Uranus Orbiter?

[3488]

Thanks to member H2Ouniverse who recently tipped me off about this, I thought I would start a topic on this.

LPI The Case for a Uranus Orbiter.

Uranus Orbiter presentation. March 2009.

The scientific case certainly merits this, as would a Neptune one (though we will get a Neptune / Triton pass with ARGO / New Horizons 2 if approved). These would compliment the Galileo Jupiter & Cassini Saturn missions well.

Below, a crescent Uranus as seen from Voyager 2. Something impossible to see from Earth.

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Andrew Brown.

 

[scottb50]

All seriousness aside, I couldn't help but think of the old Klingon orbiting Uranus joke when I saw this.

 

[brandbll]

Wow, thanks for posting this Andrew! I'd REALLY like to see a Uranus or Neptune mission. Personally i'd rather see a Neptune mission just because that planet facinates me more and you get to study Triton as well, but the material you posted gives a good argument for Uranus over Neptune. Plus, as you mentioned if NH2 gets approved then we'd get a Neptune visit.

I've got a few of questions though. It doesn't seem like they are very positive about whether a solar powered mission is possible or not. How do they decide whether that is possible or not? And if it isn't possible could that push the mission more towards Neptune or at least give it more consideration?

Last, could attempting something like this further push NH2 on the backburner?

 

[EarthlingX]

Wow, thanks for posting this Andrew! I'd REALLY like to see a Uranus or Neptune mission. Personally i'd rather see a Neptune mission just because that planet fascinates me more and you get to study Triton as well, but the material you posted gives a good argument for Uranus over Neptune. Plus, as you mentioned if NH2 gets approved then we'd get a Neptune visit.

It is about time for such a mission too. It would be very nice if there were something for a visible light among the instruments too, some small 10 cm lens perhaps, with a tiny IR sensor .. :roll:

I've got a few of questions though. It doesn't seem like they are very positive about whether a solar powered mission is possible or not. How do they decide whether that is possible or not? And if it isn't possible could that push the mission more towards Neptune or at least give it more consideration?

Last, could attempting something like this further push NH2 on the backburner?

 

[3488]

Thanks for the feed back everyone.

I am a little disappointed by the fact that the mission appears very narrow in it's aims, i.e no cameras for mapping, weather monitoring, no mention at all of the moons of Uranus as the orbit is very tight around Uranus with relativley little differnece between periuranion & apouranion..

Myself I would like to see a New Horizons type clone (which could also be kept witin the New Frontiers budget) that could be placed into orbit & carry out a Galileo or Cassini type mission.

Five of the major Uranian moons display a wide range of geological features & histories.

Miranda, possibly either being smahed apart & reformed or swallowed former two co orbitals,

Ariel, certainly has seen massive cryovolcanism in the not so distant past IMO, lofty mountains, cayons, faulting.

Titania, large smoother area with smaller craters, giant canyons.

Oberon, cryovolcanic flooding on large scale, lofty mountains & some cleaned up images suggest rifting & faulting there too.

The middle one Umbriel appears to be the only unevolved one, a kind of Uranian version of Jupiter's Callisto or Saturn's Rhea.

Also no mention of ring observations.

However this mission is still better than no mission. The scientific case certainly exists for ARGO / NH2 to proceed. We'll get a post Cassini close look at Saturn & Titan, also Neptune & Triton pass (Triton to within 750 KM) then onto to the Kuiper Belt, not to mention a Jovian trailling Trojan pass & a possible Main Belt asteroid pass.

Andrew Brown.

 

[h2ouniverse]

Hi all,

To me the criterion for the value of a "small" orbiter on Uranus is whether or not it is able to answer a question such as "are there plumes on Ariel similar to the ones of Enceladus ?"
If the instrumentation does not pass this simple test, then...

 

[Boris_Badenov]

These outer planet missions always give me the opportunity to beat the drum for a Nuclear Powered Ship. (I'll bet nobody saw that coming :ugeek: )
A Bimodal MITEE engine in the 500kg range could get the mission to Uranus in 3 years with no gravity assists & generate enough electricity to power 3 times the instruments that are on Cassini.
Building the first Nuclear Powered mission will not be easy or cheap. It would be politically difficult & would bring out the crazies to protest it's launch in a big way, but the benefits are immense. The demonstration of it's sheer speed would prove it's worth.

 

[warpfactor999]

I'm sorry...but how could Captain Kirk not be orbiting your anus...i mean Uranus for clingons....I mean cling ons :lol: sorry!!

 

[h2ouniverse]

Hi Andrew and all,

So NASA has shortlisted its next New Frontiers mission down to SAGE, SPAB and OSIRIS. Bye bye the Uranus Orbiter...
Next time may be...

 

[3488]

Hi Andrew and all,

So NASA has shortlisted its next New Frontiers mission down to SAGE, SPAB and OSIRIS. Bye bye the Uranus Orbiter...
Next time may be...

That's true, but I did think that the proposed spacecraft was vastly underpowered & not very capable. If this had been a Voyager, Galileo, Cassini, New Horizons type craft, than the disappointment would have been much greater.

