What metals are spacecraft constructed of?

[MeteorWayne]

Over in Technology, chiliwili (?) asked this question. <br /><br />I thought I'd throw it over here since this is where the experts are. MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[bdewoody]

I'd say various aluminum alloys, titanium and probably some steel but not much. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[tohaki]

<blockquote><font class="small">In reply to:</font><hr /><p>I'd say various aluminum alloys, titanium and probably some steel but not much.<p><hr /></p></p></blockquote>That would be my guess as well.

 

[ckikilwai]

chiliwili! LOL <img src="/images/icons/laugh.gif" /><br />But thanks replacement and the answers!<br />We will probably use the element aluminium for the exercice,<br />because we don't have titanium in the list of normpotentials.<br /><br /> <br />

 

[spacester]

There is a vast selection of Aluminum alloys, and in almost no case is pure Aluminum used. Pure aluminum corrodes in the presence of Oxygen and water (and just about anything else AFAIK). Pure Aluminum is rarely found outside the laboratory.<br /><br />The most widely used Aluminum alloy is called 6061 and as you can see, more than a few standards apply.<br /><br />"Aluminum" comes in an incredibly wide range of alloys, and the manufacturing process is an important factor as well.<br /><br />Space Shuttle External Tanks are made with a special alloy using Lithium, in order to maintain high strength at lower weight.<br /><br />And no matter what you hear from our British friends, there are only 4 syllables in the word, not 5. <img src="/images/icons/laugh.gif" /><br /><br />hth <div class="Discussion_UserSignature"> </div>

 

[docm]

Orion's shell will be primarily aluminum-lithium alloy;<br /><br />NASA article....<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Kirsch's team gathered at Goddard Space Flight Center last week for a three-week stint at the concurrent engineering center there to wring out requirements and divvy up the work that will be necessary to build a composite pressure shell for Orion. The actual flight component will be built of aluminum lithium because NESC engineers didn't find a "significant discriminator" for composites over the lightweight aluminum alloy.<p><hr /></p></p></blockquote><br /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

SOrry about that ckikilwai.<br />I have no idea where that came from.<br /><br />Glad you got some answers despite my brain lockup <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[ckikilwai]

"There would be a severe weight penalty, but aluminum has a fatal flaw at high temperatures. It loses much of its strength far below the melting point."<br /><br />Far below the melting point? Dont you mean near the melting point?<br /><br />But I think my teacher meant an unprotected spacecraft, like the one that fly free in space, or like the mars rovers.<br />Or are they to mainly made of titanium?<br />

 

[ckikilwai]

<blockquote><font class="small">In reply to:</font><hr /><p>"Far below the melting point? Dont you mean near the melting point? "<br /><br />No he does mean far below the melting point. On the Shuttle Orbiter we need to keep the aluminum skin below 200 deg F. <br /><p><hr /></p></p></blockquote><br /><br />Ok, now I'm confused...<br />If you want to keep the aluminium strong, it should not be far below its melting point (1120° F).<br /><br />Now you say the aluminium skin of the Shuttle must be below 200° F, but isn't this to prevent it from getting near its melting point? <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>And no matter what you hear from our British friends, there are only 4 syllables in the word, not 5. <p><hr /></p></p></blockquote><br />Oh you mean the word Alumin(i)um! <img src="/images/icons/laugh.gif" /><br />I didn't notice that it is written differently in american english, but I use aluminium because we use it this way in dutch. <img src="/images/icons/wink.gif" />

 

[tohaki]

<blockquote><font class="small">In reply to:</font><hr /><p>Oh you mean the word Alumin(i)um!<br />I didn't notice that it is written differently in american english, but I use aluminium because we use it this way in dutch.<p><hr /></p></p></blockquote>It is the same in Norwegian. I think most languages use some form of the 5 syllable version. It is the same with the US confusion over what exactly a billion is.

 

[MeteorWayne]

Hmmm, sounds like tonights science experiment <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[spacester]

