4 ms·

How is it possible to still be able to get a signal from a spacecraft that's so far away? How can the antenna be directional enough while still being pointed ri

How is it possible to still be able to get a signal from a spacecraft that's so far away? How can the antenna be directional enough while still being pointed right at the Earth? How do we remove the noise?

laweijfmvo 3y ago
[flagged]
- HenryBemis 3y ago
  MITM attack? Well they won't get away with this! Some humans are super-intelligent - they already discovered that the Earth is flat, and sitting on the bank of a giant turtle (yes it's turtles all the way down)
  - rcthompson 3y ago
    MITM, of course, stands for Martian In The Middle.
munificent 3y ago
Voyager 1 has a large 12-foot diameter directional radio antenna that it keeps pointed at Earth. If you look at photos of Voyager, the antenna (the big dish) basically is most of what you see: it's bigger than everything else on craft. There are radio antennas across the Earth listening to its very weak signal. More details: https://space.stackexchange.com/questions/24338/how-to-calculate-data-rate-of-voyager-1 https://space.stackexchange.com/questions/24338/how-to-calcu...
- freeqaz 3y ago
  That post is awesome. Thank you for sharing! There are some truly brilliant humans on this planet with us.
WJW 3y ago
Signal processing algorithms can pull out a signal from well below the noise floor these days. Even the small and nondirectional antennas on your phone are good enough to receive GPS signals even all the way down at -125 dBm, which is WAY less than your phone receives in interference from random radio stations and faulty LED bulbs nearby. The tech used to receive Voyager signals is not really different, just more sensitive and sophisticated (and expensive).
- lima 3y ago
  Slightly larger antennas, too.
  - kQq9oHeAz6wLLS 3y ago
    You mean you don't have a 70 meter dish attached to your iPhone?
    - I_Am_Nous 3y ago
      I did but the FCC had some words to say to me
      - jamala1 3y ago
        Do you really need to be certified if you only use it for receiving?
        I_Am_Nous 3y ago
        I think that would fall under the "must accept interference" portion of FCC Part 15, my phone communicating back to the tower might raise some alarms if I tried amplifying it at all though!
    - giantrobot 3y ago
      For that you'll need the iPhone 16 Pro Plus Max.
- 3y ago
TrackerFF 3y ago
The communication bands (X- and S-band, which are the microwave range) are pretty well regulated, so they aren't that noisy, relative to other bands. And on the receiving end, we have decent arrays of antennas to pick up the signals. Here's a nifty document detailing the coms of Voyager: https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--141029.pdf https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--14... Fig 3-4 on page 46 (page 10 in the document) shows the signal flow.
calamari4065 3y ago
A ridiculously huge and powerful array of antennas spread across the planet. NASA has a dashboard online for the Deep Space Network and you can see live which spacecraft we're communicating with. The Voyagers are usually active any time I look.
- maccam912 3y ago
  How live is it? Voyager 1 seemed to be shown there just now.
  - skissane 3y ago
    According to the article, they can send commands to Voyager 1, and it executes them, and it is still sending data back - the problem is the data coming back is gibberish (repeated patterns of 0s and 1s). They are still hoping they can work out a sequence of commands to reset its computers and resolve the problem. So it makes sense the DSN is currently talking to it.
    - oneshtein 3y ago
      For me, it looks like it computer damaged by interstellar radiation, which is much more energetic than solar radiation, so it's unlikely that reset will help.
      - skissane 3y ago
        According to NASA's blog [0] they believe the problem is between the FDS computer and the TMU (the outbound radio modulator). The other two onboard computer systems, CCS and AACS, they believe are still working. All three systems are dual redundant pairs of computers. So, even if one FDS was damaged, in theory they should be able to switch to the other. The blog post is vague on what exactly they tried - "the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data" - so I don't think we can rule out there are other things they can still try. [0] https://blogs.nasa.gov/sunspot/2023/12/12/engineers-working-to-resolve-issue-with-voyager-1-computer/ https://blogs.nasa.gov/sunspot/2023/12/12/engineers-working-...
basementcat 3y ago
Voyager's X-band carrier is pretty "loud" by radio astronomy standards. https://www.space.com/22787-voyager-1-signal-interstellar-space-photo.html https://www.space.com/22787-voyager-1-signal-interstellar-sp...

