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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

#221

Post by saberdancer »

exDM69 wrote: post #216
saberdancer wrote: post #199

Earlier quoted context omitted.

Putting a spy telescope on Moon seems like a bad idea. - Moon moves across the sky very slowly (relative to stars) which means that your spy satellite would have about 30 days to cover full earth, and would be able to see only a part of Earth at any given moment (theoretically half, but lot of it would be from very bad angles) - Moon is in an ecliptic? orbit, so spying on anything close to the poles will be from an a…

The moon moves slowly but the Earth rotates quickly. Most of the earth surface can be seen during one day. The earth is not illuminated by sunlight all the time, about half of the lunar month would be completely dark. Moon is in an inclined orbit, which is slightly elliptic. I assume this is what you meant by "ecliptic" (which refers to the orbital plane of the Earth around the Sun). The orbital inclination has the m…

You are right about Earth rotating. I spaced out on that one.

About the ecliptic, I was trying to say that any observatory on the moon would have issues observing polar regions because the Earth surface in polar regions would be at a low angle. I know some spy sats "look ahead" to get better detail resolution but they have ability to look from different angles as well. Moon would be a bad spot for that.

Rest of it I mostly agree. One thing up to debate is whether an outpost on the moon would be useful. If you can manufacture fuel on the Moon, it would be very useful. Another aspect is human health in zero G. Moon with low gravity may be enough to help with long term human stay.

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

#222

Post by mikro2nd »

snoshy wrote: post #51
spike021 wrote: post #32

Not a big space person, but this makes me wonder: why have we not planned for a new ISS? We must have better tech nowadays from all the working countries/groups currently involved, plus SpaceX and other space companies' backing that would not have existed as it does now back when this ISS was first designed/created.

Largely because it's a fantastically expensive undertaking, and hasn't quite borne out the fruits that were speculated about over the years. USA provides a huge bulk of the funding, expertise, and personnel required to keep the program running. That's not to say that Russia, Canada, Japan, etc. don't do their part, but it's really not as much of a truly global joint effort as you might be led to believe. Then there's…

The program might not have borne all the speculative fruits, but the one very major thing that has come out of it is the learning about the effects of living in micro-gravity on the human body. If ever we want to get humans out into the rest of the solar system, this knowledge is priceless. Oh, I know that NASA has this constant pressure to justify that learning in terms of stuff like "medical benefits" (and there surely are a bunch of those!) but really it's the foundational pure science that's critical here. I don't think there's any monetary value can be put on that.

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

#223

Post by techdragon »

geocrasher wrote: post #165
rcthompson wrote: post #145

Earlier quoted context omitted.

Part of the joke is that's it's NASA. (NASA stands for Not A Standard Acronym, of course.)

Brings my mind to the ultimate acronym: PCMCIA People Can't Memorize Computer Industry Acronyms

How have I gone my entire career without hearing this one.

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

#224

Post by Blikkentrekker »

godelski wrote: post #117
bnralt wrote: post #92

Earlier quoted context omitted.

> The first big space push was mostly a political pissing match (i.e. not really driven by doing it for its own sake). My understanding is that the Defense Department was interested in human manned spy satellites liked the planned Manned Orbital Laboratory early on, but that automation progressed to the point where it was preferable. I think that's one thing people miss when they talk about lack of progress in space.…

There's still a lot of defense reasons to go to the moon. You can put much larger telescopes there, though you're back to windows of time you can look at a location but you can have good will and dedicate time to scientists. Though they might not want to reveal the resolution even though this can be roughly back tracked through size. There's also the weapons incentive even though that's illegal. But if you're able to…

All of what you said can better be done by machines and many such things are done by machines.

The milestones that get people existed are when men reach places hitherto unreached, but there is no practical purpose to risking the life of a man who needs far more complicated facilities to survive, other than bragging rights.

The I.S.S. was largely a political and not a scientific endeavor, and it's a shame it consumed so many resources, that could have gone to more serious scientific efforts.

The cost of the I.S.S. could have easily given mankind nuclear fusion, — the ability to power entire countries with a couple of litres of seawater. It's strange where priorities lie.

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

#225

Post by exDM69 »

saberdancer wrote: post #221
exDM69 wrote: post #216

Earlier quoted context omitted.

The moon moves slowly but the Earth rotates quickly. Most of the earth surface can be seen during one day. The earth is not illuminated by sunlight all the time, about half of the lunar month would be completely dark. Moon is in an inclined orbit, which is slightly elliptic. I assume this is what you meant by "ecliptic" (which refers to the orbital plane of the Earth around the Sun). The orbital inclination has the m…

You are right about Earth rotating. I spaced out on that one. About the ecliptic, I was trying to say that any observatory on the moon would have issues observing polar regions because the Earth surface in polar regions would be at a low angle. I know some spy sats "look ahead" to get better detail resolution but they have ability to look from different angles as well. Moon would be a bad spot for that. Rest of it I…

The lunar orbit is inclined so that the moon moves between about +/- 28 degrees north/south latitude with reference to the Earth equatorial plane.

