For Questions That Don't Merit Their Own Thread

[DDE]

On 4/22/2023 at 10:09 AM, SunlitZelkova said:

what do you guys think the prospects are for a North Korean man in space?

I think it's going to be as simple and silly as, unless SK announces they're going for a sovereign human launch capability, NK aren't going to make a meaningful push either. There is reason and method to their bluster.

[darthgently]

On 4/22/2023 at 3:09 AM, SunlitZelkova said:

So now that North Korea is reliably building a large number of heavy lift liquid fueled ICBMs, what do you guys think the prospects are for a North Korean man in space?

Given his popularity among his subjects, given the opportunity, they would cram him into one of those ICBM payload containers and voluntold Kim Jun Il to be their first suborbital astronaut and paper heat shield tester

[kerbiloid]

https://en.wikipedia.org/wiki/Atlas_LV-3B

Mass	120,000 kilograms (260,000 lb)
Stages	1½

 Atlas LV-3B, Atlas D Mercury Launch Vehicle or Mercury-Atlas Launch Vehicle, was a human-rated expendable launch system used as part of the United States Project Mercury to send astronauts into low Earth orbit.

https://en.wikipedia.org/wiki/Hwasong-17

Mass	≈80,000–150,000 kilograms (180,000–330,000 lb)[1][2]
Warhead	nuclear weapon, possibly MRV
Warhead weight	≈2,000–3,500 kg (4,400–7,700 lb)[1][2]

Hwasong-17 is an equivalent of Atlas-D, which was sending Mercuries in LEO.

Hwasong throws a warhead 1.5..2 times heavier than Mercury was, this provides enough delta-V for LEO. 

The same about the space and military Atlas.

exp( 1 km/s of delta-V / 3.5 km/s of exhaust speed) ~= 1.33.

Mercury mass = 1.4 t

1.4* 1.33 ~2 t.

So, Hwasong-17 can easily deliver the Mercury to LEO, the question is only in intentions.

***

Probably, 2 .. 3.5 t difference is for 11 000 km and 5 500 km distance, which define the "ICBM" term in the treaties.

So, what can send 2 t to 11 000 km, is enough to send 1.4 t to LEO.

Edited April 25, 2023 by kerbiloid

[Gargamel]

12 hours ago, K^2 said:

They might be able to put a small satellite into space with it, but not a human. Especially not with any chance of returning back.

Technically, survivability was not part of the question.  

[burn n crash]

5 hours ago, Gargamel said:

Technically, survivability was not part of the question.  

It never is if you're doing spaceflight right.

[K^2]

On 4/24/2023 at 11:36 PM, kerbiloid said:

exp( 1 km/s of delta-V / 3.5 km/s of exhaust speed) ~= 1.33.

You need nearly 2km/s of delta-V to go from 15,000km range ballistic to LEO. Plus mass of the engine to provide that delta-V and the tanks which all counts towards the payload mass increase, since you can't jettison them until you have established orbit. I also don't know where NK is going to get orbital insertion engine stage with a 3.5km/s performance. You can't get a particularly long nozzle into the rocket anyways. The closest I'm seeing that should be available to them is something like the Soviet RD-0109, which was used to push the final stage of the Vostok rockets to orbit. That has less than 3.2km/s in vacuum.

So optimistically, 1.7T for Mercury orbiter + kicker stage, multiply by exp(2/3.2) = 3.2T. Which is way over the minimum warhead mass given, which is where you get the maximum 15,000km range.

And that's with optimistic numbers and giving North Korea a lot of undeserved credit.

Wikipedia claims 1.4T for Mercury, but the source link is dead. Best I was able to find is Boeing claiming it's over 1.6T here. Which is still quite impressive. Vostok 1's orbiter was nearly 5T split almost evenly between the lander capsule with its massive 800kg+ heat shield and it's service module containing reentry engines.

In short, no, even cutting NK every bit of slack we can, they can't get a human piloted vehicle on Hwasong-17. And if NK had the tech to build something even sleeker and lighter than a Mercury capsule to do it, they wouldn't be struggling so much with the ICBMs in the first place.

[kerbiloid]

So, Atlas-D could not launch Mercury.

The same problem with ICBM Titan II which could not put Gemini in LEO.

