Anyone selling house-size CO2 absorbers to keep CO2 in my house to more like pre-industrial 200ppm rather than the 800ppm that's more common of house air in cities?
kragen 2 hours ago [-]
You'd only need a few hundred grams of triethanolamine if you regenerate it several times a day (with a vent to outdoors), but there are probably some spill risks and maybe mist. Soda-lime is cheaper but requires inconveniently high temperatures to regenerate, which probably result in unwanted emissions requiring mitigation as well as too much energy use. Regular lime (without the soda) avoids the emissions but takes a month to absorb the carbon dioxide. Alkali-metal oxides, hydroxides, and peroxides like those discussed in the article are extremely compact and fast-acting but even more difficult to regenerate. Bioreactors with spirulina or chlorella have been tested successfully but require hundreds of kilograms of algae per person and are finicky, being prone to infection. I think it's eminently possible at a technical level, but at a political level, basically you can only do this kind of experimentation if you live in China.
An actually physically feasible thing you can do is to whitewash some walls. You need to apply about 7kg of whitewash per person per week, so you are going to need a lot of walls, on the order of 400 square meters of wall per person, because the whitewash is regular lime, not soda lime. (If you're daring enough to dope your whitewash with lye, maybe you can get by with less wall area, but you still need to keep applying the whitewash at 7kg per person per week.) You can make them out of plywood, sheetrock, sheet metal, old sheets, whatever whitewash will stick to. After a few months you will need to start throwing out 14kg of fully cured whitewash per person per week, or calcining it to make fresh whitewash. Try to get whitewash with as little chalk in it as possible.
At this small scale, dozens of kilograms per week, you might be able to calcine the used whitewash in a pottery kiln on your patio. Beware that electric kilns generally do not handle reducing atmospheres well. I'm not sure if carbon dioxide would be too much for them. I think it should be fine, but don't blame me if you ruin your Kanthal.
coppsilgold 3 hours ago [-]
The average human exhales about 1 kilogram of carbon dioxide on an average day.
Carbon makes up 27.3% of that: ~300 grams. That's the weight of a smartphone.
The logistics would be complicated, average plants aren't going to be accumulating so much mass so quickly. You would need aquariums full of algae. Just isn't worth it.
2 hours ago [-]
changoplatanero 5 hours ago [-]
Not sure what city you live in but in the big cities I’ve lived in it was always easy to get the level down to 500ppm by opening windows.
wpm 4 hours ago [-]
Yeah I live in Chicago and it is not hard to keep it at 450ppm. Right now it’s 493ppm in here.
kijiki 4 hours ago [-]
A HRV or ERV, depending on how humid it is where you live will help immensely. Unfortunately hard to retrofit into existing construction.
24 minutes ago [-]
strontian 4 hours ago [-]
Hah! Glad someone else wants to try this!
hinkley 12 hours ago [-]
PSA: Apollo 13 is currently marked as “Leaving Soon” on Netflix.
laidoffamazon 11 hours ago [-]
The scenes where they identify the square peg/round hole problem and where John Aaron and Ken Mattingly get the power draw down are some of my favorite in any movie. Must watch for any engineer
schiffern 11 hours ago [-]
I love how their solution was not to fit the square peg into the round hole, but to use the suit air hose system to pull air through the filter instead.
They achieved the important function ("flow cabin air through the filter") in a totally different way.
pretty sure you can't call it spoilers if the movie itself is 30 years old.
cshokie 7 hours ago [-]
…based on a true story that was 55 years ago…
breakyerself 14 hours ago [-]
It's a fun read. It does seem to imply that the parachutes slowed them down from 25,000 mph, but the heat shield smashing through the atmosphere would have slowed them down first.
HeyLaughingBoy 12 hours ago [-]
That would be one helluva parachute.
schiffern 2 hours ago [-]
I don't know of any actual parachutes, but the closest thing is probably inflatable heat shields like HIAD or MOOSE.
It's worth remembering that this is 1960s technology.
rkagerer 4 hours ago [-]
So... like... it's tough, generally works, and doesn't show you ads. Sign me up!
intrasight 6 hours ago [-]
I watched the moon landing as a young kid. On our rich neighbors TV. We didn't have one. I do hope that live to see another one. Not sure as they keep delaying it.
croisillon 14 minutes ago [-]
I hope your rich neighbours live long enough to allow you to watch it!
kragen 6 hours ago [-]
Which, apparently, nobody knows how to replicate today.
breput 10 hours ago [-]
We shake our heads at round vs. square filter in the distant 1970 past, but flash forward 55 years and we have that a very similar situation in the active American space capsules - none of the spacesuits are compatible with any of the other ships.
