11 ms·
Metals Fuse Together in Space
- Lerc 3y agoI have often wondered if you could chop a nickle-iron asteroid into 1 meter cubes whether you could construct a space-station Minecraft style. I would probably have some tapered+oxidized surfaces so you could align things nicely before the fusing happens, but it sounds like a fun way to make huge structures. Chopping up the asteroid left as an exercise for the reader.
- jamiek88 3y agoWell if you look at the accuracy and precision cutting and tessellation of some of the stone work the ancients did, starting with the Sumerians in the very first cities it would be fitting if our first cities in space were made by similar techniques but this time, with lasers!
- psd1 3y agoEasy! Start by chopping the asteroid into tessellating hendecahedra, then use one of the faces of each solid as a reference surface to project a cube of known size.
- lstodd 3y agoNonono, no such abomination please. Let's do it with rhombododecahedra.
- mberning 3y agoIf you are interested in this type of thing look up gauge blocks. And wringing gauge blocks.
- anonymousiam 3y agoThe article says "it has happened" and cites a footnote mentioning the Galileo antenna deployment. I was part of the team that built the Galileo Jupiter Atmospheric Probe and followed most aspects of the whole mission closely, but I have never before heard of this being the cause of the antenna deployment problem. I just read the cited paper (from 1994) and it does seem to be conclusive. If websites like HN had been operating in 1994, this news probably would have reached me almost three decades ago. https://en.wikipedia.org/wiki/Galileo_(spacecraft)#Galileo_entry_probe https://en.wikipedia.org/wiki/Galileo_(spacecraft)#Galileo_e...
- silentsea90 3y agoWow! You were part of NASA in the 80s? So cool.
- anonymousiam 3y agoNot part of NASA -- I worked for Hughes Aircraft Space & Communications Group, on contract with JPL to produce the probe. The contract was awarded to Hughes because of their previous work on the Venus probes: https://en.wikipedia.org/wiki/Pioneer_Venus_Multiprobe#Spacecraft https://en.wikipedia.org/wiki/Pioneer_Venus_Multiprobe#Space... Those probes were created and launched a few years before I joined the company. I was a new employee when Hughes was producing the Galileo probe and my role was minor. I spent 35 years with the company -- the last half with Boeing, who acquired it from GM around the year 2001. For the most part, it was my dream job and I really enjoyed working with the best and brightest people.
- silentsea90 3y agoVery very cool. Did working at your dream job involve explorations + leaps of faith + backing yourself, or did you just organically get there with hard work and always choosing what you were excited about? This leaks into career advice land but I struggle with even defining a dream job let alone being in one, though I certainly find certain problem spaces a LOT cooler (but more risky) than others. Eg. self driving cars, robotics.
- anonymousiam 3y agoMy career consisted of two separate paths. I had 'day jobs', and the Hughes job was my fourth technical job, and orders of magnitude better than any of the previous ones. Separately, I've also maintained a consulting gig, which did involve explorations/leaps of faith/backing myself. The hardest part of it all was trying to find balance between work and family. I always felt like I was failing them both.
- kortilla 3y ago
- Terr_ 3y agoThat reminds me of a fictional space-engineer: > "Some of them are visibly fused. Some idiot must have welded them.” > “Welded, yes. But not by some idiot. By the sun.” > “Leo, it doesn’t get that hot—” > “Not directly. What you’re seeing is spontaneous vacuum diffusion welding. Metal molecules are evaporating off the surfaces of the pieces in the vacuum. Slowly, to be sure, but it’s a measurable phenomenon. On the clamped areas they migrate into their neighboring surfaces and eventually achieve quite a nice bond. A little faster for the hot pieces on the sun side, a little slower for the cold pieces in the shade—but I’ll bet some of those clamps have been in place for twenty years.” -- Falling Free (1988) by Lois McMaster Bujold
- jamiek88 3y agoYou know, I’m a hyper voracious reader of sci fi and I’ve never read any Bujold. I’m down to correct that strange oversight, do you recommend that novel as a decent starting point? If that quote is representative it seems right up my street!
