Potentially Stupid Science/Engineering Question

[Zipper730]

This is going to probably be a bizarre question, but I was watching an old experiment I saw when I was a child. We all probably saw something similar: Somebody took some liquid nitrogen, and submerged a rubber ball within it, then threw it to the ground and shattered it. The extreme cold, as I understand it, removed the rubber ball's elasticity and flexibility, so it shattered when thrown on the ground.

I remember hearing of cases where people were able to shatter metal locks by using liquid nitrogen as well and that caused me to wonder something: Why don't spacecraft shatter in the cold of space? Clearly, they don't or we'd probably have never been able to put anything into space, but why don't they?

T ThomasP

BTW: I tried asking this on a reddit forum called r/askscience or r/askphysics. They seem to have a problem where lots of messages are auto-deleted for one reason or another. I asked other questions that were far less "out there" than this one, and it was deleted. I tried varying the wording, altering a few things, and at the point I was thinking of typing "Who do I gotta blow in order to a get a message through the auto-filter?" as a title, I was curious of other people ahd this problem, and apparently it was a known problem. I should have just asked the question here to begin with since most people here are knowledgeable on scientific matters, and I wouldn't have had to deal with auto-deletion

 

[Thumpalumpacus]

The spacecraft is warmed from the inside, either for the benefit of human occupants or, if unmanned, to keep the electronics at optimal temperatures. That's got to be a big factor in answering your Q.

 

[swampyankee]

It's not a stupid question.

Many steels have a temperature below which they become brittle. For some steel alloys this temperature is quite high -- above 0 degrees Celsius -- and for some it's much lower. This temperature is called the nil ductility temperature (NDT), which an important property of steel. It can certainly be affected by its constituents, with sulfur and phosphorus being especially bad. Since early-20th Century steel processing wasn't good at removing either, the source of the iron alloy could be very important to the material properties.

High NDT can have very serious real-world problems. It was, for example, responsible for the disastrous failures of Liberty ships and T2 tankers, especially on North Atlantic service, during WW2: once a crack was started, the steel's lack of ductility led to the crack propagating at very high speed, about that of the speed of sound in steel. NDT is one of the reasons that aluminum is frequently used for the containers uses for the transport of cryogenic liquids. There are steel alloys that are suitable for cryogenic service; frequently this involves additions of manganese, chromium, niobium, and other metals, and minimization of phosphorus and sulfur.

It's unlikely a fairly low-priced lock will be made from steels suitable for cryogenic service, so chilling one in liquid nitrogen or even in some brines will drop the temperature below the NDT, where the steel becomes as brittle as glass.

 

[ThomasP]

What Thumpalumpacus and swampyankee said covers most of it.

There are 2 things I can think of to add.

1. To expand on a different aspect of what Thumpalumpacus said, the problem with heat in outer space is getting rid of it. Space is effectively a vacuum - ie no gases, liquids, or solids, to act as conductors and convectors. Therefore the only way to prevent heat from being absorbed is by use of reflective surfaces, and the only way to shed heat (either absorbed from the sun or generated from within the object) is through radiating. Reflectance is usually accomplished through the use of bright white surfaces and/or mirror surfaces, and/or reflective/deflective sun shades. Radiating of heat is usually done by the use of actual radiating arrays/elements that sit in the shade of the object, and/or by rotation of the object.

2. As swampyankee mentioned, many types of steels have relatively high NDTs. In general, materials with face-centered cubic structures, such as aluminum alloys, 300 series stainless steels, nickel alloys, and copper alloys, have very low NDTs. There are other materials that have very low or no NDT (depending on how you look at it) as well, and the space program makes use of many of these.

 

[MIflyer]

A while back a SpaceX booster on a Space Station resully mission exploded during ascent. SpaceX had used a clever design approach, submerging the Helium tanks in the Liquid Oxygen tank, thereby chilling down the HE so that more of it could be packed into the same size pressure tank. The USAF Atlas used a somewhat similar approach, with open (not sealed) jackets around the He bottles that were filled with liquid Nitrogen before launch, for the same reason. Obviously, the Space X approach was more efficient and lighter in weight, since the LOX propellant that had to be there anyway served the purpose of the liquid Nitrogen.

