Rescue Satellite Makes Space Navigation History - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

Rescue Satellite Makes Space Navigation History

In late February, Northrop Grumman’s Mission Extension Vehicle MEV-1 autonomously docked with another satellite in geostationary orbit in space, making navigation history.  It simultaneously took the next step in satellite operation by extending Intelsat 901’s lifetime beyond its original plan. The so-called “rescue satellite,” built by Northrop Grumman subsidiary Space Logistics, used a combination of traditional ranging, optical orbit determination from ground, and on-board sensors (visible, infrared, and LiDAR)  for relative navigation in space to make its ultra-precise rendezvous 35,786 km above Earth.

The successful operation means a potential sea change in satellite operation: their lifetimes can be extended, and defunct satellites can be moved to safer orbit even after their fuel supplies are exhausted.

The complex series of maneuvers to bring the two satellites together began with an October 2019 launch of the MEV-1. Northrop Grumman controllers undertook a series of engine burns to raise MEV-1’s orbit from its highly elliptical geostationary transfer orbit up to a circular orbit 300 km above the geosynchronous belt. Shortly thereafter, Intelsat decommissioned its satellite 901, and it used the last of its propellant to move into the GEO graveyard orbit.

MEV-1 approached.

For 19 days, MEV-1 advanced upon and withdrew from Intelsat 901, calibrating its navigation sensors: optical cameras, infrared cameras and side-scanning LiDAR to orient and position itself relative to Intelsat 901.

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Images courtesy Northrop Grumman.

For the final delicate and very precise maneuver, on February 25 MEV-1 autonomously flew to 20-meter distance, pausing before resuming travel to the critical 1-meter docking position. It autonomously extended a docking probe, engaging an engine nozzle aboard Intelsat 901. A nozzle, by the way, that was never designed for docking purposes.

MEV-1 then extended a group of internal grippers to anchor the two satellites together.

The satellite duo are now jointly performing stack on-orbit checkouts. Later this month, MEV-1 will relocating the two of them to a GEO spot over the central Atlantic, where Intelsat 901 will take over services for another Intelsat satellite, providing C-band service in the Americas, Europe, and Africa.

MEV-1 will then, like the Lone Ranger, bid farewell to Intelsat 901 and move on to a new mission.