The issue with the a "tree's worth of oxygen" is that in people's mind a tree is very big, so this comparison gives the impression of a very large amount of oxygen is being produced, when, in fact, barely any is produced at all.
A better analogy would be anything that can be expressed in volumes. For this reason, "4 football stadiums" and "2 school buses" would actually be pretty good.
I think a better measurement would be something like "Enough breathable air for x people"... At least it instantly gives the information of how many machine you need to sustain x people.
I ran the calculations, 6 grams an hour seems to be about 15% of a single astronaut's oxygen consumption.
The planned larger machine they talk about, about the size of a chest freezer producing 3 kilograms of oxygen an hour, should be enough for ~85 astronauts. Though I assume that's also needing to produce rocket oxidiser for the return trip.
There was a guy who sealed himself in a "greenhouse" full of trees, he was trying to produce as much oxygen as he consumed, as well as scrub as much CO2 as he exhaled. It turned out he still didn't have enough oxygen/CO2 scrubbing, but it was enough to slow down his asphyxiation for a couple days or so. Unfortunately I can't find the YouTube video at the moment, but based on that video, I don't even think "10 trees worth of oxygen" is enough for an Astronaut.
> Managing CO2 levels was a particular challenge, and a source of controversy regarding the Biosphere 2 project's alleged misrepresentation to the public. [...] The crew worked to manage the CO2 by occasionally turning on a CO2 scrubber [...] In November 1991, investigative reporting in The Village Voice alleged that the crew had secretly installed the CO2 scrubber device, and claimed that this violated Biosphere 2's advertised goal of recycling all materials naturally.
> A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen.
But he probably isn't the only oxygen consumer in the greenhouse.
There will most likely be insects, bacteria, fungi; All which also consume oxygen.
On top of organic things, the Earth2 experiment famously ran into a problem where the concrete they used to build the biosphere kept curing long after construction finished, and kept sucking oxygen out of the atmosphere.
And don't forget to take into account that NASA's machine can produce oxygen all day, everyday, where trees stop producing oxygen at night, and over winter (and actually start consuming oxygen)
No, I don't think so. The numbers people throw around are generally not accurate as was discovered by that experimenter. So in general it should probably be avoided to describe oxygen production/consumption in terms of "trees worth", especially when it doesn't really account for any carbon dioxide scrubbing, either.
You are missing the biggest part of this. It doesn't matter if it's a lot of oxygen or a little bit. Because it's marketing to people who don't know and don't care exactly how much oxygen a single tree makes. It's just supposed to sound "neat" to normal people who vote and got a C in high school bio.
Yeah I have no idea how much oxygen a tree makes. How many trees would be needed to keep me alive in a sealed room? How big would they have to be? I have no idea…
A better analogy would be anything that can be expressed in volumes. For this reason, "4 football stadiums" and "2 school buses" would actually be pretty good.