Double vacuum
Isn't double zero the same as the square root of naff all?
(Yes, I know what he *means*, but that's less funny than the wilful misinterpretation)
Elon Musk revealed the first official photo of the SpaceX "spacesuit" today on Instagram. "First picture of SpaceX spacesuit," the billionaire breathlessly wrote in his caption. "More in days to follow. Worth noting that this actually works (not a mockup). Already tested to double vacuum pressure. Was incredibly hard to …
"I'm trying to think of a situation where the pressure increases inside a space suit."
Safety factor is an engineering thing...
You test to double the stress expected to give some margin of safety in operation...
"How do you know you know what he means, he's talking gibberish"
Clearly double vacuum means that the pressure difference has been tested tontwice the difference expected in use - normally done by adding air to the suit until its well above atmospheric pressure...
"I'm trying to think of a situation where the pressure increases inside a space suit."
An hour or so after reconstituting a tarka dall followed by egg curry, saag aloo, and beans masala meal?
( unfortunately no alcohol like Guinness in space for extra pressure, or .... piquancy)
How do you know you know what he means, he's talking gibberish! My best guess is he means 2 bar pressure but he could mean he tested with a Hoover and a Dyson for all we know! If the astronauts used pure Oxygen it might only need testing to 1 bar for "double vacuum" although I think pure O2 is frowned upon nowadays.
Or perhaps it's like a double rainbow and there's a Youtube clip...
'If the astronauts used pure Oxygen it might only need testing to 1 bar for "double vacuum" '
That would actually be "triple vacuum" I think.
I seem to recall from the early Apollo days (pre-fire) that when using pure O2 the pressure required to get the same amount of oxygen into our blood stream as we get from air is only about 4psi, ie., the partial pressure of O2 in air at standard temperature and pressure is about 4 psi.
We are designed to operate on a mixture of about 80% inert gas and just under 20% oxygen - goldfish excepted - so if you filled a suit with pure O2 to 1 bar (about 15psi) then that would be a little over three times as much oxygen as called for in the spec and probably well on the way to causing seizures and/or death.
Oxygen toxicity is all down to the ppo2 - partial pressure of oxygen.
It's important to understand this if you do technical diving as you tend to accelerate decompression with ever higher percentages of oxygen, up to 100%.
We generally accept that a ppo2 of 1.6 whilst stationary on decompression is safe.
At 1bar, ppo2 is .21 so you can use a bit of maths to calculate you cannot use 100% O2 safely below 6m.
Pure O2 of course is explosive in any manner of interesting ways, such as if it comes into contact with silicon hence the need for "O2 clean" diving kit.
Apollo capsules were once in space pressurized to 5psi pure oxygen. For the on-pad and initial climb to orbit it was a two gas oxygen nitrogen then was bled down from 14psi at sea level, to 5 psi pure O2
Suits were 4.7psi slightly higher in O2 concentration than at MSL. Standard 02 pressure is 3.0psi, plus ~1psi for CO2 and Water vapor each.
It looks like a launch and entry suit not a whole lot of micro meteoroid protection, would be interesting to see how they solved the sweat sublimation problem.
BvB
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> "The idea of removing u from colour and vapour was an attempt to remove French influences."
Tut tut. The BBC thinks differently. Basically they say one Noah Webster was in a position (around 1800) to "clean up" a lot of English spellings for the US, and he went in with both hands. His choices became set in stone in US Academia forever after. Kinda like how Javascript became the scripting of the web, because someone was there at a critical moment and did something to change the future.
So that's where all those U's went, in the dumper with most of the other non-phonetic Chaucerian/Frankish baggage (according to Noah's dictates anyway).
Was it justified? Heck yes! The savings in ink alone...
"The idea of removing u from colour and vapour was an attempt to remove French influences"
Actually it was an attempt tp phoneticise the language and spell it as Bostonians of the time pronounced it.
There _is_ a difference between "honor" and "honour", just be glad Webster didn't set the spelling to onah
"Actually it was an attempt to phoneticise the language and spell it as Bostonians of the time pronounced it."
I assume he didn't take a knife to all non-phonetic spellings because he knew turning a knight into nite would cause too knotty a problem; perhaps Webster thought he might have got kneed, knouted, or rapped on the knuckles for such efforts, however well he might otherwise have knitted a new orthography. He seems to have had a knavish knack for avoiding the worst knockers.
