The United States Space Force is taking a measured, long-term approach to developing and acquiring on-orbit satellite servicing capabilities such as refueling and repair. While there is growing interest from U.S. Space Command operators and an emerging commercial industry, the Space Force is proceeding cautiously – conducting cost-benefit analyses and limited experiments rather than making major near-term investments or commitments.
Space Force leaders believe that incorporating servicing capabilities like refueling into future satellite constellations could extend spacecraft lifetimes, enable more maneuvering, and ultimately save money compared to frequently replacing satellites. However, they assess that significant technical and economic uncertainties remain regarding the viability and value of these nascent technologies. As a result, the Space Force is taking an incremental approach focused on studies and targeted demonstrations in the near-term, with an eye towards potentially integrating servicing capabilities into next-generation satellite architectures a decade or more in the future.
The Promise and Challenges of Satellite Servicing
The ability to refuel, repair, upgrade or otherwise service satellites after they are launched into orbit has long been a tantalizing prospect for spacecraft operators. GEO satellites are extremely expensive assets that often cost hundreds of millions of dollars to develop, build and launch. Once in space, they typically carry only a finite supply of fuel and are subject to gradual degradation from the harsh environment of space. When satellites run out of propellant or suffer component failures, they usually have to be replaced with new spacecraft at great expense.
On-orbit servicing could change this paradigm by enabling satellites to be refueled, allowing them to operate for significantly longer periods. Servicing could also potentially be used to repair or upgrade components, further extending lifetimes. For military satellites, the ability to maneuver more frequently and unpredictably by refueling on orbit could provide important tactical advantages. However, the technologies and techniques needed to safely and reliably service satellites in the challenging domain of space are still in their infancy.
Key technical obstacles include the need for very precise navigation and robotic manipulation to safely approach, grasp and manipulate client satellites without damaging them. Refueling interfaces and techniques that work reliably in the vacuum of space also need to be perfected. Just as importantly, the economic case for servicing needs to be firmly established. Servicing missions will require specialized spacecraft and likely on-orbit depots for storing fuel and spares. They will also entail significant operational complexity and risk.
To be worthwhile, the costs of servicing architectures and the launch costs to put them in orbit need to be less than the savings from extending satellite lifetimes and reducing replacement rates. The lack of clear technical and economic feasibility is a key reason why the Space Force is being cautious about investing in servicing capabilities in the near-term.
Space Force Takes an Incremental Approach
Rather than making major programmatic commitments, the Space Force is pursuing an incremental approach to on-orbit servicing centered on studies, analysis and limited experiments. “The jury is still out,” said Lt. Gen. Philip Garrant, head of Space Systems Command (SSC), regarding whether servicing capabilities being developed over “the next 10 or 15 years” will make sense to acquire.
While the Space Force thinks “it’s an important capability,” Garrant said in May 2024 that more analysis is needed on what to do in the near-term. As a result, the service is concentrating on analytical efforts and a few small-scale demonstrations and prototypes using $30 million appropriated by Congress for on-orbit servicing in fiscal year 2024.
In one pathfinder effort, SSC awarded a $25 million contract to commercial startup Astroscale in September 2023 to develop a small refueling vehicle and demonstrate it on orbit by 2026. The Space Force requested another $20 million for similar projects in fiscal year 2025. However, these are modest investments compared to the billions the Space Force spends annually to develop and acquire new satellites.
The Space Force’s approach seems calibrated to allow the service to gain knowledge and reduce technical risk, while letting the private sector take the lead in attempting to prove out the technologies and business case for on-orbit servicing in the near-term. The service appears to be in no rush to make servicing a core element of its space architecture.
A Growing Commercial Ecosystem
Indeed, multiple commercial companies are moving forward with plans to establish on-orbit servicing as a viable industry, even without major government commitments. Startups such as Astroscale, Orbit Fab, and Starfish Space have raised hundreds of millions in private capital to develop servicing vehicles and technologies.
Established aerospace companies like Northrop Grumman and Maxar are also investing internal funds to create servicing capabilities that they hope to sell to both government and commercial satellite operators. With a growing number of commercial companies operating large fleets of communications and remote sensing satellites in low Earth orbit and beyond, there is optimism that a robust market for on-orbit servicing could emerge within the next decade.
Many of these commercial efforts remain in the early stages, however. Astroscale and Orbit Fab have launched small-scale technology demonstrations, but fully-functional servicing systems are still in development. It remains to be seen whether servicing missions can be performed at a price point and with sufficient reliability to make them economically attractive to satellite operators.
The Space Force appears content to let these commercial dynamics play out before making major investments of its own. By taking a go-slow approach, the service can leverage private sector progress and innovation while avoiding the risk of prematurely committing to servicing architectures that may not prove out.
Preparing for a Servicing Future
While taking a cautious stance on near-term acquisition, Space Force leaders do expect on-orbit servicing to become an important element of military space operations in the coming decades. “In the longer term, the constellations will incorporate that into their capabilities,” said Lt. Gen. Garrant regarding the potential for future Space Force satellite systems to be designed for servicing from the start.
This could entail equipping satellites with standard refueling interfaces and designing them to be more modular and robotically serviceable. Spacecraft could potentially be launched with more propellant if they are intended to be refueled periodically. Constellations could also be structured to take advantage of servicing, with a mix of high-capability “mothership” satellites that can be upgraded over time and simpler short-lived craft that are replaced on a regular cycle.
Enabling this future will require significant foundational work in the near-term. In addition to evaluating the technical feasibility of various servicing approaches, the Space Force will need to consider the operational concepts, infrastructure, and support systems needed to make servicing a routine part of space operations.
This could include establishing on-orbit depots to store fuel and spares, as well as investing in space domain awareness capabilities to track and safely navigate around an increasing number of servicing vehicles and client satellites. New training pipelines and operational practices will be needed to plan and execute servicing missions alongside traditional space operations.
Summary
On-orbit satellite servicing holds immense potential to transform the economics and logistics of space operations in the coming decades. The ability to refuel and repair spacecraft could greatly extend satellite lifetimes, reduce the cost of sustaining critical space capabilities, and enable new operational paradigms.
However, the technologies and systems needed to make servicing a practical reality are still maturing, and the economic case remains uncertain. The U.S. Space Force is taking a prudent long-term view – closely tracking commercial developments and selectively investing in studies and experiments to inform future acquisitions.
By taking an incremental approach, the Space Force can position itself to take advantage of servicing capabilities as they are proven out, without taking on excessive risk. In the long run, servicing seems likely to become an integral part of military space operations. Laying the groundwork in terms of technology, infrastructure, and operational concepts will be key to enabling the Space Force to fully harness this game-changing capability in the decades to come.
