Uranus and/or Neptune Exploration Options

[James S.]

I'm 49 and will be 50 in January. With the success of New Horizons, being the first humans to ever see Pluto is mind blowing, I was wondering if I/we will ever see a probe or exploration of Uranus and Neptune? Are there any plans for exploring these two planets in the near future?

Thanks,
James Sontag

[tedstryk]

No

[mcaplinger]

Are there any plans for exploring these two planets in the near future?

Depends on your definitions of "plans" and "near".

There are always plans. See, for example, "Uranus and Neptune Orbiter and Probe Concept Studies", http://sites.nationalacademies.org/cs/grou.../ssb_059323.pdf

In the last decadal survey (for missions through 2022), a Uranus orbiter and probe mission was ranked third after a Mars sample return cacher and a Europa orbiter/multiple flyby mission. Given budget realities, I think it's very unlikely that a Uranus mission will happen in that time period, and after that, who knows?

[JRehling]

It seems like Europa, Titan, Io, and Enceladus could keep trumping Uranus and Neptune plans for decades. Titan, certainly, has merit comparable to Mars for repeated generations of missions, except the cruise time is unfortunately much longer so the iterations would have to be ~decadal instead of biennial, and the same may be said of Europa.

I just posted about the incredible capabilities expected of the EELT when it comes online in Chile c. 2024. Boasting 16 times the resolution of HST, it could view the Uranus system with about half the resolution that HST can image Mars. That could perform some pretty nice science from the ground. In the case of Uranus, that's particularly nice because the axial inclination means that the full range of seasons/latitudes could only be observed by a long-life orbiter, while something on the ground can sit and wait for the opportunities as they come.

[James S.]

Depends on your definitions of "plans" and "near".

There are always plans. See, for example, "Uranus and Neptune Orbiter and Probe Concept Studies", http://sites.nationalacademies.org/cs/grou.../ssb_059323.pdf

In the last decadal survey (for missions through 2022), a Uranus orbiter and probe mission was ranked third after a Mars sample return cacher and a Europa orbiter/multiple flyby mission. Given budget realities, I think it's very unlikely that a Uranus mission will happen in that time period, and after that, who knows?

Thank you for the link for the Uranus and Neptune Orbiter and Probe Concept Studies. It is fascinating reading.

[Brian Burns]

I'm hoping for the same thing, but am guessing other things will get more attention and money, unless mission costs come way down somehow (AI, robot manufacturing, nanosatellites, laser sails, who knows...). I'm about the same age so have another 40 years or so to see what happens.

But here are some proposed Uranus/Neptune orbiters anyway, with some possible launch dates -

Uranus Orbiter and Probe (JPL), launch 2025
https://en.wikipedia.org/wiki/Uranus_orbiter_and_probe

MUSE (Mission to Uranus for Science and Exploration) (ESA), launch 2026
https://en.wikipedia.org/wiki/MUSE_(spacecraft)

ODINUS (Origins, Dynamics, and Interiors of the Neptunian and Uranian Systems) (ESA)
Dual Uranus and Neptune orbiters, launch 2034
https://en.wikipedia.org/wiki/ODINUS

Some more info -
https://en.wikipedia.org/wiki/Exploration_of_Uranus
https://en.wikipedia.org/wiki/Exploration_of_Neptune

I like the idea of using more powerful telescopes with adaptive optics to image them, e.g. Uranus from Keck in 2004 - http://www.keckobservatory.org/images/made...3_3_800_623.jpg (from http://www.keckobservatory.org/recent/entr...rom_the_ground), and Hubble - http://cdn.spacetelescope.org/archives/ima...en/opo9736a.jpg (from https://www.spacetelescope.org/images/opo9736a/).

And the JWST...

I've been playing with the Voyager 2 images of Uranus and Neptune - I figure that'll be the closest thing to visiting them again for a while (eg some rough Uranus movies - http://www.unmannedspaceflight.com/index.p...t&p=231787).

[jasedm]

Thank you for the link for the Uranus and Neptune Orbiter and Probe Concept Studies. It is fascinating reading.

Fascinating indeed. I think Uranus has more chance of a green flag of the two, as the proposed mission has a similar launch/cruise timescale to New Horizons (NH). Interesting that 50% of the instruments proposed have NH heritage too, and that the proposed orbiter itself looks superficially like New Horizons.

Aerocapture seems to be a serious consideration, albeit with a $150-$200 million price tag for development.

Science priorities are focussed on atmosphere/magnetosphere/gravity and thermal emission science with satellite imagery taking a back seat. Without wanting to be controversial, I wonder how memorable to the general public the Cassini mission would have been had the satellite observations been descoped due to costs....

