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One satellite services another in orbit for the first time

A satellite that was ready for retirement has been given a new lease of life after being serviced in orbit by another satellite containing enough fuel to get it back up and running, the first time such a feat has been achieved.

The Northrop-Grumman satellite MEV-1 (Mission Extension Vehicle) docked with communications satellite Intelsat 901 and is now serving as its engine.

Intelsat 901 (pictured below) had almost run out of fuel and been shifted into a so called 'graveyard orbit' to prepare for the end of its useful life.

MEV-1 will now use its own thrusters and fuel supply to extend the satellite’s lifespan by performing station-keeping manoeuvres. It should be able to extend the useful lifespan of Intelsat 901 by up to five years before undocking and moving on to the next client satellite.

On average, there are about 20 satellites each year that expend all their fuel and must be retired.

“Our MEV is a multi-use vehicle,” said Joe Anderson of Northrop Grumman’s satellite servicing operations unit. “It has a 15-year design life, but there’s much more than 15 years of life extension fuel in the vehicle. This will allow us to service satellites in inclined orbits too.”

MEV-1 launched on October 9 last year, it is the first life-extension vehicle and is under a contract with Intelsat, the world’s largest commercial satellite operator.

Once launched, MEV-1 raised its orbit to rendezvous with Intelsat 901 in geosynchronous equatorial orbit (GEO).

This process took three and a half months from launch and used both chemical and electric propulsion systems.

The two satellites initially docked in a graveyard orbit, which is situated approximately 180 miles above GEO and more than 22,000 miles above Earth, as a precautionary measure.

A few weeks after the MEV-1 launch, Intelsat 901 began to raise its own orbit from GEO to the graveyard, where the two vehicles rendezvoused and finally docked in late February 2020, moving at a rate of approximately 7,000 miles per hour while successfully aligning. Future MEV dockings are planned to take place directly in GEO. Intelsat 901 was returned to full service on April 2.

Currently, MEV-1’s docking method takes advantage of a liquid apogee engine (LAE), which is present on around 80 per cent of GEO satellites, all bearing similar designs.

The LAE is normally used to finalise a craft's orbit at the start of its life but is never used again.

MEV-1 is able to capture and dock by inserting itself into the cone of the LAE to capture the client satellite.

Once captured, the mechanism retracts and the MEV’s stanchions make firm contact with the client vehicle’s launch adapter ring ensuring a secure docking.

The docking procedure is purely mechanical at the moment, thereby avoiding the complications of fluid transfers and electrical or data connections.

In March, the US Space Force underwent its first satellite launch to bolster its constellation providing secure military communications.

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