Questions tagged [communication]

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

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12
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1answer
497 views

Has DSS-43 ever been used in high power mode (>>20 kW) for an emergency situation?

This answer notes that while most Deep Space Network transmitters are 20 kW of power or less, one dish (DSS-43 in Canberra) is equipped with a transmitter capable of 400 kW. As described in 101, 70-m ...
3
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2answers
286 views

Earth-Mars Radio Blackout: Is it possible to define an extended solar radius to solve this as a geometric problem?

Solar atmosphere causes difficulties in communication during opposition (when Mars is almost behind the sun w.r.t. Earth). The question is: is it possible to define an extended radius for the sun, ...
-1
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2answers
928 views

Why are there so many satellites around the moon if they are blocked out of radio communication half the time?

They state there are about 500 or so satellites orbiting around the moon. However according to NASA back when they said we landed on the moon, when the astronauts orbited around the dark side of the ...
11
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2answers
2k views

What (actually) makes Iridium “the world's only truly global mobile satellite communications company”?

In this article about how the SpaceX anomaly will affect Iridium it says: In its official website, Iridium describes itself as "the world's only truly global mobile satellite communications company....
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0answers
320 views

All Optical Global Network - how does the space-to-ground link avoid clouds?

I just saw the news item in Lightwave's online website: Laser Light to leverage free-space optics in space for Optical Satellite as a Service. All Optical Hybrid Global Network (or HALO, as laser ...
7
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1answer
397 views

Is it possible for the Deep Space Network to use MSPA and antenna arraying simultaneously?

Suppose Mars Odyssey (ODY) and the Mars Reconnaissance Orbiter (MRO) are being tracked by antenna A (just for example) at the Goldstone Deep Space Network complex in MSPA mode. Is it possible for ...
3
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2answers
589 views

Characteristics of the inter-satellite optical link

I'm currently diving into this topic and as I understand from the brief search there are two main types of inter-satellite link: radio and optical. As I can see, one of the main distinction of optical ...
2
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1answer
203 views

Is there a fax machine on the ISS ?

I know some older space stations had fax machine (since Sayult 7 at least). Do they still have it on the ISS ? Does is support in/out or only one way communications ?
9
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2answers
1k views

Standard communications protocol for cubesats

Is there a well-accepted standard protocol for communicating between a cubesat and ground station? On what basis would I choose the protocol?
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1answer
111 views

Voyager's distance from Earth

If it took Voyager’s radio signal 4 hours to cross the solar system and reach Earth, roughly how far away in AU was Voyager from Earth when it sent that signal?
8
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1answer
1k views

What makes an antenna “high gain”, and high gain as opposed to what alternative(s)?

Whenever communications to/from a space vehicle are described or discussed, there is inevitably a reference to the vehicle's "high gain" antenna. What is it about such an antenna (specific technical ...
2
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2answers
419 views

Why does the UN not have its own satellites?

Be it weather, crops, global warming, atmosphere, ocean, roads, birds, forest, intelligence, safety, connectivity, land/space transmission, why does the UN not have its own satellites? It could ...
4
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1answer
2k views

Current communication delay to mars

I read that the communication delay between earth and mars is between 3 and 21 minutes. So the delay changes over time (since the distance between earth and mars changes over time). How can I get ...
5
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0answers
256 views

Frequency responses of Voyager's S-band high gain antenna's feed-horn and receiver front end & IF?

I'm working on this question. This is the farthest (known) communications link humans have ever engineered - an one node is running in deep space on 40 year old technology. Pretty amazing! In the ...
2
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0answers
399 views

How exactly does the live feed from ISS work?

Using my cell phone in a city to download lots of data very fast is common, thanks due to the dense net of base stations close to me (~1 km). But with the space station about 400 km above ground and ...
6
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2answers
2k views

When will Juno send us some pictures from it's tight orbit?

Juno probe has sent few pictures as it approached Jupiter from afar, but Jupiter looks as large as Moon on our sky on those photos. After that it went into (intentional) silence while it was trying to ...
0
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1answer
634 views

How does NASA communicate to spacecrafts? [duplicate]

In Our communication systems we have limitations like signal strength to achieve communication between two points in the same country we have to build towers / etc .. my question is how does NASA ...
19
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5answers
27k views

How long does it take for a signal to travel between Earth, and Juno at Jupiter?

How long would it take for Juno's communication to reach the Earth? In other words: what is the time delay between perception by Juno and perception by NASA researchers?
9
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4answers
1k views

What typically ends a satellite's life?

It has been my opinion that running out of station keeping propellent is what usually ends a satellite's useful life. Is this true? How much do different factors play in a satellite's lifespan? Some ...
3
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1answer
252 views

How powerful an antenna needs to be to signal Earth from other solar systems?

If a probe, equipped with a current state-of-the-art antenna, were to send data to Earth from Proxima Centauri orbit, what power would the antenna need to emit for the signal to be usefully readable ...
8
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1answer
1k views

Do antennae on the ISS have to constantly move to maintain data links?

In this question and answer pair I see that the ISS can maintain data links to earth through direct access to ground stations as well as through the TDRSS geostationary satellite network. What kind ...
3
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1answer
165 views

Are there discussions or plans for extending the internet into space beyond Earth?

Many years ago I remember reading about the upcoming implementation of the internet protocol IPv6 - which is now in place. In that article it mentioned that there was some discussion about space - I ...
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0answers
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Which colleges in the US are researching Astrionics/ Space communication systems?

An example is the Space Engineering Research Center at University of Southern California Viterbi School of Engineering. What other colleges in the US are contributing to research on these topics?
14
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1answer
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Did USSR discontinue radio transmissions, relocate ships, to aid the US in response to Apollo 13?

