# Have solid dish antennas on deep space spacecraft (as opposed to meshes) ever provided any other helpful function? As meteor shields perhaps?

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

To my understanding, most if not all deep space dishes are solid these days and many/most Earth orbit dishes are solid. For small ones on big satellites it's not worth it to "go mesh" and for communications in GEO you really want to be absolutely sure that your reflector figure is correct, both for multi-transponder arrays with narrow beams on a single dish and carefully beam-forming irregular dish surfaces for fancy footprints.

A notable exception are the recent TDRS big dishes in (inclined) geosynchronous orbits which are actually folded up like a flower bud for compactness at launch.

Question: Do solid dish antennas on deep space spacecraft (as opposed to meshes) provide any other helpful function? As meteor shields perhaps? As a thermal shield? And even if not designed that way, have they been used in a pinch for anything other than high-gain radio linking?

Adapted from Source Click for larger view of flexible mesh antenna

(Am I the only one reminded of "Audrey II, an evil and boisterous flytrap-like extraterrestrial plant" from Frank Oz's 1986 Little Shop of Horrors?)

The video Donald Cornwell plenary talk: NASA's Optical Communications Program: 2015 and Beyond was presented at SPIE Photonics West 2015. It's a great talk and worth the time.

After 20:12 a slide is shown that promotes a hybrid deep space communications system where the SDR transmitter electronics can modulate either radio or optical and both are provided. The antenna is shown as a mesh to save weight, with the captions

Knitted gold plated molybdenum mesh >98% reflective at Ka-band.

Low density mesh RF annulus

• There was an early design for Parker Solar Probe where the dish doubled as a heat shield that I asked about here. – Jack Apr 9 at 20:50
• @Jack please consider writing a short answer. You can mention that while it never actually flew, that since the DESCANSO editors thought it so notable and unique as to put in the report that it's worthy of mention here as well. A screenshot of Fig. 9a, b really helps as well. I hope you don't mind, I've added one to your linked question. – uhoh Apr 9 at 22:09

A few months before Cassini made its mission-ending dive into Saturn's atmosphere, it skirted the region between Saturn's atmosphere and the innermost ring.

From NASA Spacecraft Dives Between Saturn and Its Rings, emphasis mine,

The gap between the rings and the top of Saturn's atmosphere is about 1,500 miles (2,000 kilometers) wide. The best models for the region suggested that if there were ring particles in the area where Cassini crossed the ring plane, they would be tiny, on the scale of smoke particles. The spacecraft zipped through this region at speeds of about 77,000 mph (124,000 kph) relative to the planet, so small particles hitting a sensitive area could potentially have disabled the spacecraft.

As a protective measure, the spacecraft used its large, dish-shaped high-gain antenna (13 feet or 4 meters across) as a shield, orienting it in the direction of oncoming ring particles. This meant that the spacecraft was out of contact with Earth during the ring-plane crossing, which took place at 2 a.m. PDT (5 a.m. EDT) on April 26. Cassini was programmed to collect science data while close to the planet and turn toward Earth to make contact about 20 hours after the crossing.

• I'm guessing very small particles, since at those relative speeds a grain of sand probably penetrates the dish without even slowing down. – Carl Witthoft Apr 9 at 13:32
• @CarlWitthoft The linked article talks about particles "on the scale of smoke particles". So yeah, tiny. – David Hammen Apr 9 at 14:17