5 ms·

>If we're going to eventually be able to send high-definition video messages to and from Mars without a significant delay, then this is a step towards the tech

>If we're going to eventually be able to send high-definition video messages to and from Mars without a significant delay, then this is a step towards the tech we need. Won’t all Mars messages have a significant delay due to the speed of light more than bandwidth?

zardo 3y ago
Just a few minutes. Bandwidth could make that delay months.
mr_sturd 3y ago
In the case of Perseverance, I think data has to be sent in batches to a relay satellite and the forwarded back to Earth. That time when the satellite has line-of-sight with the rover is short, before the signal is lost, and it has to wait before continuing. It'll mean more data can be sent in these batches from what I understand.
thrance 3y ago
I think they meant "more significant than it need to be". Recently I looked up how long it takes light to go to Mars from Earth : it's between 3 and 20 minutes depending on their relative positions.
- mytailorisrich 3y ago
  That's my interpretation as well. Traditionally deep space bandwidth is low so that sending huge amount of data takes a long time in addition to time of travel.
- sneak 3y ago
  Yup, no realtime communications of any sort, even texting, with people living in the Mars cities. I think living in the moon will be much more attractive to people, given that you can still have video/voice calls with a slight lag (2600ms roundtrip) and text conversations with no perceptible latency increase (vs ones to people still on Earth).
  - dotnet00 3y ago
    Personally I don't think an up to 20-40 minute lag for communications will be that big of a deal, it'll take a bit of getting used to, plus mechanisms to synchronize internet data with Earth, but we're pretty used to asynchronous communications, and prior to the advent of electricity, not having realtime communication over large distances was normal and tolerable.
    - thfuran 3y ago
      >plus mechanisms to synchronize internet data with Earth Even in a future where there's a city on Mars, that seems unlikely.
      - dotnet00 3y ago
        I disagree, long term I think we'd have at least a significant portion of internet data synchronized between the two. Of course early on it'd probably just be in the form of certain popular entertainment sources and informational resources being periodically uploaded from Earth, more akin to a Plex or Invidious server and Wikipedia backup for Mars. But as the size of a colony grows, it just makes more and more sense to sync up as much data as possible. Eg a YouTube Mars which downlinks ahead of time trending videos + videos from people subscribed to by Martians + videos the algorithm thinks Martians will like and uplinks the same stuff for Earth.
        thfuran 3y ago
        Some very small subset is perhaps plausible, but I think you're overestimating how much Google or Netflix would care about addressing a small and inconvenient market.
        sneak 3y ago
        A major self-sustaining colony on Mars will probably take 50-100 years, at which point Google as well as its current jurisdiction of registration (Delaware) will likely both be history.
thecosmicfrog 3y ago
This is why Star Trek uses "subspace" as a plot handwavium[1] to explain how a starship can hail Earth from hundreds of lightyears away with seemingly no latency. [1] handwavium, my favourite new word: https://www.urbandictionary.com/define.php?term=handwavium https://www.urbandictionary.com/define.php?term=handwavium
- macintux 3y ago
  For some illogical reason I never had a problem with sending messages across such vast distances, but when the Enterprise detected another ship starting its engines from a light year away my suspension of disbelief collapsed.
  - jryb 3y ago
    Easy fix: subspace-based sensors. If the other ship is transmitting in any way, or its engine produces visible artifacts in the subspace field, it could be detected.
sigmoid10 3y ago
You're mixing up two concepts here: Bandwidth and latency (ping). Latency will always be limited by the speed of light, but bandwidth is currently limited by radio transmission. The upload speed for rovers like Curiosity and Perseverance peaks at like 2000kb/s tops under ideal conditions and is also limited to a few minutes at a time when the relay orbiter is in the right position. With lasers, bandwidth is measured in hundreds of Gb/s. That's the difference between sending an image in less than a second vs. having to wait a day.
- fallingknife 3y ago
  This will get us to Mars orbit, but don't we have to go to radio anyway to relay through the atmosphere to the surface?
  - sigmoid10 3y ago
    Mars atmosphere can barely be called that. It's less than one percent of earth's pressure. People just have a wrong perception of it because of wildly inaccurate depictions in movies like The Martian. And even if you want to transmit using radio between the surface and low orbit, it's far less of a bandwidth issue than transmitting over millions of kilometers. Deep space transmissions of the future will use optical wavelengths instead of radio, there's no question about it.
    - estiaan 3y ago
      It’s not just the atmosphere that’s an issue though, having a laser in earth’s orbit track something on mars’ surface and vice versa would require some incredible tracking, it would be easier to go from orbit to orbit
      - sigmoid10 3y ago
        It's not that hard with modern electronics. Telescopes with adaptive optics have been doing that since the 90s. Also beware that a laser doesn't remain perfectly coherent over many kilometers (let alone millions). So it's not like you need to perfectly hit a satellite dish area of a few m^2 on the surface of mars from earth. It's not really any harder to do from the surface than from orbit. In fact it might actually be easier since you don't just have to account for the rotation and orbit of earth but also for the orbital velocity of the relay.
farmdve 3y ago
It will. It always will, no technology on Earth now or likely in the future allow this to change. The only thing that will change is bandwidth or how much data can be sent at once.
- thfuran 3y ago
  Yes, and that changes how long you have to wait for a fixed amount of data to arrive, especially when transmission windows are narrow and sufficiently low bandwidth would mean having to waste time waiting between several.
  - mewpmewp2 3y ago
    But the delay will always be significant either way.
    - thfuran 3y ago
      No, the minimum delay is no more than a few minutes time of flight. But the transmission windows are only a few minutes long and they're hours apart. If you can't finish in one, you need to wait hours more to resume transmitting.
      - mewpmewp2 3y ago
        > the minimum delay is no more than a few minutes time of flight And how is that not significant?
- rasz 3y ago
  In time we might find ways to glitch the simulation.
IIAOPSW 3y ago
Yeah, but the throughput will be incredible.

