# What are these two very large, round panels on opposite sides of AngoSat-1?

The Spaceflight101 article AngoSat-1 Satellite Overview Shows several images of the large communication satellite designed for GEO.

Two color photos show that the spacectraft has two large (roughly 3 meter diameter) flat circular disks on opposite sides of the spacecraft.

The monochrome image is one I've produced by showing Red minus Green with levels between -0.15 and 0.0 scaled to full black to while. This brings out more clearly a strange pattern produced by about 20 circles arranged in a square, plus a central hexagon surrounded by six hexagons around it.

As shown, if one faces the Earth, the other will face away from the Earth.

They don't look like they will become parabolic dishes, but instead remain flat.

What are they? How do they work?

below: From Spaceflight101. Credit: Roscosmos

below: From Spaceflight101. Credit: RSC Energia

They are "antenna reflectors". They deploy out from the spacecraft bus.

There are cones/tubes on the spacecraft bus pointing at the reflectors in their extended position. You can see them in the picture from the question which has the personnel in it. Speculation: this allows the electronic apparatus to remain mounted on the bus instead of having to be deployable.

Source

• okay, let's see what happens. (comment cleanup)
– uhoh
May 17, 2018 at 18:47
• Thanks for the answer, the 3D situation is much clearer now. I'll hold out to see if someone adds an answer that addresses how these flat reflectors work. I was off a factor of 2 before, so my estimate is that these have a radius of about 1/5 of the distance to the feed, meaning the subtended angle is about the same as the Earth would be at GEO. Still curious why they are flat.
– uhoh
May 17, 2018 at 18:50
• They aren't flat - look at the vertical seams above and below the center hexagon in your B/W image.
– amI
Nov 13, 2018 at 18:38
• Aha! Yes finally I see what you mean. I still don't understand why the hexagonal segmentation, or those ghost-like circles in a squarish pattern, but there's no question that these are reflectors. Thanks!
– uhoh
Feb 10, 2019 at 11:25
• Seeing this tweet I am beginning to think that the squarish array of circles simply reflects some kind of mounting bolt pattern, rather than something high-tech.
– uhoh
Feb 22, 2019 at 1:57