Rapidly Attachable FluidTransfer Interface (RAFTI) developed by Orbit Fab, a US-based aerospace startup.

According to reports by foreign media, the Passive Refueling Module (PRM) developed by Northrop Grumman in the US has been selected as the first refueling interface to refuel US military satellites in space.

Thriving space refueling 

The term "space refueling", also known as on-orbit refueling, refers to the collective name for fuel replenishment technology applied to various spacecraft, including satellites. It is an important component of the on-orbit service system in space.

The lifetime of a satellite is clearly limited by the fuel it carries. Many satellites are unable to perform attitude control and on-orbit operations just because they run out of fuel, and either become space debris or fall into the atmosphere and burn up. And when that happens, various payloads on the satellite may have not reached their design life and can still function normally. Therefore, on-orbit refueling of satellites is an effective way to extend their service life.

In recent years, the aerospace departments of the US have shown increasing interest in space refueling technology, spurring continuous research in this field by some traditional military industrial enterprises and space startups. One notable example is "Space Logistics", a company specializing in on-orbit satellite services, which is actively developing new generation mission vehicles. These vehicles will be used to provide on-orbit services such as maintenance, attitude control, and refueling for geosynchronous satellites. The company plans to launch them in 2025.

Technological development of multiple enterprises

Due to the nascent stage of space refueling technology, there is intense competition among US space enterprises in this field. Northrop Grumman’s Passive Refueling Module has become the preferred military satellite standard for the US Space Force, granting the company a pioneering advantage in this domain.

Meanwhile, the US Space Force has also stated that, after selecting the “Passive Refueling Module” as the military satellite standard, it still welcomes other companies to provide solutions. For instance, the Rapidly Attachable Fluid Transfer Interface (RAFTI) developed by the US-based space startup Orbit Fab with an alternative technology approach, has also been acknowledged and is set to conduct testing in an on-orbit refueling test program led by the US Space Force. Blue Ring, an on-orbit service platform developed by Blue Origin, another space startup, also features a refueling interface.

Focusing on militarized applications

In recent years, in the context of new geopolitical trends and the strategy of "great power competition", the US Space Force has unmistakably granted a militarized nature to the space refueling” technology.

Since its establishment in 2019, the US Space Force has consistently emphasized the restructuring of space warfare concepts, with "space mobility" being one of its key focuses. The Deputy Commander of the US Space Command once stated that the Space Force not only aims to develop satellite constellations with lower costs and broader coverage, but also pursues flexible space operations. Providing continuous maneuvering capability for combat platforms on orbit is a prerequisite to support these operations.

In the future, the US Space Force will widely equip military satellites with on-orbit refueling interfaces to implement space refueling, in a bid to extend the service life and enhance the maneuverability of military satellites.