zardo 3y ago

Just a few minutes. Bandwidth could make that delay months.

mr_sturd 3y ago

In the case of Perseverance, I think data has to be sent in batches to a relay satellite and the forwarded back to Earth. That time when the satellite has line-of-sight with the rover is short, before the signal is lost, and it has to wait before continuing. It'll mean more data can be sent in these batches from what I understand.

thrance 3y ago

I think they meant "more significant than it need to be". Recently I looked up how long it takes light to go to Mars from Earth : it's between 3 and 20 minutes depending on their relative positions.

mytailorisrich 3y ago
That's my interpretation as well. Traditionally deep space bandwidth is low so that sending huge amount of data takes a long time in addition to time of travel.
sneak 3y ago
Yup, no realtime communications of any sort, even texting, with people living in the Mars cities. I think living in the moon will be much more attractive to people, given that you can still have video/voice calls with a slight lag (2600ms roundtrip) and text conversations with no perceptible latency increase (vs ones to people still on Earth).
- dotnet00 3y ago
  Personally I don't think an up to 20-40 minute lag for communications will be that big of a deal, it'll take a bit of getting used to, plus mechanisms to synchronize internet data with Earth, but we're pretty used to asynchronous communications, and prior to the advent of electricity, not having realtime communication over large distances was normal and tolerable.
  - thfuran 3y ago
    >plus mechanisms to synchronize internet data with Earth Even in a future where there's a city on Mars, that seems unlikely.
    - dotnet00 3y ago
      I disagree, long term I think we'd have at least a significant portion of internet data synchronized between the two. Of course early on it'd probably just be in the form of certain popular entertainment sources and informational resources being periodically uploaded from Earth, more akin to a Plex or Invidious server and Wikipedia backup for Mars. But as the size of a colony grows, it just makes more and more sense to sync up as much data as possible. Eg a YouTube Mars which downlinks ahead of time trending videos + videos from people subscribed to by Martians + videos the algorithm thinks Martians will like and uplinks the same stuff for Earth.
      - thfuran 3y ago
        Some very small subset is perhaps plausible, but I think you're overestimating how much Google or Netflix would care about addressing a small and inconvenient market.
      - sneak 3y ago
        A major self-sustaining colony on Mars will probably take 50-100 years, at which point Google as well as its current jurisdiction of registration (Delaware) will likely both be history.

thecosmicfrog 3y ago

This is why Star Trek uses "subspace" as a plot handwavium[1] to explain how a starship can hail Earth from hundreds of lightyears away with seemingly no latency. [1] handwavium, my favourite new word: https://www.urbandictionary.com/define.php?term=handwavium https://www.urbandictionary.com/define.php?term=handwavium

macintux 3y ago
For some illogical reason I never had a problem with sending messages across such vast distances, but when the Enterprise detected another ship starting its engines from a light year away my suspension of disbelief collapsed.
- jryb 3y ago
  Easy fix: subspace-based sensors. If the other ship is transmitting in any way, or its engine produces visible artifacts in the subspace field, it could be detected.

sigmoid10 3y ago

You're mixing up two concepts here: Bandwidth and latency (ping). Latency will always be limited by the speed of light, but bandwidth is currently limited by radio transmission. The upload speed for rovers like Curiosity and Perseverance peaks at like 2000kb/s tops under ideal conditions and is also limited to a few minutes at a time when the relay orbiter is in the right position. With lasers, bandwidth is measured in hundreds of Gb/s. That's the difference between sending an image in less than a second vs. having to wait a day.

fallingknife 3y ago
This will get us to Mars orbit, but don't we have to go to radio anyway to relay through the atmosphere to the surface?
- sigmoid10 3y ago
  Mars atmosphere can barely be called that. It's less than one percent of earth's pressure. People just have a wrong perception of it because of wildly inaccurate depictions in movies like The Martian. And even if you want to transmit using radio between the surface and low orbit, it's far less of a bandwidth issue than transmitting over millions of kilometers. Deep space transmissions of the future will use optical wavelengths instead of radio, there's no question about it.
  - estiaan 3y ago
    It’s not just the atmosphere that’s an issue though, having a laser in earth’s orbit track something on mars’ surface and vice versa would require some incredible tracking, it would be easier to go from orbit to orbit
    - sigmoid10 3y ago
      It's not that hard with modern electronics. Telescopes with adaptive optics have been doing that since the 90s. Also beware that a laser doesn't remain perfectly coherent over many kilometers (let alone millions). So it's not like you need to perfectly hit a satellite dish area of a few m^2 on the surface of mars from earth. It's not really any harder to do from the surface than from orbit. In fact it might actually be easier since you don't just have to account for the rotation and orbit of earth but also for the orbital velocity of the relay.

farmdve 3y ago

It will. It always will, no technology on Earth now or likely in the future allow this to change. The only thing that will change is bandwidth or how much data can be sent at once.

thfuran 3y ago
Yes, and that changes how long you have to wait for a fixed amount of data to arrive, especially when transmission windows are narrow and sufficiently low bandwidth would mean having to waste time waiting between several.
- mewpmewp2 3y ago
  But the delay will always be significant either way.
  - thfuran 3y ago
    No, the minimum delay is no more than a few minutes time of flight. But the transmission windows are only a few minutes long and they're hours apart. If you can't finish in one, you need to wait hours more to resume transmitting.
    - mewpmewp2 3y ago
      > the minimum delay is no more than a few minutes time of flight And how is that not significant?
rasz 3y ago
In time we might find ways to glitch the simulation.

IIAOPSW 3y ago

Yeah, but the throughput will be incredible.