What is in-orbit servicing?
In-orbit servicing (IOS) refers to the range of activities performed by robotic spacecraft (servicing vehicles) that interact with existing satellites in orbit: inspection, refuelling, repair, component replacement, orbit raising or relocation, life extension, and deorbit. IOS represents a fundamental shift in the economics of space: instead of replacing a $300 million GEO satellite when it runs out of fuel after 15 years, a servicing vehicle can refuel it for a fraction of the cost and extend its life by a decade.
Operational systems
Northrop Grumman Mission Extension Vehicle (MEV): MEV-1 docked with Intelsat 901 in April 2020 — the first commercial satellite servicing mission. By latching onto the Intelsat satellite's apogee kick motor nozzle and taking over attitude control and station-keeping with its own thrusters, MEV-1 extended Intelsat 901's life by 5 years. MEV-2 repeated the feat with Intelsat 10-02 in 2021. The Mission Robotic Vehicle (MRV) will add robotic arm capability for more complex servicing tasks. Astroscale ELSA-d and ELSA-M: Life extension services using magnetic docking interfaces pre-installed on client satellites during manufacturing.
Life extension economics
A GEO satellite costs $200–400 million to manufacture, launch, and insure. A refuelling servicing mission might cost $50–100 million. If the serviced satellite retains revenue-generating capacity, the economic case is compelling — particularly as GEO orbital slots are finite and difficult to replace quickly. Northrop charges approximately $13 million per year for MEV station-keeping services.
Future capabilities
Next-generation servicing vehicles will offer robotic arm manipulation for component replacement, in-space assembly (replacing degraded solar arrays, reflectors), orbit relocation, and debris removal. DARPA's RSGS programme and NASA's OSAM-1 mission are developing the robotic manipulation capabilities needed for complex IOS operations.