So, not only Apollos never reached the Moon. 

And R-36M converted to Dnepr can't deliver the nominal 4.3 t using its ICBM head (officially ~9 t, half is the post-boost vehicle).

Space is illusion.

[K^2]

2 hours ago, kerbiloid said:

So, Atlas-D could not launch Mercury.

You might as well claim that R-7 launched the Vostok spacecraft by the same exact logic. Atlas LV-3B is a significant improvement on Atlas D. Looking at the boosters alone, the Rocketdyne XLR-89-5 of the LV-3B are about a 10% improvement in thrust over LR-89 of Atlas D. Do you think that maybe significant? Or do you suppose that North Korea is likely to squeeze a 10% improvement out of the RD-250 they're using for Hwasong-17?

North Korea is not building their own engines for their own rapidly emerging space program, where an ICBM is just a prototype for a bigger, more capable rocket once they improve the tech. They are using old Soviet designs and trying to make them fly with their ICBMs for the past 30+ years. Hwasong-17 has a 15,000km range, because that's all you're squeezing out of a Hwasong-17. They aren't getting another 2km/s out of that rocket. They will need a new rocket.

[kerbiloid]

31 minutes ago, K^2 said:

You might as well claim that R-7 launched the Vostok spacecraft by the same exact logic.

R-7 Vostok had an additional upper stage.

31 minutes ago, K^2 said:

Atlas LV-3B is a significant improvement on Atlas D. Looking at the boosters alone, the Rocketdyne XLR-89-5 of the LV-3B are about a 10% improvement in thrust over LR-89 of Atlas D. Do you think that maybe significant?

https://en.wikipedia.org/wiki/Atlas_LV-3B

Numerous improvements of SAS, controls, electrics, other systems, and just because the military Atlas D was a frighteningly bad rocket exploding too often.
This doesn't affect delta-V.

Quote

Propulsion systems used for the Mercury vehicles would be limited to standard D-series Atlas models of the Rocketdyne MA-2 engines which had been tested and found to have performance parameters closely matching NASA's specifications. NASA decided that the best choice of engines would be units with roughly medium-tier performance. Engines with higher than average performance were not considered acceptable because nobody could determine exactly why a given set of engines performed the way it did, and so it was considered safest to use medium-performance ones.

 

35 minutes ago, K^2 said:

North Korea is not building their own engines for their own rapidly emerging space program, where an ICBM is just a prototype for a bigger, more capable rocket once they improve the tech. They are using old Soviet designs and trying to make them fly with their ICBMs for the past 30+ years.

Even if so, the engines origin doesn't play a role. The talk is not about the NK industrial abilities (which still look rather better than the SK propaganda tells).
 

37 minutes ago, K^2 said:

Hwasong-17 has a 15,000km range, because that's all you're squeezing out of a Hwasong-17.

Most of ICBM have ~11 000 km range.
15 000 is significantly greater and closer to the LEO needs..

[DDE]

So China and now Russia are pressing towards national TCP/IP substitutes.

https://www.ft.com/content/c78be2cf-a1a1-40b1-8ab7-904d7095e0f2

https://www.cnews.ru/news/top/2023-05-02_v_rossii_poyavitsya_suverennyj

If these are pushed into consumer adoption, would the resulting networks be able to work with the old Internet?

[Terwin]

1 hour ago, DDE said:

If these are pushed into consumer adoption, would the resulting networks be able to work with the old Internet?

The internet is designed to be a network of networks, so if the networks are connected to the existing internet and they support  IP(Internet Protocol, mostly handles routing), then they will just be invisibly incorporated.

If they are not IP compatible(or are preventing from interoperating but are still connected), then some sort of interface node may be required for translating between the incompatible networks.   This may require minor changes(like connecting to IPv6),  it may block all communications that are not white-listed, or the seems might be completely invisible.  It all depends on how they are allowed to interact(if at all).

If the networks are not connected, then obviously there will be no interactions, but maintaining an air-gap would be very difficult.

 

Edit:

The China article is just about adding an additional protocol in top of IP

Currently we have UDP(intended for time sensitive broadcasts where missing data is less important than timely data and is never used), and TCP(best-effort protocol that will check for missing bits and re-request them before delivering the intact package to the application, even if the messages are not delivered in the order they were sent, this is the protocol that *everything* is using because losing random parts of your message is generally not considered acceptable).