That said, I'm all for a mission of any description to an ice giant, I just hope I'm around to marvel at the results.

[Floyd]

I hope I'm around too, but turning 70--so I need to have data coming back by 2036 if I make it to 90 (with luck), 2046 if I make it to 100 (not too likely).

[acastillo]

Recent material on mission studies for Uranus and Neptune.

Fact chart on the Oceanus mission:
http://www.lpi.usra.edu/opag/meetings/aug2...sters/Elder.pdf

More comprehensive presentation on the status of mission studies done at JPL:
http://www.lpi.usra.edu/opag/meetings/aug2.../Hofstadter.pdf


I just hope to see one of these missions in my lifetime. These are amazing worlds in the own right.

[Explorer1]

Slide 15 of the second PDF is rather amusing, with the comically large panels; thanks for the links though!

[Juramike]

Well might as well post this here, too. Was our Planetary Science School study of a Neptune flyby mission. Went through Team X.

Presentation on TRIDENT student exercise study for a Neptune mission that was presented at the Outer Planets Assessment Group (OPAG).
http://www.lpi.usra.edu/opag/jan2014/prese...s/17_uckert.pdf

Full article (Alibay et al., IEEE) is available on ResearchGate: https://www.researchgate.net/publication/26...eptunian_system

(at the time of the study, we only had an Atlas 551 launch vehicle available. We tried for an orbiter mission, but in the end had to settle for a flyby mission trying to keep under a $1B cost cap.)

[Station]

Hello,

Any update about studies around Uranus / Neptune mission? Is there any hope such mission will be launched till, lets say, 2030 ?

I cannot imagine noone (any space agency) is not interested in sending a probe to these two celestial bodies. The Voyager data are just nothing more than a tip of the iceberg...

Meanwhile it seems there will be .... 3 missions to Europa...

[Paolo]

you may want to check presentations and finidings of the latest OPAG meeting
http://www.lpi.usra.edu/opag/

[JRehling]

I would hope that the several newer national space programs will start to carve out niches for themselves, exploring some places that are otherwise being ignored. For the time being, it's not surprising that these programs have sent a few missions to the Moon and Mars, but perhaps they'll branch out to plant their metaphorical flag somewhere they can be first. But Uranus and Neptune aren't easy targets to start with, and don't provide a speedy payoff in terms of PR and national pride.

The outer solar system has several remarkable targets competing for few launches with very long cruise times. Uranus and Neptune could get bumped by other priorities for a long time. In the meantime, the capabilities of Earth-based telescopes are improving dramatically, and those two planets themselves will be monitored remotely more or less continuously from now on. The satellites, however, are hard to resolve without a dedicated mission.

[Station]

Imho there is no other option than sending dedicated orbiter (or even a lander) to the uranian / neptunian system. You will never get such dramaticaly high quality photos of Uranus' moons using earth-based hardware. Moreover, many in-situ "investigations" give much more answers than pointing the telescope localised on Earth.

[Jackbauer]

ICE GIANTS PRE-DECADAL STUDY FINAL REPORT
(NASA)

https://twitter.com/jjfplanet/status/874366189622796288

[antipode]

Golly, now lets see what comes of it.
I'll be in my rocking chair if and when these things deliver but my god they are needed.

P

[stevesliva]

To ensure that the most productive mission is flown, we recommend the following:
• An orbiter with probe be flown to one of the ice giants
• The orbiter carry a payload between 90 and 150 kg
• The probe carry at minimum a mass spectrometer and atmospheric pressure, temperature,
and density sensors
• The development of eMMRTGs and HEEET be completed as planned
• Two-planet, two-spacecraft mission options be explored further

Launch would be 2030, arrival 2043 for Neptune
Launch would be 2031, arrival 2043 for Uranus

All of the above: Orbiter and Probe for both projected to cost $3.671B ... $125M per year for the next 30 years.

[Decepticon]

I get sad seeing those dates. I don't know if I'll be on earth anymore to observe those missions.

Uranus moons have so much to show us still.

[Explorer1]

A launch on the SLS to avoid a bunch of inner solar system gravity assists would speed the trip up.
Trouble is, getting to the ice giants faster means using more delta-v to slow down, as the paper notes. There must be some good balance of the two pressures. We can always hope for a propulsion breakthrough...

