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34 votes
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What is the function of this (apparently) fixed dish on the ISS?

That's a spare part - a spare Space to Ground Antenna dish for the Ku band. It's mounted on an External Stowage Platform. It was brought up on STS-127. From the STS-127 Press Kit Mission ...
Organic Marble's user avatar
22 votes
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Why do Teledesic satellites look so weird? What are these structures and where's the satellite bus?

After a great deal of searching, I found a PDF here, by Mark A Sturza of Teledesic. There's a basic diagram of the satellite on page 8 (Image credit: Teledesic Coporation) There is also the ...
Dave Gremlin's user avatar
  • 2,891
21 votes
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Did NASA's Borg Collective-designed antennas work? Have similar designs ever been used in spacecraft beyond testing?

Yes, an evolutionary designed antenna was flown on ST5 mission with success. From this NASA paper: In total, it took less than one month to modify our software and evolve this second antenna design,...
Uwe's user avatar
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17 votes

Why did Sputnik 1 have four antennas?

I think @PearsonArtPhoto 's answer misses several major points. From http://www.cs.mcgill.ca/~rwest/link-suggestion/wpcd_2008-09_augmented/wp/s/Sputnik_1.htm The satellite carried two antennas ...
uhoh's user avatar
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16 votes
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How do these cubesats' whip antennas work?

I think most of this can be seen from the picture: There are two antennae made of spring(blue) steel, so will automatically return to a straight line once the far end is released -the near end of ...
MikeB's user avatar
  • 467
16 votes
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What antenna is this in an Apollo 15 LM photo?

It's one of the VHF antennae. Locations shown here. 1st image from here: http://www.ninfinger.org/karld/My%20Space%20Museum/pjlmpics.htm 2nd image from here: https://www.hq.nasa.gov/alsj/a11/...
Organic Marble's user avatar
15 votes
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Why did Sputnik 1 have four antennas?

Sputnik was the first satellite. It was set up before we had an understanding of how difficult it would be to maintain a satellite's position, and in fact was a very simple system overall. The 4 ...
PearsonArtPhoto's user avatar
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13 votes

How do these cubesats' whip antennas work?

This photo confirms @MikeBrockington's answers: dual antennas, nested when stowed, opposed when deployed. A later photo at https://www.up.edu.ph/index.php/with-maya-1-flying-high-dost-up-aim-to-train-...
Camille Goudeseune's user avatar
12 votes
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What is the large circular device with a dozen concentric circles on Sentinel 3B?

It appears to match the "X band antenna" on this diagram: (Taken from https://directory.eoportal.org/web/eoportal/satellite-missions/c-missions/copernicus-sentinel-3 -- But they credit ESA for that ...
Saiboogu's user avatar
  • 6,417
12 votes
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What are the parameters of the Voyager high-gain antenna?

tl;dr: From Fig. 3.14 below: Focal Point of "Best Fit" Parabola = 48.671 in. (123.62 cm) Focal Length of "Best Fit" Parabola = 48.626 in. (123.51 cm) And: "The antennas ...
uhoh's user avatar
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11 votes
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Could the Voyager spacecraft be spin-stabilized to keep their high gain antennas pointing towards the Sun (and therefore Earth)?

There is enough hydrazine to last beyond the end of the mission, about 25% of total tank volume is still available. From Descanso volume 4, you can see enough hydrazine for attitude control is ...
Hobbes's user avatar
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11 votes
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What is the pop-up circular disk with spiral pattern in this NASA animation of the Dragonfly helicopter for Titan? Antenna? Kind, band, target?

Quick answer, bit short of time atm: What is the pop-up circular disk with spiral pattern in this NASA animation of the Dragonfly helicopter for Titan? Is it a high gain antenna? If so, what kind, ...
blobbymcblobby's user avatar
10 votes

What is the function of this (apparently) fixed dish on the ISS?

To complement: The SGANT is the antenna that transmits high data rate signals, including many up/down video feeds, from/to the ISS. There is a total of 3 antennas: 2 at the end of booms on the Z1 ...
Daniel's user avatar
  • 121
10 votes
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How did this structure fit into the Shuttle and then expand to 28 meters?

Yes, the whole strut-and-lens system was a giant balloon. There is good information in this paper. Folded up and deflated, it looked like this. This fit into a box mounted on the side of the SPARTAN-...
Organic Marble's user avatar
9 votes
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How does Curiosity know how to point and move it's high gain antenna in real time?

