Rendezvous with Neptune
October 30, 2012 2:18 AM   Subscribe

In case you felt that your week was missing an interview of Carl Sagan by Sidney Poitier during the 1989 Voyager Neptune encounter, you're welcome.


The rest of the one-hour TV special featuring Carl Sagan, Ann Druyan, and many others, aired on August 27, 1989 on TBS SuperStation to commemorate Voyager 2's rendezvous with Neptune can be found here.

Voyager 2's closest approach to Neptune occurred on August 25, 1989. Since this was the last planet of our Solar System that Voyager 2 could visit, the Chief Project Scientist, his staff members, and the flight controllers decided to also perform a close fly-by of Triton, the larger of Neptune's two originally known moons, so as to gather as much information on Neptune and Triton as possible, regardless of what angle at which Voyager 2 would fly away from Neptune. This was just like the case of Voyager 1's encounters with Saturn and its massive moon Titan.

Through repeated computerized test simulations of trajectories through the Neptunian system conducted in advance, flight controllers determined the best way to route Voyager 2 through the Neptune-Triton system. Since the plane of the orbit of Triton is tilted significantly with respect to the plane of the ecliptic, through mid-course corrections, Voyager 2 was directed into a path several thousand miles over the north pole of Neptune. At that time, Triton was behind and below (south of) Neptune (at an angle of about 25 degrees below the Ecliptic), close to the apoapsis of its elliptical orbit. The gravitational pull of Neptune bent the trajectory of Voyager 2 down in the direction of Triton. In less than 24 hours, Voyager 2 traversed the distance between Neptune and Triton, and then observed the northern hemisphere of Triton as it passed over the moon's north pole.

The net and final effect on the trajectory of Voyager 2 was to bend its trajectory south below the plane of the Ecliptic by about 30 degrees. Voyager 2 is on this path permanently, and hence, it is exploring space south of the plane of the Ecliptic, measuring magnetic fields, charged particles, etc., there, and sending the measurements back to the Earth via telemetry.

While in the neighborhood of Neptune, Voyager 2 discovered the "Great Dark Spot", which has since disappeared, according to observations by the Hubble Space Telescope. Originally thought to be a large cloud itself, the "Great Dark Spot" was later hypothesized to be a hole in the visible cloud deck of Neptune.

Neptune's atmosphere consists of hydrogen, helium, and methane. The methane in Neptune's upper atmosphere absorbs the red light from the Sun, but it reflects the blue light from the Sun back into space. This is why Neptune looks blue.
posted by Blasdelb (10 comments total) 22 users marked this as a favorite
"... and the sun should look red on any planet with a massive atmosphere..."

I did not know that.
posted by adamt at 3:52 AM on October 30, 2012

Man, 1989 seems all ancient and wood-paneled. I do recall going to the local museum where they had live feed from NASA or whatever of the Neptune flyby projected onto a big screen. It was pretty neat.
posted by KokuRyu at 4:22 AM on October 30, 2012 [1 favorite]

"Man, 1989 seems all ancient and wood-paneled."

Seriously, its so foreign seeming. Hell, I was 13 months old.
posted by Blasdelb at 4:26 AM on October 30, 2012

I remember Poitier from that science-fiction film "Guess Who's Coming to Rigel 7", where an earthling is transported to a distant planet in a distant solar system and the alien family says "what, you brought a black guy?"
posted by twoleftfeet at 5:10 AM on October 30, 2012

It's a sad truth, but for all that work, Sagan was only paid thousands and thousands.
posted by twoleftfeet at 6:11 AM on October 30, 2012 [1 favorite]

Good material, twoleftfeet. Will you be here all week?
posted by General Tonic at 7:31 AM on October 30, 2012 [1 favorite]

Too much cool in one frame.
posted by RobotVoodooPower at 7:46 AM on October 30, 2012

Neat vids. From part 2: "The signal from Neptune is so very weak that when it gets back to Earth, it's 20 billion times fainter than the power level needed to operate a modern-day electronic digital watch."

And that's with V'ger using a 23-watt transmitter driving a 14-foot antenna. Power received at Earth: 6 x 10-21 watts/m^2. (Calculations)
posted by Twang at 1:17 PM on October 30, 2012

Goddamn do I miss Carl Sagan.
posted by Scientist at 6:13 PM on October 30, 2012 [1 favorite]

"Man, 1989 seems all ancient and wood-paneled."

Seriously, its so foreign seeming. Hell, I was 13 months old.

I was fifteen. I remember seeing a live feed of the Neptune approach on a television in a shop window.

By chance I'm currently in the middle of re-watching Cosmos for the first time since I was a kid. It's interesting to see how much I remembered (the blue-shifted kid on the scooter) and how much I had forgotten (the focus on evolution).

And yeah, seeing Sagan with his infectious enthusiasm is bittersweet.
posted by ambivalentic at 3:13 AM on October 31, 2012

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