Given the stunning success of NASA’s New Horizon’s flyby of Pluto, I’ve been struggling to understand why neither Voyager 1 or 2 attempted a similar flyby of Pluto to that undertaken for Neptune.
Having looked into the Voyager mission from its conception in July 1965, Pluto was not initially considered by Gary Flandro’s Grand Tour Opportunity outline, but as more detailed mission planning got underway it was included in James Long’s 1966 trajectory design.
The primary problem of a Pluto flyby was not distance (as between February 1979 and February 1999 Pluto was within the orbit of Neptune), so much as the difficulty of getting the probe into a 25 degree tilt from the plane of the ecliptic to reach Pluto.
Voyager 1 was initially on track to undertake the Pluto flyby, but the decision to undertake a close flyby of Titan meant that this had to be abandoned. Given the lack of success of Voyager at Titan (due to the depth of cloud cover), this seems to me a terrible shame.
When questioned in regard to Voyager 1, Ed Stone (JPL Director & Voyager scientist), came out with the rather glib answer “Well, Titan was 3 hours away, and Pluto was 3 years away – and I had to make payroll.“. I never could stand Ed Stone, the guy might be a great scientist, but he’s also a complete twat.
Voyager 2 was scheduled to flyby Neptune and Triton in August 1989 and although this was a very closely timed visit, it seems to me that a different approach could have allowed the necessary gravitational sling shot to send the craft on to Pluto, even if it meant a more limited encounter with Neptune / Triton.
The justification from NASA I am struggling to understand:
Voyager 2, theoretically, could have been aimed for Pluto, but the aim point would have been inside the planet of Neptune – not very practical. So Pluto was the only outer planet the Voyagers didn’t visit.
Is “not very practical” code for something? In light of the subsequent discoveries at Pluto by New Horizons, having the Voyager 2 probe visit in late 1991 would have provide a fantastic contrast, with tools that were unavailable this time around (primarily plasma analysis).
A Voyager 2 encounter would have allowed us a much better view of Pluto during it’s late summer when the atmosphere was thicker as well as being able to take more detailed photographs of the dark side of Pluto which we have only captured in low resolution with New Horizons.
In short, I cannot understand why after visiting Neptune, Voyager 2 wasn’t swung around and up to reach Pluto. The only conclusion that I can come to is that it was a lack of foresight and relative importance.
I mean it’s not like Voyager 2 had anywhere else to go after the Neptune / Triton encounter and it seems to me that any impact on the Voyager Interstellar Mission would have been slight, perhaps delaying that by a year or two.
The simplest answer seems to be that by leaving Pluto out, NASA thought they could get funding for another mission, which if true is a bit crap.