Have been sent or sent?

Saturn was first visited by Pioneer 11 back in September 1979 in a fly by.Saturn was next visited by Voyager 1 in November 1980 in a fly by.Saturn was next visited by Voyager 2 in August 1981 in a...

I believe they are both incorrect.

That's really two questions. See the related links for the answers to each part of the question: What probes have been sent to Mars? What probes will be sent to Mars?

1, voyager2 and startrek voyager

It has legally been "sent" at the time it was postmarked.