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Posted by Thomas Lee Elifritz on October 9, 2006, 2:56 pm
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CERES - Ceres Experimental Reconnaissance and Exploration Spacecraft.
We're talking about a small planet out there, with lots of water.
Dawn is great, but we need a real Ceres Reconnaissance Orbiter.
We can get it down tight, and then map it to the square foot.
http://cosmic.lifeform.org
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Posted by Chip Flintknapper on October 25, 2006, 6:38 am
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Thomas Lee Elifritz wrote:
> CERES - Ceres Experimental Reconnaissance and Exploration Spacecraft.
>
> We're talking about a small planet out there, with lots of water.
>
> Dawn is great, but we need a real Ceres Reconnaissance Orbiter.
>
> We can get it down tight, and then map it to the square foot.
>
> http://cosmic.lifeform.org
Wow, thanks Thomas, I got 42 photos of Enceladus (a moon of Saturn) out
of that link. They were quite large and viewable.
I have a large collection of solar moons, mostly jpegs, but many png's
as well, and this one was new to me.
But there are so many of them, I suppose that new ones will always be
getting "discovered".
By the way, I am against declassifying Pluto as a planet, and I think
the folks behind it are just nitpickers. How about if they fly up there
and prove that something besides philosophy can be done.
Three cheers for exploration, and forget the theories! Let's get off our
duffs and do it.
It has been told that there are great globs of ice orbiting around
Jupiter. What if we were to tow a few of them to Mars, and shave them,
and put them into the atmosphere? Do you think it might begin to rain on
Mars? I do.
Great day,
//mh
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Posted by Thomas Lee Elifritz on October 25, 2006, 10:52 am
Please log in for more thread options Chip Flintknapper wrote:
> Thomas Lee Elifritz wrote:
>> CERES - Ceres Experimental Reconnaissance and Exploration Spacecraft.
>>
>> We're talking about a small planet out there, with lots of water.
>>
>> Dawn is great, but we need a real Ceres Reconnaissance Orbiter.
>>
>> We can get it down tight, and then map it to the square foot.
>>
>> http://cosmic.lifeform.org
>
> Wow, thanks Thomas, I got 42 photos of Enceladus (a moon of Saturn) out
> of that link. They were quite large and viewable.
Actually, we just added Enceladus as a secondary planetary 'class' of
'ice moons' on the Meghar Scale of Planetary Mass :
http://cosmic.lifeform.org/?p=222
http://cosmic.lifeform.org/?p=166
and I posted a thread about it :
http://groups.google.com/group/alt.sci.planetary/msg/1db389a0aa644b08?hl=en&
These are very tiny 'planets' (when found in extrasolar systems) but on
the other end of the scale, super gas giant planets and brown dwarfs are
very 'large'. That's ten decimal orders of magnitude in planetary mass,
before one moves into the realm of 'dwarf stars' and ordinary stars.
>
> I have a large collection of solar moons, mostly jpegs, but many png's
> as well, and this one was new to me.
>
> But there are so many of them, I suppose that new ones will always be
> getting "discovered".
Use this page as a start :
http://en.wikipedia.org/wiki/List_of_solar_system_objects_by_mass
And then when you click on an asteroid you get an asteroid navigator
link at the bottom to page through the entire list of them :
http://en.wikipedia.org/wiki/List_of_solar_system_objects_by_mass
Many of them are quite large, as are many of the ice moons, and there
are often good photos of them, for instance :
http://en.wikipedia.org/wiki/Proteus_%28moon%29
Discovered by Voyager 2 en route, and then imaged up close. For
instance, if we had a Triton orbiter, we could probably learn a great
deal about Proteus as it flies right by Triton every single day.
> By the way, I am against declassifying Pluto as a planet, and I think
> the folks behind it are just nitpickers. How about if they fly up there
> and prove that something besides philosophy can be done.
It certainly should be retained as a representative of a planetary
'class' of objects, as certainly Ceres should too. Ceres is awesome. If
a previously neglected fifth planet that is largely unknown doesn't
excite school children, then I just don't know what would. We need to be
a dedicated high resolution Ceres Reconnaissance Orbiter out there now.
At the very least it should be ready to launch by 2015. If we could get
it in the queue now, then possibly Dawn could be redirected to Pallas.
> Three cheers for exploration, and forget the theories! Let's get off our
> duffs and do it.