(http://www.todayifoundout.com/index.php/2014/10/noah-webster-moving-away-british-english/ is mildly interesting)
For instance, when the Editors of the Guide were sued by the families of those who had died as a result of taking the entry on the planet Tralal literally (it said "Ravenous Bugblatter Beasts often make a very good meal for visiting tourists: instead of "Ravenous Bugblatter Beasts often make a very good meal of visiting tourists").
They claimed that the first version of the sentence was the more aesthetically pleasing, summoned a qualified poet to testify under oath that beauty was truth, truth beauty and hoped thereby to prove that the guilty party in this case was Life itself for failing to be either beautiful or true.
The judges concurred, and in a moving speech held that Life itself was in contempt of court, and duly confiscated it from all those there present before going off to enjoy a pleasant evening's ultragolf.”
O ye pedants, crying in defense of a canon that does not exist! There is not and has never been an accepted Standard English Spelling. Attempts to "reform" it are centuries-old and generally ignored. Bowing to this simple fact, many words have more than one accepted spelling. What you smugly call "Proper English" is itself a collection of older "proper" words that were bastardized and adapted for local conventions. All this was true long before Americans started making changes.
British English is not the pure and perfect creation you pretend it to be. Americanized English is just as valid. Vive la Difference! The point is to communicate, and they both work fine for that.
With that said, sharp agreement on spelling is a good idea for space launches and such!
"There is not and has never been an accepted Standard English Spelling. "
The quite simple explanation is that "english" isn't technically a language and it has the additional habit of chasing other languages down dark alleys to mug them and riffle through their pockets for useful words.
It's a creole derived from a pidgin which is in turn derived from a creole derived from a pidgin.
(Pidgin = trading language when people from different languages interact
creole = pidgin spoken natively by the children of those traders and expanded over time)
The reversal of various grammatical word orders compared to the parent languages is a common trait of most pidgins.
Years ago, I found these gems on-line:
English doesn't just go to bed with every language that passes by, it dresses up in a PVC mini and cruises the dockside looking for hot foreign languages to drag into alleyways for a quick standup.
-- Peter da Silva
apparently a restatement of James Nicoll's original:
The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary.
-- James Nicoll
These are for the manned Dragon crew to wear as they are taken to/from ISS. They won't be for EVA because that isn't required (and adds systems for heat management, waste disposal, longer self-contained life support etc, which isn't needed in a Dragon). However, the people wearing them will be real astronauts who may do spacewalks from ISS in different spacesuits later.
Space tourists are going to expect others to be able to clearly see their face. With this design no one can tell it is you in that selfie. Add in the expectations created by Hollywood, namely lights inside the helmet, and it should be obvious to everyone that this suit version is going to be a commercial flop.
As long as only NASA(and partners) astronauts are the only people using this it won't be a huge problem.
You have a point, but we really can't make the faces visible and still allow good vision.
Or.. can we...?
What about having some kind of flexible display laid across the glass, which can't be seen from the inside? I believe tech like that exists, doesn't it? Then a tiny cam inside the helmet could watch the 'naut's face and display it clearly to the cosmos, on the glass.
A side benefit is the ability to modify the vid stream to suit moods, frighten Predators, and generally get creative.
Most suits I've seen (on telly only sadly) have various levels of pull down sunvisor. So if you're working in shade, the helmet is clear - if you're working in direct sunlight it's incredibly dark. So I imagine they've got the dark one slid down for this piccie.
Nah, this won't inhibit people one bit. Do you believe people will really pass up a flight into SPACE because they don't think the suit is sexy enough? Most prospective space visitors would wear a fuzzy Hello Kitty suit if it's required to fly. Faces aren't that important anyway. People take photos of all kinds of activities with fully-obscured faces..
Real world example. I motorcycle with full armor, as do my ride buddies. With smoked visors and sunglasses, no useful face can be seen. We take pictures among ourselves all the time! It's not about the face but where we are and what we're doing. We know who's in the armor.
We imagine the people wearing it won't care: as long as it keeps them alive
While above is one end of the spectrum :-) I would imagine that keeping them at a good working temperature and dry is rather important. I believe that venting heat and managing humidity are issues for the human body in a space suit.