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Dwarf Planet Eris, formerly known as 'Xena'
stevesliva
post Sep 15 2006, 03:53 PM
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QUOTE (dvandorn @ Sep 14 2006, 10:01 PM) *
It's sort of like going into the Harry Potter universe and naming a new planet 'Voldemort,' if you know what I mean.

So you've got me searching the minor planet names list:
http://cfa-www.harvard.edu/iau/lists/MPNames.html

There is a "(1930) Lucifer." There must be some others in there.

Actually, I'm surprised by the dearth of "evil" names. I'd love to name some asteroids War, Famine, Pestilence and Death.
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dvandorn
post Sep 15 2006, 04:02 PM
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Here's one from that list that caught my eye:

(25924) Douglasadams

If that's a NEO, maybe, at some time in the far future, it *will* be time for the dolphins to say "So long, and thanks for all the fish"... laugh.gif

-the other Doug


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ljk4-1
post Sep 15 2006, 05:09 PM
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QUOTE (stevesliva @ Sep 15 2006, 11:53 AM) *
So you've got me searching the minor planet names list:
http://cfa-www.harvard.edu/iau/lists/MPNames.html

There is a "(1930) Lucifer." There must be some others in there.

Actually, I'm surprised by the dearth of "evil" names. I'd love to name some asteroids War, Famine, Pestilence and Death.


I've heard that Mars has two moons with names like that....

wink.gif


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and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
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not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

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Jyril
post Sep 15 2006, 06:33 PM
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QUOTE (dvandorn @ Sep 15 2006, 07:02 PM) *
Here's one from that list that caught my eye:

(25924) Douglasadams

If that's a NEO, maybe, at some time in the far future, it *will* be time for the dolphins to say "So long, and thanks for all the fish"... laugh.gif

-the other Doug


It is a regular asteroid. But look at its provisional designation, 2001 DA42: 2001 is the year of his death, DA his initials and 42...

The name of the asteroid (18610) Arthurdent was supposedly published on the day of his death. However, the name was actually published a few days earler. A sick quirk of fate anyway...


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yg1968
post Oct 7 2007, 06:20 PM
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Would a mission to Eris be possible? Is anybody talking about it?
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alan
post Oct 7 2007, 08:52 PM
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Eris is currently 97 AU from the sun. It took Voyager 1, currently the most distant functioning probe, nearly 30 years to reach that distance. NASA probably would have to develop some new propulsion technology before a mission to Eris would be considered.
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Greg Hullender
post Oct 7 2007, 10:33 PM
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Dawn manages an acceleration of 7 m/s/d or about 81 microns/sec^2. :-) If it could accelerate full-time half-way to Eris and then decelerate full-time the other half, I figure it'd take under 70 years. However, if we could kick that up to 50 m/s/d, then it'd take right at 10 years.

(Someone should double-check these figures before launching their own mission, of course.) :-)

--Greg
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dvanavery
post Oct 8 2007, 04:03 AM
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QUOTE (alan @ Oct 7 2007, 04:52 PM) *
Eris is currently 97 AU from the sun. It took Voyager 1, currently the most distant functioning probe, nearly 30 years to reach that distance. NASA probably would have to develop some new propulsion technology before a mission to Eris would be considered.


Yes, but the Voyager trajectories were formulated with something other than raw speed to the outer Kuiper belt in mind. I'm not saying that new propulsion tech wouldn't be needed, but I would bet something substantially faster than V1 could be sent using present day tech (and some well timed flybys of outer planets along the way). You might have to wait a decade or five for the proper alignment to reach Eris, though.

this brings up an interesting question, what is the fastest possible solar system escape velocity possible using only presently available launch vehicles and gravitational assists from th outer planets? Assume you have an RTG-powered mission of some useful mass (300-500kg, no ion thrusters of any kind, no solar sails..........), basically a New Horizons clone, and no new propulsion tech. What's the theoretical maximum? There are probably once-in-a-millennium alignments of Jupiter and Saturn that would allow for speeds well in excess of anything we've sent so far. Someone has to have done a simulation at some point......

-dave V.
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edstrick
post Oct 8 2007, 04:22 AM
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Probably some perfect "grand tour" type alignment, where each spacecraft-planet encounter is as close-in to the planet as possible for a departure trajectory that's approximately tangent to the planet's orbit or as close to tangent as possible.
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JRehling
post Oct 8 2007, 05:22 AM
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QUOTE (edstrick @ Oct 7 2007, 09:22 PM) *
Probably some perfect "grand tour" type alignment, where each spacecraft-planet encounter is as close-in to the planet as possible for a departure trajectory that's approximately tangent to the planet's orbit or as close to tangent as possible.


Eris is also well off of the ecliptic at present (and for a long time coming). I doubt that keeping things in the ecliptic for three flybys then counting on Neptune to provide all of the work to acquire a high inclination is feasible. Maybe a Jupiter-Saturn combo could do it, assuming the rings weren't a problem.

That would actually be a scenario that would unfold fairly often.

Uranus is actually in a pretty good position right now for an assist to Eris, but it'll soon move out of that good position and not come back for 8 decades. Neptune, however, is moving into position, but again, Neptune can't bend the path down in very good proportion to Jupiter's bending it out.

In only 230 years or so, Eris will come within 40 AU of the Sun. Let's plan on an Eris Orbiter/Lander then. Start the buzz now.
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jamescanvin
post Aug 12 2008, 03:13 PM
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Moved posts to a new thread The Great Planet Debate conference

Will make it easier to close when the arguments start wink.gif (I hope i'm wrong, play nice.)


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Juramike
post Nov 19 2008, 09:33 PM
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Eris has weather!

space.com article about seasonal atmospheric ices transfer on Eris: http://www.space.com/scienceastronomy/0811...arf-planet.html

Nitrogen sublimates first, then deposits first on the colder pole.
Methane sublimates next, then deposits on top of nitrogen on the colder pole.

If I understand this correctly, the layering would be unstable, with the more volatile (nitrogen woofs off at a lower temperature) component buried under the methane layer.

Could make some really impressive nitrogen jets through the methane ice surface during the spring "warm up".

-Mike


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MarcF
post Oct 27 2011, 07:51 AM
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In the journal Nature from today:

"A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation
B. Sicardy et al.
The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 ut. The event is consistent with a spherical shape for Eris, with radius 1,163 ± 6 kilometres, density 2.52 ± 0.05 grams per cm3 and a high visible geometric albedo. No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ~1 nanobar, about 10,000 times more tenuous than Pluto's present atmosphere. As Pluto's radius is estimated to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun."

Cheers,
Marc.
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Paolo
post Oct 27 2011, 08:53 AM
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I just read the Nature paper. Eris is quite an interesting object.
a few notes:

- Eris is probably a rocky body with an icy crust. its density is quite higher than that of Pluto (almost 30 p.c.) and of other KBO but compatible with that of Makemake.
- Eris is one of the brightest objects in the solar system. its albedo is 0.96. only Enceladus has a greater albedo

too bad I fear none of us will be around when Eris gets its first visit sad.gif


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