Well, these dedicated missions run about 750 million dollars. If we
could get a standard multiple asteroid rendezvous mission down to the
250 million dollar range, and a new Deep Space Network to handle the
data, then we could start mapping out entire ranges of larger classes.
If we can't get private industry involved, it will have to be nations.
> It has been told that there are great globs of ice orbiting around
> Jupiter. What if we were to tow a few of them to Mars, and shave them,
> and put them into the atmosphere? Do you think it might begin to rain on
> Mars? I do.
Right now we're just thinking about automated regolith collection
devices, where the regolith is 'pumped' into empty fuel tanks for future
use as astronaut shielding. Shielding is the biggest requirement for
manned two year duration missions to Phobos, Ceres and the asteroids.
Regolith characterization is also required for any resource utilization.
The next big mission will be a Phobos sample return mission, hopefully
the Russians and the Japanese will collaborate on it, as the Japanese
now have experience, and the Russians are anxious to get over their
previous planetary mission failures to Mars and Phobos.
> Great day,
Thanks, you as well.
http://cosmic.lifeform.org
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Posted by Margo Schulter on October 26, 2006, 4:56 am
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> Actually, we just added Enceladus as a secondary planetary 'class' of
> 'ice moons' on the Meghar Scale of Planetary Mass :
>
> http://cosmic.lifeform.org/?p=222
>
> http://cosmic.lifeform.org/?p=166
>
> and I posted a thread about it :
>
> http://groups.google.com/group/alt.sci.planetary/msg/1db389a0aa644b08?hl=en&
>
> These are very tiny 'planets' (when found in extrasolar systems) but on
> the other end of the scale, super gas giant planets and brown dwarfs are
> very 'large'. That's ten decimal orders of magnitude in planetary mass,
> before one moves into the realm of 'dwarf stars' and ordinary stars.
Hello, there, Thomas, and please let thank you for your many posts, and
express my regrets for not participating in these dialogues more often.
The Enceladus class makes sense, of course, when we realize that the mass
requirements for hydrostatic equilibrium or gravitational relaxation are
lower for icy than for rocky planets. This is one reason why I'm in favor
of an even more inclusive definition of "planet" than the hydrostatic
equilibrium test, which in the approach I advocate more specifically
defines a "macroplanet," in contrast to microplanets such as 243 Ida or
25143 Itokawa which can take a variety of shapes.
We could also, in this approach, call Enceladus a very small
"macrosatellite" or "macrosecondary."
I'd be very interested in getting any feedback on a recent paper, which
might be most relevant here because how one approaches the general scope
of the term "planet" can affect one's approach to finer classifications.
<http://www.bestII.com/~mschulter/inclusive_planet_def100.txt>
>> But there are so many of them, I suppose that new ones will always be
>> getting "discovered".
>
> Use this page as a start :
>
> http://en.wikipedia.org/wiki/List_of_solar_system_objects_by_mass
Yes, I like this list very much too!
. . . .
>> By the way, I am against declassifying Pluto as a planet, and I think
>> the folks behind it are just nitpickers. How about if they fly up there
>> and prove that something besides philosophy can be done.
>
> It certainly should be retained as a representative of a planetary
> 'class' of objects, as certainly Ceres should too. Ceres is awesome. If
> a previously neglected fifth planet that is largely unknown doesn't
> excite school children, then I just don't know what would. We need to be
> a dedicated high resolution Ceres Reconnaissance Orbiter out there now.
> At the very least it should be ready to launch by 2015. If we could get
> it in the queue now, then possibly Dawn could be redirected to Pallas.
Please let me certainly agree that belt planets deserve a lot more
recognition. On 1 January 1801, Giuseppe Piazzi discovered not only a
new planet, but a new _type_ of planet -- Ceres, indeed fifth macroplanet
from the Sun and the first known belt planet. By the way, while I use
"minor planet" in my paper because it's a traditional term, "belt planet"
might be more specific and descriptive.
Those first enigmatic images showing some of the topography should indeed
impel us to more adequate observations -- the questions of differentiation,
geology (to use a geocentric term!), and water should add an irresistible
edge to our thirst for knowledge.
The same kind of observation, of course, can be made for Clyde Tombaugh
and the discovery not only of Pluto in 1930 but, as it turned out, the
first KBO, and more generally TNO. If discovering a single planet like
Uranus or Neptune is a notable achievement, which of course it is, how
about discovering a whole new community of planets? There seems something
ungenerous about attempting to restrict the concept of "planet" when our
knowledge of an immense variety of planetary bodies is radically increasing,
both in our own Solar System and in other stellar systems.