This answer is based on a book called "The Design and Engineering of Curiosity" https://doi.org/10.1007/978-3-319-68146-7 On chapter 6 it is mention that The Hazcams and Navcams are flight ...
Eviatar.E's user avatar
  • 958
9 votes
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How does the pattern on the MarCo cubesat's antenna boost data-transmission?

It's the electrical equivalent of a Fresnel mirror; the reflective cousin of a Fresnel lens. Each of the little square patterns is actually a little passive circuit that reflects the incident ...
uhoh's user avatar
  • 149k
9 votes
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Why do these satellite antennas look so weird? (strangely shaped with little white dots...)

The irregular shape of the reflector is to shape the beam coming from feed in such way that it is tailored to match the contours of geographic region of service area. Here's a short paper on shaped ...
Ohsin's user avatar
  • 1,812
9 votes

X-Band range and data

You want to use a X-band communication link from a cubesat in Earth orbit to another cubesat in orbit around Titan? I don't think it is possible, at least at an acceptable data rate. Lets compare ...
Uwe's user avatar
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9 votes
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Alternatives to the X-Band

The quick answer: yes, Ka-band. There are other deep-space frequency bands, such as S-band, L-band, and UHF, but Ka-band offers unique advantages — but some disadvantages too. You can always trade ...
Tom Spilker's user avatar
  • 18.3k
8 votes

What is the large circular device with a dozen concentric circles on Sentinel 3B?

After reading @ Saiboogu's answer explaining what this is, I found some additional helpful information. This is an isoflux antenna, designed to provide an approximately constant flux of broadcast ...
uhoh's user avatar
  • 149k
8 votes
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Why were the antennas on the spherical surface of some early satellites spiral-shaped?

Those are spiral antennas. Spiral antennas belong to the class of frequency independent antennas which operate over a wide range of frequencies. Polarization, radiation pattern and impedance of ...
Hobbes's user avatar
  • 128k
7 votes
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Deep space craft antenna aiming

Spacecraft use a star tracker to find their orientation (attitude). Here's a random example: Dimensions and Mass: Camera 120 by 120 by 33 mm, 1.0 kg (note: optics protrude 58 mm inside baffle) ...
Hobbes's user avatar
  • 128k
7 votes
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How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints?

I can't speak specifically for the tech on SES-10 since I didn't work with that (yet), but on the previous GEO spacecraft I've worked on, the idea is to alter the radiation pattern. Specifically, ...
ChrisR's user avatar
  • 6,180
7 votes

What is this spinning object seen on a spacecraft above the ISS?

This is a rotating antenna, part of the Kurs docking system on Soyuz and Progress spacecraft See e.g. This video of a docking
oefe's user avatar
  • 2,179
7 votes
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What is the largest antenna deployed in space?

The single largest commercial satellite reflector (18m) is on Terrestar-1. But Japan's ETS-VIII had two reflectors, each of which was almost as big (19m x 17m). Classified satellites are rumored to ...
Organic Marble's user avatar
7 votes
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When scientific and engineering data are sent from space probes, are the signals repeated to minimize transmission error?

Signals are not repeated, but instead coded in a special way that allows to reconstruct the original data on the receiver side in presence of noise/errors. It is called forward error correction. FEC ...
filo's user avatar
  • 1,432
7 votes
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How were the 100+ antennas around Telstar 1 and 2 configured?

Telstar 1 carried a single transponder with 6390MHz uplink and 4170MHz downlink. All the 72 ports in the small-aperture ring were ganged together to make a single receive antenna with a toroidal ...
Bob Jacobsen's user avatar
  • 12.7k
7 votes
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Help understanding how these components of a Honeysuckle Creek dish antenna work

The photo you have is of DSS-46, which is actually at Tidbinbilla. It used to be DSS-44 at Honeysuckle Creek, but when that site was closed in 1981 the antenna was moved. When it was re-assembled in ...
Starfish Prime's user avatar
7 votes

What is the pop-up circular disk with spiral pattern in this NASA animation of the Dragonfly helicopter for Titan? Antenna? Kind, band, target?

I am the designer of this antenna at JHUAPL. It is actually still under development, and the slot pattern shown is an artist's rendition and would not result in a working antenna. The current ...
MBray's user avatar
  • 71
7 votes
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Has there ever been a dish antenna on a lander? If so, which was the first? How about rovers?

tl:dr The first lander to have a dish antenna was the lunar module for Apollo 11 in July 1969. The first rover to have a dish antenna was the lunar rover for Apollo 15 in August 1971. Rovers The ...
Fred's user avatar
  • 13.1k

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