Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why no video streams of space?

  1. May 25, 2010 #1
    Video encoding hardware is cheap and inexpensive. Even the tiniest trickle of bandwidth is enough for crisp, sharp, colourful moving images.


    Browsing these images you really wonder our cameraman in space is just taking static portraits. Why not amazing video? Even 3D polarised video is now available for moviemaking.

  2. jcsd
  3. May 27, 2010 #2
    Well I believe the exposure time required to take one still is a few minutes. All you would end up with in a 'live-feed' is a static image that changes every few minutes... Not so exciting. It would be even worse if it were from a 'camera' in orbit around earth. Exposure times would be a lot more. As well the images are HUGE and highly detailed.

    I suspect if you put a regular old 'webcam' into orbit and aimed it into outer space you wouldn't see much. I don't even think you'd be able to see the stars... maybe every now and then you'd see some peace of debris wizz by, or the moon or something but ... not too exciting...
  4. May 27, 2010 #3


    User Avatar
    Science Advisor
    Homework Helper

    It's mostly the phone bill.
    Cassini is currently about 1bn miles away and unless you have a vast antennae and lots of power it's hard to send HD video over that sort of distance. I'm guessing Cassini's bandwidth is closer to a 1980s acoustic modem.

    Even for stills the imagers on Cassini and all other space probes are mono with a set of color filters. To get a single color image takes 3x as long as a mono image and takes 3x the bandwidth to send home.
  5. May 27, 2010 #4
    It would still be cool to set up a live feed on the ISS or any satellite really, just to watch the motion of the earth or sun.
  6. May 27, 2010 #5


    User Avatar
    Science Advisor
    Homework Helper

    True. A decent HD 1080p camera on the ISS just looking down (say a Canon 5Mkii) could produce some interesting data simply because the repeated passes over the same area could tell you a lot about micro-weather / pollution / waves etc.
    Bandwidth is probably still too much to have more than webcam quality, but returning astronauts could sneaker-net back a bunch of 1Tb drives.
  7. May 27, 2010 #6
    24 seconds video encoded without audio to Ogg Theora. 720x576

    No loss - 5 MiB
    Video quality 8/10 (no noticeable change) - 2.4 MiB
    Video quality 4/10 (slightly grainy) - 829 KiB

    Let's say 4 MiB for a grainy HD video of a minute. It could be smaller since colour could realistically be transmitted for just a single frame and that image sampled for the other monotone frames by CGI here on earth.

    Typical acoustic speed is about 300 bits/second

    4 MiB * 8 bits / 300 bits = 4, 000, 000 * 8 / 300 ~ 110 Ksecs (rounding up)

    Thirty hours.

    A satellite could swing around in orbit transmitting for a single day what could inspire thousands of new scientists. Images of an alien planet.

    Motion is the life that characterises our universe. Video was our window to other cultures decades ago. And now... other worlds?
  8. May 29, 2010 #7
    Picture #15 on that site is amazing. (saved)
    It's like your standing on one moon (Enceladus) looking at another moon (Titan) with Saturn's rings in between.
  9. May 29, 2010 #8


    User Avatar
    Gold Member

    Sorry, what exactly would you be pointing this video at?
  10. May 29, 2010 #9
    Record for a min, transmit for a day.
  11. May 29, 2010 #10


    User Avatar
    Gold Member

    You didn't answer my question.

    Oh, OK. You're talking about a camera on one of our interplanetary probes that visit solar system planets. Didn't get that.
  12. May 30, 2010 #11

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    And that already happened. Cassini is taking pictures constantly, sending them back, and anyone playing them in sequence has a video.
  13. May 30, 2010 #12
    I think hes talking about like having a camera on the iss and having it point out into random space. I honestly don't see a real demand for that so that's probably why it hasn't happened.
  14. May 30, 2010 #13


    User Avatar
    Staff Emeritus
    Science Advisor

    There is already plenty of satellite observation of the earth.

    One can get real time information on weather patterns, particularly storm systems, by simply contacting NOAA and getting the data. Meterological models are developed and verified against these data.

    http://www.osei.noaa.gov/ [Broken]

    NASA is watching the earth as well - http://eospso.gsfc.nasa.gov/
    and ESA - http://www.esa.int/esaEO/index.html
    for example - http://www.esa.int/esaEO/SEM9UI19Y8G_index_0.html

    And NASA is constantly watch the Sun
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook