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Uranus Orbiter, The other proposed ice-giant mission
mchan
post Sep 23 2007, 09:09 PM
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Will RTG power levels be sufficient to operate all the instruments in 2030?

Re-assembling a team to run 35 year old instruments on a 20-30 year old operational model could be costly compared to operations with the current technology of the time. While it would likely be cheaper than a future ground up Uranus flyby mission, the future mission would have better instrumentation for better science return.
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tedstryk
post Sep 24 2007, 10:11 AM
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Well, 42 years, really. That's how long till the next equinox (shifting from north back to south at that time). I think the problem that we run into is that in the coming decade or two, if any money comes up for Uranus and Neptune, it will be for Neptune, thanks to the fact that it put on a better show for Voyager, plus the Triton factor. In addition to not having a moon the at is active (or known to be active), a Uranus orbiter would take a hell of a lot of fuel, since it has no Galilean Moons/Titan/Triton to use for gravity assists. NH2 would have been a cool mission. At equinox, a spacecraft could have flown by much as Voyager flew through the Jovian, Saturnian, and Neptunian systems, encountering a moon at a time, for the most part. If you look at the Voyager images on the PDS, you will notice that the amount of close coverage per moon pales in comparison to the other three planets Voyager encountered, because flying through the Uranian system near solstice, it passed through like it was hitting a dart board - all the closest approaches happened at the same time, so only a handful of images could be taken.


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ugordan
post Sep 24 2007, 11:05 AM
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QUOTE (tedstryk @ Sep 24 2007, 12:11 PM) *
a Uranus orbiter would take a hell of a lot of fuel, since it has no Galilean Moons/Titan/Triton to use for gravity assists.

There was a paper Alex Blackwell referenced some time ago in this very thread about the feasibility of a Galileo-style tour of the Uranian system. In short, Uranus acts like a miniature version of the Jovian system in that interesting flybys are possible using the moons' gravities (feeble as they are).


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tasp
post Sep 24 2007, 12:51 PM
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The Galileo style tour of the Uranian system is quite exciting. With the 'scale' being smaller, the mission generates very close encounters of Ariel, Miranda, Titania and Oberon in fairly a fairly short time interval.

Additionally, with even Oberon being less than (IIRC) 600,000 miles out from Uranus, you are having virtually continuous (well, not quite) reasonably close encounters with non-targeted moons on each orbit.

With the (IMO) near certainty of ongoing geological process on Ariel, and a good chance perhaps for Titania, too, a Uranus orbiter is looking like a pretty useful mission.

Our understanding of these smaller bodies grows synergistically with each one we study.

To learn more about the 'Enceladus phenomena', study Ariel.

And possibily, to learn more about Cassini Regio, study Umbriel.


A Uranus orbiter mission is a lot of bang for the buck.
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djellison
post Sep 24 2007, 01:52 PM
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QUOTE (tasp @ Sep 24 2007, 01:51 PM) *
A Uranus orbiter mission is a lot of bang for the buck.


That may be true - to be honest, it would take a Uranus orbiter to find out. One thing that IS for sure, is that while it may be a lot of bang per buck...it'll also be a lot of buck.

Doug
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JRehling
post Sep 24 2007, 03:41 PM
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I think one difficulty owing to the no-big-moon situation would be lifting the orbit out of the equatorial plane to get a good look at the rings. If the whole mission were spent in the equatorial plane, the rings would be very hard to study. Whereas if the mission were spent in an inclined orbit, satellite flybys would be severely limited. Either some fuel or a Titania boost would be needed to get the UO out of the equatorial plane on one pass, beginning a period of ring observations, and then back down there afterwards.

We could start a pool on which will happen first: a Uranus Orbiter mission or D.C. statehood.
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djellison
post Sep 24 2007, 03:46 PM
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The paper cited above actually discusses the plane change issue.

Doug
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dvandorn
post Sep 24 2007, 04:32 PM
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QUOTE (JRehling @ Sep 24 2007, 10:41 AM) *
We could start a pool on which will happen first: a Uranus Orbiter mission or D.C. statehood.

