A major consideration for many satellite busses is the propulsion systems required to maneuver in orbit both for station keeping and debris avoidance maneuvers. While the thrusters, lines, and tanks for these systems have a large on-orbit heritage, the sizing of the system for each satellite will change based on many factors, with just a few being the orbit and life expectancy of the mission. With propulsion fuels being an expendable item, once the satellite is out of fuel it is no longer able to continue performing its mission and is de-orbited. While the expansion of proliferated and inexpensive satellites has created the ability to quickly replace these missions, there are still many large and exquisite systems on orbit that don’t have plans to be replaced with a proliferated architecture. These large systems have been designed for a set number of years before the mission will end, typically with the limit of their propulsion being the final deorbit criteria.
New advancements in the space industry have worked to create a ‘gas station in space’ that can remove one major hurdle in satellite lifetimes – running out of expendable propellant. With the ability to refuel a satellite, many years or decades can be added on to the original estimated lifetime of the satellite. This has the potential to save tens of billions of dollars and reduce a burden on launch providers as the replacement rate for some systems may slow. However, the extended timeline of these missions may not be a benefit for all the space architecture. Already there are extensive cyber vulnerabilities present from new as well as 20-year-old systems. While future policy reform may help secure upcoming systems to some cyber vulnerabilities, there is little being done to secure decades old systems that were once thought to be on their way out the door. If these systems are given a full tank of propellant to stay on orbit for 5, 10, or 20 more years, they will undoubtably become targets for cyber actors to exploit.
Orbit Fab is one of the leading companies in the on-orbit space refueling industry with backing from many government and commercial spacecraft programs. Leaders of Orbit Fab believe that the U.S. is only months away from fully implanting an orbital refueling as opposed to the many years that some predict. While this is welcome news to many including the Space Force leaders who wish for the ability to “maneuver without regret”, Orbit Fab does not present any public information on the cyber vulnerabilities that are present in their refueling systems or any indications of negative after-effects to the satellites they refuel.
Another cyber risk to this program is the Rendezvous and Proximity Operations (RPOs) that will be required to dock the refueling spacecraft to the target satellite. While RPOs have been conducted with many missions, they still present a high level of risk during the maneuvering and docking phase. If a cyber actor is able to interrupt the commanding and control during these key moments in operations, there could be devasting debris causing consequences.
While on-orbit refueling operations are a key innovation to maintain space operations for commercial and Space Force operations, the implementation of this technology must be done carefully. Continued failures to recognize cyber vulnerabilities in satellites and space infrastructure leaves aging but newly refueled satellites open attack. While innovations in upcoming operating software security is necessary and ongoing, further research needs to be put towards the on-orbit updating of the operating systems of satellites getting refueled to extend their missions. While achieving space refueling is an essential capability, the excitement could quickly fade if newly fueled satellites are quickly targeted and destroyed or seized by adversary cyber actions.