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I like the way NASA phrase it as a “Communications Pause”
https://blogs.nasa.gov/sunspot/2023/07/
Though the Independent is reporting that it can still be heard at least
https://www.independent.co.uk/news/ap-earth-nasa-cape-canaveral-california-b2385612.htmlAnd in the body of NASA’s blog post they refer to it as “the quiet period”, as if it was chilling out.
Do you suppose anyone has suggested switching it off and on again?
The spacecraft antenna pointing would be based on on-board sun and star tracker data so I assume they have a stored ephemeris for offsetting the pointing from the Sun to get peak gain towards the Earth. Voyager 2 is currently around 160au away so the Earth is always within 0.35 deg of the Sun anyway but this is what will happen in mid-October when it executes its next pointing update.
Voyager 2’s antenna is a 3.7-m diameter paraboloid and at S-band (2 GHz) a 2 degree pointing error would imply a link budget loss of around 6dB which is huge. It is probable that the 70-m DSN antenna at Canberra will be able to detect and lock to the residual downlink carrier but unlikely that they will be able to decode any data. They could decide to array lots of antennas to improve the downlink SNR but the main problem would be getting commands up to the spacecraft to reset the pointing.
Given the low science return from Voyager now it is probably easiest just to wait until the next antenna pointing update.
Voyager 2 is currently around 160au away so the Earth is always within 0.35 deg of the Sun
That prompted me to grab a virtual pencil and back of envelope. So to the unaided eye from there the Sun appears star-like (unresolved at just ~12 arcsec diameter) and ~mag -15.7, ~15x brighter than the full moon.
I guess the noise floor in the signal received at Voyager must be pretty high, aimed so close to the Sun ?
I’d put in the distance from memory. It is actually “only” 134au so that increases the angle a bit but not much. Sorry about that!
Yes, sending commands to Voyager 2 is a lot harder than receiving the telemetry. The spacecraft receiver is a bit unstable due to a capacitor failure and the noise temperature is high since the antenna is effectively looking at the Sun. The only ground station in the DSN that can command Voyager 2 is DSS-43 at Canberra. This has a huge 400kW power amplifier (the other 70-m stations have 20kW) but there are all sorts of restrictions on its use. I wouldn’t want to be a bird in the beam of that thing when it is transmitting at full power.
If you want some fun bedtime reading have a look at these links:
https://descanso.jpl.nasa.gov/DPSummary/Descanso4–Voyager_new.pdf
http://deepspace.jpl.nasa.gov/dsndocs/810-005/101/101E.pdf
https://deepspace.jpl.nasa.gov/dsndocs/810-005/relnotice49.pdf
https://space.stackexchange.com/questions/18956/has-dss-43-ever-been-used-in-high-power-mode-20-kw-for-an-emergency-situationVery slightly off topic but if they ever build another Voyager to send to the stars I hope they can find room for the Youtube videos of Baris and Aybuke. This young couple truly understand how lucky we are to live on a very special planet. The videos are short and often stunning….the joy captured when Aybuke sees the simple beauty of a bird in flight or walks on a sandy beach.
https://www.youtube.com/watch?v=LQc3EkD1rVE
https://www.youtube.com/watch?v=diwRarXS1mEFull contact has been re-established!
I wonder what power level they used for their “interstellar shout”. DSS-43 has the capability to go to 400kW at S-band although I don’t think that has ever been used. Normal command uplinks are done at 70kW so they may have turned the wick all the way up for this. A 2-deg antenna offset is a loss of around 6dB so that would imply they would need nearly all of the 400kW to restore the link margin. Not much technical info on the NASA report though:
https://www.jpl.nasa.gov/news/nasa-mission-update-voyager-2-communications-pause
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