why was it done?
Its objectives included flybys of Jupiter, Saturn, and Saturn's largest moon, Titan.
Voyager 1
The probe's objectives included flybys of Jupiter, Saturn, and Saturn's largest moon, Titan. 
what does voyager 1 currently hold the record for UNANSWERABLE what was it? A space probe when was it launched? September 5, 1977
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Voyager 1 [SEP] Introduction
Two years later, "Voyager 1" began experiencing a third "tsunami wave" of coronal mass ejections from the Sun, that has continued to at least December 15, 2014, further confirming that the probe is indeed in interstellar space.