- loeg 3y agoIf you want the author's recommendation on reading order, http://www.dendarii.com/reading_order.html http://www.dendarii.com/reading_order.html . The whole series is pretty good.
- robto 3y agoFalling Free is a great place to start, as it has a stand-alone plot and introduces the setting very well. If you like it then I'd also recommend the Vorkosigan saga.
- simpaticoder 3y agoLois McMaster Bujold is one of those authors that never got as popular as they deserved. She does have a niche following, though. The Vorkosigan saga is very solid space opera with, unusually for SF, innovative and sensitive character work.
- foobiekr 3y agoIt appears "Falling Free" is currently part of Audible Plus, if you are an Audible user and audiobook kind of person.
- swayvil 3y agoHey physics guys. So atoms in metal share electrons. I hear that's like a plasma (floaty electrons, conductive) So is metal a solid plasma?
- Rury 3y agoPlasmas, and the states of matter, are more of a convenient categorical heuristic than actual things. We categorize matter as so, so we can conveniently convey information about a material's conditional properties, but any material can be a solid/liquid/gas/plasma under the right conditions... But a solid is not a plasma, as by definition a plasma also has properties of a gas. So a solid metal is not a plasma even if they share some properties. In other words, a plasma is not a solid, and so "solid plasma" is a kind of an oxymoron. To really drive the point... any metal can be in either the solid or plasma states, so thinking of them as "solid plasmas" isn't really correct.
- uoaei 3y ago"Solid chunk with electrons free to conduct through it" and "gaseous chunk with electrons free to conduct through it" are pretty similar. Sure it's technically an oxymoron but really rather close to accurate. Maybe pedants would be happier with "solidified plasma".
- Rury 3y agoNot really... I mean, the issue starts with the equating of 'metal' to mean 'solid', let alone how 'solid' is a bit of an oxymoron for 'plasma'. Additionally, all materials are free to conduct electrons through it, in solid, liquid, or gaseous forms (the differences are just in the energy/distance thresholds in order to do so). So "Solid chunk with electrons free to conduct through it" doesn't quite grasp what metals actually are. I mean, you can have solid chunks of oxygen with electrons free to conduct through it, given the right conditions, and oxygen isn't a metal. But then again, this is entirely a matter of an arbitrary line we've chosen to categorize matter for convenience and communication purposes, and we call those conditions for elements like oxygen "metallic", so if it helps comprehend things then I don't see anything wrong with that.
- westurner 3y agoCold welding: https://en.wikipedia.org/wiki/Cold_welding https://en.wikipedia.org/wiki/Cold_welding "Autonomous healing of fatigue cracks via cold welding" (2023) https://www.nature.com/articles/s41586-023-06223-0 https://www.nature.com/articles/s41586-023-06223-0 : > [...] However, unexpectedly, cracks were also observed to heal by a process that can be described as crack flank cold welding induced by a combination of local stress state and grain boundary migration. The premise that fatigue cracks can autonomously heal in metals through local interaction with microstructural features challenges the most fundamental theories on how engineers design and evaluate fatigue life in structural materials. We discuss the implications for fatigue in a variety of service environments. .. https://www.agriculture.com/machinery/maintenance--repair/impressive-strength-of-cold-weld-putty_567-ar51299 https://www.agriculture.com/machinery/maintenance--repair/im... : > Cold weld is a common – although incorrect – term used to describe the process of using filled epoxy glue to repair broken metal machinery components. The product is a combination of a plastic resin compound and finely powdered steel. A catalyst, or hardener, is added to this mixture to cause a chemical reaction, which hardens the putty into a solid mass .. Cold spraying: https://en.wikipedia.org/wiki/Cold_spraying https://en.wikipedia.org/wiki/Cold_spraying
- ThrowawayTestr 3y agoCold welding is the kind of thing that makes sense when you think about it but is still crazy that it actually happens.
