По времени:
Если осталось больше суток - This wormhole has not yet begun its natural cycle of decay and should last at least another day.
Если осталось меньше суток, но больше 4 часов - This wormhole is beginning to decay, and probably won't last another day.
Если осталось меньше 4 часов - This wormhole is reaching the end of its natural lifetime.
Осталось совсем мало (точно пока неизвестно) - This wormhole is on the verge of dissipating into the ether.
По массе:
Если осталось больше половины - This wormhole has not yet had its stability significantly disrupted by ships passing through it.
Меньше половины, но больше одной десятой - This wormhole has had its stability reduced by ships passing through it, but not to a critical degree yet.