At worse, China will configure internal networks to drop all TCP packets and require only using their internal(and presumably easier to control) 'New IP' packets for in-country usage, and we will need to use(presumably state-controlled) translation nodes for swapping between TCP/IP and 'New IP'.

To outside users it will probably just look like an upgrade to the 'Great Firewall of China'.

Edited May 4, 2023 by Terwin

[kerbiloid]

1 hour ago, DDE said:

So China and now Russia are pressing towards national TCP/IP substitutes.

https://www.ft.com/content/c78be2cf-a1a1-40b1-8ab7-904d7095e0f2

https://www.cnews.ru/news/top/2023-05-02_v_rossii_poyavitsya_suverennyj

If these are pushed into consumer adoption, would the resulting networks be able to work with the old Internet?

It's an inevitable reaction on the CyberFlag initiative.

As it was described in 2020 or 2021 (before the current events, but after the known POTUS election discussions) in a dedicated interview on the purely pro-Western Russian-speaking youtube channel (can't recall now), it's an initiative of splitting of the world-wide internet into the well-protected cyberfortress for the Western and pro-Western countries, and other for others.

As it was described, the former ones will be well-protected from the latter ones, have their internal cyberjob market, resources, and so on, unreachable from the other countries.

As China mostly has its own toy box, and probably would be keeping that course, probably it was predictable since 2020, just with the question of timeline.

So, probably there will be bridges, but it's unclear if there will be something to watch for free on that side of the wall.

[K^2]

5 hours ago, DDE said:

If these are pushed into consumer adoption, would the resulting networks be able to work with the old Internet?

If you have gateways that talk to both protocols, and can implement tunnels for the parts of the network that doesn't support one or the other, then the network remains fully connected. It's a bit like tunneling IPv4 traffic over IPv6 or vice versa.

In practice, I expect Russia not to have resources to implement a new protocol at all, because where are they going to get enough custom switches even from? And China isn't going to shoot itself in the foot so hard as to cut themselves off from the WWW. I fully expect China to have gateways and tunnels natively supporting TCP/IP.

[monophonic]

15 hours ago, Terwin said:

Currently we have UDP(intended for time sensitive broadcasts where missing data is less important than timely data and is never used), and TCP(best-effort protocol that will check for missing bits and re-request them before delivering the intact package to the application, even if the messages are not delivered in the order they were sent, this is the protocol that *everything* is using because losing random parts of your message is generally not considered acceptable).

You forgot about only 140 protocols that are currently defined in the standards. See https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers for the list. Granted many of those are mainly used by trunk connection providers and others have quite esoteric uses, but UDP is very much used for various purposes. Most peoples' wifi routers configure their devices using DHCP, and DNS service translates familiar server names to IP addresses required for routing the traffic. Both work on top of UDP (although secure DNS using protocols on top of TCP is taking over lately). Most taxing  use of UDP consumers typically interact with would be high performance online gaming, which fits your description nicely. TCP abstracts away the packet nature of IP and guarantees two-way delivery of a stream of bytes in order and without gaps. It is by far more common of the two because most purposes do need that reliability, like you say, and proper security is easier to implement on top of it. Basically you just use TLS and that covers encryption and authentication out of the box for you. Of course similar protocols exist for UDP but their support is not quite as ubiquitous as TLS'.

The part about the Chinese protocol I just plain agree with you.

[Terwin]

7 hours ago, monophonic said:

You forgot about only 140 protocols that are currently defined in the standards. See https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers for the list. Granted many of those are mainly used by trunk connection providers and others have quite esoteric uses, but UDP is very much used for various purposes.

Clearly my networks class was a long time ago(IPv6 which is related to #41 on that list only became a draft standard half way through  my Senior year), so I'm glad to hear UDP is finally getting some love.

Other than TCP, UDP, and IP4/IP6 encapsulation, are you aware of any other protocols currently in use for bulk data transfers?

