[extraduder_ire]

The Zvezda module has been in orbit since July 2000.

I don't think any crewed interplanetary mission is going to last that long for the foreseeable future.

[oersted]

There have been quite a few instances over the years of Zvezda requiring repairs that would have been impossible without resupply from Earth.

I suppose that they were counting on the capability to resupply, otherwise they might have carried more contingencies from launch, but still.