Frankly, I think you'll see the U.S. split up into several smaller polities before you see a Uranian orbiter... *sigh*...

-the other Doug


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AscendingNode
post Sep 24 2007, 05:34 PM
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QUOTE (djellison @ Sep 24 2007, 06:52 AM) *
That may be true - to be honest, it would take a Uranus orbiter to find out. One thing that IS for sure, is that while it may be a lot of bang per buck...it'll also be a lot of buck.


It is very much not for sure that a Uranian tour spacecraft would be a lot of buck. I'd guess it could be done for ~ $1.5 Billion (or $75 mill a year for 20 years). And a big chunk of that could be saved if we could figure out how do do spacecraft hibernation better (i.e. improve upon New Horizon's hibernation). Sure that's more than a new frontiers mission, but it's about half a flagship mission cost.

Rough outline for a cheap mission: something New Horizon's like in the suite of instrument and in the mass of instruments, launch on a falcon 9, interplanetary trajectory like Venus-Earth-Earth-Jupiter, 12 year (mostly-hibernating) cruise, 1 year inclined tour with Titania flybys, 1 year equatorial tour with flybys of all of the moons. That's a 14 year mission, which is very much doable with current technology.

A Neptune mission on the other hand, would be a lot of buck since the interplanetary cruise times are beyond current technology unless we find a way to capture at Neptune from a high-energy transfer, which is also beyond current technology. Sure there are lots of technologies that could be developed... but that costs $$$.
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AscendingNode
post Sep 24 2007, 05:37 PM
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QUOTE (JRehling @ Sep 24 2007, 08:41 AM) *
I think one difficulty owing to the no-big-moon situation would be lifting the orbit out of the equatorial plane to get a good look at the rings. If the whole mission were spent in the equatorial plane, the rings would be very hard to study. Whereas if the mission were spent in an inclined orbit, satellite flybys would be severely limited. Either some fuel or a Titania boost would be needed to get the UO out of the equatorial plane on one pass, beginning a period of ring observations, and then back down there afterwards.


Unless you arrive right at equinox, you'll start outside of the equatorial plane. If you arrive around solstice, you could have a very high inclination (60-80 deg). From this high inclination, you can then use Titania flybys to slowly bring you down into the equatorial plane. It takes a while, but it doable.
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djellison
post Sep 24 2007, 05:49 PM
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QUOTE (AscendingNode @ Sep 24 2007, 06:34 PM) *
It is very much not for sure that a Uranian tour spacecraft would be a lot of buck. I'd guess it could be done for ~ $1.5 Billion (or $75 mill a year for 20 years).


$1.5B is low-end Flagship class. That's a lot of buck.

Doug
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infocat13
post Sep 24 2007, 10:45 PM
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QUOTE (Spirit @ Sep 22 2007, 07:45 AM) *
What about building two identical probes and launching one to Uranus and the second to Neptune? It will certainly lower the cost of the missions. And if we launch them at appropriate times, we can have the same team working on both projects - first on Uranus Orbiter and later on Neptune Orbiter.


Spirit,

I remember A while back NASA had idea much like yours , it was called Mariner Mark 2 I believe. You could goggle this.I think it is a great idea perhaps now in our era a massed produced space craft modeled after the Jupiter and Saturn orbiters could be built minus the instruments and electronics and stored(off the shelf)then as opportunities came up do to orbital mechanics science instruments specific to that mission would be added to the off the shelf spacecraft body and launched.
Questions I would have would be assuming we are using the Galileo design and we where building two space craft for Uranus Neptune and a re flight to Saturn and Jupiter IE 8 space craft with one atmospheric probe each. what would a JPL cost engineer cost these out as ?
Issues..................
(1) can a modular mass produce space craft design accept somewhat different scientific instrument suite for each outer planet?
(2) would a mass produced set off atmospheric probes work at each outer planet? each would need a somewhat different reentry cone?
(3) Could the Deep space network handle a outer planet mission launched every year or every two years?

mariner mark 2 according to Wiki
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AscendingNode
post Sep 25 2007, 12:12 AM
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QUOTE (infocat13 @ Sep 24 2007, 03:45 PM) *
Questions I would have would be assuming we are using the Galileo design and we where building two space craft for Uranus Neptune and a re flight to Saturn and Jupiter IE 8 space craft with one atmospheric probe each. what would a JPL cost engineer cost these out as ?