The Boeing spacesuit isn't compatible with the SpaceX capsule, which was recently an issue with the Crew 9 mission. And neither are compatible with the NASA Orion capsule.
wolfi1 14 hours ago [-]
and I thought the most famous carbon dioxide absorber would be caustic potash solution
Many of us knew the story from books, or even the Tom Hanks Apollo 13 film, but the detail here is fascinating.
hinkley 12 hours ago [-]
The triumph of the movie, as described at the time, was making people care about a story they already knew the ending to. Opie sure turned out good.
JadeNB 12 hours ago [-]
> The triumph of the movie, as described at the time, was making people care about a story they already knew the ending to.
One could, I think, argue the same about any movie about a historical event. I think that it would seem strange, for example, to say that that was the main achievement of Sands of Iwo Jima.
hinkley 12 hours ago [-]
I think it’s different when you’re talking about an army versus three people in that army.
We don’t know if Private Ryan or any of the other characters make it. We can assume most of the actors make it off the beach at the beginning, but that’s about it.
AStonesThrow 12 hours ago [-]
I mean it was also way better than the first 12 prequels
The comments have time stamps for some particularly interesting moments, but the incident occurs 8 minutes in, and the infamous "Houston, we've had a problem" remark happens at 9:20.
The blog post talked about how everything had to be communicated verbally because you could not share images, but since we're so used to Hollywood adaptions or documentaries, I find the recordings really drive the point home.
jrflowers 14 hours ago [-]
> On July 21, 1969, Neil Armstrong stepped off the ladder of his spacecraft and became the first human to walk on the Moon. The first words spoken by him on the Moon that day are still remembered.
>[img that misquotes Neil Armstrong]
is a hilarious way to start
RandallBrown 14 hours ago [-]
I believe Neil Armstrong said that is the correct quote, it just dropped the "a" in the transmission.
nrds 13 hours ago [-]
Until recently I believed that too. However, I came across some discussion which made me realize I was mixing up the sequence. The transmission interruption, which can be clearly heard, didn't happen at that point in the quote; it happened a moment later, after the word "man". The critical part of the quote seems to come through clear. It's more of a linguistic question about how "for a" and "for" may sound almost indistinguishable in Armstrong's accent.
alnwlsn 12 hours ago [-]
I have a similar accent and we would say it like "furrah-man". For me, the "ah" becomes a lot weaker going into the "m", so I can easily see it.
I'm also intrigued by the idea that it was a flub which he realized instantly (if you listen to the recording):
... step for man <pause> (dammit) ... one giant leap...
euroderf 12 hours ago [-]
IIRC Armstrong said some years later that he had unintentionally left out the "a".
Also, the blog post in the submission omits a major detail: the on-orbit docking maneuvers for the CSM to mate with the LM. A minor detail is that the Saturn V's third stage performed TLI (trans-lunar injection) and it actually impacted the Moon. After this TLI, the LM and the CSM were flying free in space, with a bit of separation, and it was the CSM pilot who needed to turn 180° and nose-in to the LM in order to be in the proper configuration for the hypothetical Moon landing.
It was an unusual configuration for Apollo 13, to say the least, because of course they did not land on the Moon, but also because the "base/legs" part of the LM wouldn't be "left behind" on the lunar surface, so they sort of lugged it around awhile. I don't know the exact sequence of jettisoning that base, but they certainly relied on the LM "head" as a lifeboat and a source of additional life-support functions.
mandevil 10 hours ago [-]
At one point they discussed jettisoning the landing stage of the LM, for less mass so that the PC+2 burn would get them home faster, but most of the batteries and O2 tanks on the LM were in the descent stage (4 of the 6 batteries, I don't remember the distribution of the tanks) so dropping the landing stage made their other problems even worse. The landing stage stayed attached to the ascent stage for the entire life of Odyssey, and was dumped into a deep trench in the Pacific Ocean because there was a nuclear RTG to power the ALSEP attached to one of the legs of the lander.
userbinator 10 hours ago [-]
There is a whole controversy and analysis about that particular syllable
Oh FFS... this guy went to the Moon and all people can argue about is what he said? How far we've fallen...
krapp 10 hours ago [-]
Be glad people still believe anyone ever went to the moon at all. That may not be the case in a few more years.
dreamcompiler 9 hours ago [-]
Pretty soon it will be possible for tourists to visit the moon and see the litter we left with their own eyes.
In fact, job 1 needs to be building fences around the landing sites so people don't trample all over them.
PaulHoule 5 hours ago [-]
The moon is further away than you think. The Apollo mission architecture was a lot more feasible than others that have been considered. The current plan to use a Starship returns about the same payload with a much larger and taller vehicle that is inclined to tip over. You really want a landing pad.
Refueling from lunar materials might be possible but volatiles seem precious. The mission with that vehicle that makes the most sense to me is to land it with a full payload and use it for habitat, workshop, storage tanks or scrap metal.