But on that failed mission the strut that held the He tank had failed, causing it to break free and dump it contents into the LOX tank, overpressurizing it and causing it to fail catastropically. In response SpaceX changed the design of the strut and switched to a different manufacturer. But in reality, Space X had specified the use of a commercial grade steel that was not rated for use at cryogenic temperatures rather than an aerospace steel alloy that was rated for cryogenics, and that probably had more to do with the failure than the type of manufacturing used in the strut.

Another example: You know how people say that "steel does not burn" when trying to claim that the World Trade Center should not have collapsed due to that airliner impact and subsequent fire? Well, steel does burn if you get the oxygen content up high enough, but if you look up standard commercial grade 1020 steel in Mil Handbook 4, an internationally accepted source of information on materials , and look for its properties at 600 degrees you will see that there is no data on that. The reason there is no data is that 1020 steel strength drops so low at that that tempertaure that no one would ever use it. The steel did not have to melt to cause the structure to collapse.

And recall when the Space Shuttle Challenger exploded in Jan 1986? The temperature at Pad 39 was "only" 28 degrees, which would not have bothered Atlas or Thor boosters, but the Shuttle was different. Atlas, Thor, Titan were all modified USAF ballistic missiles. The standard military specification used in the 1950's when the rockets were designed specified the capability to withstand tempertaures down to -65F. The reason for that temperature limit was sipmle: at 50,000 ft and above it is -65F. It would have been silly to build a jet airplane or a missile capable of attaining that altitude that could not withstand the temperature there. Besides that, it would no do to have ICBMs deployed at places like Minot AFB or FE Warren AFB and have them not be able to launch in the winter.

But the Space Shuttle was not designed as a military weapons system and thus was not built to those specifications. It had NO launch weather temperature design requirements at all. NASA did eventually come up with a generic agency-wide requirement that its hardware had to be able to operate as low as at least 32F but that was never applied to the Space Shuttle during its design process.

Of course it can be easy to get carried away such specifications. One piece of USN aircraft ground support equipment had military specifications as references that if applied would have required it operate at 50,000 ft, when in reality it would never leave the ground or the deck of an aircraft carrier. The US Military specification for tortillias originally ran to 27 pages. Ans I pointed out at the Pentagon that a requirement that equipment modifications be capable be being removed within 24 hours made no sense because we DON'T MODIFY BOOSTERS AND SPACECRAFT AFTER THEY ARE LAUNCHED. The response was, in view of that, we would not be allowed to modify them before launch.

 

[SaparotRob]

A while back a SpaceX booster on a Space Station resully mission exploded during ascent. SpaceX had used a clever design approach, submerging the Helium tanks in the Liquid Oxygen tank, thereby chilling down the HE so that more of it could be packed into the same size pressure tank. The USAF Atlas used a somewhat similar approach, with open (not sealed) jackets around the He bottles that were filled with liquid Nitrogen before launch, for the same reason. Obviously, the Space X approach was more efficient and lighter in weight, since the LOX propellant that had to be there anyway served the purpose of the liquid Nitrogen.

But on that failed mission the strut that held the He tank had failed, causing it to break free and dump it contents into the LOX tank, overpressurizing it and causing it to fail catastropically. In response SpaceX changed the design of the strut and switched to a different manufacturer. But in reality, Space X had specified the use of a commercial grade steel that was not rated for use at cryogenic temperatures rather than an aerospace steel alloy that was rated for cryogenics, and that probably had more to do with the failure than the type of manufacturing used in the strut.

Another example: You know how people say that "steel does not burn" when trying to claim that the World Trade Center should not have collapsed due to that airliner impact and subsequent fire? Well, steel does burn if you get the oxygen content up high enough, but if you look up standard commercial grade 1020 steel in Mil Handbook 4, an internationally accepted source of information on materials , and look for its properties at 600 degrees you will see that there is no data on that. The reason there is no data is that 1020 steel strength drops so low at that that tempertaure that no one would ever use it. The steel did not have to melt to cause the structure to collapse.

