Imagine a square meter of a 1 <math>mm^2</math> surface in outer space, at 400 K, with an . Assume that its emissivity of is 1, . Also assume that it is facing away from the sun (i.e. in the direction opposite to the sun) or other heat sources. From Using the Stefan–Boltzmann law, we can show that this surface will radiate 1452 watts. Now imagine placing if we place a thin (but opaque) layer 1 cm away from the plate, (thermally insulated from it), and also with an emissivity of 1. This new , then this layer will cool until it is radiating 726 watts from each sideboth its sides. Once this point is reached, at which point everything is will be in balance. The new layer receives gets 1452 watts from the original plate. , out of which 726 watts is radiated back to the original plate, and 726 watts is radiated to space. The original surface plate still radiates 1452 watts, but gets 726 back from the new layerslayer, for a which makes the net loss of to be 726 watts. So overall, the radiation losses have been reduced by half halved by adding the additional new layer. <ref>https://www.revolvy.com/main/index.php?s=Multi-layer+insulation&uid=1575</ref> <br \>

The simplest MLI construction , in its simplest form, is a layered blanket which is assembled from thin embossed Mylar sheets. Each sheet has, on one side, each with a vacuum-deposited aluminum finish on one side. As a result Because of the embossing, the sheets touch come in contact at only a few points, and thereby minimizing the conductive heat paths between layers are thus minimized. The layers are aluminized have an aluminum finish on one side only so that the Mylar can act somewhat as a somewhat low-conductivity spacer. Higher-A construction which gives higher performance construction is composed of Mylar film metalized (with aluminum or gold) on both surfaces with sides. These have silk or Dacron net as the low-conductance spacers. <ref name = "ref4">https://books.google.co.in/books?isbn=188498911X</ref> <br \>Heat transfer through MLI is a combination of radiation, solid conduction, radiation and, under atmospheric conditions, gaseous conduction. These All of these forms of heat transfer are minimized in different ways. Radiative heat transfer is minimized by interposing Interposing as many enclosing reflective surfaces (metalized metallized sheets) as is practical practically possible between the object being insulated and its surroundingsminimizes radiative heat transfer. Solid-One can minimize solid conduction heat transfer is minimized by keeping minimizing the density of the low-conductance spacers between the reflective surfaces as low as possible and making the blanket "fluffy" in order to minimize contact between layers. <ref name = "ref4"/> <br \>Because the The heat transfer mechanisms operate simultaneously and interact with each other. Therefore, a useful technique is to refer to derive either an apparent thermal conductivity, <math>K_{eff}</math>, or an effective emittance, <math>\varepsilon^*</math>, through the blanket. Both values We can be derived experimentally during derive both the values for steady-state heat transfer. <br \>In theoryTheoretically, for a highly evacuated MLI systemssystem, the emittance <math>\varepsilon</math> for a blanket comprising of N non-contacting layers of having emissivities <math>\varepsilon_1</math> and <math>\varepsilon_2</math> on opposite sides is computed as:

In satellite applications, the MLI will be is full of air at launch time. As the rocket ascendsthrough the atmosphere, this air must should be able to escape without damaging the blanket. This may require Therefore, holes or perforations are required in the layers, even though this reduces their has an associated reduction in effectiveness. <br \>MLI blankets are traditionally constructed with sewing technology. The layers are cut, then stacked on top of each other, and finally sewn together at the edges. Seams and gaps in the insulation are responsible for the cause of most of the heat leakage leakages through MLI blankets. A new method is being developed to use polyetheretherketone (PEEK) tag pins (similar to plastic hooks used to attach price tags to garments) to fix the film layers in place instead of sewing to improve the thermal performance. Traditionally, MLI blankets are sewn together; the multi-layered blanket being held together by stitches<ref>https://en. However, any kind of hole that punches through the layers tends to degrade the overall thermal performance of the blanketwikipedia. Another method, of using tagorg/wiki/Multi-pins - the small nylon "I" looking pins that are used to hook price tags to clothes in stores - to fix the layers in place, has been mentioned in the literature, see paper by R. Hatakenaka, here). That way you don't need to punch as many holes as when you are sewing, and tagging - a few inches between tags - is faster and less error-prone than sewing around the whole perimeter of the blanket. Moreover, the tag-pins allow you to fasten the layers together without compressing them, which reduces stress around the holes. Lastly, the blankets tend to contract in the direction of sewing which might lead them to be to small if not oversized properly. layer_insulation</ref> <br \>In some applications the insulating layers must be grounded, so that they cannot do not build up a charge and arc, causing which cause radio interference. Spacecraft Satellites may also may use MLI as a first line of defense protection against dust impacts. <br \>