<font color="yellow">It is the same in Norwegian. I think most languages use some form of the 5 syllable version.</font><br /><br />Arrrrrgghh<br /><br />I was not aware that the cancer had spread that far. <img src="/images/icons/wink.gif" /><br /><br />Look at the Periodic Table of the Elements: How many syllables? <img src="/images/icons/laugh.gif" /><br />***<br />The temperature dependence of the strength of Aluminum is an excellent point. In an effort to clarify, a little Material Science 101 might be helpful:<br /><br />For most materials, engineers talk about two kinds of strength: Ultimate Strength and Yield Strength. They are both used to predict "failure modes."<br /><br />Consider a common metal paper clip: <br /><br />If you bend the wire just a bit, it will spring back to the same shape it was before. No failure mode here.<br /><br />If you bend the wire further, it will stay there (or spring back just a bit but not all the way). This means the Yield Strength was exceeded, it has undergone what is called Plastic Deformation, it 'yielded' to the applied load by acting like a 'plastic' material.<br /><br />Exceeding the Ultimate strength means that you put so much load on the paper clip that it breaks into two pieces. The applied load caused an Ultimate failure.<br /><br />The paper clip will rarely fail by just bending it once or twice. That is because the energy put into the bending action is 'absorbed' by the plastic deformation, and normally the length of wire that is permanently bent is long enough that the load stays below the ultimate strength at all places.<br /><br />If you bend it at a very sharp corner, you will find that the Ultimate strength can be exceeded because you concentrate that distortion energy over a short length of the wire. You can break it into two pieces if the bend radius is small enough. It's not easy to do.<br /><br />When you bend the paper clip repeatedly until it breaks, that is a different failure mode called Fatigue Failure. (We've prol <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

I'm glad I signed up for materials science 101.<br /><br />Thanx spacester!!<br /><br />MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>"If you want to keep the aluminium strong, it should not be far below its melting point (1120° F). " <br /><br />"Now you say the aluminium skin of the Shuttle must be below 200° F, but isn't this to prevent it from getting near its melting point? " <br /><br /><br />No, the aluminium must be below 200 deg F. otherwise it's strength is reduced to a point where it is no longer a good structural material. <p><hr /></p></p></blockquote><br /><br />Allow me to elaborate <img src="/images/icons/smile.gif" /><br /><br /><b>Any</b> metals strength is a function of temperature. Generally speaking, its strength goes down as temperature goes up. At some temperature below its melting point, the metal doesn't "break" per se, but goes soft like a wet-noodle, therefore becomes useless in supporting any kind of weight. <br /><br />Now comparing aluminum to steel, here is the trade-off. Suppose your 'spacecraft" structure needs to support a weight and forces from the environment your spacecraft will see, for example all the rattling and shaking during launch, so you will design the necessary amount of <font color="yellow">strength</font>into your selected metal. This pretty much comes down to its "strength modulus" (often called the Young's modulus) and thickness. For example, if you use aluminum vs. steel, chances are the aluminum is at a lower density (lighter per unit weight) but will required a thicker layer to handle the strength, as compared to steel. So for a large surface area structure but not at a highly concentrated force area, such as the Shuttle ET and/or the orbiter, aluminum is preferred. Whereas for the high strength area, steel and/or titanium is preferred.<br /><br />For a Venus spacecraft, you've just introduce another key environmental factor into the spacecraft structure design selection -- that is the Venus atmosphere <font color="yellow">temperature effect on the spacecraft</font> Venus' atmosp <div class="Discussion_UserSignature"> </div>

 

[propforce]

from ckikilwai<blockquote><font class="small">In reply to:</font><hr /><p><br />Hi everyone <br />I had a chemistry lesson today, and we were learning about redox reactions. <br />It was a bit boring untill she began to talk about the atmosphere and surface of Venus. <br />We read an article about it, and beneath it were 2 questions. <br />One of them was "what is the effect of the atmosphere on a spacecraft?" <p><hr /></p></p></blockquote><br /><br />Just re-read your original question. This is really a chemistry-related question.<br /><br />A "redox" reaction is a chemical reaction that does either a "reduction" or an "oxidation" reaction.<br /><br />The Venus atmosphere contains 96.5% carbon dioxide, CO2, 3.5% nitrogen, N2, and traces of sufur dioxide, SO2, at 0.015% and water, H2O at 0.002%. <br /><br />This makes the Venus atmosphere forms "acid rain" which could easily forms a "redox" reaction with bare metal on your Venus spacecraft. Sulfur, oxygen and water vapor forms sulfuric acid that will attack metal surfaces, effectively corroding it and eats away its strength. <br /><br />The current approach in preventing corrosion and/or atmospheric oxidation of spacecrafts and propellant tanks of large launch vehicles that use aluminum is through the process called anodizing. The anodizing process is an electrochemical reaction that produces a thin layer of aluminum oxide coating thus preventing atmospheric oxygen and water vapor from attacking the bare metal.<br /><br />As you can see from responding posts, <i>"...the effect of the atmosphere on a spacecraft?"</i> HAS EVERYTHING TO DO WITH how a spacecraft material selection is made and how it is designed. <br /><br />Hope this helps <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[ckikilwai]

wow <img src="/images/icons/blush.gif" /><br />So in short, aluminium is used for probes and satellites just in cold space, while you use titanium to withstand high pressure and high temperatures, because aluminium and steel would melt and bent, although aluminium can get protected by anodizing?<br /><br />But does the explanation behind it explain why aluminum looses its strength when it gets too cold?