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?

[tasp]

I'll digress to Uranus orbiting briefly.

Assuming Uranian orbit is achieved via aerobraking or whatever means, would orbit shaping form Oberon (for purposes of discussion) be possible?

I'm thinking an elliptical orbit around Uranus that grazes (safely) the rings at perigee, has an apogee way out past Oberon. And if inclined to equatorial plane, not inclined too much.

Would a series of orbital encounters with Oberon give us an interesting mission by modifying our orbit sufficiently?

Idea:

Always have the modification have the same effect on the craft orbit. I'm thinking every Oberon encounter could be oriented to raise the perigee of our orbit slightly. More by 'dumb luck' than design, as the perigee slowly (over many orbits) rises through the Uranian system, you will inevitably get a reasonably close flyby of everything interior to Oberon.

The big trick; every Oberon encounter needs to put the craft in an orbit that eventually encounters Oberon again. If you hit a period for the craft that doesn't divide into Oberon's period very well, you next flyby might not happen for a while.

Once you get your perigee above Titania, you can start using the Oberon encounters to change the plane of the orbit. Having the period at 2X or 3X Oberon's means every encounter can nudge your orbit inclination a tad more.

Then you can study the magnetic field and checkout the higher latitudes of Uranus.


Granted, Oberon isn't that massive, but its mass ratio to Uranus isn't terribly different from that of one of the Galileans to Jupiter, with out doing the math, (a trait of mine I am not likely to change) it seems that this might be feasible.

A possible advantage (snicker) of this idea is I think it would take a very long time to do the orbit shaping with Oberon, and therefore, you get to watch the Uranian system for a nice long arc around the sun, and maybe we eventually get to see some things that perhaps we might have thought would take a second probe.

[JRehling]

I'll digress to Uranus orbiting briefly.

Assuming Uranian orbit is achieved via aerobraking or whatever means, would orbit shaping form Oberon (for purposes of discussion) be possible?

Idea:

Always have the modification have the same effect on the craft orbit.  I'm thinking every Oberon encounter could be oriented to raise the perigee of our orbit slightly.  More by 'dumb luck' than design, as the perigee slowly (over many orbits) rises through the Uranian system, you will inevitably get a reasonably close flyby of everything interior to Oberon.

If the craft arrives near solstice, it will be irrelevant: each world will be half in decades-long dark, and every flyby will illuminate the same half. An orbit that is modestly inclined WRT the moons' could eventually give a good look at each moon, leaving us equally (and eternally?) ignorant of their other hemisphere. And we would also miss out dramatic high-phase illumination of most of the hemisphere we see -- note that all of Cassini's long-range view of the icy satellites of Saturn with the terminator in different places is eventually going to help us build DEMs of their topography.

Arriving near equinox will allow the kind of illumination change that would be highly desirable. Unfortunately, equinox is coming up soon, and we're obviously not going to make it in time. So this plan won't possibly come off before 2050. At which time, I'll be on soft foods.

[tasp]

If the craft arrives near solstice, it will be irrelevant: each world will be half in decades-long dark, and every flyby will illuminate the same half. An orbit that is modestly inclined WRT the moons' could eventually give a good look at each moon, leaving us equally (and eternally?) ignorant of their other hemisphere. And we would also miss out dramatic high-phase illumination of most of the hemisphere we see -- note that all of Cassini's long-range view of the icy satellites of Saturn with the terminator in different places is eventually going to help us build DEMs of their topography.

Arriving near equinox will allow the kind of illumination change that would be highly desirable. Unfortunately, equinox is coming up soon, and we're obviously not going to make it in time. So this plan won't possibly come off before 2050. At which time, I'll be on soft foods.

Can 'Uranus shine' help out illumination of moons? Cassini took some pix of Iapetus that way, might help when equatorial plane of Uranus is perpendicular to orbital path around sun. 20 year mission life at the target gets you 90 degrees around the sun, that would help global coverage of satellites, too.

Voyagers are coming up on 30 years longevity, so craft lifetime of 20 years at Uranus might be feasible. Way cheaper than two missions.