Is the premise that as one craft arrives, it transfers it's kinetic energy to the orbiting craft such that they swap velocities? What would such a setup look like?

I can imagine one such possibility, but I need some to check and see if my intuition matches the realities of physics...

In my setup, you would have a two craft of equal mass. The craft orbiting Mars would be orbiting in such a way that the plane of it's orbit was perpendicular to the approaching velocity vector of the craft arriving from Earth. A tether of sufficient length is paid out such that it's endpoint is at the same orbital altitude as the orbiting craft, and lies in the orbital plane. It's length is sufficient not to over-G either craft in the upcoming maneuver.

The arriving craft hooks into the end of the tether, and they do a 180-degree swap before the post-orbiting craft, now departing craft, let's go, leaving the arriving craft in the same orbit as the departing craft.

The focus isn't to send the craft returning to Earth on the exact vector. Rather, it's to ensure the arriving craft is in a proper orbit.

Once there, the arriving craft reels in the tether, takes care of business, and awaits the return of the next craft so that it, too, can be flung back in the general direction of Earth.

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that.

I am human. Fully human.