worth reading for rich's crazy jokes alone. the fact he is telling them to senior military brass in the context of negotiating his division's survival after kelly johnson's retirement makes them even funnier. my favorite - a boy comes home from school, finds his dad, and proudly declares "dad, i saved 25 cents by running alongside the bus instead of riding it!". the father shakes his head and replies sternly, "you fool, you should have run next to a taxi and saved five dollars"
i agree its crazy but i thought tfa did a good job explaining why the original chart ended up looking the way it did. regime change in a dataset can expose bad assumptions about relationships between balance sheet items you thought could be summed, etc.
Moby Duck literally broke my brain and soul when I read it for the first time last year. I still think about that book about once a week, with some sense of foreboding excitement/dread.
the best translations will usually have a brief explanation of the function various forms of patronymic & affectionate name forms which carry meaning in russian. translating every instance of an affectionate name to "hun" or "buster" or whatever modern english uses would be a bit too much, i think. some of the more formal honorific aliases may have no real english equivalent but once explained its not hard to follow along with the author's intent. "oh this weasel is laying it on thick..." etc.
i also reacted negatively to the title but found the article to be redemptively unpretentious. i think any fan of dostoevsky would agree with his conclusions and be happy that this robot found a heart.
Totally different application/need though. Locomotives need to generate enormous amounts of force, for long periods of time, regardless of speed. Often at zero speed.
That capability is much more important than the efficiency loss of the generator/motor powertrain.
Such capability is not necessary on a bicycle, where efficiency is extremely important.
Bikes handle much differently from diesel trains. This may work for some but I can see it occupying some kind of uncanny valley in the riders' psyche for a while.
You ever ride in one of those bar on wheels things you find in touristy places?
It's got "barstools" along both sides and the passengers/revelers are supposed to turn the pedals under their seats while the bartender/driver steers.
In reality, the pedaling charges the battery somewhat but the vast majority of the battery power comes from being plugged in at a charger before the ride. You can't actually rely on a bunch of drunk sods to keep it moving.
Entertaining but also a lot of nonsense. I stopped watching after he made a show of wandering around aiming a pair of cheap folding solar panels at the sky. "These tiny solar panels won't charge my phone on a cloudy day!"
1)He compares $30 worth of solar panel to a device that probably cost several hundred dollars to build (each of those heatsinks he used cost as much as the solar panel he was waving about.) A $100 (~100W) solar panel would, even on an overcast day, produce 5-10W pretty easily.
2)You don't just use solar for power. You use solar with batteries. The panels are sized based on solar equivalent hours. There are charts that tell you what areas get in terms of "full hours of sun" each day, in summer and winter. You then figure out your typical load, how much battery capacity you want (ie how many days of zero solar output can you tolerate), and how long you want your system to recover from being completely drained while powering your typical load.
I feel there is a certain irony in Deckers hate of solar cells. Because they're pretty low tech functionally. And it's not like every other material you can acquire isn't tied to some complex industrial infrastructure.
it's wild to me, given all the delays and complexity and risk, that the mission length is only 5-10 years max. but even if it blows up on the launchpad we've learned a ton, if only about the difficulty of manufacturing such devices in the 21st century. i am praying it does work, though, and that we get 10 years of amazing data from it before eagerly deploying a replacement.
Is 10 years a hard max (like does it crash into the moon or something?) or is it just a projected max timeframe?
I wonder that mostly because we've managed to use a lot of our other space equipment well past their their mission lengths. I'd be interested if JWST is possibly the same.
The article you linked says absolutely nothing about the helium cooling medium.
Three of the four imagers on the telescope are passively cooled and will work as long as they don't succumb to radiation, diffusion, etc. The fourth one (MIRI) has a cryocooler that uses liquid helium, but it will leak out very slowly and mechanical wear and electronics lifespan is expected to be the limiting factor there. [0, 1]
As stated in other comments, the primary driver of lifespan is a combination of how stable the telescope orbit is, and the resulting amount of fuel needed to keep the telescope in a stable orbit. Depending on how things go it has enough fuel for somewhere between 5.5 and 40 years of operation. Assuming nothing else goes wrong. :)
"Webb is designed to have a mission lifetime of not less than 5-1/2 years after launch, with the goal of having a lifetime greater than 10 years." [2]
As pointed out to us by Drs. Jason Kalirai and Jason Tumlinson at the Space Telescope Science Institute (STScI), as well as Mr. Sykes, our article misstated the reason for the finite lifetime of the upcoming James Webb Space Telescope. The mission duration of 5.5 to 10 years is not limited by the supply of liquid helium, as we stated. Rather, it is limited by the supply of hydrazine fuel needed to maintain the spacecraft’s orbit.
Thanks for the correction, will edit my parent reply.
Does this mean an ion thruster or solar sail could have significantly increased the service life? Or would something else give out shortly after the fuel runs out?
No, that's not true. It will be orbiting around L2 and not stay at L2, so it will have access to sunlight, which powers the solar array that faces the sun. The actual observatory and the mirror are shielded by the sunshield.
Can't they design the tank system modularly to be replaceable? Like (also projecting how SpaceX etc are also making space cargo much cheaper) having a rocket carry payload that would replace the tank cartgridge with a new one, giving, say, another 5 years' worth of propeller.
I'm pretty much 100% sure NASA knows this better than me of course, but I'd love to see the reasoning behind planning to retire such an expensive project after a (relatively) short ~10 years.
It's a hard limit due needing fuel to maintain its orbit. It's in a lagrange point (https://en.wikipedia.org/wiki/Lagrange_point) which requires occasional orbital corrections.
-ish. They have no firm plans for servicing it, but it does have a docking adapter and the fuel/coolant connections are designed to be usable in space.
Basically, because there is no reasonable way to service something in L2, they can't really plan for it, but it's expensive enough that they made sure there is the capability if someone in the future would, say, build a spaceship that is orbitally refuelable and designed so it can take crew that far out.
Well it's not strictly a hard limit but it's currently planned to be a hard limit. If SpaceX can pull off even a fraction of what they claim with Starship, it's not unrealistic to think that it'd be financially viable to attempt a refuelling of the JWST.
I wonder how credulous I've been about those estimates. Underpromise, overdeliver is an old tool for managing expectations. I wonder what NASA really expects for these projects.
(The projects are still amazing; I'm not complaining about the engineering or performance!)
Through the lacings of the leaves, the great sun seemed a flying shuttle weaving the unwearied verdure. Oh, busy weaver! unseen weaver!--pause!--one word!--whither flows the fabric? what palace may it deck? wherefore all these ceaseless toilings? Speak, weaver!
