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Questions tagged [communication]

Questions regarding information transfer between spacecraft, and between spacecraft and Earth.

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What channel does a launch vehicle telemetry system see? Is it AWGN?

What is the kind of channel seen by a communication system (for telemetry data) on-board a launcher during various phases of launch. Is it a fading channel or AWGN channel? (Additive white Gaussian ...
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Why not send Voyager 3 and 4 following up the paths taken by Voyager 1 and 2 to re-transmit signals of later as they fly away from Earth?

Voyager 1 and Voyager 2 spacecrafts are on their journey out of solar system. They collected so much of important data that helped us understand our solar system. As these spacecrafts moving out of ...
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What is the lowest latency achievable in reliable Earth - Moon communications?

I know that radio waves travel at the speed of light in vacuum so the minimal latency to communicate between Earth and Moon would be about 1.25 second each way. This latency figure will then increase ...
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What kind of signal Voyager 1 is sending to us?

I was reading on wiki about Voyager 1 mission and I found very interesting! One thing I did not manage to find: what is the signal Voyager 1 is sending to us? Is it simply a sinewave or something more ...
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Could “live” video be transmitted from Mars?

With the approach of InSight to Mars today, and the two cubesats watching it, much is being made about seeing "Live Video" from the cubesats. I'm pretty sure that simply can't happen, but I'm ...
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Why no recent information about or photos of Ultima Thule?

It's been two weeks since New Horizons flew past Ultima Thule but the most recent news on the Johns Hopkins site is dated the fourth of January The image gallery has had no new pictures since the ...
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Difference in communication delay on ISS

What cause the difference in communication delay, about 11 seconds in this video: and apparently almost no delay on this one: ...
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From whence (what ground stations) do all the world's space agencies receive signals from their missions?

The ISRO web page Ground Segment says: SRO Telemetry Tracking and Command Network (ISTRAC) will be providing support of the TTC ground stations, communications network between ground stations and ...
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Would communication with Houston still be possible in a LEO debris cascade?

In the film Gravity (2013), the astronauts on STS-157 & the ISS lose communications with mission control in Houston, supposedly due to the chain reaction of debris collisions taking out ...
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What is astronaut Alexander Gerst signaling with this K-shaped hand signal?

In this AP/WISN news item Air leak at International Space Station temporarily plugged by a thumb they show a file photo of German astronaut Alexander Gerst at the Baikonur cosmodrome, making what ...
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What technology will SpaceX's StarLink satellites most likely use for sat-to-sat linking?

The question How does SpaceX plan to make money with StarLink Broadband? has got me thinking about how the satellites will link to each other. Wikipedia says it's something greater than 10,000 GHz ...
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why do astronauts in the ISS still use wired microphones?

While I watched the DM-1 hatch opening, I noticed that astronauts use the wired microphone to talk to Huston. It was particularly strange seeing that even because during hatch opening, they were ...
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Have guidelines for red & green navigation light placement on spacecraft been established?

update: Cropped screen capture from SpaceX Demo-1 Crew Dragon Docking to ISS - Part 2 after about 00:25:00 in the video: I am curious if guidelines for the ...
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What are the prospects for comms with cubesats using “normal” internet connections?

Can a cubesat in orbit be operated like a R/C airplane in real time? edit: if the link here and the end aren't clear, I'm interested in the ease and convenience of access, the frequency of possible ...
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Did NASA's Borg Collective-designed antennas work? Have similar designs ever been used in spacecraft beyond testing?

This interesting answer to the question Do antenna farms on spacecraft make any sense or are they purely aesthetic? in Worldbuilding SE links to the NASA Ames page 'Borg' Computer Collective Designs ...
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Why is Sentinel 3B's dish antenna overwrapped with metallized film?

The Spaceflight Now article Photos: Sentinel 3B satellite prepared for launch from Plesetsk Cosmodrome has of course lots of photos. One of them shows a dish antenna covered with shiny, metallized ...
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Pictures from Mars

How is it that NASA receives broadcasts from 300 million miles away but Sprint needs to install transmitters every 500ft for 5G wireless?
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What is the meaning of “T.M”?

