So do NASA use gold foil to protect their equipment?

[RainDreamer]

I have been trying to educate myself about this matter, but I can't find a conclusive source that tell me whether NASA do use gold foil or not. I have seen sources saying that NASA uses Multi-Layer insulation material that looks like gold foil but is infact multiple layers of plastic and aluminum coating. Then I saw other sources saying that NASA do uses gold foil, due to gold being good at reflecting solar radiation-especially infrared light, being easily malleable when stretched and more durable, etc... and they already use gold for the coating of the astronaut visor to filter out IR light.

So..do they or do they not? Or did they use it in the past and now they use MLI? Or they use both and each has its own specific purposes?

[Kryten]

The 'foil' is alumunised mylar. Gold backing on windows or visors is actual gold foil. Trying to make an actual insulating covering out of gold foil would be an exercise in futility, it's nearly as soft as lead and tears very easily.

[linkxsc]

I thought most of it on the landers and such was Kapton insulation

[RainDreamer]

So yeah, anyone has any kind of source that let us know what they use for things exactly? I am confused.

[Nibb31]

You're confused because you're not being very specific about which equipment you are talking about.

If you are talking about the Apollo LM descent module insulation, what you see was gold-colored Mylar, which was a material created by DuPont for the Apollo program. It wasn't actual gold. That was only the outer layer of several layers of foils and Inconel that served an thermal insulation and MMOD protection.

The Apollo CMs were covered in Avcoat ablator material and then silver-colored Kapton tape, which is what gives them their shiny appearance in the photos taken from space. After reentry, most of the Kapton burned off. As you can soo on the CMs that are in museums, the rest of the Kapton layer was removed and some bits of it were packaged and given away as mementos to VIPs.

The Apollo helmet visors were gold-coated to block IR and shade from the sun. This gave them a slight greenish tinge, which is why the Apollo astronauts could lift the visors when they were not facing the sun to get a better view of the actual colors.

On the ISS, the EVA helmets don't use gold, but some new-fangled reflective film material that doesn't alter color viewing.

- - - Updated - - -

I thought most of it on the landers and such was Kapton insulation

Kapton is an adhesive tape. Mylar is a foil-like film material.

Edited February 12, 2015 by Nibb31

[RainDreamer]

Ah I see. I was more or less asking if NASA use gold foil at all for protection of any of their equipment though.

[Nibb31]

Ah I see. I was more or less asking if NASA use gold foil at all for protection of any of their equipment though.

No, they use gold-colored mylar.

[Moar Boosters]

They do use gold to protect their equipment, it's just not the same as the big areas of gold mylar you see on the outside of spacecraft.

It's for internal components which use gold either for it's shielding or anti-corrosive properties. I'm not sure if it's classified as foil, gold leaf, or something else, as it's usually applied with lasers.

I'm sure you can find more information about the scientific reasons on this website.

http://www.lasergold.com/

[RainDreamer]

I think it is gold coat/painted? Or gold laser tattooed!

Interesting stuff about where gold are used though.

[Moar Boosters]

I imagine there are different advantages and disadvantages to different application techniques. The reason they use gold is because it's got many unique properties, but unfortunately has the undesirable properties of being fragile and heavy; so I expect they're still developing new techniques to get what they want from it without suffering the penalties.

I guess it's easy to see where the confusion comes from as well, as most of the components that are actually covered in gold are then encased in something else, to protect the gold.

[Sampa]

The 'foil' is alumunised mylar. Gold backing on windows or visors is actual gold foil. Trying to make an actual insulating covering out of gold foil would be an exercise in futility, it's nearly as soft as lead and tears very easily.

that, and it's gets to be pretty expensive and is very conductive and heavy

[cyberquipment]

I got some MLI blankets from http://www.nasa.gov/centers/wstf/home/index.html that were destroyed to the point of scrap. So I had some of it assayed! Report came back a 5% gold content. For pictures, contact me

[Jeb1969]

Contrary to what people think the metallic foil that often covers most unmanned spacecraft the material is not gold, however there is a metal involved (Aluminum). The foil is usually made of a polymide film known as Kapton, because Kapton appears translucent yellow to amber, the Kapton layered with the Aluminum foil gives the Illusion of gold when really it is just sheets of plastic overlapped with aluminum foil.

In some cases Mylar is added for durability.

The reason why they use Kapton is because the material has amazing thermal properties which is ideal for the vacuum of space, not to mention it helps dissipate ultraviolet radiation emanating from the sun from damaging critical and sensitive spacecraft assets such as bulkheads, scientific instruments, fuel lines, electrical conduits etc.

Kapton Foil has also been applied on crewed spacecraft as well, most notably on the descent stage of the Apollo Lunar Excursion Module. 

 

[Nuke]

i use kapton on my 3d printer, i just wipe it down with alcohol and my prints stick fairly well. insane heat tolerance, you can poke it with your soldering iron and it wont burn or melt. people have used it to dead bug smd parts, kapton under the pads, glue the package to your protoboard and then you can solder each trace to magnet wire. generally good stuff. the down side is its expensive.

[lajoswinkler]

Basically all you need to know is here and available on the links in the document.

https://en.wikipedia.org/wiki/Space_blanket

[peadar1987]

As a tangential topic, say I wanted to conduct the maximum amount of electricity for the minimum amount of weight (and my voltage is fixed)

What's the best way of doing it? Gold is very conductive but heavy, aluminium less conductive but lighter... Is there a generally accepted material that gives the best conductivity to weight ratio, or does it depend very much on the application?

