> I think the comparison to a "tree's worth of oxygen" is misleading, because trees overall produce very little of the Earth's oxygen They produce quite a lot

> I think the comparison to a "tree's worth of oxygen" is misleading, because trees overall produce very little of the Earth's oxygen They produce quite a lot of oxygen. The main issue is that they don't produce much surplus oxygen as they consume it too. And make no oxygen when the sun goes down. > Shipping tons of single-celled organisms to another planet (once we're sure it's devoid of life otherwise, a high bar, I suppose) is going to produce oxygen much more quickly if you can give them a good environment to do so. Yes. But then, these are living organisms that need to be cared for and fed. If there's a malfunction that wipes out your oxygen producing organisms, you have a big problem. You need to give them light, control the temperature and keep it in a very narrow range, provide them with water, nutrients, shield them from radiation, avoid contamination by other organisms, etc. Water and nutrients are not easy to come by in Mars, at least not yet. At this point, they aren't very different from a machine, it's just going to be a large bioreactor. At large scale, they are probably still the best bet. But it will take a while until we have the proper environment for them. The good news is that, once there's such an environment, we don't have to ship tons of them. Let them replicate. MOXIE is nice as it's a machine. You can store it away, bring more capacity online, etc. It can be added to both bases and vehicles (potentially suits(?)).