In the movie, First Man (2018), Neil Armstrong is getting into Gemini 8 space craft. He overhears capcom voice: CARNARVON CAPCOM: Guaymas, read you loud and clear. We have S band track. We have ...
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What was the last message to Opportunity today (13 Feb '19)?

Several articles have mentioned that the last ever commands were sent to the unresponsive Opportunity rover today by NASA. Now, I know that it wasn't a verbal message, but was there anything digital ...
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When scientific and engineering data are sent from space probes, are the signals repeated to minimize transmission error?

I would think that this would be the case. In any one transmission there will be a systematic error due to the fundamentals of the transmitter / receiver. Is there also a transient or stochastic error ...
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“Luckily with no Lunar Module, Tidbinbilla was able to keep tracking with no interruption…” Why is no LM significant?

@PearsonArtPhoto's answer links to the page Apollo 8, 21 – 28 December 1968 by Hamish Lindsay at honeysucklecreek.net. The page describes a problem with one of the dish antennas that needed to be ...
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How did NASA achieve their live TV broadcast in 1969?

In 1969, NASA not only went to the moon, but broadcast the whole thing live on TV. How did they achieve the TV broadcast? What technology did they need to use to send a video and audio signal from ...
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What was the last message Opportunity sent?

Everybody seems to be abuzz with the idea that Opportunity's last transmission was "My battery is low and it's getting dark." Of course, that would be a human interpretation of some sort of ...
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How do you calculate the lat and lon of a point on the earth using azimuth and elevation seen from a geostationary satellite?

I am given the longitude of a geostationary satellite and a pointing vector from the satellite in the form of azimuth and elevation angles looking from the satellite towards the earth (where zero ...
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How have the 'gift' transponders on ISRO's GSAT-9 been used by other countries?

edit: It's been seven months close to two years now, have any of the 'gift' transponders been used or at least tested yet by the gift recipient nation? The BBC news item India launches 'invaluable' ...
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Would radio / wifi and other communications work on Jupiter's moons?

I've read that Jupiter emits a lot of EM radiation, and can also be heard on ham radio. If you were much closer would it drown out radio and other forms of communication, or is it confined to specific ...
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Apollo communication between the Earth and Moon

How was it possible for astronauts to send back tv/radio signals to earth from the moon? I have just been teaching my son about waves behavior and understand that radio waves are reflected back to ...
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Do moon rovers on near side need a relay communication satellite?

Wikipedia says direct communication is not possible from the far side of the moon. So I'm guessing it should be possible for the satellite to communicate directly without relay satellite from the near ...
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How to communicate with a lunar polar mission?

We can easily communicate with a spacecraft on the Moon on the near side. The Far Side allows for a L2 halo communication relay satellite easily enough. How would a polar mission communicate with ...
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How long did New Horizons take to upload all of its data from the Jupiter encounter?

It's a pretty well known fact among the regulars of this site that New Horizons will take up to 18 months to completely upload the data from the Pluto encounter. When it was at Jupiter, it was much ...
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Transmission time per day for Chang'e 4?

Congratulations for the sucessfull landing on the back side of the Moon. There is continuous line of site available for radio connection from the lander to the Queqiao relay satellite at the Earth-...
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What will China's new “space station” in Argentinian Patagonia be used for?

The New York Times (fairly strongly worded) article From a Space Station in Argentina, China Expands Its Reach in Latin America describes a "space station" or base equipped with (among other things) a ...
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Could we use a narrow paradigm, say laser, to get info faster from New Horizons? (With a moon base.)

There was just a question (actually, on Astronomy) about why the data rate from New Horizons is low. Of course, even with the most directional radio antennas, the spread is enormous. I guess ...
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What is carrier lock and bit lock?