Perhaps JAXA, or ESA could show an initiative????????? Still hope ARGO is still being considered for a future selection.

Andrew Brown.

 

[bdewoody]

How long will it be until one of the inner gas giants will be in a position to give a boost to a Neptune or Uranus probe? As I understand it the planetary positions for the Voyagers only happens once every two or three hundred years. Also if you build up enough speed to get there in a reasonble amount of time won't the mission be limited to a flyby as with the Pluto mission?

 

[MeteorWayne]

That's a very important point. The only way to get into orbit around a planet or asteroid is to approach it at a very slow speed. To do that for Uranus, the term "reasonable time" need not apply. The Martian orbiters were aimed to catch up from behind at a slow relative speed. The Dawn Mission takes 4 years to gently shift it's orbit so it meets Vesta at a very slow relative speed so it will be captured. To do that for Uranus, you need to get it into roughly the same 84 year orbit that the planet takes. Such a mission done like Dawn would take centuries, unfortunately. The other option is to carry enough prepellant to slow down when you get there...unfortunately that means the mission would be far too expensive to ever be launched in the first place.

The deifferent speeds of high velocity to get the Uranus in the first place (in a reasonable time), and slow speed once you get there cause a real conflict.

 

[tanstaafl76]

What about using one or multiple ion engines that accelerate the first half of the trip and decelerate the second half?

 

[MeteorWayne]

That's still a several hundred year mission for an orbiter....

 

[SteveMick]

" That's still a several hundred year mission for an orbiter...."

That really got me thinking. Thinking about aerobraking at Uranus.
Whatever the pros and cons it sure seems like a good way to slow down to at least a highly elliptical orbit
Just for the sake of argument let/s say your approach delta V to Uranus.s atmosphere can be 100,000 mph. That would mean you could get there pretty quickly( in a few years) if of course you could get going pretty fast in the first place.

Some years ago I wrote about a mission I called "Fire and Ice" which would approach the Sun to gain the velocity for a quick fly-by of Pluto. Using a solar thermal rocket at perihelion to gain a large boost of hyperbolic excess velocity - adding speed when going very fast relative to the Sun has a multiplier effect. To get that close to the Sun it first had to travel to Jupiter for a gravity assist. Using this or something like it might just make a Uranus Orbiter something that had a five year flight time.

Just a thought.
Steve

 

[High_Evolutionary]

It is a shame this mission did not receive funding. Personnally I feel a lot good science would have of this mission. Excellent proposal presentation as well. Ty for posting the white paper! :ugeek:

 

[3488]

Hi SteveMick, great idea it really is, the only real downside & it is a major downside would the thickness & therefore mass of the ablation shield required to achieve that aerobraking maneuver.

As Wayne said about fuel mass, this would replace fuel mass with ablation shield mass. As Wayne pointed out a large increase in mass would cause the cost to 'sky rocket' (I know crap pun) so it would not be funded.

Andrew Brown..

 

[silylene]

Hi SteveMick, great idea it really is, the only real downside & it is a major downside would the thickness & therefore mass of the ablation shield required to achieve that aerobraking maneuver.

As Wayne said about fuel mass, this would replace fuel mass with ablation shield mass. As Wayne pointed out a large increase in mass would cause the cost to 'sky rocket' (I know crap pun) so it would not be funded.

Andrew Brown..

We'd also have to understand the height/density profile of the Uranian atmosphere before we could plan such a mission. So an aerobrake mission would need to be the second Uranian orbiter.

However, an atmospheric 'dipping' orbit could be planned to circularize the orbit of the first orbiter, after we better understand the above.

 

[SteveMick]

Very good points.
I agree that the atmosphere would have to be characterized and a significant amount of mass devoted to ablative materials.
It seems ironic that the problem isn't so much getting there fairly quickly -
the problem is slowing down when you get there. The Jupiter assisted perihelion idea is a favorite for getting velocities in the 200,000 mph range or a little more than a 10,000 mile velocity increase at perihelion and doing science at both extremes of the solar system but absent aerobraking all I can think of is of course electric propulsion to slow down. That will of course make the trip take a lot longer.
Even though sunlight's intensity at Uranus is about 1/300th(?) or so of that at Earth it may still be a viable option for power. This is only if very advanced solar concentrator mirrors (or very thin film PV, but the sizes get enormous) of very low mass are developed. The lowest mass one I've ever thought of would be a diamond film simple(thin. long focal length) lens that had holes smaller than the wavelengths of visible light. In theory these could have more than 1000 ft.^2 per lb. which would translate to about 400W thermal per lb. If concentrator type solar cells (at over 40% efficiency currently) are used, the concentrator would contribute about one pound to every 160W electric generated. Of course every KW of electric power would require about 6000 sq. ft. of concentrator area. If aluminum or sodium mirror type concentrators are used the mass goes up since it takes more atoms to reflect than slightly bend light; but the mirrors can double as large radar, radio telescope, orhigh baud communications antennas. The support structure can be made of hollow tubes and used as a waste heat radiator for the concentrator PV or nuclear power system if used.
At Neptune you need 5(?) times the concentrator area but their multiple functions and possibly low cost may make them the choice even there.

Steve