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Neptune Orbiter, Another proposed mission
Rob Pinnegar
post Nov 10 2005, 03:51 PM
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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?
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elakdawalla
post Nov 10 2005, 04:43 PM
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I don't know much myself about what's possible either, but I know a good place to start would be to look up Thomas Spilker, who has done a lot of thinking about future Uranus and Neptune missions (he's also Cassini Deputy Project Scientist Linda Spilker's husband). He can talk your ear off very passionately about creative and mind-bending ideas for ways to tour giant planet systems, including one way to have an orbit that perpetually bounces on one side of a giant planet ring plane. I didn't understand the details -- I'd love it if someone could look into his publications and abstracts and figure out how this would work.

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tedstryk
post Nov 10 2005, 05:26 PM
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I would really like to see a Neptune orbiter with a small Triton lander. I have also wondered about flyby missions, to at least check up on changes. Maybe this is a crazy idea, but I always thought that a Neptune flyby craft could be carried like a probe on a Jupiter or Saturn mission, and separate before JOI or SOI, and instead use its engines in conjunction with the gravity assist to accelerate on to Neptune.


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Rob Pinnegar
post Nov 10 2005, 05:59 PM
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QUOTE (tedstryk @ Nov 10 2005, 11:26 AM)
Maybe this is a crazy idea, but I always thought that a Neptune flyby craft could be carried like a probe on a Jupiter or Saturn mission, and separate before JOI or SOI, and instead use its engines in conjunction with the gravity assist to accelerate on to Neptune.

That doesn't sound crazy at all -- it seems like a perfectly sensible idea. So I guess there are two things to consider: (1) would a combined mission be cheaper and more fuel efficient that two separate launches, and (2) is it worth the risk of losing both if something goes wrong?
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elakdawalla
post Nov 10 2005, 06:20 PM
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QUOTE (tedstryk @ Nov 10 2005, 10:26 AM)
I would really like to see a Neptune orbiter with a small Triton lander.  I have also wondered about flyby missions, to at least check up on changes.  Maybe this is a crazy idea, but I always thought that a Neptune flyby craft could be carried like a probe on a Jupiter or Saturn mission, and separate before JOI or SOI, and instead use its engines in conjunction with the gravity assist to accelerate on to Neptune.
*

Well, it may be crazy, but it's not out of the mainstream crazy smile.gif. In fact Sushil Atreya and Toby Owen are pushing for a mission concept called "Multiple Probes to Multiple Planets," which consists of a flyby spacecraft ("delivery truck") dropping two deep atmospheric probes at each giant planet. See
http://www.lpi.usra.edu/opag/feb_05_meetin...atmospheres.pdf
However I'm not sure when there would be a launch opportunity that would permit such a repeat of Voyager 2's flyby "grand tour" -- that would be my first question.
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JRehling
post Nov 10 2005, 07:09 PM
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QUOTE (elakdawalla @ Nov 10 2005, 11:20 AM)
However I'm not sure when there would be a launch opportunity that would permit such a repeat of Voyager 2's flyby "grand tour" -- that would be my first question.
--Emily
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Jupiter "laps" the outer planets every thirteen or so years, so opportunities will always keep coming around for J->U or J->N gravity assists.

I think a strategic plan is needed. Given the apparent rejection of NH2 as a Uranus flyby, it's a blank slate.

One nice bit of synergy is that Saturn, Uranus, and Neptune all have similar atmospheric profiles, so one probe design might accomodate all three. (Saturn's higher escape velocity may, however, mean that the Saturn probe would unavoidably arrive at higher velocity.) It would be nice to us Jupiter gravity assists to fling the two outer ones on their way, perhaps as add-ons, and get the synergy of unified manufacture and parallel investigations at three planets.

Proper flyby craft for remote sensing of the satellite systems (of Uranus and Neptune) are other options, but redundant if orbiters are planned, which for Neptune, at least, it should be.

Finally, there are an ever-increasing number of opportunities for KBO exploration and mini-Grand Tours. (Add in Sedna, which isn't a KBO!) I hope a broad view is taken in planning opportunities, because it could be a colossal waste to identify priorities, and pluck missions off of the top of the list, missing out on two-in-one possibilities.
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tedstryk
post Nov 10 2005, 07:13 PM
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If an orbiter is a long way off, I think a Triton flyby would be very useful, as it would allow for change detection since Voyager and, of course, when the orbiter finally gets there, its data can also be compared. Unlike the other moons of these two planets Triton is a dynamic world. Of course, the other issue is that the coverage of the Uranian moon's souther hemispheres is going to get poorer and poorer the longer we wait.


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RNeuhaus
post Nov 10 2005, 07:38 PM
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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
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ljk4-1
post Nov 10 2005, 07:53 PM
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QUOTE (tedstryk @ Nov 10 2005, 02:13 PM)
If an orbiter is a long way off, I think a Triton flyby would be very useful, as it would allow for change detection since Voyager and, of course, when the orbiter finally gets there, its data can also be compared.  Unlike the other moons of these two planets Triton is a dynamic world.  Of course, the other issue is that the coverage of the Uranian moon's souther hemispheres is going to get poorer and poorer the longer we wait.
*


We should drop a lander right into one of Triton's geysers. Talk about a relatively easy entry into the moon's subsurface.


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tasp
post Nov 10 2005, 09:49 PM
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QUOTE (RNeuhaus @ Nov 10 2005, 01:38 PM)
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'.
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RNeuhaus
post Nov 10 2005, 10:00 PM
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QUOTE (tasp @ Nov 10 2005, 04:49 PM)
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'.
*

It seems that the reality would be become beyond the year 2030-2040...after the Earth's world economic becomes stronger and also the science, engineering and technology becomes highly feasible and capable to develop greater projects likes ones of Spaceship of Space Odyssey 2001 which is highly capable to ram among planets of our solar system.

Rodolfo
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JRehling
post Nov 10 2005, 10:06 PM
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QUOTE (tasp @ Nov 10 2005, 02:49 PM)
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'.
*


Prometheus is canceled, and the reasons for that ought to speak to the idea of putting multiple orbiters on a single launch -- extraordinarily unrealistic.

Prometheus offered lots of electricity, but remember, that's not unlimited thrust. You still need to have some sort of fuel to push off against, and when that mass becomes enormous, so does the requirement of how much chemical thrust is needed to put the thing into space (from Earth's surface) in the first place.

Prometheus was already wildly unrealistic.

I think there's plenty of useful reality-based discussion we can have before we plan the 24th century's missions.
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Decepticon
post Nov 11 2005, 12:42 AM
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There where some ideas for Neptune orbiter in Astronomy magazine (Forgot When)
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tasp
post Nov 11 2005, 12:59 AM
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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.
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tasp
post Nov 11 2005, 01:09 AM
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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.
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