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> [The S-band] uses a different frequency than the X-band transmitters signal is significantly fainter. The flight team was not certain the S-band could be dete

by Aachen 2y ago

> [The S-band] uses a different frequency than the X-band transmitters signal is significantly fainter. The flight team was not certain the S-band could be detected at Earth due to the spacecraft’s distance, but [it turned out to work] This is the most fascinating part to me. Isn't it well-established how sensitive a signal we can hear? Did they implement something like a new signal analysis method that enabled it? And it says this wasn't used or even tried since the 80s anymore, I guess it grew too faint. Looking up the frequencies, X is 8–12 GHz and S is 2–4. Doesn't that mean X gets more data across at the same redundancy level? Why have this slower transmitter at all for only the first years, power conservation despite the fresh RTG?

drmpeg 2y ago
> Did they implement something like a new signal analysis method that enabled it? They arrayed three antennas together. > Doesn't that mean X gets more data across at the same redundancy level? There's nothing special about the frequency itself. The advantage for X-band is that the antennas at both ends have more gain. 12 dB for the spacecraft and 11 dB for the ground station for a total of 23 dB.
- Keysh 2y ago
  > They arrayed three antennas together. No, they didn’t. The three antennas are in California, Spain, an Australia; they can’t all point at the same point in the sky at once, and even if two could do so, they’re not designed to work as an interferometric array.
  - drmpeg 2y ago
    There's more than one antenna at each site. https://x.com/CanberraDSN/status/1851446497453494663 https://x.com/CanberraDSN/status/1851446497453494663 https://x.com/vlex26/status/1849618522823065655 https://x.com/vlex26/status/1849618522823065655
    - Keysh 2y ago
      Ah, OK, thanks for the link.
  - shagie 2y ago
    https://eyes.nasa.gov/apps/dsn-now/dsn.html https://eyes.nasa.gov/apps/dsn-now/dsn.html for the "what is it looking at right now" If you catch a site commutating with Voyager you will sometimes see it using two dishes... though most often it's just the one big one at the site. When they do, its not getting signal on two, but having one of the track the carrier wave (I think). https://www.cdscc.nasa.gov/Pages/antennas.html https://www.cdscc.nasa.gov/Pages/antennas.html ... and to "even if two could do so, they’re not designed to work as an interferometric array." They can. > The DSN anticipates and responds to user needs. The DSN maintains and upgrades its facilities to accommodate all of its users. This includes not only the implementation of enhancements to improve the scientific return from current experiments and observations, but also long-range research and development to meet the needs of future scientific endeavours. > Interferometry > The accurate measurement of radio source positions; includes astrometry, very long baseline interferometry, connected element interferometry, interferometry arrays and orbiting interferometry. Measurement of station locations and Earth orientation for studies of the Earth. > Very Long Baseline Interferometry > The purpose of the Very Long Baseline Interferometry (VLBI) System is to provide the means of directly measuring plane-of-the-sky angular positions of radio sources (natural or spacecraft), DSN station locations, interstation time and frequency offsets, and Earth orientation parameters.
jgrahamc 2y ago
Did they implement something like a new signal analysis method that enabled it? Well, we do keep building bigger and bigger antennas and antenna arrays. So while Voyager can't change, we do. And we can build more and more sensitive (i.e. noise rejecting) equipment. X is 8–12 GHz and S is 2–4 I don't know much about the Voyager design but the beam width is related to the frequency and so the S-band transmitter will have a larger beam width and thus can point less accurately that the X-band when trying to talk to Earth. Conversely, X-band is higher frequency than S-band and it's likely they would be able to use more bandwidth. So, interesting trade offs.
prettyStandard 2y ago
I'm wondering also. Based on the wording here. I suspect we have more and better telescopes than we did when it launched. > The flight team was not certain the S-band could be detected at Earth due to the spacecraft’s distance, but engineers with the Deep Space Network were able to find it.
- Aachen 2y ago
  Certainly, but then isn't it expected now with the new antennas? They installed some upgrade but don't know to what sensitivity it goes? Surely they do so the article must be handwavy about it if I'm understanding things correctly Someone else commented about a wider spread in this other band, though. Perhaps the operators were not sure what that does for adsorptions and reflections by intervening dust or so?
  - quotemstr 2y ago
    Haven't you ever written code that you thought should work, but didn't due to a reason you couldn't foresee? I don't think the uncertainty here comes from question marks in the link budget equations but from the possibility of unforeseen problems making detection not work when it should.

