Candles are useful when oxygen has been consumed because of respiration or a fire. They're not useful in a leak.
Conservation of mass: if a cubic meter of air escapes, that's 1.25 kg, and you need at least that much in candles. (You actually need 2 kg because the candle isn't solid oxygen)
There's ultimately 1.2 t of atmosphere on the ISS. This will also result in a pure oxygen atmosphere, which is dangerous. You need nitrogen.
I think you're double counting; you need 1.25 kg of oxygen and nitrogen combined to replace 1 cubic metre of air.
1.2t of candles doesn't seem like an unreasonable amount of extra payload if they would really be valuable in an emergency. The ISS weighs 400 tons and a napkin estimate says it has had 1000 tons of resupply missions. The candles have a shelf life of 10+ years.
You need 1.25 kg of gas. Candles don't consist solely of oxygen, the ones the Russians use utilize lithium perchlorate (LiClO4). When they finish burning, you are left with a lithium chloride ash (LiCl), which will be 40% mass of what you started with.
It works out to be more efficient, at least in terms of mass, to send up large tanks of compressed gas instead.
NASA used pure O2 in space until the end of the Apollo program, but the Shuttle and later used the same air we breathe today, 1atm 80% N2/20% O2. Note that in space, the pure O2 was at 0.4atm, so roughly twice the oxygen partial pressure, but only slightly more dangerous than the air we are breathing now. (You need about 0.4atm to keep your lungs from collapsing, so that's the lower limit.)
Why the difference? It's a question of what risks you were most afraid of. Even today, every single spacewalk is done at 0.4atm pure O2- trying to do a spacewalk at 100kPa even the strongest man in the world would have trouble bending his arms- so before a spacewalk the astronauts need to spend several hours pre-breathing pure O2 to get all the nitrogen out of their bloodstream before they can do a spacewalk. The Apollo program thought it was safer if the astronauts could do a spacewalk at literally any point in the mission, so that's what the spacecraft was designed around.
On the other hand, for long duration spaceflight, introducing a different pressure and atmosphere is just another potential source of health problems. Even today, the largest source of information on how human bodies last under 0.4atm pure O2 is the three Skylab missions from 1973-1974. And so the Soviets- who were always more interested in space stations than the moon- and NASA during the Shuttle era went with the atmosphere that seemed like it offered less health risks for people staying on a space station.
Okay, so what about the Apollo 1 fire? To speed up testing, Apollo 1 did two tests at the same time: the Plugs-Out Test, where the astronauts were in the spacecraft with everything running and practicing their countdown, and the Overpressure test where they pressurized the spacecraft to 1.4 atm (to mimic the pressure differential in outer space). And they did it with pure O2. So you had all of these electronics running in an environment at 1.4atm pure O2. And that was incredibly dangerous, in a way that actual spaceflight, a mere 0.4atm O2, was not. But it was just a test, another in a long string of them, and no one involved ever really analyzed it as a potential hazard.
After Apollo 1 a few things were changed: one was that they did the Plugs Out test and the Overpressure test at different times, and a lot of stuff was turned off for the Overpressure test. Another was that the Apollo capsule at takeoff was 1atm 80/20 until a couple of minutes into flight, when it dumped the cabin atmosphere overboard and replaced it with pure O2 at 0.4atm. That's why the astronauts carried little packs in their arms in all the pictures of them getting into the spacecraft, that's the pure O2 tank that they were breathing off of until they could switch to the atmosphere in the cabin after it was replaced.
They breathe a normal mixture of O2 and nitrogen at 1 atmosphere of pressure. A pure oxygen environment is horrifically dangerous if fire ever breaks out.
And the 1961 fire that killed cosmonaut Valentin Bondarenko in an altitude chamber. The Soviets covered it up until the 1980's, so NASA made the same mistake.
Because it's not an actual investment and can't run out. Like US Social Security and many other national schemes, the UK is pay-as-you-go. Money coming in is immediately paid out.
Any funds lying around are supposed to be for temporary imbalances, but became significant due to a major demographic imbalance: the Baby Boom.
As they should. There are fundamental differences in hardware and capability between 1992 and 2026.
The most immediate are pull-down menus at the top of the screen. They work good on a 9 inch screen, they are awful with 27 inch displays.
Another related change are modal dialog boxes. When you have a 9 inch screen you're fundamentally looking at one document in one app at a time. When you got 2 27's that's not true anymore.
You don't have it "now" unless you didn't upgrade to 26.3.
But yes. The only way you can resize windows through System 7 is the resize widget. You cannot grab anywhere else and drag. They couldn't afford the extra chrome pixels, again, on a 512 x 342 screen.
It's still a "known issue" in 26.3
(Though I haven't upgraded to Tahoe at all yet so maybe the release notes are wrong? But everything I've read indicates apple said they fixed it then changed to say they didn't.)
https://developer.apple.com/documentation/macos-release-note...
There was a study which menus work better, on a screen edge or context menus that appear right under a mouse pointer. One might think that the second kind would win, because they are so close. No, the first kind was faster. Apparently the stability and the fixed location also play a role. People basically just use them almost without looking, while context menus always require a conscious choice.
Not for the majority of retirement savings in the US, where Social Security makes up only about 25%.
In the case of 401(k)s/DC plans and private pensions/DB plans, the government allowed savings without "confiscation," i.e. immediate taxation. They gave us the benefit of deferred taxation if you wait until retirement age.
They get Social Security and Medicare, which while insufficient for many these days is a lot more than they would have gotten 100 years ago.
No one is going to argue that the system is perfect or can't be improved. Good people get screwed over all the time and always will, the most we can try to do is minimize that population.
Logistics requires lots of humans, and worse, humans traveling. That's inherently risky and a difficult physical job. People simply would rather have an information economy job like a software developer where the danger is a severe coffee spill.
The humans who do work in logistics have been demanding higher standards of living and therefore better pay and healthcare in first-world countries.
UPS drivers are unionized in the US and their cost to the company (salary + healthcare + pension) is now over $170,000/year each.
Original 1984 critical hardware: the box has an EEPROM module, you swap it on the plane.
FMS (which requires monthly nav data updates) and all modern hardware: the box can be updated over the ARINC 429 serial bus or Ethernet (newer systems/planes), called dataloading
Dataloading had different methods. A320s through the 2000's, most airlines had a 3.5 floppy disk drive on board (Airbus FDDU), and a mechanic fed floppies in. It was slow. Evolution of that was a USB port that took a flash drive.
Most current planes of older models just got rid of on-board dataloading. The mechanic uses a laptop with a cable or purpose-built tablet and plugs into a port. The mechanic can download the software via Wi-Fi or cellular onto the device: https://www.teledynecontrols.com/products/hardware-systems/p...
Airlines can indeed buy a on-board box that connects to Wi-Fi and LTE at the gate which downloads software. This is standard for the latest models that produce more data (A350, 787), but optional for older models. The mechanic still needs to go to the plane and push the buttons to tell it to load.
Not true. 7th gen gained Mode Based Execution Control which greatly decreases the overhead of VBS. 7th gen also gained SMM Security Mitigations 1.0 and some UEFI hardening.
Conservation of mass: if a cubic meter of air escapes, that's 1.25 kg, and you need at least that much in candles. (You actually need 2 kg because the candle isn't solid oxygen)
There's ultimately 1.2 t of atmosphere on the ISS. This will also result in a pure oxygen atmosphere, which is dangerous. You need nitrogen.
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