I think Asmi’s ECLSS is mod that you have waited. It’s an useful mod.
– From now on each crewmember consumes oxygen and produce carbon dioxide, once they are outside breathable atmosphere (14km for Kerbin).
– Crew can not live without oxygen outside of breatheable atmosphere, and as such, they will die a horrible death if you won’t supply them with sufficient supply of oxygen.
– Just in case worse comes to worst, crew can use O2 candles as emergency source of oxygen. But they won’t last long, and they are HEAVY, so don’t rely on them. Each capsule contains few of them.
– Contain oxygen regenerator, which could be used to reprocess some of CO2 back into oxygen. Consumes a considerable amount of electricity, so be prepared to supply it.
– From now on, when kerbal goes onto EVA, he takes RCS and oxygen from vessel’s tanks. Upon return, any excess resources are returned to vessel tanks. Be careful – if there is no RCS onboard, kerbal might not be able to return to the vessel!!!
– If you’ll forget about that, system will notify you once oxygen level lowers below caution or warning thresholds. These thresholds could be modified on per-vessel basis, by default they are 25% and 5% of onboard capacity.
– GUI added to just about any screen, which displays current O2/CO2 levels. In the Map and Tracking Station views, you can view that information for any vessel without having to switch to it. There is also summary screen which list all your vessels and essential ECLSS-related information about them.
– Package includes configuration file for ModuleManager that adds life support-related resources.
– Package also includes tanks for both oxygen and CO2, and regenerator, courtesy of awesome BobCat.
– and the KILLER FEATURE: ALL OF THAT is happening AT ALL TIMES, FOR ALL VESSELS, INCLUDING INACTIVE, even when you are at the Space Center, or Tracking Station.
Try it out and please leave some feedbacks.