/sci/ - Science & Math

>The ISS Propulsion module was proposed as a backup to functions performed by the Zvezda Service Module and Progress spacecraft. Critical ISS functionality such as guidance, navigation, control and propulsion are provided only by Russian (Zvezda and Progress) and the European (ATV) spacecraft.
>A Propulsion Module would have been needed for ISS altitude maintenance and reboost, debris avoidance maneuvers, attitude control and propellant supply in the event the Zvezda Service Module was not available (launch failure, etc.) to the International Space Station.
So apparently there's been some thought on what to do should Zvezda be unavailable