I'm not sure if this question belongs here or in Amateur Radio, but during the acquisition of signal from New Horizons on New Year's Day, I heard the controllers call out "carrier lock", "symbol lock",...
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Can I text on my cell phone from the ISS to Earth?

We know from Can we detect the cell phone, satellite phone, or walkie talkie of someone walking on Mars from Earth? that cell phone signals on Mars are potentially observable on Earth. I am not an ...
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Is the prompt relay of landing telemetry by the MarCo cubesats to Earth really a “first”?

The MarCo cubesats travelled from Earth to Mars alongside InSight and relayed signals from InSight (UHF) to Earth (X-band) during it's descent and landing on the surface of Mars. The NPR podcast and ...
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Are there plans or a program for an optical relay pathfinder for deep space?

In Glenn Research Center's Richard Reinhart's slides Space Communication and Navigation TestbedCommunications Technology for Exploration for the 2013 ISS Research and Development Conference I saw an ...
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What is the delay of the YT live stream for ISS?

On YT, we can see a live stream from ISS. What is the delay here (given you have a modern high speed internet access)?
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What would an XCOM transmitter look like?

The NASA news article NASA’s NavCube Could Support an X-ray Communications Demonstration in Space — A NASA First mentions the potential use of X-ray wavelengths for improved range of deep space ...
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Satellites around outer planets that act like amplifier to signals from voyager like objects

One issue of deep space exploration is that once the object (like Voyager) is far out in the solar system the physical distance is so great that the signal reaching Earth is very weak. I was wondering ...
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If a Voyager crashes into something, would we know?

A recent question asked about the feasibility of using Voyager 2 to detect objects in the Oort cloud. The answers indicate, among other issues, the instruments on-board the Voyagers would likely be ...
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Is it possible for Curiosity to broadcast live HD television from Mars to Earth?

Current Mars rovers collect large amounts of data and image sequences on Mars and store them in memory, and usually they then transfer the data to a spacecraft in Mars orbit for rebroadcast to Earth ...
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Are Martian winds as strong as portrayed in “The Martian”?

I read Andy Weir's "The Martian" and saw the movie, which is supposed to be realistic science fiction. And I immediately saw a couple of huge flaws, one of which I'd like to tackle with this question: ...
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Why is Queqiao's dish antenna so big? (Chang'e-4 relay satellite) Largest ever on/near the Moon?

Source: Chinese language blogpost The NASA Spaceflight article Queqiao relay satellite launched ahead of Chang’e-4 lunar mission describes the communications relay satellite that will be used to ...
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Why were the antennas on the spherical surface of some early satellites spiral-shaped?

In the question What's the spiral pattern on this satellite? I show this image of a spiral-shaped pattern on the spherical surface of a (presumably) vintage satellite or model thereof. @OrganicMarble'...
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Is Quantum Entanglement technology possible for interplanetary communication in future to achieve low real-time latency?

There is a small debate over the comment session in NASA Lands InSight on Mars video uploaded by JPL. The 1 minute and a half video is about the essential part of InSight's EDL event cropped out from ...
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What bitrates are currently achievable for communication with interplanetary space probes?

In communication with interplanetary space probes, it is clear that one has to take the delay caused by speed of light into account. Besides that, what are current limits for the data upload and ...
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Why will radioastronomy telescopes be used to listen to InSight's entry into Mars' atmosphere instead of DSN?

The JPL News article How NASA Will Know When InSight Touches Down is interesting and worth a read. It says that during the atmospheric entry, descent and landing, the Mars InSight probe will be ...
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Has the Curiosity rover ever communicated directly with Earth via its high-gain antenna? Signal strength & data rate?

In the question How does Curiosity know how to point and move it's high gain antenna in real time? I show an image of the hexagonal, articulated high gain antenna on the curiosity rover, as well as ...
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What does the ISS Mission control center do?

This related question asks about Mission Control's responsibilities during a hurricane. But there's a more general question underneath: what do the people in Mission Control do, what are their ...