[craigmcg]

This week's Planetary Radio also mentioned briefly that there was an option to fly Cassini to Uranus, although she characterized it as a "1%" option.

http://www.planetary.org/multimedia/planet...er-cassini.html

[Explorer1]

There were a number of such concepts for Cassini EOM. More details here (http://www.lpi.usra.edu/opag/march_08_meeting/presentations/spilker.pdf)
20 (!) years to get to Uranus after Saturn escape! Easier to just go from Earth with a whole new mission.

[tedstryk]

Launch would be 2030, arrival 2043 for Neptune
Launch would be 2031, arrival 2043 for Uranus

Brings new meaning to, "When I'm 64" (or 63 if it's early in the year).

[Explorer1]

On the bright side, if a orbiter is at Neptune in April 2046 with a good imager, it will have quite the show: http://xplanet.sourceforge.net/Gallery/20460429_jupiter/

[James S.]

On the bright side, if a orbiter is at Neptune in April 2046 with a good imager, it will have quite the show: http://xplanet.sourceforge.net/Gallery/20460429_jupiter/

That would be awesome. I'll be 79 if I'm still alive.

[Explorer1]

Looking at the maps of the solid bodies in the outer solar system, I figured this to be the best place to ask (as we all want better maps!):
Given the high axial tilts of the Uranian moons (and Triton), when combined with their lengthy seasons, how would an orbiter conduct mapping the geography/geology of the unlit hemispheres? As we saw at Pluto, one ends up with a giant fraction of the map remaining completely unknown; even a future Pluto orbiter would have to wait many decades for sunlight to reach the southern hemisphere.
What sort of instrumentation could deal with this? There is only so much reflected light from the planet one can use like Cassini did (and even then only for the planet-facing hemisphere). Is RADAR like Cassini's practical at all? Something like MOLA on Mars Global Surveyor? Star occultations behind the limb during a flyby could get outlines of particular dramatic topography, like Miranda's canyons? Maybe a really big flashlight? Just brainstorming, and I'm curious if anyone else has thought about it.

[tasp]

Here's a combined view of Enceladus in light and radar (radar scan is in the arc shaped area). Radar appears to have worked quite well. (Haven't posted a picture here in years, hope I do it right)

[ngunn]

That's a really interesting enquiry. I would first like to add a complicating factor which is that the superficial appearance of these bodies may change significantly on a seasonal timescale. For example the parts of Pluto and Triton that we saw by day might look quite different during a long polar night as a result of 'repainting' by mobile volatile materials. Even a perfect night-time flashlight might show a different map. That said, the topography would not change and that could be reliably mapped by radar. How much do we learn from visible light images compared with a really good topographic survey? I don't know but would be interested in expert opinions.

[JRehling]

A few thoughts here…

A mission that arrived just before equinox would soon see the entire surfaces of the whole system, so that would be one approach (two flyby craft would be another), but doesn't address the question of seasons.

These worlds have a lot less gravity than Triton or Pluto and they're much closer to the Sun, so I'd be skeptical about seasonal dynamics on a grand scale.

It's always possible that a seasonal change would consist of a very thin layer that has profound implications for albedo but would be invisible on the scale of geomorphology. Earth and Mars both show such things. Radar may see right through a thin layer, but depending upon its dielectric properties, may see it as a major change in radar albedo.

I don't think radar is likely to make the cut for a Uranus orbiter simply because the use case is speculative and radar is both heavy and places constraints on the trajectory (very close encounters are required).

In terms of seeing dark sides in uranus-shine, the geometry produces a quirky result. Near uranian solstice, half of each moon would be seen in daylight. Half of the other half could be lit favorably for uranus-shine observations. So, we might end up with 3/4 of each moon mapped.

Keep in mind that terrestrial telescopes are going to be able to observe uranian moons with increasing resolution as the massive South American telescopes come online in the next decade, so we might get some imaging of value to supplement whatever a mission would fail to see.

My suspicion for all of the above, though, is that we're whistling past the graveyard. I don't think Uranus or Neptune are going to get an orbiter until Europa, Titan, and Enceladus each have a turn or two in the queue, and we're talking about a good chunk of a century before that would run its course.

If the Breakthrough Starshot technology to visit another star goes anywhere, Uranus and Neptune might make some nice test cases, though.

[antipode]

Outer Solar System Exploration:
A Compelling and Unified Dual Mission Decadal Strategy for
Exploring Uranus, Neptune, Triton, Dwarf Planets, and Small KBOs and Centaurs
A.A. Simon (NASA GSFC), S.A. Stern (SwRI), M. Hofstadter (Caltech/JPL)

https://arxiv.org/ftp/arxiv/papers/1807/1807.08769.pdf

Yep, not perfect (I'd prefer the Uranus orbiter and the Nepture / KBO flyby) but I understand the rationale.
Something has got to happen soon, or just about everyone on this board will be pushing up daisies before we return to the outer solar system.