[Green Baron]

Good ole graphite ?

 

[p1t1o]

31 minutes ago, peadar1987 said:

As a tangential topic, say I wanted to conduct the maximum amount of electricity for the minimum amount of weight (and my voltage is fixed)

What's the best way of doing it? Gold is very conductive but heavy, aluminium less conductive but lighter... Is there a generally accepted material that gives the best conductivity to weight ratio, or does it depend very much on the application?

Copper and alloys thereof would be my bet. I just saw them install some new power lines at my local train station, they appear to be pure copper or some copper-rich alloy, weight would be an important concern there, combined with tensile strength. I dunno if its the absolute pinnacle of conductivity-to-weight but it must be pretty good.

[peadar1987]

Just played around with some numbers on this (The lower the value the better):

Copper - 0.15 Ωg/m²

Silver - 0.17 Ωg/m²

Gold- 0.42 Ωg/m²

Aluminium- 0.07 Ωg/m²

Iron- 0.76 Ωg/m²

Graphite- 81 Ωg/m²

Tungsten- 0.96 Ωg/m²

Graphene- 0.075 Ωg/m²

So from this, it looks like Graphene is 10 times better than the next best substance, which is aluminium. However, I'd take the values of graphene with a pinch of salt, because as far as I know, we've never made bulk graphene before, so its properties are hard to pin down exactly.

Edit: Uncovered in my digging that although aluminium is in theory better than copper in terms of mass, it is harder to work with and form into wires, has different thermal expansion properties, which can lead to loosening of joints and fatigue, and also tends to form oxide films at contacts, which means that copper is usually the go-to material.

Edited July 29, 2016 by peadar1987

[radonek]

Hell, most of my country was wired with aluminium around eighties and it worked. Mostly. It is true that electricians nowadays are not happy working with wires that like to snap when bent. Thermal expansion is an issue if you combine Al with iron parts, use more suitable contact metal and you are ok. So, if you take some precautions and do no use it for something that is to be rewired often, aluminium certainly could work.
 

[Green Baron]

Sadly aluminium is at the far end of metals in the galvanic row, only magnesium and zinc are worse. When in contact with other metals like iron. a current is flowing and a conductor is present (water: rain) it looses mass quickly (dissolves).

Edit: ok, in space not a problem. Or is aether a conductor :-) ?

Edited July 30, 2016 by Green Baron

[DDE]

Copper and bronze see plenty of use in rocketry; not only for electric conductivity, but don't forget heat conductivity.

Also, speaking about unexpected colours... those are bronze:

[cryogen]

I think the answers in this thread about MLI are only partly right (as is the Wikipedia page on MLI). From some research, it looks like multi-layer insulation (MLI) can use either aluminized or goldized Kapton; while the aluminized version has a deceptively "gold-color" appearance, there's a different type that uses actual gold (Au), the element, vacuum-deposited on Kapton film.

This makes sense, since gold has pretty unique radiative properties; it has significantly higher α/ε ratio than aluminum -- it's a "warmer" material in direct sunlight.

Here's one source, a NASA technical document about MLI:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990047691.pdf

Here's a second source, an article by a company that manufactures MLI films (note it's one of the vendors listed in the previous table):

http://www.sheldahl.com/documents/Thermal Control Overview.pdf

Quote

A first surface mirror consists of a metallic coating (typically aluminum or gold) on a substrate. For multilayer insulation (MLI) blankets the substrate is usually PET or polyimide film [note regarding brand names, Mylar is a PET, and Kapton is a polyimide --cryogen], though FEP is used in some applications. Metallic coatings have very low emittance, so films coated on both sides are typically used for the inner layers of insulation blankets to minimize heat transfer.

Aluminum is the most commonly used coating; it combines low absorptance and emittance with low cost. The surface emittance, and hence energy transfer, can be reduced further through the use of gold coatings. Because gold is nearly inert, it has also been used in applications where the MLI blankets will be subjected to moist (salty) atmosphere for extended periods (e.g. space shuttle). As an alternative in this application, the aluminum can be protected with a corrosion resistant AOC coating. 

According to the first pdf (NASA), the MLI insulation on the Solar Maximum Mission in the 1980's was goldized Kapton. Here's a picture of it, showing a very unique color, darker and more reddish than other spacecraft (unless there's something wrong with the color camera?)

http://solarscience.msfc.nasa.gov/SMM.shtml

A couple more photos of goldized Kapton MLI. The source pdf is

http://esmat.esa.int/esa_str-241.pdf

For comparison, here's Cassini's MLI insulation, which looks quite different, rather yellow-ish. According to this source, these are aluminized films, including Kapton, Mylar, and Dacron; 

http://www.jpl.nasa.gov/releases/97/csblank.html

Edited August 1, 2016 by cryogen
misc edits

[Jeb1969]

On 7/28/2016 at 8:42 PM, Nuke said:

i use kapton on my 3d printer, i just wipe it down with alcohol and my prints stick fairly well. insane heat tolerance, you can poke it with your soldering iron and it wont burn or melt. people have used it to dead bug smd parts, kapton under the pads, glue the package to your protoboard and then you can solder each trace to magnet wire. generally good stuff. the down side is its expensive.

I knew about that application, Not to mention kapton is also used in the electronics industry to manufacture flexible circuit boards and is sometimes used to insulate copper wire, again it is the material's thermal properties that promote it's use in non-aerospace applications. Not to mention the material makes an Ideal base material for tape in the electronics and aerospace industry because it binds well with adhesives.