by Aachen 2y ago

drmpeg 2y ago

> Did they implement something like a new signal analysis method that enabled it? They arrayed three antennas together. > Doesn't that mean X gets more data across at the same redundancy level? There's nothing special about the frequency itself. The advantage for X-band is that the antennas at both ends have more gain. 12 dB for the spacecraft and 11 dB for the ground station for a total of 23 dB.

Keysh 2y ago
> They arrayed three antennas together. No, they didn’t. The three antennas are in California, Spain, an Australia; they can’t all point at the same point in the sky at once, and even if two could do so, they’re not designed to work as an interferometric array.
- drmpeg 2y ago
  There's more than one antenna at each site. https://x.com/CanberraDSN/status/1851446497453494663 https://x.com/CanberraDSN/status/1851446497453494663 https://x.com/vlex26/status/1849618522823065655 https://x.com/vlex26/status/1849618522823065655
  - Keysh 2y ago
    Ah, OK, thanks for the link.
- shagie 2y ago
  https://eyes.nasa.gov/apps/dsn-now/dsn.html https://eyes.nasa.gov/apps/dsn-now/dsn.html for the "what is it looking at right now" If you catch a site commutating with Voyager you will sometimes see it using two dishes... though most often it's just the one big one at the site. When they do, its not getting signal on two, but having one of the track the carrier wave (I think). https://www.cdscc.nasa.gov/Pages/antennas.html https://www.cdscc.nasa.gov/Pages/antennas.html ... and to "even if two could do so, they’re not designed to work as an interferometric array." They can. > The DSN anticipates and responds to user needs. The DSN maintains and upgrades its facilities to accommodate all of its users. This includes not only the implementation of enhancements to improve the scientific return from current experiments and observations, but also long-range research and development to meet the needs of future scientific endeavours. > Interferometry > The accurate measurement of radio source positions; includes astrometry, very long baseline interferometry, connected element interferometry, interferometry arrays and orbiting interferometry. Measurement of station locations and Earth orientation for studies of the Earth. > Very Long Baseline Interferometry > The purpose of the Very Long Baseline Interferometry (VLBI) System is to provide the means of directly measuring plane-of-the-sky angular positions of radio sources (natural or spacecraft), DSN station locations, interstation time and frequency offsets, and Earth orientation parameters.

jgrahamc 2y ago

Did they implement something like a new signal analysis method that enabled it? Well, we do keep building bigger and bigger antennas and antenna arrays. So while Voyager can't change, we do. And we can build more and more sensitive (i.e. noise rejecting) equipment. X is 8–12 GHz and S is 2–4 I don't know much about the Voyager design but the beam width is related to the frequency and so the S-band transmitter will have a larger beam width and thus can point less accurately that the X-band when trying to talk to Earth. Conversely, X-band is higher frequency than S-band and it's likely they would be able to use more bandwidth. So, interesting trade offs.

prettyStandard 2y ago

I'm wondering also. Based on the wording here. I suspect we have more and better telescopes than we did when it launched. > The flight team was not certain the S-band could be detected at Earth due to the spacecraft’s distance, but engineers with the Deep Space Network were able to find it.

Aachen 2y ago
Certainly, but then isn't it expected now with the new antennas? They installed some upgrade but don't know to what sensitivity it goes? Surely they do so the article must be handwavy about it if I'm understanding things correctly Someone else commented about a wider spread in this other band, though. Perhaps the operators were not sure what that does for adsorptions and reflections by intervening dust or so?
- quotemstr 2y ago
  Haven't you ever written code that you thought should work, but didn't due to a reason you couldn't foresee? I don't think the uncertainty here comes from question marks in the link budget equations but from the possibility of unforeseen problems making detection not work when it should.