And recall when the Space Shuttle Challenger exploded in Jan 1986? The temperature at Pad 39 was "only" 28 degrees, which would not have bothered Atlas or Thor boosters, but the Shuttle was different. Atlas, Thor, Titan were all modified USAF ballistic missiles. The standard military specification used in the 1950's when the rockets were designed specified the capability to withstand tempertaures down to -65F. The reason for that temperature limit was sipmle: at 50,000 ft and above it is -65F. It would have been silly to build a jet airplane or a missile capable of attaining that altitude that could not withstand the temperature there. Besides that, it would no do to have ICBMs deployed at places like Minot AFB or FE Warren AFB and have them not be able to launch in the winter.

But the Space Shuttle was not designed as a military weapons system and thus was not built to those specifications. It had NO launch weather temperature design requirements at all. NASA did eventually come up with a generic agency-wide requirement that its hardware had to be able to operate as low as at least 32F but that was never applied to the Space Shuttle during its design process.

Of course it can be easy to get carried away such specifications. One piece of USN aircraft ground support equipment had military specifications as references that if applied would have required it operate at 50,000 ft, when in reality it would never leave the ground or the deck of an aircraft carrier. The US Military specification for tortillias originally ran to 27 pages. Ans I pointed out at the Pentagon that a requirement that equipment modifications be capable be being removed within 24 hours made no sense because we DON'T MODIFY BOOSTERS AND SPACECRAFT AFTER THEY ARE LAUNCHED. The response was, in view of that, we would not be allowed to modify them before launch.

Very informative. The last line, however, broke me up. I imagined it being said by Bob Newhart.

 

[Thumpalumpacus]

Very informative. The last line, however, broke me up. I imagined it being said by Bob Newhart.

Newhart could make reading the dictionary a show worth paying for.

 

[fannum]

The US Military specification for tortillas originally ran to 27 pages.

My Uncle, then USN Capt. R. G. Mills was put in charge of the Subic Bay Ship Repair Facility at an early stage of the Vietnam extended war games. His predecessors kept grossly over-running the budget, and Congress/Pentagon had little sympathy for the reasoning that any materials had to be not only shipped halfway around the world, but ordered long in advance of need, from a supply chain not on a war footing, and more than willing to tack on outrageous 'expediting fees' when pressed.
The bulk of needs, not only in cost, but volume were not guns, but butter ... and MilSpec suppliers were few in number, and knew it. It was not the weapons or ordnance that was the problem, but 2x4's, salad oil, shampoo, flour, etc. that verified Napolean's statement: "An army runs on its stomach!"
He quietly emphasized sourcing items locally from trusted suppliers in Japan, Taiwan, Australia, Indonesia, India, and in country when possible as Congress had declared an emergency status, and that allowed them to bypass specifications when the mission was at risk, and they just did so judiciously. He kept a thick book handy to show any doubters, the MilSpec volume that set standards for Saltine Crackers.
When there in Naval Air, I was one of the recipients of these substitutes, and most were considered better and a welcome change, especially the Japanese, Aussie and Philippine beer.
Uncle Bob was promoted to Rear Admiral and headed up Pearl Harbor until he retired with 37 years' service. Among his awards was a high medal for his Subic Bay management (Legion of Merit?) that he'd refer to as his "Saltine medal."

 

[GregP]

• Malleability: A material's ability to deform under compressive stress, or to be bent or shaped easily. Malleable materials can be hammered or rolled into thin sheets. Gold is considered the most malleable metal.
• Ductility: A material's ability to deform under tensile stress, or to be stretched into a wire.
• 
  
• 
  
• Most of the issue in space is dealing with cold, and metals that get VERY cold mostly shrink. So, you need something with good malleability. Not so much ductility. In space, most of the outside metal is generally aluminum, not steel. Steel is heavy and much more susceptible to corrosion than aluminum. In working to restore old airplanes, I can tell you that aerospace aluminum alloys will shrink quite controllably compared with steel.

While metals are typically both malleable and ductile, the degree of each can vary significantly. For example, silver is both malleable and ductile, making it a good choice for jewelry and silverware. Not too sure you'd want a silver spacecraft, and silver isn't very strong .... but it ALSO doesn't break when shrunk to normal levels, kind of like aluminum. Aluminum will take much more heat than silver, too, which comes in handy when experiencing aero-heating due to speed during launch.