A good way to estimate costs of doing multiple identical spacecraft (based off of MER experience, I think) is that if you build the spacecraft at the same time and they really are identical.... each spacecraft after the first costs 50% of the first. If anything is different or if you have time between when you build the spacecraft almost all of the savings is lost.

This is because almost all of the cost of spacecraft is in the brain-power used to build them. If you change something you have to think about all of the effects of the change and that often is as much work as designing from scratch. And if you have a gap in time between doing the designs, you probably need to get new people... so you have to pay full price.

As far as how much a mission costs... check out this link: http://www.lpi.usra.edu/opag/TitanEnceladu...onDollarBox.pdf

This is the billion-dollar box study of what could be done at Titan or Enceladus for a billion dollars. (answer: not much) The main problem is that a new Saturn mission has to do something Cassini didn't (and Jupiter missions have to beat Galileo). For Uranus and Neptune you have to beat Voyager. Thinking that way, and looking at the cost of the mission ideas in the above study, I think a Uranus or Neptune mission would cost $1 billion at least. An that would be a very minimal mission.

But I think, for $2-$3 billion you could do something amazing that would be worth more scientifically than splitting that same number across 2-3 new frontiers missions. (Just look at all we got from one Cassini Iapetus flyby... that's a new frontiers-class science return from one flyby).

I think NASA needs to start thinking of outer planet exploration as a program that costs X dollars a year and then plan multiple flagships in that budget to overlap. Start with a Europa or Titan mission and then after it ramps up (maybe 5 years down the road), then start studying the next one. The flight times to the outer planets are so long that you can easily stagger the arrival times.
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nprev
post Sep 25 2007, 01:00 AM
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Infocat, I and others on the board have had variations on the same idea before. However, as AscendingNode points out, requirements for planetary missions tend to increase & specialize over time as we build on the results of previous missions, complicated by the fact that technology changes rapidly. This applies even to the bus, not just the payload. Therefore, mass-producing modular "COTS" spacecraft for planetary missions just isn't feasible. (I know; I think it sucks, too!) sad.gif


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brellis
post Sep 25 2007, 01:30 AM
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QUOTE
requirements for planetary missions tend to increase & specialize over time as we build on the results of previous missions, complicated by the fact that technology changes rapidly. This applies even to the bus, not just the payload. Therefore, mass-producing modular "COTS" spacecraft for planetary missions just isn't feasible. (I know; I think it sucks, too!)


It isn't "mass-producing". It's reproducing maybe a couple of dozen spacecraft that have common traits and interchangeable parts.

My area of work involves an analogy of sorts. I do soundtrack music for films. The technology involved requires a considerable investment of time to learn software, etc. At the dawn of the age of technology for us musicians, there was a feeling of exclusivity to our world.

When embarking on my music career, I tried to get the biggest, fastest, most versatile and bug-proof hardware/software available. The biggest part of this investment was a Synclavier. Almost 25 years later, I still use my Synclav primarily. The other software I use, ProTools, is almost 20 years old now, with lots of upgrades. It's not worth the effort to learn something that will be obsolete next year. It's worth it if there's a longterm possibility of success.

Spacecraft design must involve these longterm visions. Make the software easy to upgrade, and make the hardware as potent as possible, so it can be relevant 20 years hence. Build it and they will come. Send a fleet of well-built spacecraft to the outer planets, and the software designers will surely keep them relevant.

What made Galileo great was: first, they managed to launch it, and then, by hook or crook they milked everything they could out of the mission. Equipment failure didn't stop them. The philosophy of longterm investment of money, hardware, software and human effort was worth it.

Missions to the outer planets are worth the wait, and the machinery should be designed accordingly.
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