system
Given the following post, respond as if you're commenting on Reddit:
human
Is the International Space Station's orbit altered by the weight of new supply deliveries?

I read that the ISS receives several tons of supplies at each delivery.  Does this change the momentum or overall energy, or otherwise do anything to the object's orbit, and does its path need to be adjusted or boosted somehow to compensate for the additional mass?
gpt
Yes and no!

When the new supplies arrive, the rocket that delivered them has already boosted them up to the correct orbital velocity/energy to be in the same orbit as the ISS. So although the supplies add mass to the ISS when they come aboard, they also bring all the kinetic energy they've been given, which exactly balances the increased mass - because if they didn't have the same velocity as the ISS they'd be crashing into it or missing it rather than being carried along the docking tunnel!

Likewise, when stuff leaves the ISS, it has the same velocity (right until the capsule starts gently maneuvering away), so it carries away just enough momentum/kinetic energy to balance the mass it takes away. The re-entry craft then fires engines to change that into a trajectory going down to Earth, and all that energy it's taken from the ISS is turned into heat when aerobraking, in parachutes, etc.