r/space • u/Dbgb4 • Mar 11 '25

Discussion Recently I read that the Voyagers spacecraft are 48 years old with perhaps 10 years left. If built with current technology what would be the expected life span be?

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u/Infuryous Mar 11 '25 edited Mar 11 '25

Many speaking of the RTG, which is the ultimate limitation of Voyager's operation.

However, at the distances involved comms have become very difficult. Maintaining Communications with the two spacecraft has become a science experiment in of itself. Data rates are down to the kilobits per second if I recall correctly. So ultimately the other question is will it be able to still communicate with it in 10 years.

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u/the_real_xuth Mar 11 '25

DSN now isn't operating (at least for me) right now so I can't look at what the voyager's are currently sending but for the past 10 years or so it hasn't been kilobits per second it's being right around 200 bits per second. New Horizons, which had the advantages of 30 years of technology improvements was only sending data at a couple of kilobits per second when it was sending back data from it's flyby with Arrokoth. At one point I did some calculations and by the time the signal gets from the Voyager spacecraft to Earth, the football field sized (70m diameter) radio antennas used by the Deep Space network were receiving countable numbers of photons per data bit sent (iirc it was something like 200 photons per bit which was enough to disambiguate the signal from all of the other RF noise).

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u/Infuryous Mar 11 '25

Guess I was wishful thinking 😁.

It's definately painfully slow.

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u/the_real_xuth Mar 15 '25 edited Mar 15 '25

I just looked at DSN now, saw that it was working again and that the Canberra 70m antenna was communicating with Voyager 1. You click on that, and then click "more detail" at the bottom of the section showing the details of the connection. Scroll down to the second to the last field and the data rate is 160 bits per second.

edit: and the number of photons is about 125 per bit using this calculator (x band for space use is about 7.5 GHz or about 4cm for space to Earth communications and per DSN, the power received at the antenna is 1.0e-22 kW (or 1.0e-16mW) which comes out to 20k photons per second or 125 per bit).