- quickthrower2 3y agoHmm: Does frozen water do the same in space? Why doesn’t it do it on earth? Is it the air in the way?
- mcswell 3y agoDunno, but I've heard that tongues can weld themselves to icicles on Earth.
- febusravenga 3y agoSome of us even experienced it in person. :)
- tanbog5 3y agoYour applying a liquid (water in your tongue) to an object at the freezing point of that water. The water is freezing onto the surface of the ice. I don't think this is cold welding but I could be wrong.
- 20after4 3y agoice cubes stick to other ice cubes, I would assume it's because of melting and refreezing but I can see one reason why cold welding might not happen: Ice is dihydrogen oxide, so that oxygen atom might be a problem for cold welding.
- georgeburdell 3y agoI worked with vacuum systems in grad school and this sometimes happened if we scraped one metal part a bit too hard on another when positioning a sample inside a characterization chamber. Cue having to vent the system to extricate the sample manually, followed by at least a couple of days of effort to get the chamber back to ultra high vacuum, such as wrapping the chamber with heating pads to force adsorbed water to leave quicker.
- badcppdev 3y agoI know it's not trivial but do organisation working with vacuum chambers ever set it up so that the atmosphere inside a pressure vessel is kept full of dehydrated oxygen/nitrogen air at positive pressure during maintenance activities? I know they make sure that all the workers suit up to prevent oil from skin ruining any chance at a high vacuum.
- V1ndaar 3y agoSure, it's very common to flush a system with dry nitrogen for that reason. But of course if you have to fully open a part of the system you're usually out of luck (also you usually don't have valves at every intersection etc., so some part may still be exposed to the atmosphere even if part is "kept dry").
- HPsquared 3y agoHow about running a continuous purge with dry nitrogen + oxygen mix? That would keep the moisture out, but not asphyxiate anyone.
- lettergram 3y agoWonder if this is what verda space can really accelerate at?
- lucubratory 3y agoThere are probably manufacturing benefits of vacuum welding for some niche use cases, but it's a thing that happens with vacuum, not microgravity. Because it's cheaper to build a volume under high vacuum here on Earth than it is to send equipment up to space, that means it can't be an economic reason to go to space. It's more that it's one of those "If you're already in space, this probably has uses" things, rather than a "This is going to return on the investment of going to space" thing like Avatar's unobtainium or Andy Weir's special fiber optics.
- xwdv 3y agoSo essentially if you break a metal rod in space you can just stick the broken ends back together and it fuses up again.
- analog31 3y agoIf it fits perfectly. Unfortunately, the breaking probably deforms the two ends. There's a process in optics called "optical contacting" where you take two super-flat surfaces, push them together, and they stick. This is used in some specialized components where there can be no gap or optical adhesive at the interface. The pieces really do stick together. With optics, you don't have to worry about the materials oxidizing at the surface. Also if you break a rod in space, you'd better be holding on to both pieces. ;-)
- drunkonvinyl 3y agoI’ve done this with two hard drive platters. Never knew it had a name. Cool.
- genter 3y agoMachinists calls it wringing. http://starrett-webber.com/GB46.html http://starrett-webber.com/GB46.html
- Brian_K_White 3y agoWringing is not fusing. Wringing is just a special form of suction.
- BenjiWiebe 3y agoAnd yet it works in a vacuum chamber. https://www.youtube.com/watch?v=Z5XOk1oMFh0 https://www.youtube.com/watch?v=Z5XOk1oMFh0 It's not just suction.
- ilyt 3y ago
- kstrauser 3y agoSomeone explained cold welding to me this way: "So you have 2 pieces of metal pressed together. How does an atom know which piece it belongs to?" Oh. I know there's more to it than that, but that unblocked my understanding of it.
- thsksbd 3y agoBy the massive free volume between them. Even if you clamp the two metals together tightly, unless the surfaces are atomically smooth you'll get void spaces that are large kinetic barriers. Even if you are dealing with atomically smooth surfaces, you'll get a grain boundary which is still a kinetic barrier, and a large grain boundary too. That being said, your friend's point is still fundamentally valid - why wouldn't an atom on occasion cross the boundary and switch sides?
