For the first time ever, two satellites in a geosynchronous graveyard orbit have docked with one another. On Tuesday February 25th at 0215 EST / 0715 GMT, the MEV-1, or Mission Extension Vehicle, successfully autonomously docked with an aging commercial communications satellite, Intelsat 901 high above the Pacific Ocean.

IS-901, like many older geostationary (GEO) satellites, is still capable of performing its intended mission but is low on the fuel needed for attitude adjustment and station keeping. After its launch back in June of 2001, it served well beyond its planned 13 year lifespan, and was raised from its operational orbit to a GEO graveyard orbit late last year. The GEO graveyard orbit is the nearest convenient place to decommission GEO satellites to keep them out of the way of currently operational satellites. Thanks to the gravitational pull of the Moon and the Sun, the orbit of these satellites becomes inclined and increasingly distant over time, further decreasing the chance of them interfering with spacecraft lower down. 

Knowing that fuel was running low, Intelsat signed on with SpaceLogistics LLC (a wholly owned subsidiary of Northrop Grumman) to have IS-901 become the first craft to test a design where an otherwise operational spacecraft could have its mission extended by docking with MEV-1, which would provide the needed fuel and thruster control to keep IS-901 properly orientated in space.

• Docking gives Intelsat telecoms satellite new lease of life
• Northrop Grumman’s MEV-1 servicer docks with Intelsat satellite
• Two commercial satellites link up in space for first time
• Photos: Servicing spacecraft approaches Intelsat satellite high above Earth

The mission profile of the MEV-1 is simple in theory: launch to space with plenty of fuel and a robust attitude control and navigational system. Then, meet up with a target satellite in orbit, latch on, and for the next five years provide the target satellite with stantion-keeping services it simply cannot provide for itself. But if rocket science has taught us anything, it’s that execution is sometimes much more difficult than theory.

The MEV-1 launched from Baikonur Cosmodrome in Kazakhstan last October and spent several months using its low-impulse ion engines to reach the proper orbit. It finally arrived in the neighborhood of IS-901 back on the 5th of February, and after taking several pictures of the target, ground controllers gave the green light. MEV-1 then used its higher-powered, more responsive liquid fueled jets to approach IS-901 from the spaceward or apogee side of the craft, first parking at an 80 meter distance, then again at 20 meters away. At each pause, ground controllers reviewed the data sent back and gave the GO for the craft’s next phase; each time the craft received the GO it executed its next phase autonomously without help from the ground.

Finally approaching to within 5 meters, the MEV-1 extended a long probe into the throat of the apogee engine nozzle of the IS-901 spacecraft. Once inside several mechanical fingers deployed, grabbing IS-901 and pulling the two craft physically into contact. 

The MEV-1 is now in the process of returning IS-901 back down into the Clarke belt, where it will operate over the Atlantic Ocean at a longitude of 27 degrees West. It should complete this maneuver by the end of this month, performing various operational checks as it goes. Intelsat is reportedly paying $13 million per year for this operation, as compared to initial construction and launch costs of reportedly over $700 million for a planned life of 13 years. Once the five years are up, MEV-1 will return IS-901 to graveyard orbit, then move on to another customer to provide the same service. The craft is reportedly able to perform this same five year mission for up to three separate satellites.

The operation went so smoothly that Intelsat has announced that MEV-2 will perform its docking maneuver while the target satellite is still in GEO, rather than moving that satellite into a graveyard orbit. MEV-2 is expected to launch in June of this year from French Guiana along with Intelsat’s new Galaxy 30 spacecraft aboard an Ariane V. 

However, despite the apparent success, Northrop-Grumman has no plans to build additional MEV’s.  Instead, they are focusing on developing Mission Robotic Vehicles. Rather than acting like a tugboat for out-of-fuel satellites, these Mission Robotic Vehicles (also known as MRVs) will act more like an in-flight adjustment and refuel service.  Using a device called Mission Extension Pod, the MRVs will be able to autonomously refuel a satellite before undocking and moving on to the next customer.

That said, Northrop-Grumman has said there is nothing preventing them from constructing other MEV’s if market demand exists.

Link to Press Release