit and reentry strategy

The final destination for the ISS is yet to be determined, though the south Pacific Ocean is one of the considered locations. The debris footprint is expected to be about 2,000 kilometers long and “fairly narrow“. The ISS’s reentry will involve parts of the station, like the solar arrays, breaking apart and burning up, while denser pieces, ranging from the size of a microwave to a small sedan, may survive reentry.

The timing for the ISS to drift down is variable and influenced by the solar cycle. Post-splashdown evaluations of the reentry site may be conducted to assess any recoverable debris, although Bowersox mentioned that most of the station is expected to burn up during reentry.

Additionally, during the teleconference, Walker highlighted that SpaceX’s top priority remains resolving the second stage issue with the Falcon 9 rocket, which emerged last week during a Starlink launch.

A liquid oxygen leak developed in the Falcon’s second stage, preventing to circularize the orbit with the second burn. The Starlink satellites were deployed, but cannot be saved due to atmospheric drag pulling them down. The FAA is overseeing the SpaceX-led investigation, with Falcon launches currently on hold.

However, on the afternoon of July 18th, marine assets used for Falcon 9’s landings and recovery were deployed to sea, meaning a possible return to flight soon.

Concurrently, the company continues pre-launch preparations for missions like Crew-9, Polaris Dawn, and CRS-31, according to Walker.

The press conference concluded with an acknowledgment of the commonality between the Deorbit Vehicle and Dragon XL, with Walker noting that despite their differences in purpose, both spacecraft share certain design elements, already approved by NASA and used on the current Dragon spacecraft.