[FleshJeb]

6 hours ago, Terwin said:

Other than TCP, UDP, and IP4/IP6 encapsulation, are you aware of any other protocols currently in use for bulk data transfers?

https://www.wired.com/2016/12/amazons-snowmobile-actually-truck-hauling-huge-hard-drive/

https://en.wikipedia.org/wiki/IP_over_Avian_Carriers?useskin=vector

[AckSed]

If you had a hyper-efficient fusion drive like in BattleTech, how viable would it be to mine Sol's asteroid belt for rare elements like germanium? It's part of the canon that fusion is calling upon dimensional quirks to extract more energy than put in: mere tons of fuel can lift multi-kiloton dropships into orbit, and push them to Lagrange points on even less. It's also canon that their FTL needs vast quantities of germanium to build the cores.

[K^2]

7 hours ago, AckSed said:

If you had a hyper-efficient fusion drive like in BattleTech, how viable would it be to mine Sol's asteroid belt for rare elements like germanium?

I don't know if you even need a fusion drive for it to become worth it. There are a lot of materials in the asteroids that are pretty easy to reach compared to Earth, and you can use rather destructive means without worrying about causing environmental damage. You can then use linear accelerator magrails to launch cargo to wherever it needs to go. In a vacuum of space and with some massive rock serving as your anchor, getting a few km/s of delta-V is not hard. The only thing in this scheme that you'd need efficient drives for is delivering human workers, so the more automation you can come up with for the process, the less relevant that becomes.

[JoeSchmuckatelli]

Google 'age of the universe' and you get about '13 billion years old' 

Webb has spotted galaxies 13 billion light years away. 

Expansionists see expansion in every direction they look. Also, Galaxies as far as we have eyes to see.  13 billion light year away galaxies. 

Our star alone is estimated to be 4 billion years old. 

... 

So, why are the estimates persistent about 13 billion years?  

If a fully formed galaxy is 13 billion years away - isn't it absurd to think that all of its stars are brand new?  (Shouldn't we at least estimate the age to be some average of Star lifespan - perhaps granting a guesstimate of 17 billion years?) 

Why not guess we are in a bubble of time - only able to resolve stars 13 billion years away in all directions - and that the universe may be wider and older than we can see?  (Why presume 13 billion years of visible redshift = age of everything?) 

[mikegarrison]

1 hour ago, JoeSchmuckatelli said:

Google 'age of the universe' and you get about '13 billion years old' 

Webb has spotted galaxies 13 billion light years away. 

Expansionists see expansion in every direction they look. Also, Galaxies as far as we have eyes to see.  13 billion light year away galaxies. 

Our star alone is estimated to be 4 billion years old. 

... 

So, why are the estimates persistent about 13 billion years?  

If a fully formed galaxy is 13 billion years away - isn't it absurd to think that all of its stars are brand new?  (Shouldn't we at least estimate the age to be some average of Star lifespan - perhaps granting a guesstimate of 17 billion years?) 

Why not guess we are in a bubble of time - only able to resolve stars 13 billion years away in all directions - and that the universe may be wider and older than we can see?  (Why presume 13 billion years of visible redshift = age of everything?) 

Suggest you read something like Katie Mack's The End Of Everything, if you haven't already. It's complicated.

The idea that the universe was created in some specific location is (if I understand the theory correctly) not accurate, because "locations" did not exist until the universe came into being. The beginning of the universe happened in every location, and no particular location.

Anyway, it seems that it is accepted that there are parts of the universe farther away than the age of the universe would allow light to reach us. So when we see light from 13 billion years away, we are not seeing "the edge of the universe" but simply the edge of the part of the universe that is within our causality bubble.

It's all more complicated than I was able/willing to commit to memory.

I understand what you are asking about, but what if it only took a few thousand years for galaxies to form? What if it only took five minutes? Things happened much more quickly then because everything was closer together. Or at least, that's the idea (if I understand it correctly).

I'm not really sure if any of it matters to us anyway. Although, some of the theories also suggest that the universe could end at any instant. (But if it did, I'm not sure that would matter to me either, since I would no longer exist.)

[Terwin]

2 hours ago, JoeSchmuckatelli said:

Why not guess we are in a bubble of time - only able to resolve stars 13 billion years away in all directions - and that the universe may be wider and older than we can see?  (Why presume 13 billion years of visible redshift = age of everything?) 

