BY:SpaceEyeNews.
A Game-Changing Orbital Milestone
China has quietly achieved a breakthrough that could transform how we operate satellites in space. In early June 2025, two Chinese satellites—Shijian-25 and Shijian-21—executed a precise rendezvous in geostationary orbit (GEO), 36,000 kilometers above Earth. What happened next is being hailed as the first satellite-to-satellite refueling operation ever performed in this orbital zone.
During the operation, Shijian-25 approached Shijian-21 and successfully transferred 142 kilograms of hydrazine fuel—enough to extend Shijian-21’s operational life by up to eight years. This historic refueling maneuver took place in one of the most valuable orbital regions, where satellites deliver global communications, navigation, and environmental monitoring.
The significance of this feat goes beyond the fuel itself. It introduces a new phase of orbital capability—where satellites can be serviced, supported, and sustained after launch. In other words, they’re no longer bound by the fuel they’re launched with. This moment marks a clear transition toward a more resilient and sustainable future in space.
Refueled in Orbit?! China’s Bold Space Milestone at 36,000 KM!
How Refueling in Space Became Reality
This milestone didn’t come with dramatic announcements. It was revealed through orbital tracking, which showed that Shijian-25 gradually closed the gap with Shijian-21 until the two satellites reached matching velocities and positions in GEO. Shortly afterward, both satellites moved in sync, indicating that docking had likely occurred.
Shijian-21 was a logical choice for this experiment. It had already proven its maneuvering capabilities back in 2022 when it successfully docked with and relocated an inactive satellite to a graveyard orbit. That maneuver had demonstrated that Shijian-21 was capable of advanced in-orbit handling. Shijian-25, launched in January 2025, was known to be intended for orbital servicing missions, and its behavior in June aligned perfectly with that goal.
Fuel transfer in space is an incredibly delicate task. Hydrazine is a powerful propellant but also highly toxic and volatile. To transfer it safely, the satellites needed to dock precisely, maintain pressure control, and ensure fuel flow without leaks or misalignment. Achieving that at GEO altitude—far beyond the reach of most previous servicing tests—is a testament to the technical precision of the mission.
The entire event unfolded without the satellites deviating from their expected orbits, another sign that the operation was both intentional and successful. And while no formal statement was released, multiple satellite observers confirmed the behavior was consistent with in-orbit refueling.
Why This Is a Big Deal
Satellite operations have long been limited by fuel. Once a satellite runs out, it loses the ability to maintain its position, even if all its systems are still working. That usually means retirement or relocation to a graveyard orbit. And in GEO, where most communications and weather satellites operate, launching a replacement can cost hundreds of millions of dollars and take years to plan.
What makes this maneuver so important is that it challenges that entire model. If satellites can be refueled in orbit, they can keep operating well past their original mission timelines. That means fewer replacements, less orbital congestion, and much greater return on investment.
By transferring 142 kilograms of hydrazine to Shijian-21, China demonstrated that satellite lifespans don’t have to be finite. They can be extended. The fact that this happened in GEO—where servicing is most difficult due to the altitude and environmental factors—makes it even more impressive.
Beyond just saving costs, orbital refueling also reduces the need for frequent launches, cutting back on rocket emissions and space debris. And it allows satellites to be used more flexibly over time, adjusting their missions or positions as needed, rather than being locked into a single-use design.
This is not just a one-time experiment. It’s a foundational step toward a new model of satellite infrastructure—one where spacecraft are managed like Earth-based systems, with servicing missions ensuring performance over decades.
Overcoming the Engineering Challenges
Refueling in space, particularly in GEO, is incredibly complex. At 36,000 kilometers above Earth, satellites must maintain exact positions to prevent orbital drift. Even slight misalignments can result in lost contact or unintended movement over time.
To accomplish docking and fuel transfer, both satellites must match their orbits precisely—position, speed, and orientation. Once docked, a sealed connection must be established to move propellant from one satellite to the other. Any error could cause a leak, equipment damage, or unexpected orbital shifts.
What made this mission stand out is that it was conducted completely autonomously, with no external mechanical intervention. The satellites had to manage approach, docking, stabilization, and fueling entirely on their own, using onboard systems.
No external boosters were used, and no human-in-the-loop controls were observed. This shows an advanced level of space autonomy—a growing trend as orbital distances increase and real-time human control becomes impractical.
The fact that this operation was done in GEO makes it even more extraordinary. Previous servicing attempts, including in-orbit refueling tests, were done in lower orbits. GEO introduces longer communication delays, more radiation exposure, and a more sensitive orbital environment, requiring even greater precision.
By completing this task successfully in such a difficult setting, the mission has effectively raised the bar for what satellite servicing can be.
The Rise of Sustainable Space Infrastructure
The concept of long-term space infrastructure isn’t new, but it’s rarely been realized in practice. Satellites have traditionally been treated as disposable tools—launched, used, and replaced. But this refueling success suggests a future where satellites are built to last, and regularly serviced to remain active for years or even decades longer.
This changes how satellites might be designed in the near future. Instead of overloading them with extra fuel for longer missions, engineers could build leaner systems designed for in-orbit refueling. This would lower launch mass and allow for more modular spacecraft—satellites built with servicing ports, plug-and-play components, and reconfigurable systems.
It also creates opportunities for new types of space missions. Servicing satellites, like Shijian-25, could become standard tools—stationed in orbit and dispatched as needed to top up fuel, replace aging components, or even reconfigure a satellite’s orbit.
On a larger scale, this shift opens the door to collaborative infrastructure in space. Nations and companies might begin developing shared servicing systems or fuel depots—just like gas stations in orbit—to support entire fleets of commercial and government satellites.
And as orbital space becomes more crowded, being able to refuel and reposition satellites safely and responsibly will become not just a technical advantage, but a requirement for maintaining long-term access to critical orbits like GEO.
What Comes Next for Refueling Missions
The success of this refueling test suggests that similar missions may soon follow. China could expand this model to service other satellites—possibly both domestically and internationally. Future servicing satellites might carry not only fuel, but also replacement parts, new sensors, or even robotic arms to make mechanical repairs.
This also sets the stage for new commercial markets. Satellite refueling as a service could emerge as a new business model, especially as the cost of launches remains high. Satellite operators may begin buying servicing contracts instead of launching full replacements.
At the same time, other spacefaring nations are likely to accelerate their own servicing programs. The U.S., Europe, and Japan have been developing in-orbit servicing concepts for years, and this successful Chinese mission will no doubt prompt greater urgency.
The biggest challenge going forward will be coordination. As more satellites become capable of approaching and docking with others, regulations will be needed to ensure safe and predictable operations. Guidelines for approach distances, communication protocols, and technical compatibility will help prevent conflicts or accidents in orbit.
International collaboration will also be key. If servicing missions become common, they must operate with transparency and mutual understanding, especially in shared orbital environments like GEO.
Conclusion: Space Enters the Age of Support and Sustainability
China’s refueling of a satellite in geostationary orbit isn’t just a technical success—it’s a turning point. It signals that space operations are moving beyond the era of one-time-use missions. We’re entering a new chapter where space assets can be supported, maintained, and extended for the long haul.
With this capability, satellites become part of a living, evolving infrastructure—much like highways, power grids, or aircraft. They can be repaired when needed, upgraded when necessary, and sustained for as long as they’re useful.
This is the future of space: efficient, modular, and sustainable. And now that future has officially begun.
Stay tuned to SpaceEyeNews for more in-depth coverage on space servicing, orbital logistics, and the next wave of innovation above Earth.
References:
https://interestingengineering.com/space/china-to-perform-critical-satellite-refueling