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Parabolic Arc's Mission Extension Vehicle Headed for Space discusses Northrop Grumman's Mission Extension Vehicle, which is only briefly described in Wikipedia.

The article states:

A satellite launched into space can only bring so much fuel with it, and many times the fuel runs out before the satellite’s components stop functioning. This is where the MEV comes in. It is designed to locate and connect to a satellite running low on fuel, and provide the attitude control and orbit maintenance.

The MEV can dock with about 80% of satellites currently in a geostationary orbit, even if the satellite was not designed to be serviced, and can operate for about 15 years. That means the spacecraft could attach to one satellite for a few years, undock and then help out other satellites in need.

First, I wonder if "dock" is not really the right word, and perhaps it's more of a grappling effect, but hopefully not like this!

Whatever it is, I'd like to understand how it can be done to "about 80% of satellites currently in a geostationary orbit". Glue? Magic fingers? Magnets?

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    $\begingroup$ Like MDA SIS, MEV would grab the Apogee Kick Motor (assuming it is retained). This goes back to Orbital Express ASTRO: en.wikipedia.org/wiki/File:Orbital_Express_1.jpg artists conception shows 3 'fingers' to grasp the AKM ring. $\endgroup$ – amI Oct 7 '19 at 4:40
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    $\begingroup$ Like aml says, they essentially harpoon the engine bell and dock that way. $\endgroup$ – mothman Oct 7 '19 at 5:09
  • $\begingroup$ @mothman I stand corrected! Looking at that weird probe shown in OM's answer, it does look like slo-mo harpooning! $\endgroup$ – uhoh Oct 8 '19 at 3:24
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    $\begingroup$ So what I thought were 'fingers' are just passive bumpers. $\endgroup$ – amI Oct 8 '19 at 6:24
  • $\begingroup$ @uhoh sorry, I have no source other than myself for that info. It's the case. The second sentence/paragraph of Organic Marbles answer is exactly correct. $\endgroup$ – mothman Oct 9 '19 at 7:38
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There isn't much information publicly available, but the MEV appears to dock to the one component many satellites have in common: the rocket engine nozzle.

An extensible probe from the MEV (on the left) enters the rocket nozzle and (presumably) expands its tip.

enter image description here

Frame from a video on the Space Logistics website, annotation mine.

A line in the fact sheet also mentions being able to hook on to "standard launch adaptors"

Docking mechanisms to interface with standard liquid apogee engines and launch adaptors

Full video below.

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  • $\begingroup$ So the MEV would do all thrust and attitude control maneuvers for a satellite being out of fuel? $\endgroup$ – Uwe Oct 7 '19 at 14:23
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    $\begingroup$ Apparently, the fact sheet (northropgrumman.com/Capabilities/SpaceLogistics/Documents/…) says " Once docked, the MEV will take over the attitude and orbit maintenance of the combined vehicle stack to meet the pointing and station keeping needs of the customer." $\endgroup$ – Organic Marble Oct 7 '19 at 14:29
  • $\begingroup$ I wonder how a satellite not designed for being docked by a MEV behaves friendly to overtaking control by the MEV, especially if there is a little fuel left. Two different attitude controls fighting each other would waste MEV fuel. $\endgroup$ – Uwe Oct 7 '19 at 14:37
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    $\begingroup$ Agreed, they'd likely have to shut down the original attitude control system. The MEV must have a highly configurable attitude control system! $\endgroup$ – Organic Marble Oct 7 '19 at 14:56
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    $\begingroup$ I don't know how this would work unless the sat. being captured was able to maintain a stable attitude during capture. Capturing a tumbling satellite seems really, really difficult. $\endgroup$ – Wayne Conrad Oct 7 '19 at 15:21

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