P

[James S.]

Outer Solar System Exploration:
A Compelling and Unified Dual Mission Decadal Strategy for
Exploring Uranus, Neptune, Triton, Dwarf Planets, and Small KBOs and Centaurs
A.A. Simon (NASA GSFC), S.A. Stern (SwRI), M. Hofstadter (Caltech/JPL)

https://arxiv.org/ftp/arxiv/papers/1807/1807.08769.pdf

Yep, not perfect (I'd prefer the Uranus orbiter and the Nepture / KBO flyby) but I understand the rationale.
Something has got to happen soon, or just about everyone on this board will be pushing up daisies before we return to the outer solar system.

P

Thanks for the info, my friend. I hear you in that I do hope something does happen soon as I'm 51 and if it doesn't, I'll be pushing up daisies like you said. It would be a dream come true, a proper exploration of Uranus & Neptune.

James

[JohnVV]

Thanks for the info, my friend. I hear you in that I do hope something does happen soon as I'm 51 and if it doesn't, I'll be pushing up daisies like you said. It would be a dream come true, a proper exploration of Uranus & Neptune.

James

51 also , and if things do not change soon then....

well there is still a lot of older imaging data to work through with new tools

[scalbers]

Concepts for Uranus and Neptune from our now 2020 vantage point:

https://eos.org/articles/the-ice-giant-spac...t-of-our-dreams

[antipode]

Interesting, if speculative paper on the ArXiv today about possible electrodynamic tether spacecraft capture into orbit at Neptune.

https://arxiv.org/pdf/2003.07985.pdf

Given the similarities between both ice giants with respect to size, mass, offset dipole and field strength, I cant see why this wouldn't apply to Uranus too?

P

[antipode]

Here's the OPAG paper on the arXiv. The summary is interesting.

https://arxiv.org/ftp/arxiv/papers/2003/2003.11182.pdf

P

[antipode]

White paper for a New Frontiers class mission to Uranus.

"A New Frontiers Class
Mission for the Uranian System that Focuses on Moon, Magnetosphere, and
Ring Science"

https://drive.google.com/file/d/1YL_-_y5lSg...-GpXiZrp7k/view

P

[Explorer1]

Uranus flagship mission!
And atmospheric probe:
https://nap.nationalacademies.org/catalog/2...anetary-science

Web Announcement in a few hours here: https://www.nationalacademies.org/event/04-...e-survey-report

Now to be prepared for a decade and a half of late night TV comedian jokes...

[antipode]

This is great news! Finally. Lets hope it happens.

Should be called 'Herschel', but of course that's been taken.

I hope the probe doesnt end up getting descoped.

P

[Bill Harris]

Asinine jokes aside, this will prove to be an epic mission.

[Phil Stooke]

"The planet that dare not speak its name"

Phil

[StargazeInWonder]

Proposals for Uranus orbiters have had flight times of about 12 years before arrival. We might optimistically expect this mission to begin in the early 2040s. Let's hope that we're all around to see this happen. Results from a Neptune orbiter are starting to look unlikely for anyone who's currently over the age of 40.

[Decepticon]

A Neptune flyby would be acceptable for me at least.


Is Neptune/Eris encounter possible with a New Horizons type mission?

[antipode]

I imagine the geometry that would allow that kind of trajectory would be very rare.

I wonder if any of the really big KBOs might be in the right position at some stage in the near future?

P

[StargazeInWonder]

There are a lot of KBOs. It wouldn't be difficult at all to have a Neptune flyby continue on to make a targeted flyby of one of them, but there would be a tradeoff between the choice of the desired KBO and the choice of the trajectory through the Neptune system, which would surely make Triton a major priority, but would allow at least some flexibility by choosing where in its orbit Triton would be at encounter time.

But to visit at least one KBO wouldn't be a challenge. I know that the scale is deceptive, but this almost makes it seem like it'd be hard not to come close to one of them after the Neptune encounter.

https://en.wikipedia.org/wiki/Kuiper_belt#/...olar_system.png

[owlsyme]

I came across this movie of Uranus and its moons moving against the stars -



"The featured video captured by the Bayfordbury Observatory in Hertfordshire, UK is a four-hour time-lapse showing Uranus with its four largest moons in tow: Titania, Oberon, Umbriel and Ariel. Uranus' apparent motion past background stars is really dominated by Earth's own orbital motion around our Sun."

https://apod.nasa.gov/apod/ap211130.html