laweijfmvo 3y ago

[flagged]

HenryBemis 3y ago
MITM attack? Well they won't get away with this! Some humans are super-intelligent - they already discovered that the Earth is flat, and sitting on the bank of a giant turtle (yes it's turtles all the way down)
- rcthompson 3y ago
  MITM, of course, stands for Martian In The Middle.

munificent 3y ago

Voyager 1 has a large 12-foot diameter directional radio antenna that it keeps pointed at Earth. If you look at photos of Voyager, the antenna (the big dish) basically is most of what you see: it's bigger than everything else on craft. There are radio antennas across the Earth listening to its very weak signal. More details: https://space.stackexchange.com/questions/24338/how-to-calculate-data-rate-of-voyager-1 https://space.stackexchange.com/questions/24338/how-to-calcu...

freeqaz 3y ago
That post is awesome. Thank you for sharing! There are some truly brilliant humans on this planet with us.

WJW 3y ago

Signal processing algorithms can pull out a signal from well below the noise floor these days. Even the small and nondirectional antennas on your phone are good enough to receive GPS signals even all the way down at -125 dBm, which is WAY less than your phone receives in interference from random radio stations and faulty LED bulbs nearby. The tech used to receive Voyager signals is not really different, just more sensitive and sophisticated (and expensive).

lima 3y ago
Slightly larger antennas, too.
- kQq9oHeAz6wLLS 3y ago
  You mean you don't have a 70 meter dish attached to your iPhone?
  - I_Am_Nous 3y ago
    I did but the FCC had some words to say to me
    - jamala1 3y ago
      Do you really need to be certified if you only use it for receiving?
      - I_Am_Nous 3y ago
        I think that would fall under the "must accept interference" portion of FCC Part 15, my phone communicating back to the tower might raise some alarms if I tried amplifying it at all though!
  - giantrobot 3y ago
    For that you'll need the iPhone 16 Pro Plus Max.
3y ago

TrackerFF 3y ago

The communication bands (X- and S-band, which are the microwave range) are pretty well regulated, so they aren't that noisy, relative to other bands. And on the receiving end, we have decent arrays of antennas to pick up the signals. Here's a nifty document detailing the coms of Voyager: https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--141029.pdf https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--14... Fig 3-4 on page 46 (page 10 in the document) shows the signal flow.

calamari4065 3y ago

A ridiculously huge and powerful array of antennas spread across the planet. NASA has a dashboard online for the Deep Space Network and you can see live which spacecraft we're communicating with. The Voyagers are usually active any time I look.

maccam912 3y ago
How live is it? Voyager 1 seemed to be shown there just now.
- skissane 3y ago
  According to the article, they can send commands to Voyager 1, and it executes them, and it is still sending data back - the problem is the data coming back is gibberish (repeated patterns of 0s and 1s). They are still hoping they can work out a sequence of commands to reset its computers and resolve the problem. So it makes sense the DSN is currently talking to it.
  - oneshtein 3y ago
    For me, it looks like it computer damaged by interstellar radiation, which is much more energetic than solar radiation, so it's unlikely that reset will help.
    - skissane 3y ago
      According to NASA's blog [0] they believe the problem is between the FDS computer and the TMU (the outbound radio modulator). The other two onboard computer systems, CCS and AACS, they believe are still working. All three systems are dual redundant pairs of computers. So, even if one FDS was damaged, in theory they should be able to switch to the other. The blog post is vague on what exactly they tried - "the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data" - so I don't think we can rule out there are other things they can still try. [0] https://blogs.nasa.gov/sunspot/2023/12/12/engineers-working-to-resolve-issue-with-voyager-1-computer/ https://blogs.nasa.gov/sunspot/2023/12/12/engineers-working-...

basementcat 3y ago

Voyager's X-band carrier is pretty "loud" by radio astronomy standards. https://www.space.com/22787-voyager-1-signal-interstellar-space-photo.html https://www.space.com/22787-voyager-1-signal-interstellar-sp...