- Brian_K_White 3y agoAnd yet, vacuum-welding is a long known actual thing, and even without vacuum right in ordinary human environment, by good, non-trivial, but not magical surface prep. But it's probably more than just proximity. In vacuum there is probably also evaporation and a form of electrolosis.
- TheSpiceIsLife 3y agoNo that huge a void. Optically flat polished metals, such as guage blocks, will form a few metallic bonds when pressed together.
- thsksbd 3y agoOf course, but the OP asked what distinguishes one group of, say, Al metals in one work piece from another --> The void and xtal misalignment.
- lstodd 3y agoOptically flat isn't even needed per se. You can weld metals by slipping two blocks a bit under pressure side by side just like that in standard atmosphere, and when there's some sort of low-pressure environment it just takes that much less of a slip. No need to go down to space-grade vacuum at all.
- garof 3y agoIt also makes me think of sticking two clean pieces of (optical) glass together without glue: https://en.wikipedia.org/wiki/Optical_contact_bonding https://en.wikipedia.org/wiki/Optical_contact_bonding
- TheSpiceIsLife 3y agoThis would be the same phenomenon that causes guage blocks to stick together, I presume?
- garof 3y agoNot sure. Contact bonding can be strong enough to pull chunks out of one or the other of the glass pieces when you try to separate them. I've not personally seen this happen, only the results.
- the__alchemist 3y agoIs this recently posted thread about diamonds self-healing related?: https://news.ycombinator.com/item?id=37785458 https://news.ycombinator.com/item?id=37785458
- mjan22640 3y agoThe molecules of a solid exert ~10x attractive force compared to molecules of a gas. In the Earths atmosphere every solid surface has a layer of gas molecules stuck to it, that prevents cold welding from happening.
- thsksbd 3y agoGauge blocks stick together quite forcibly in a dirty machine shop, never mind outer space. And how often have my glassware stuck together after I stacked them up?
- uoaei 3y agoThose are both examples of vacuum suction, not welding.
- BenjiWiebe 3y agoI don't think either of those is an example of vacuum suction. Gauge blocks are thought to work in a small part by vacuum, but mainly by other means. Glassware sticks together because of thermal expansion/contraction, combined with being quite smooth and very hard and inflexible.
- BananaaRepublik 3y agoIn school, they used to teach us about the atomic structure of metals being an orderly lattice. Being an orderly lattice, if two pieces of metals were in contact with each other, there wouldn't be any indication of where one piece ended and where the other began. Is this why it fuses in space?
- jgamman 3y agoAwesome - this is the website of the Te Awamutu space centre. "The Space Centre is a privately-funded project run by Dave Owen (Space Dave) and his family." Te Awamutu is a town with ~13,000 people. Live your best life Dave! kia kaha ;-)
- exitb 3y agoIt's always interesting how living on Earth wraps our perception and makes it somewhat difficult to understand how things really are. Like Newton's First Law, which is in a way completely obvious, but not very intuitive in an environment where all seemingly "undisturbed" moving things eventually stop. The real news is that metals don't fuse together on Earth.
- cuSetanta 3y agoCold welding is a concern that we have to account for during spacecraft assembly, sometimes you really really don't want two pieces of metal to weld themselves together after all. To prevent it we wither ensure a reasonable gap (if possible). Which has serious impacts on heat transfer. Or use dissimilar materials to prevent it from happening.
- TheRealHB 3y agoSpace welding!
- joelthelion 3y agoCould this have real-world applications on earth? Getting a good vacuum and cleaning the parts doesn't seem terribly hard. How long does the process take?
- inkcapmushroom 3y agoI could be wrong but usually melting and molding the metal is an easier way to get a specific shape on Earth. Don't see why you couldn't just do that if you wanted a combination of some shapes. I'm wondering if there's an application as a self-destruction mechanism on a lock or something like that. There's still far easier methods.