 

[Thumpalumpacus]

My Uncle, then USN Capt. R. G. Mills was put in charge of the Subic Bay Ship Repair Facility at an early stage of the Vietnam extended war games. His predecessors kept grossly over-running the budget, and Congress/Pentagon had little sympathy for the reasoning that any materials had to be not only shipped halfway around the world, but ordered long in advance of need, from a supply chain not on a war footing, and more than willing to tack on outrageous 'expediting fees' when pressed.
The bulk of needs, not only in cost, but volume were not guns, but butter ... and MilSpec suppliers were few in number, and knew it. It was not the weapons or ordnance that was the problem, but 2x4's, salad oil, shampoo, flour, etc. that verified Napolean's statement: "An army runs on its stomach!"
He quietly emphasized sourcing items locally from trusted suppliers in Japan, Taiwan, Australia, Indonesia, India, and in country when possible as Congress had declared an emergency status, and that allowed them to bypass specifications when the mission was at risk, and they just did so judiciously. He kept a thick book handy to show any doubters, the MilSpec volume that set standards for Saltine Crackers.
When there in Naval Air, I was one of the recipients of these substitutes, and most were considered better and a welcome change, especially the Japanese, Aussie and Philippine beer.
Uncle Bob was promoted to Rear Admiral and headed up Pearl Harbor until he retired with 37 years' service. Among his awards was a high medal for his Subic Bay management (Legion of Merit?) that he'd refer to as his "Saltine medal."

You gotta love any leader who looks after his troops like that. We had Spam as a main course two meals out of three from the chow hall during Desert Storm.

 

[MIflyer]

Very informative. The last line, however, broke me up. I imagined it being said by Bob Newhart.

One thing I wished I could have seen. Recall that old 50's movie, "Tarantualla" about the scientist (Leo G. Carrol) that causes a spider to grow to the size of a football stadium. The townspeople try to stop it with gunfire and explosives, to no avail. So the sheriff says he is going to call Sands Air Force Base and get some air support.

Can you imagine that phone call? I'd have loved to see Bob Newhart do one of his telephone skits about that. We used to joke about what would occur when we had Ops Duty Officer Duty at Tinker AFB on the weekends and the sheriff in Okmulgee or Okemha called in asking for help with a giant spider or ants the size of Greyhound buses, or something like that. Think we could have scrambled the F-105's of the 507th or some A-7D's or B-52's from the ALC?

But in the movie F-80s, F-84's, and F-86's show up - led by Clint Eastwood - and nape the spider in the nick of time. That was the most incredible aspect of the whole movie.

 

[MIflyer]

We had Spam as a main course two meals out of three from the chow hall during Desert Storm.

In the Korean War the USAF stationed an H-19 on one of the islands off the coast of North Korea to help with rescuing downed aircrew. Of course, supply was a challenge at that location. One day a C-119 paradropped a load of supplies there. Upon opening the boxes and finding almost nothing but Spam, the entire chopper crew did not speak one word but took aim and emptied their sidearms at the supply aircraft.

 

[Thumpalumpacus]

In the Korean War the USAF stationed an H-19 on one of the islands off the coast of North Korea to help with rescuing downed aircrew. Of course, supply was a challenge at that location. One day a C-119 paradropped a load of supplies there. Upon opening the boxes and finding almost nothing but Spam, the entire chopper crew did not speak one word but took aim and emptied their sidearms at the supply aircraft.

Breakfast at Riyadh's chow hall was "horsecock and eggs" about every damned day.

 

[SaparotRob]

Galloping gourmet?

 

[Thumpalumpacus]

Galloping gourmet?

 

[fannum]

Breakfast at Riyadh's chow hall was "horsecock and eggs" about every damned day.

