[arrrg]

They are stocked for months. As you can imagine, if your delivery mechanisms have a somewhat higher than usual risk of failure you don’t really go for just in time delivery.

There are several ways of supplying the ISS, though the very reliable Russian Progress (which also did have a failure recently – not a good year for cargo shipments to the ISS) is certainly the workhorse in terms of cargo shipments. (Though there is also the Japanese HTV and the – also recently failed – Cygnus.)

Any one or even couple failures of cargo vehicles in a row can’t do much to the supply situation. There are multiple redundancies built into the process. However, since really no one wants to abandon the ISS (just deserting it and coming back a couple months later is always risky with something as complex as the ISS that does require constant upkeep) that better be the case.

There will probably be quite some rescheduling and changing of plans happening. (I know that after the last cargo failure three people actually got to stay up in space a couple days longer, for whatever complicated scheduling related changes in plans.)