A Chinese commercial startup called Sustain Space has completed an on-orbit test of a flexible robotic arm, a piece of hardware that would let satellites refuel, repair, and extend their own operational lives rather than die when their fuel runs out. The company confirmed March 25 that its Xiyuan-0 satellite, launched March 16 on a Kuaizhou-11 rocket from Jiuquan Satellite Launch Center, successfully operated the arm in four modes: pre-programmed autonomous refueling simulation, human teleoperation, vision-based servo, and force-controlled drawing. SpaceNews
The demonstration matters less as a standalone technical proof. Simulated refueling is not the same as moving actual propellant between spacecraft, and Sustain Space is clear about that. What it signals is who is building orbital servicing infrastructure and why. China's state programs have already done the harder part. The Shijian-21 and Shijian-25 spacecraft completed what appears to be the world's first GEO refueling tests, with the two satellites separating November 29, 2025 after operations that unnamed analysts described as consistent with propellant transfer. Sustain Space is the first commercial entity outside a Chinese state-owned enterprise to develop this class of robotic arm. That distinction matters: commercial companies scale differently than government programs, sell services to multiple customers, and have different incentives around cost and reliability.
Sustain Space, founded in June 2022 as a subsidiary of Emposat, is based in Suzhou, Jiangsu. Its Xiyuan-0 satellite is also designated Yuxing-3 06, built on a platform provided by Shenzhen Mofang Satellite Technology. The robotic arm came from a team at Tsinghua University Shenzhen International Graduate School led by Wang Xueqian, who has spent more than a decade on space robotics, according to China News Service. Hunan University of Science and Technology supplied the optical payload used for vision-based control and teleoperation feedback. Emposat, the parent company, operates ground stations in China and several other countries including France, Azerbaijan, South America, Africa, Southeast Asia, and Samoa. SpaceNews
The arm uses a flexible continuum hollow design with rear-mounted cable drive transmission, routing electrical lines and eventually propellant lines inside the arm structure rather than externally. That matters for docking operations where tangling a live fuel line is exactly the kind of failure that ends missions. During a thermal vacuum test on the ground, the arm suffered uncontrolled shaking caused by temperature changes, which the team resolved within three days. Starlust China-in-Space
No actual propellant was transferred during the demonstration. The company described the tests as simulations, and outside observers have taken the statement at face value. Victoria Samson, chief director of space security and stability at the Secure World Foundation, called the level of operational detail in the company's statement impressive. "This is quite a technological accomplishment," she told SpaceNews. "I am even more impressed with the level of detail in the company statement." SpaceNews
The contrast with U.S. efforts is difficult to ignore. NASA cancelled its On-orbit Servicing, Assembly, and Manufacturing 1 (OSAM-1) project in 2024 following years of delays and cost overruns, walking away from a spacecraft already in hardware production. The U.S. does have missions in development. According to Air and Space Forces Magazine, four on-orbit satellite servicing missions are planned for 2026, including Astroscale US's Refueler spacecraft for the Space Force. But the U.S. approach remains largely government-directed. China's commercial space sector, which has grown significantly since the State Council opened the industry to private investment in 2014, appears to be moving faster toward infrastructure that could eventually serve both domestic and foreign satellite operators.
Sustain Space raised a pre-A+ funding round in September 2025, securing tens of millions of yuan (10 million yuan is roughly $1.4 million at current exchange) led by Shenzhen High-tech Investment, a state-owned fund. That is a small round by U.S. standards but not negligible in a market where Chinese commercial space investment has historically been concentrated in launch vehicles rather than servicing hardware. SpaceNews
At the end of its mission, the Xiyuan-0 satellite will inflate a 2.5-meter-wide drag-augmentation sphere to accelerate its deorbit, a standard practice for experimental spacecraft that need to clear low Earth orbit promptly after operations conclude. China-in-Space
The on-orbit servicing market is real and the demand is real. A single geostationary communications satellite can represent $500 million or more in capitalized assets, and large constellations represent billions. The ability to extend their operational lives or top off their tanks changes the economics of the entire industry. Whether Sustain Space or one of its competitors becomes the standard interface for that infrastructure is an open question. But the company just demonstrated hardware in orbit that three years ago existed only as a research paper and a slide deck. That is worth noting.