Two comments:
1) I feel for your pique at the NK spam delivery, but you're shooting the messenger just doing their job to help you.
2) In the '60s, there were endless times I'd kill for eggs! ... aboard ship ... in Antarctica ... at sea ... and even at the end of the month when the chow ration budget was tight. I lived on powdered milk, eggs, and concentrated oil butter substitute, not to mention tasteless cooking from lack of sugar and salt.
We were the first American families into Japan in '46 and spent six years without a trip back to the States in Europe '51-6. The local produce both places was non-existent, rationed to the citizens, or suspect for years and the brass as well as the grunts dealt with substitutes.
I was on the WWII Essex class USS Bennington in the South Pacific in '61. No a/c in most spaces, and designed for a crew of 2,400, we had almost 4,000 on board with increased complexity and maintenance. Every square foot was utilized.
Only the highest priority cargo was carried aboard by small aircraft/helos with 95% coming by hooking up with a tanker or transport alongside with hoses and 'highline' cables run between. Obviously, this was dependent on the sea state and flight schedule, as well as having sufficient maneuvering space ... there's less open ocean than you think!
When you did get replenished, boxes were stacked in every corner, and there were few 'reefers' or refrigerated spaces. When you could walk down a passageway without tripping over boxes, you knew there was no more milk, eggs or veggies that didn't come in a box or can.
How about taking out a tablet and writing down every stop your box of Cheerios takes from the Grand Rapids factory to a breakfast bowl in a ship in the Mariannas in WWII or Vietnam. Then estimate the time each storage/transfer took. If you count less than 50 steps/stops, you missed a WHOLE bunch.

 

[Thumpalumpacus]

Two comments:
1) I feel for your pique at the NK spam delivery, but you're shooting the messenger just doing their job to help you.
2) In the '60s, there were endless times I'd kill for eggs! ... aboard ship ... in Antarctica ... at sea ... and even at the end of the month when the chow ration budget was tight. I lived on powdered milk, eggs, and concentrated oil butter substitute, not to mention tasteless cooking from lack of sugar and salt.
We were the first American families into Japan in '46 and spent six years without a trip back to the States in Europe '51-6. The local produce both places was non-existent, rationed to the citizens, or suspect for years and the brass as well as the grunts dealt with substitutes.
I was on the WWII Essex class USS Bennington in the South Pacific in '61. No a/c in most spaces, and designed for a crew of 2,400, we had almost 4,000 on board with increased complexity and maintenance. Every square foot was utilized.
Only the highest priority cargo was carried aboard by small aircraft/helos with 95% coming by hooking up with a tanker or transport alongside with hoses and 'highline' cables run between. Obviously, this was dependent on the sea state and flight schedule, as well as having sufficient maneuvering space ... there's less open ocean than you think!
When you did get replenished, boxes were stacked in every corner, and there were few 'reefers' or refrigerated spaces. When you could walk down a passageway without tripping over boxes, you knew there was no more milk, eggs or veggies that didn't come in a box or can.
How about taking out a tablet and writing down every stop your box of Cheerios takes from the Grand Rapids factory to a breakfast bowl in a ship in the Mariannas in WWII or Vietnam. Then estimate the time each storage/transfer took. If you count less than 50 steps/stops, you missed a WHOLE bunch.

I'm not saying my lot was worst, just saying that Spam sucks, especially served every day.

Not sure why the Navy would store milk in walkways, but hey, them Navy guys are a little odd.

 

[MIflyer]

I'm not saying my lot was worst, just saying that Spam sucks, especially served every day.

I am quite sure that in WW2 Spam would have been received with the same joy as manna from heaven in much of the world, even if provided every day. One of the negative aspects of reading about aircrew escape and evasion in WW2 is that it is bad for your diet. Food was a obsession for escaped POWs and evading aircrew. Each nearly decent meal is recalled and recounted in detail. Food was not a trivial problem even for civilians in places like France, Belgium, Holland, etc. So reading about it makes you hungry.

As for Spam, I discovered the pleasures of it when cooked in a pan like bacon. Then one evening in 1979 I made a meal of it and shortly thereafter came own with a case of the stomach flu, which a friend of mine had contracted earlier that day. And I never ate Spam again. I know I was not the Spam that made me sick, but tasting it the second time around, in reverse,. finished me with the stuff.

 

[Thumpalumpacus]

I am quite sure that in WW2 Spam would have been received with the same joy as manna from heaven in much of the world, even if provided every day.

Just to say, "horsecock" as a pejorative wasn't original to us. It was invented by GIs in WWII who were served it every day.

 

[MIflyer]

Just to say, "horsecock" as a pejorative wasn't original to us. It was invented by GIs in WWII who were served it every day.

You would have preferred, perhaps, Meals Rejected By Ethiopia?