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One hull crack located in ISS, another one suspected

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Re: One hull crack located in ISS, another one suspected

#291

Post by chaboud »

HPsquared wrote: post #213
lanstin wrote: post #182

Earlier quoted context omitted.

I had an aluminum bicycle where the front fork failed suddenly. Not instantly but in maybe one or two seconds (just slowly enough to let me not have a terrible fall). My next bike was chrome/steel.

This solves something I'd wondered for a while - why my aluminium bike has a steel fork.

Years ago I totaled a mountain bike in a strange pinched-wheel-in-crack accident that bent the frame in two places but left me uninjured.

When I commented to a bike designer/engineer that it was a strange failure, he said that it was intentional, at least on hardtail mountain bikes like mine. A bent frame is ruined but doesn't lead to a catastrophic loss of control. A detached wheel or twisted fork would be next to impossible to control to a stop.

He looked at my frame and explained that that the two bends were in exactly the place they'd been designed to be, just behind the last butting. It's an impressive bit of forethought.

My guess on road bikes with steel forks, though, is that it's a matter of aerodynamic performance calling for compactness to reduce frontal area, something that would be harder to do in aluminum, and for far less weight savings than the longer tubes on the frame.

There's always titanium... The only big drawback is the cost...

Re: One hull crack located in ISS, another one suspected

#292

Post by HeyLaughingBoy »

nosianu wrote: post #234
segfaultbuserr wrote: post #148

Earlier quoted context omitted.

> He underscored that air loss due to the crack are insignificant. "This leak is like as if you’d drill the hull with a 0.2 mm diameter drill. I’m not sure such drills even exist in household. I had to check my collection of PCB drill bits when I was reading it, and yes, I confirm that I'm a proud owner of a 0.2 mm drill at home, it was the smallest one in the box ;-)

The existence of a drill is no guarantee that you can actually create a hole. I once was a battle tank maintenance guy and we had to replace a cover placed in front of the armor. The replacement had holes in different positions, no problem, just drill a new hole, right? An hour and a few broken drills later we gave up. No doubt there are drills that work on that armor-steel, my point is, depending on the material jus…

True. But if it's a PCB drill as (s)he said, then it's likely either solid carbide or has a carbide tip. Hold everything rigidly enough and run that drill at the right speed and feed rate, and there's a good chance that it will drill armor plate.

Re: One hull crack located in ISS, another one suspected

#293

Post by dotancohen »

onethought wrote: post #229
curiousllama wrote: post #163

Earlier quoted context omitted.

>Things like the ISS, JWST, etc are all one-off projects, and they cannot be allowed to fail True > "Public bad private good" isn't a coherent strategy Also true Still, an infinite series of one-off projects comprise a continuous market. If SpaceX royally screws up one project, then yes, the public is left holding the bag _on that project_. But you know who's getting a lot fewer projects? SpaceX. A federal gov't mono…

But space x work in spite of the nasa system... could you dream of nasa celebrating SN8 plowing into the ground as a raging success... it’s a huge cultural shift, not so much driven by private sector competition (Honestly who competes with space x?), more to do with leadership style. BlueOrigin is a perfect Nasa 2.0 comparison.

  > could you dream of nasa celebrating SN8 plowing into
  > the ground as a raging success.
Nobody is celebrating SN8 plowing into the ground. We are celebrating the fact that SN8 plowed into the correct square meter of ground. We also celebrate the fact that SN8 plowed into that particular meter of ground while oriented in the direction that we hoped, but barely dreamed, that it would be oriented.

Re: One hull crack located in ISS, another one suspected

#294

Post by jldugger »

sgtnoodle wrote: post #283
jldugger wrote: post #156

Earlier quoted context omitted.

What do you think the fuel charge would be on a martian round trip?

Since there's virtually no drag between the planets, the distance doesn't linearly determine the amount of fuel. What matters is velocity changes. It's about 10km/s to get into orbit, and 5km/s or so to transit to Mars. Coming back is a lot easier because Mars has less gravity and atmosphere, and you don't need to bring as much stuff back. So maybe let's call it 20km/s total? Fuel has mass, so it takes fuel to bring…

.... Did you factor in the fuel you need to actually stop? I'd prefer not to be the next martian crater.