Space tourism to a micro O’Neill colony in LEO decked out as a flashy space hotel seems more believable to me. I designed one that needs 15 Starship loads of LN2 for the atmosphere but that is fewer launches than they plan to put one Starship on the moon.
rkagerer 4 hours ago [-]
Funny thing, I bet by then authentic Armstrong poop (which comprises some of that litter) will be more valuable than moonrocks.
krapp 9 hours ago [-]
We're still in the "millionaire celebrity ego-trip to nudge against the Karman line" stage of commercial space travel. "Pretty soon" is nowhere near a likely timeframe for crowds of tourists clomping around on the moon.
rolandog 14 hours ago [-]
To be fair, they did not say they were remembered correctly.
jrflowers 14 hours ago [-]
Or who remembers them (not the person that made the image)
giraffe_lady 10 hours ago [-]
Wait did they really launch apollo 13 at 13:13 local time lol. I think of myself as not particularly superstitious but that's pushing it.
timewizard 9 hours ago [-]
No. Local time for the vehicle was 14:13. Local time for mission control was 13:13.
Rendered at 07:11:57 GMT+0000 (Coordinated Universal Time) with Vercel.
An actually physically feasible thing you can do is to whitewash some walls. You need to apply about 7kg of whitewash per person per week, so you are going to need a lot of walls, on the order of 400 square meters of wall per person, because the whitewash is regular lime, not soda lime. (If you're daring enough to dope your whitewash with lye, maybe you can get by with less wall area, but you still need to keep applying the whitewash at 7kg per person per week.) You can make them out of plywood, sheetrock, sheet metal, old sheets, whatever whitewash will stick to. After a few months you will need to start throwing out 14kg of fully cured whitewash per person per week, or calcining it to make fresh whitewash. Try to get whitewash with as little chalk in it as possible.
At this small scale, dozens of kilograms per week, you might be able to calcine the used whitewash in a pottery kiln on your patio. Beware that electric kilns generally do not handle reducing atmospheres well. I'm not sure if carbon dioxide would be too much for them. I think it should be fine, but don't blame me if you ruin your Kanthal.
The logistics would be complicated, average plants aren't going to be accumulating so much mass so quickly. You would need aquariums full of algae. Just isn't worth it.
They achieved the important function ("flow cabin air through the filter") in a totally different way.
https://www.nasa.gov/history/afj/ap13fj/15day4-mailbox.html
https://spacecenter.org/apollo-13-infographic-how-did-they-m...
https://en.wikipedia.org/wiki/HIAD#Inflatable_heat_shield_en...
https://en.wikipedia.org/wiki/MOOSE
The Boeing spacesuit isn't compatible with the SpaceX capsule, which was recently an issue with the Crew 9 mission. And neither are compatible with the NASA Orion capsule.
A not-at-all-famous-but-maybe-it-should-be CO2 absorber is azolla.
https://en.wikipedia.org/wiki/Azolla_event
One could, I think, argue the same about any movie about a historical event. I think that it would seem strange, for example, to say that that was the main achievement of Sands of Iwo Jima.
We don’t know if Private Ryan or any of the other characters make it. We can assume most of the actors make it off the beach at the beginning, but that’s about it.
The comments have time stamps for some particularly interesting moments, but the incident occurs 8 minutes in, and the infamous "Houston, we've had a problem" remark happens at 9:20.
The blog post talked about how everything had to be communicated verbally because you could not share images, but since we're so used to Hollywood adaptions or documentaries, I find the recordings really drive the point home.
>[img that misquotes Neil Armstrong]
is a hilarious way to start
I'm also intrigued by the idea that it was a flub which he realized instantly (if you listen to the recording):
... step for man <pause> (dammit) ... one giant leap...
Also, the blog post in the submission omits a major detail: the on-orbit docking maneuvers for the CSM to mate with the LM. A minor detail is that the Saturn V's third stage performed TLI (trans-lunar injection) and it actually impacted the Moon. After this TLI, the LM and the CSM were flying free in space, with a bit of separation, and it was the CSM pilot who needed to turn 180° and nose-in to the LM in order to be in the proper configuration for the hypothetical Moon landing.
It was an unusual configuration for Apollo 13, to say the least, because of course they did not land on the Moon, but also because the "base/legs" part of the LM wouldn't be "left behind" on the lunar surface, so they sort of lugged it around awhile. I don't know the exact sequence of jettisoning that base, but they certainly relied on the LM "head" as a lifeboat and a source of additional life-support functions.
Oh FFS... this guy went to the Moon and all people can argue about is what he said? How far we've fallen...
In fact, job 1 needs to be building fences around the landing sites so people don't trample all over them.
Refueling from lunar materials might be possible but volatiles seem precious. The mission with that vehicle that makes the most sense to me is to land it with a full payload and use it for habitat, workshop, storage tanks or scrap metal.
Space tourism to a micro O’Neill colony in LEO decked out as a flashy space hotel seems more believable to me. I designed one that needs 15 Starship loads of LN2 for the atmosphere but that is fewer launches than they plan to put one Starship on the moon.