Neptune Orbiter, Another proposed mission Options

[Rob Pinnegar]

This seems like a good place to start off the Uranus and Neptune forum: with the next ice-giants mission.

I will admit to not knowing a whole lot about the Neptune Orbiter With Probes (NOWP), other than the fact that it's in the planning stages, and a few other details I've gathered from Wikipedia and various other Internet sources. Anyone care to get this one going with a bit more information?

[RNeuhaus]

The trip to planets beyond than Saturn, I think the project would be most benefical to launch a big rocket along with three or four orbiters in which they are going to be dropped on each planet (Uranus, Triton, Neptune, or others) on its fast way toward a KBO... it might need a rocket which is capable to send around 10 TM to the space.

The trip to these planet is of very long time so it is very desirable that a rocket would be capable to send multiples probes, orbiters or landers in one shot.

Rodolfo

[tasp]

The trip to planets beyond than Saturn, I think the project would be most benefical to launch a big rocket along with three or four orbiters in which they are going to be dropped on each planet (Uranus, Triton, Neptune, or others) on its fast way toward a KBO... it might need a rocket which is capable to send around 10 TM to the space.

The trip to these planet is of very long time so it is very desirable that a rocket would be capable to send multiples probes, orbiters or landers in one shot.

Rodolfo

Prometheus would make a great 'carrier' type vehicle. It could send a heavy orbiter, probe, lander, and retro stage on it's way to Neptune, then return to earth for a refuel, and another payload to 'fling to the nether reaches'.

[tasp]

To revise and extend my remarks,

Would a reusable 'upper stage' (like a Prometheus, or at least an uprated ion drive) be considered a little more palatable, perhaps to the funding committees in congress? If an orbiter, lander, and atmospheric probe were too much mass, in view of the reusablity, the mssion could be flown on multiple flights.

Combining a reusable upper stage 'tug' with the VEEGA type flybys would give us even more payload, and would have the advantage of an easier return to earth of the reusable stage. Add in aerobraking at earth (yoiks! the fur will fly in the media, aerobraking a nuclear stage in earth's atmosphere!!!!) and the payload this system could send to Jupiter and beyond, repeatedly, would keep JPL hopping for decades.

I guess I'm coming around to seeing the objections to this.

Sigh.

[tasp]

Meanwhile, back at Neptune,

Has anyone considered the advantages and disadvantages of either a prograde or retrograde orbit for a Neptune orbiter?

I assume Triton will be employed similarly to Titan for orbit shaping, does it matter which way Triton goes 'round Neptune for this?

High flyby speeds for the prograde option at Triton can cause dificulty in photography, but then you reduce that problem at every other target. I'm not sure if ring plane crossings are more dangerous either way, hit something at either speed regime and the craft is toast anyhow.

Probe deploy and relay tasks seem easier if the orbiter is in a retrograde path. Perhaps Triton probe release could occcur far enough out, that orbiter and Triton (assuming we send a Huygens or better follow on) probe could each take the optimum path.

[Rob Pinnegar]

Has anyone considered the advantages and disadvantages of either a prograde or retrograde orbit for a Neptune orbiter?

I assume Triton will be employed similarly to Titan for orbit shaping, does it matter which way Triton goes 'round Neptune for this?

Hmm. That's an interesting point.

From what I remember, Triton is (probably just barely) massive enough to get an orbiter around Neptune via gravitational capture. (Titania and Oberon aren't big enough to do this at Uranus which is why aerobraking would be required for a Uranus orbiter.) Probably the probe _would_ have to enter a retrograde orbit around Neptune, unless aerobraking were used.

This isn't necessarily a bad thing, though. The situation at Neptune is different from Cassini's at Saturn. At Saturn, Titan is the main attraction, but there are several other bodies in the system (Enceladus, Iapetus, Hyperion etc.) that are also very interesting and worthy of plenty of study in their own right.

The Neptune orbiter's "Titan" is obviously Triton, but, at Neptune, there is no Iapetus, no Enceladus, and no Hyperion. Apart from some inner and outer gravel there is only Proteus which, apart from having a funny shape, seems more like a Mimas-in-waiting than a Miranda (though we could always be surprised). I wonder if there will be any chance of arranging a Nereid encounter or two? Might as well try if we're going all the way out there.

Triton isn't just the main event -- it's pretty much the only event. There is no "second stage" (a la Ozzfest) at Neptune. So if a retrograde orbit is preferable for studies of Triton, then we might as well make it a retrograde orbit -- even if aerobraking is used instead of capture.

[tedstryk]

Triton isn't just the main event -- it's pretty much the only event. There is no "second stage" (a la Ozzfest) at Neptune. So if a retrograde orbit is preferable for studies of Triton, then we might as well make it a retrograde orbit -- even if aerobraking is used instead of capture.

I don't know if I would go that far. For one thing, a flyby during approach of Neried (a la Cassini at Phoebe) would be nice. And Proteus and the others may prove to be fragments from the former Neptunian system before Triton's capture, which would be quite interesting.