That's Earth's axial tilt of ~23 deg + the inclination of the lunar orbit w.r.t. the ecliptic of ~5 deg.

This means that when the moon is at its northest (above southern Florida), it has a pretty good view over the north pole (but it's at quite an oblique angle of ~60 deg), and the south pole is not visible. About 14 days later it's the opposite.

But yeah, I agree with the conclusion that the Moon is not a good place for a Earth observation for a lot of reasons.

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

#226

Post by techdragon »

GordonS wrote: post #215
jccooper wrote: post #149

Earlier quoted context omitted.

They have put tape on suspected leak areas in Zvezda before.

So bizarre to imagine a space station patched up with duct tape o_O Assuming the ISS is never going re-enter the Earth's atmosphere, how permanent a solution is tape? Presumably the fracture underneath will get worse with time.

Other than the growth (in terms of length across the surface in question) of a crack/fracture, tape is a pretty valid solution as long as it can hold the pressure. In fact on the “inside” that’s even more strait forward since the pressure pushes the tapes bonding surface interface into the opening, so depending on how malleable the “tape” is, it might not even need “glue” to do the job of sealing a hole sufficiently to hold in the ISS’ internal atmosphere.

Effectively the major issue is “larger”width/diameter cracks/holes create greater pressures that eventually exceed the ability of simple “tape” to suffice for a workable patch. This is all ignoring any NASA engineering manuals and limits, I’m talking entirely theoretical “how long can my duct tape keep me from suffocating” type of engineering, just to be clear.

What needs emphasis in the long term for more permanent structures in space is on the poorly explored topic of welded joint fatigue, with respect to joints that were welded in low earth orbit.

We have welded with several techniques in space before (the Soviets did it) but it basically stopped there and not much has gone into studies of the long term fatigue of the resulting welded joints. If we want permanent space stations we need to be able to “patch them up” in a way that we can rely on and at least have some idea what the lifespan will be. It’s ok if we have to re-weld pressure hull segments every decade or two but not if the large scale structural welds on a space station hull assembled in space only hold for a few years before they start leaking.

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

#227

Post by hef19898 »

techdragon wrote: post #226
GordonS wrote: post #215

Earlier quoted context omitted.

So bizarre to imagine a space station patched up with duct tape o_O Assuming the ISS is never going re-enter the Earth's atmosphere, how permanent a solution is tape? Presumably the fracture underneath will get worse with time.

Other than the growth (in terms of length across the surface in question) of a crack/fracture, tape is a pretty valid solution as long as it can hold the pressure. In fact on the “inside” that’s even more strait forward since the pressure pushes the tapes bonding surface interface into the opening, so depending on how malleable the “tape” is, it might not even need “glue” to do the job of sealing a hole sufficiently…

The pressure difference is one bar, so duct tape is more than enough to hold that. Aging is different story all together, so.

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

#228

Post by mdiesel »

WalterBright wrote: post #202
sudosysgen wrote: post #194

Earlier quoted context omitted.

In 2021, the cheapest and most reliable way to send a man to space is to use a Soyuz, for a cost of 19-22 million dollars per person. This is of course a communist design launched by a public space agency built by a majority public ownership factory. I think it might be time to accept that in these cases its pretty often not the inherent efficiency of the free market - which can often be less efficient than alternati…

> 19-22 million dollars per person That doesn't mean it was profitable. The price could have been set for political reasons. Or it could have been set by the marginal cost of the launch, ignoring entirely the development cost that was written off when the USSR collapsed. Or it could have been enough to simply pay for the weight of the astronaut in a rocket that was going up anyway, like a hotel will sell rooms at a d…

> If communism produces goods and services cheaper than the free market, we'd be awash in Soviet goods.

Which we aren't, because they're undercut by Chinese goods...

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

#229

Post by onethought »

curiousllama wrote: post #163
lordlic wrote: post #140

Earlier quoted context omitted.

Gigadollar-scale space projects seem like a particularly poor fit for the private industry model, though. Conventionally the idea of free-market competition is that companies stand to gain if they succeed but have to eat the losses if they fail, and so competition eventually selects the best. But we're not talking about making widgets or sandwiches or launch vehicles. Things like the ISS, JWST, etc are all one-off pr…

>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.

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

#230

Post by onethought »

snoshy wrote: post #123
onethought wrote: post #95

Earlier quoted context omitted.

The problem with Privatised space industry is your country doesn't control the agenda. SpaceX is a pretty rare thing, the rest of the private space industry (Blue Origin, Virgin, Boeing) is as much of a money pit as NASA was. Then you have rapidly progressing government run space programs like China and India. The fact that the US banned China from the ISS and banned Non-Americans from participating in what it deems…

Echoing the sister comment to add more color, I think when it comes to this scale of money, it becomes too easy to conflate public and private capability. The ISS cost $150 billion. That is a kind of cost that even the tech behemoths of the world today would not be able to stomach. Some efforts really require country-coffer levels of money to be realized. That means the US government directly controls which projects…

China is more crazy because SpaceX got access to Nasa research and development (through people and location)... China have kind of home grown there whole system in an insanely short time
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