When Voyager 1 and 2 left Earth, their internal computers were programmed to use Golay error correction codes. Images transmitted from Jupiter and Saturn were encoded using Golay codes. After leaving Saturn, the software was upgraded to use Reed-Solomon error correction codes.
I didn’t realize how much difference the change of encoding made until I ran across a JPL report that elaborated on the efficiency of both codes.
Encoding these data has a price, and that paid for the old Golay encoding algorithm (used at Jupiter and Saturn) was one code bit overhead for every data bit (100 percent). The new RS encoding scheme reduces this overhead to about 20 percent. In addition, it reduces the number of bit errors from 5 in 100,000 to only 1 in a million!
So switching to Reed-Solomon cut overhead by 5x and improved error correction 50x.
There’s a reason CDs use Reed-Solomon codes and not Golay codes.
There are techniques today that are even more efficient (in terms of overhead bits for a given error rate) but they’re more computationally intense. CDs are 45-year-old tech and the equipment to read them had to be practically affordable in 1980 (the same time Voyager was flying by Saturn). Current deep-space missions are more likely to use Turbo codes, developed in the 1990s (and also probably used by your cell phone).