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A long time ago I was considering asking why the dish antennas on some deep-space probes were perforated metal or mesh (presumably to save weight), while others were solid.

I'm trying to finally getting a round tuit but now I can't find many that weren't solid.

So for this question I'd like to ask only which deep space spacecraft had dish antennas that were perforated or made from mesh?

The only example I have found so far is Venera 4.


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Source: NSSDCA Master Catalog Search for NSSDCA/COSPAR ID: 1967-058A

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Source and Source

right: (click for full size)

Mockup (1:3) of the spacecraft Venera 4 at Memorial Museum of Astronautics (Moscow)

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Galileo's troubled high gain antenna was made from "a gold-plated molybdenum wire mesh stretched across 18 graphite-epoxy support ribs".

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It was a copy of a TDRSS antenna, and after its long storage / trajectory rework / redesign / launch history, failed to deploy fully.

This resulted in data transmission rates much, much slower than designed.

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Source: Open! Open! Open! Galileo High Gain Antenna Anomaly Workarounds (linked above)

Image Source: JPL

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    $\begingroup$ I wonder if this was simultaneously the first and last NASA deep space craft to use a folding mesh. (The newest TRDSs have some really cool looking ones) $\endgroup$ – uhoh Dec 7 '19 at 11:42
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    $\begingroup$ It's been a long time since I looked into it, but at one time, a leading theory for the cause of the failure was the probe being driven coast-to-coast in a shipping crate more times than expected, with subsequent vibrations, etc. $\endgroup$ – Organic Marble Dec 7 '19 at 11:46
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KRT-10 radiotelescope on Salyut-6

The KRT-10 radio telescope consisted of a 10-meter diameter parabolic mesh antenna. Радиотелескоп КРТ-10 состоял из зеркальной параболической сетчатой антенны диаметром 10 метров.

The main mirror KRT-10 was a hexagonal die cut from a paraboloid of revolution. The mirror frame consisted of diagonal rods of aluminum alloys with a cross section of 6×12 mm and cables with a diameter of 1 mm. The nodes were made of aluminum alloys, and the springs were made of high-strength steels. As a reflective surface, a specially developed knitted mesh cloth of metal wires with a diameter of 50 μm was used. The mass of the mirror was 65 kg, and when folded, it was a hexagonal prism with a maximum size of 0.5 m at the base and a total length of 0.9 m Главное зеркало КРТ-10 представляло собой шестиугольную высечку из параболоида вращения. Каркас зеркала состоял из диагональных стержней из алюминиевых сплавов сечением 6 × 12 мм и тросиков диаметром 1 мм. Узлы были выполнены из алюминиевых сплавов, а пружины — из высокопрочных сталей. В качестве отражающей поверхности использовалось специально разработанное трикотажное сетчатое полотно из металлических проволочек диаметром 50 мкм. Масса зеркала составляла 65 кг, и в сложенном виде оно представляло собой шестиугольную призму с максимальным размером у основания 0,5 м и общей длиной 0,9 м.

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    $\begingroup$ I didn't know about this radio telescope, I'll read further about it now, thanks! It's not a deep space spacecraft but its interesting nonetheless. $\endgroup$ – uhoh Dec 7 '19 at 22:42
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    $\begingroup$ @uhoh Technically, this is a very deep space :) . The antenna was used for test observations of several space radio sources. $\endgroup$ – A. Rumlin Dec 8 '19 at 5:59
  • $\begingroup$ indeed it is! ;-) $\endgroup$ – uhoh Dec 8 '19 at 6:04
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From the perspective of electromagnetism alone, so long as the holes in the mesh are much smaller than the wavelength of the electromagnetic radiation to be reflected, there isn't much of a difference between a mesh antenna and a solid antenna. The radiation cannot get through the small holes. This is, for example, why one should stay in ones car during a lightning storm. The car's big windows are invisible holes at the very low frequencies of a bolt of lightning.

An example closer to the problem at hand: A mesh with 1.4 mm holes (e.g., a square mesh made of wires separated by 1 mm) will appear to be quite solid to electromagnetic radiation with a wavelength of 1.67 cm or longer. That includes the Ku band (wavelength between 1.67 and 2.5 cm), and everything with a wavelength longer than that. (A mesh antenna intended for the Ka band would require an even finer mesh.)

However, these electromagnetic concerns are not the only concerns. A fine mesh made of flimsy wires might fall apart when transported back and forth across the country, not to mention falling apart during the rather rough 8 to 10 minutes that follow launch or falling apart due to the sudden jolt that occurs when the upper stage reignites. The significant mass savings that can result from using a mesh antenna versus a solid antenna amount to nothing if the mesh antenna fails due to its inherent flimsiness.

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  • $\begingroup$ Great info, but doesn't answer the question that was asked. "... I'd like to ask only which deep space spacecraft had dish antennas that were perforated or made from mesh?" $\endgroup$ – Organic Marble Dec 7 '19 at 15:16
  • $\begingroup$ @OrganicMarble - How does this not answer the question? The intent of the question is why so few satellites have mesh antenna, even though such antenna are equivalent to solid antennae from the perspective of EM equivalence and are better than solid antennae the perspective of saving a good amount of weight. $\endgroup$ – David Hammen Dec 7 '19 at 15:21
  • $\begingroup$ No, the text says he intended to ask that, but this question is only asking for examples. Reread it.".. I'd like to ask only which deep space spacecraft had dish antennas that were perforated or made from mesh?" $\endgroup$ – Organic Marble Dec 7 '19 at 15:23
  • $\begingroup$ @OrganicMarble - There have been many occasions where an overly literal reading of question as asked is not the question what the intended. And uhoh unfortunately is very good at asking such questions. $\endgroup$ – David Hammen Dec 7 '19 at 15:25
  • $\begingroup$ We'll have to agree to disagree on this one. $\endgroup$ – Organic Marble Dec 7 '19 at 15:27

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