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30 years ago: Voyager 2's historic Neptune flyby (phys.org)
119 points by dnetesn 26 days ago | hide | past | web | favorite | 22 comments

I was 10 when Voyager 2 flew by. I was certain trips to Neptune, pictures, and further exploration would become common. And 30 years later, we haven’t gone back. It’s far, expensive, priorities, and all that. And now enough time has passed I may never see us get there again.


There's hope, the New Horizons to Pluto was much faster, and before that I was _sure_ I'd never live to see Pluto.

The price of that speed is don’t blink or you’ll miss it. We should have something orbiting Neptune, now.

Why? How should we decide to spend the resources it orbit Neptune? Why not Saturn or Jupiter; why not land on a comet? Why not put a human on the moon again or perhaps spend the money or medical research or nuclear fusion. What about Neptune seems so compelling to you? I would never have thought it an important or memorable goal and just want to hear why Neptune is so alluring.

Because the 10-year-old me was teased with pictures and mysteries I want answers to. Because it’s so far. Because it can’t see more than a pale dot in my telescope. Because it’s so alien. And because we have been there, done that on everything you mentioned.

Perhaps if I’m ever granted the opportunity to present my case before NASA and Congress, I might offer a more well-thought-out explanation. But right now, “because it would be awesome” should suffice.

Check out the recently proposed Trident mission, and I guess write your congressperson while you're at it

Because it's a mostly unexplored corner of our solar system. The Voyagers were survey probes: they saw glimpses of a lot of interesting things, but couldn't stick around and solve any of the hard mysteries. (For example, just what is going on with the weather on both Uranus and Neptune? It's weird!) Orbiters such as Galileo, Juno, and Cassini are able to stick around long enough to do deep science.

Orbiters for one or both of our ice giants ought to be much higher on our space exploration priority lists than they seem to be.

I wonder how expensive (and feasible) it would be to send a cubesat to low earth orbit then send it to Neptune via solar sails..

Setting aside the feasibility of solar sail propulsion, power will be an enemy: just getting a typical cubesat level of 5W is much harder at Neptune, since Neptune gets just 1/900th the solar flux. By way of comparison: the "Juno" probe produces 486W at Jupiter (solar flux 1/27th of Earth's) from about 72m^2 of solar panels, weighing 340kg. So if similarly scaled 5W at Neptune is about 110kg + 24m^2 of solar panel.

And that's assuming that 5W suffices: "New Horizons" has 200W and a 2 metre diameter radio dish, and still took 15 months to download the data from its brief Pluto encounter (although at a slightly greater distance than Neptune's orbit)

If you want it to be an orbiter rather than a brief flyby then it needs some way to shed a lot of velocity: either a lengthy rocket burn and/or aerobraking by grazing Neptune's atmosphere.

So unfortunately it seems well beyond cubesat terrain: even a "cheap" probe to the outer planets is a large and complex machine.

You'd probably need a nuclear generator to power the thing.

AFAIK solar sails aren't able to slow down, so you'd need another form of propulsion to establish orbit.

If (and it’s still a substantial “if”) SpaceX’s BFR flies and comes close to living up to its promises, I’m hoping we’ll see a renaissance in space probes. With this combination of heavy lift and low cost, probes could be built much larger and substantially cheaper, and be launched on faster trajectories.

Live broadcast from that day: https://youtu.be/Y11CVuxfvPE

Wow, we really took for granted having Carl Sagan on tap for this kind of thing.

I'm kind of relieved he's not around to see what's become of everything these days. Though the rise of the private space enterprise and its associated new space race would give him a lot of hope.

I remember "Neptune All Night" on PBS from WHYY that night. It was one the first things I ever videotaped. It was awesome seeing the images coming down.

I stayed up, well, all night watching it with my father. Amazing experience.

Sometime around then, we also got a computer modem, and one of the first things we did with it was find some NASA BBS where you could download images from Voyager 2. At a blazing 300bps. The long-distance charges were probably more than what I pay for a week of gigabit internet service at home now.

My dad and I would set the VCR to record the daily press conferences and watch them in the evening. Good times.

I remember reading in a 1986 SciAm about how the team worked around spacecraft failures, like compensating for temperature and the doppler effect in the sole functioning radio receiver, and slowly rolling the entire platform to compensate for seizing motor shafts: https://books.google.com/books?id=rYIJJP7audkC&pg=PA42#v=one... (New Scientist)

We need another Voyager mission with updated cameras/sensors.

The voyager program was made possible by a very specific alignment of the planets which only occurs every 175 years

The joke the JPL crew always say is that the last time the planets aligned like that was when Thomas Jefferson was President and he blew it.

That joke was actually used on President Nixon. It’s mentioned in the movie The Farthest.


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