In this article there is following statement by Dr. Ernst Stuhlinger: Let me only remind you of the recent near-tragedy of Apollo 13. When the time of the crucial reentry of the astronauts ...
12
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1answer
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From which Apollo mission is this audio sample?

I found this page where Evgeny Molotov, former head of the Research institute of Space instruments, plays supposed intercepted communication of unknown Apollo mission. Can anyone identify from which ...
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4answers
2k views

Does communications with spacecraft red shift the further away they are?

As Voyager 1 and 2 proceed further away do the radio waves red shift (change frequency)? If so, then don't we have to compensate for that red shift by modulating the frequency so that it arrives at ...
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0answers
66 views

Tools to evaluate telecommunications link budget [closed]

Can you name some of the commercially and non-commercially available tools to evaluate the link budget for a space mission? Aside Satellite Tool Kit, of course ;)
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4answers
422 views

How will Yuri Milner and Stephen Hawking's nanobots decelerate and transmit data upon arrival at Alpha Centauri?

Does anyone know what exactly is their plan, once they get there? How is that nano-thing going to slow down / take images / send data back to us? I couldn't find any information on this.
3
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1answer
106 views

What is the Mars “network science mission” referred to in NASA's Mars Design Reference Architecture?

I've been reading over NASA's Human Exploration of Mars Design Reference Architecture 5.0. In section 3.1.2, "Scientific objectives for Mars: present and future", when discussing future science ...
8
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1answer
243 views

What do the different “Testing” codes mean on NASA's Deep Space Network website?

If you haven't seen it, you can monitor the status of the Deep Space Network's radio dishes (which communicate with pretty much all of our space probes and satellites) from this website. At times, ...
15
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2answers
4k views

How are GPS satellite clocks synchronized with each other in the earth's frame of reference?

I have been looking at different threads. It seems like the receiver clock on Earth doesn't have to be synchronized with the satellite clocks. But I believe the satellite clocks need to be ...
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3answers
1k views

How well can Voyager 1 separate Earth signals from Solar noise these days?

This is a follow-up question to this question and this and this answer. UPDATED: see additional information and discussion below. As it continues to move farther from the Sun, the angular separation ...
23
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4answers
5k views

Can Voyager 1 receive signals from Earth?

There are answers about Voyager 1 sending messages to Earth, but can Earth still send signals to Voyager 1? I am just wondering if the signal of the Sun will eventually overcome the signal from Earth ...
4
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1answer
224 views

What is the meaning of: New Horizons' communication rate at 1kbit/s between the probe and Earth?

Is it a real-time communication rate measure? As in it would take one second to receive 1 kbit from Pluto?
2
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3answers
677 views

Does any satellite communicate only through laser?

I have read (here) and heard (on astronomy podcast) that radio waves decay or are indistinguishable the more distance they travel. Do any of man made satellites communicate with Earth solely by ...
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3answers
182 views

Would it be practical to lay a fiber optic cable to Alpha Centauri?

Would it be possible to lay a fiber optic cable over long distances and use it to transfer information- for example, as a sort of telescope?
4
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3answers
238 views

Would plasma sheathes from reentry heating block optical/UV communications as well as radio?

During reentry, it's routine for the ionized atmosphere surrounding the spacecraft to cut off radio communications for a certain period. As far as I know, this can't be avoided, except perhaps by ...
3
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1answer
224 views

What was the modulation used in the Space Shuttle Ku-band comm system?

The Ku-band system consisted of a directional antenna mounted in the orbiter payload bay and provided high BW communication with a ground station. This page: KU-BAND SYSTEM describes the system as ...
3
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1answer
429 views

Why were we able to have a more or less real-time conversation with the Moon?

So I understand what was said here and here, but not everything is clear to me. If they were able to transmit from the Moon, then why in 1985 were we not able to have an audio/video song performed by ...
12
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1answer
3k views

When does the ISS have a loss-of-signal?

The ISS has a camera mounted streaming live video from space (HDEV). From time to time, there is a blue screen visible, which is noted to be during times of "loss of signal". What exactly defines a "...
19
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3answers
18k views

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 ...
5
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3answers
1k views

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: ...
9
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1answer
386 views

What's the current timeline for NASA's Mars orbiter laser communications?

Dr. Jim Green, Director, NASA Planetary Science Division, mentioned during his "The Martian": Science Fiction & Science Fact talk for the 18th Annual International Mars Society Convention (you can ...
2
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2answers
544 views

Efficiency of communications between spacecraft and control center

In space vehicle control and fault recovery, how it works is that a big brother copy is on the ground and being fed with most recent data from spacecraft, the little brother. This ground one is an ...
13
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7answers
4k views

Where are the pictures during the time the pictures are sent from space to home?

Obviously the pics aren't floating around, but how can I explain this to a 10 year old?
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0answers
35 views

Spot size of interplanetary communications [duplicate]

From what I know, to communicate with Earth, a space probe locates signals sent from Earth and then sends data (in that direction). For probes that are several light hours away (Voyagers, New Horizons)...
2
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1answer
456 views

Why is the file transfer speed of New Horizon so slow? [duplicate]

The transmitting speed of the New Horizon probe is $4$ kb/s. Thus, NASA states that it will take around 16 months to download all of the data that the probe gathered in its flyby. Why is this? P.S. ...
5
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1answer
969 views

Error detection and correction techniques on New Horizons data

As New Horizon's signal is so weak, probability exists of errors in detected signal. What error detection and correction codes are used in the signal? Is it known, what is the error rate in received ...
11
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1answer
492 views

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 ...
4
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2answers
836 views

How can we form a data-communication relay chain for deep space exploration?

The power that deep space probes have allows an RF communication capacity of a few kbps from a range like Pluto-Earth. If we go into optics, the range will be better. But, of course, we want to send ...