Re: One hull crack located in ISS, another one suspected

#295

Post by NortySpock »

rtkwe wrote: post #270
NortySpock wrote: post #84

Earlier quoted context omitted.

low attenuation fiber optic cables? https://madeinspace.us/capabilities-and-technology/fiber-opt... (similar to, but not the same as, zero attenuation fiber optic from the fictional book Artemis by Andy Weir) https://en.wikipedia.org/wiki/Artemis_(novel)

Maybe, but you'll need more than just one thing to really take off. Also terrestrial fiber seems plenty fast for most applications at the moment?

low attenuation means fewer repeaters needed on oceanic cables, reducing the cost of operating the fiber optic cable.

"Using estimates for the theoretical loss limit of ZBLAN glass, a 2,000-km length of ZBLAN fiber could have the same optical loss as 10 km of silica fiber, which would be an extraordinary performance gain."

https://upward.issnationallab.org/the-race-to-manufacture-zb...

"Fluoride fibers inherently provide naturally a much wider bandwidth than silica with up to 100x usable number of data channels, https://www.spiedigitallibrary.org/conference-proceedings-of...

Re: One hull crack located in ISS, another one suspected

#296

Post by sudosysgen »

Andrew_nenakhov wrote: post #282
sudosysgen wrote: post #278

Earlier quoted context omitted.

Well, it does remain anecdotal evidence. The point of the above commenter is that while they could be made the lack of creativity in planned economies lead to them not being made, not that there were made.

You talk about planned economy shows that you learned about it from third-party sources. There was an abundance of creativity, it just wasn't aimed at creating consumer goods, because they just could not be made in the planned economy at all .

That might very well be true, I'm just trying to iron-man their argument. Do you have some sources about that and why that is?

Re: One hull crack located in ISS, another one suspected

#297

Post by NortySpock »

posix_me_less wrote: post #251
NortySpock wrote: post #84

Earlier quoted context omitted.

low attenuation fiber optic cables? https://madeinspace.us/capabilities-and-technology/fiber-opt... (similar to, but not the same as, zero attenuation fiber optic from the fictional book Artemis by Andy Weir) https://en.wikipedia.org/wiki/Artemis_(novel)

Is the new book any good? I liked Martian.

I thought Artemis was decent.

It ain't The Martian, but if you like the hard sci-fi of The Martian, Artemis is more of that (except with a touristy moon base).

Re: One hull crack located in ISS, another one suspected

#298

Post by WalterBright »

edgyquant wrote: post #290
Andrew_nenakhov wrote: post #266

Earlier quoted context omitted.

You mean my whole youth lived around Soviet-made goods is an 'anecdotal evidence'? Well, perhaps I should have tried living in those fantasy Soviet Unions some people on the internet love so much. Those must have been magnificent states!

Yes what you present is anecdotal evidence. Also nobody is saying they like the Soviet Union that is an idiotic strawman. My point is that they could be made but the USSR wasn’t gearing its economy towards consumer goods because it was a military state who cared almost entirely about heavy industry to benefit its military industrial complex and competition with the US.

The US free economy produced a better military and plenty of high quality consumer goods.

Re: One hull crack located in ISS, another one suspected

#299

Post by WalterBright »

blackrock wrote: post #232
NewLogic wrote: post #188

Earlier quoted context omitted.

It was actually the side-mount design that made the least sense. It left the heatshield completely exposed to ice and insulation strikes.

Could they have mounted 2 space shuttles, bottom to bottom, instead? Where the 2nd space shuttle was the fuel tank, and it lands somewhere down range, and is then transported back to the launch center by barge.

Another set of heavy wings and landing gear to push up.

Re: One hull crack located in ISS, another one suspected

#300

Post by WalterBright »

gregmac wrote: post #286
gspr wrote: post #239

Earlier quoted context omitted.

> The pressure difference is one bar, so duct tape is more than enough to hold that. This is something I have to consciously remind myself of a lot when thinking about space technology. I have this reflex-like feeling that "the vacuum of space" must be a huge obstacle. But then one remembers that 1 atmosphere is the equivalent pressure of a water depth of 10 m. This always blows my mind. In some sense, humans do live…

This reminds me of one of my favorite Futurama lines as their ship is going underwater: "Dear lord! That's over 150 atm of pressure!" "How many atmospheres can the ship withstand?" "We'll, it's a spaceship, so I'd say anywhere between 0 and 1." https://youtu.be/Ewu-zHH5Qwg

Space craft are run at much less than 1 atm.
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