I thought the 13 billion year estimate was based on calculations related to the microwave background temperature, not visible red-shift.

I am pretty sure there was another, independent age calculation as well, and they overlapped in their uncertainties(at least until recently)

Also, I think we can also see things that are further away than the calculated age of the universe, mostly because space itself is expanding, so while the light has only been traveling for 13bln years, the observed location would currently be further than that because the distance has increased while the light was traveling.

[K^2]

2 hours ago, JoeSchmuckatelli said:

Why not guess we are in a bubble of time - only able to resolve stars 13 billion years away in all directions - and that the universe may be wider and older than we can see?  (Why presume 13 billion years of visible redshift = age of everything?) 

We don't assume that there is nothing beyond that bubble. It's just irrelevant. No interaction from beyond what we call observable universe could ever, at any point in the past or the future, have any impact on any piece of matter that we will every be able to observe.

Whether we say there is more universe out there, there is absolutely nothing out there, or if we put some dragons, like on the old maps, and call it the land of terrifying monsters, doesn't matter to anything, nor will it ever. It couldn't have impacted our history, nor will it in the future. It cannot impact the history of any place we can travel to. It can't even impact the history of any place we can detect with our best space observatories. We will literally never experience any impact of that potential outer space on us.

So from perspective of science, it's not physical. It might as well be imaginary.

If we ever figure out FTL or time travel, this might become relevant. Until then, we just don't worry about it.

[sevenperforce]

On 5/6/2023 at 6:43 PM, K^2 said:

On 5/6/2023 at 10:37 AM, AckSed said:

If you had a hyper-efficient fusion drive like in BattleTech, how viable would it be to mine Sol's asteroid belt for rare elements like germanium?

I don't know if you even need a fusion drive for it to become worth it. There are a lot of materials in the asteroids that are pretty easy to reach compared to Earth, and you can use rather destructive means without worrying about causing environmental damage. You can then use linear accelerator magrails to launch cargo to wherever it needs to go. In a vacuum of space and with some massive rock serving as your anchor, getting a few km/s of delta-V is not hard.

Ideally you could have some sort of basic, low-granularity refinery spaceship that does a basic grind-out of low grade ore, removes the dross, and then uses the dross as reaction mass with a linear accelerator to push the whole asteroid closer and closer to Earth. By the time you get to cislunar space or thereabouts, you've already got a lot of workable ore.

22 hours ago, JoeSchmuckatelli said:

Our star alone is estimated to be 4 billion years old. 

... 

So, why are the estimates persistent about 13 billion years?  

If a fully formed galaxy is 13 billion years away - isn't it absurd to think that all of its stars are brand new?  (Shouldn't we at least estimate the age to be some average of Star lifespan - perhaps granting a guesstimate of 17 billion years?) 

Some of the other comments have gotten at this, but I think you're just conceptualizing it wrong.

The universe is 13.8 billion years old, and the most distant galaxies we see at the edge of the observable universe (like JADES-GS-Z13-0) appear to have formed a few hundred million years after the Big Bang. They are basically just clumpy masses of hydrogen gas with relatively few, cosmically-young stars. A star takes only a million years or so to form from a collapsing gas cloud, and very very large giant stars (like those formed out of giant clumpy clouds of pure hydrogen) only have a lifespan of 10 to 20 million years. So a young galaxy forming shortly after the Big Bang could accumulate a dozen cycles of giant star births and deaths in as little as 200 million years.

An observer in JADES-GS-Z13-0 looking in our direction would see the Milky Way region as it appeared 13+ billion years ago...probably looking a lot like JADES-GS-Z13-0 appears to us.

[JoeSchmuckatelli]

5 hours ago, sevenperforce said:

I think you're just conceptualizing it wrong

Had I made the observation before Webb, I'd be forced to agree... But some of what I read (acknowledged: conflicting studies and articles) suggests that I may not be. 

The early universe is apparently stranger than expected 

[mikegarrison]

6 hours ago, JoeSchmuckatelli said:

The early universe is apparently stranger than expected 

We are like viruses trying to understand the Solar System. It's not amazing that we don't fully understand it -- it's amazing that we do at least partially seem to understand it.

Edited May 11, 2023 by mikegarrison