Maybe our problem is what I'm tempted to call the "Microsoft definition of
planethood" -- a celestial body only deserves recognition as a planet if it
controls 99% of the neighborhood market. As we've both written, there are
fascinating planetary dynamics other than clearing the neighborhood -- filling
it can be interesting too (thanks for this way of putting it).
The Enceladus class does highlight one reason why I'm in favor of an inclusive
definition of planethood long urged by people such as Daniel Green of the
Minor Planet Center and attested in places like the OED -- basically anything
larger than a meteoroid, say at least 10-100 meters across, and smaller than a
"star" (however we define that, with the deuterium fusion limit of around
13 Jupiter masses or otherwise, another topic for dialogue with various
views).
If hydrostatic equilibrium sets the lower limit for a "planet" -- as opposed
to a macroplanet, where I find it a useful if sometimes fuzzy line -- then
what about 4 Vesta, considerably more massive than a macroplanetary body such
as Enceladus, but evidently not quite massive as a rocky planet to be fully
gravitationally relaxed?
Indeed Vesta seems to be a differentiated small terrestrial planet -- but must
one either possibly stretch the hydrostatic equilibrium test, or else risk
having to exclude Vesta from planethood? The advantage of also including
microplanets like 243 Ida is that the question of Vesta becomes much more
pleasant and the dilemma much more gentle: Is Vesta one of the smallest rocky
macroplanets or largest rocky microplanets?
This is where general approaches to planetary definitions can affect finer
classifications. While Stern and Levison use the term "dwarf" for the size
range of the major or dominant terrestrial planets or our Solar System and
"subdwarf" for rocky or terrestrial planets such as Ceres as well as icy
planets such as 134340 Pluto (and now also 136399 Eris, for example), the
IAU use of the term "dwarf planets" for the latter might invite some
modification of this nomenclature.
While an IAU "dwarf planet" basically means any belt macroplanet, it happens
that in our Solar System (so far!) the known belt macroplanets are
consistently smaller than the major or dominant ones. However, if the term
does stick and becomes associated generally with the smallest classes of
planets in hydrostatic equilibrium (whether dominant or belt), then maybe
"rocky subdwarf" could be descriptive for Vesta, and "rocky superdwarf" for
a planet like our Earth.
Of course, I realize that the Meghar Scale is much finer even than the
Stern/Levison scheme with five categories for what I term macroplanets. If we
recognize the planethood of microplanets as well -- and possibly even
craft a middle category of "mesoplanets" such as Vesta largely but not quite
"regularly" shaped by self-gravity -- then finer classifications would become
yet more intriguing and awesome, encompassing yet more orders of magnitude.
At this point I'm considering, on a kind of Stern/Levison-like level, an
"eightfold way" with three categories of microplanets plus their five
categories of macroplanets. The scheme would go generally like this, again
with the Stern/Levison "subdwarf" and "dwarf" for the smallest macroplanets
becoming "dwarf" and "superdwarf" (with a caution for terrestrials not to
this label serve as a prompting to hybris). This table is for planets
below the deuterium fusion limit -- leaving it open how the whole
brown dwarf or "fusor" question gets addressed for substars not reaching
the main sequence:
--------------------------------------------------------------------------
Macroplanets -- gravitationally relaxed
--------------------------------------------------------------------------
Supergiant 2-13 Jupiter masses
Giant 100 Earth masses - 2 Jupiter masses
Subgiant 10-100 Earth masses
Superdwarf 0.03-10 Earth masses
Dwarf <0.03 Earth masses, with hydrostatic equilibrium
--------------------------------------------------------------------------
Microplanets -- may have various shapes
--------------------------------------------------------------------------
Subdwarf >100 km, without full hydrostatic equilibrium
Planetesimal 1-100 km
Subplanetesimal <1 km, larger than meteoroid (at least ~10 m)
--------------------------------------------------------------------------
I'm indebted to Gibor Basri as well as Stern/Levison and others for much
of this scheme, although I can claim credit for what might be considered
dubious additions, revisions, and introduced flaws <grin>.
Anyway, I hope that there can be dialogue on this whole question of
classes and terminology, as belt planet discoveries move further into
a very exciting third century.
Most appreciatively,
Margo Schulter
mschulter@calweb.com
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Posted by Hop David on October 25, 2006, 8:47 pm
Please log in for more thread options Chip Flintknapper wrote:
> It has been told that there are great globs of ice orbiting around
> Jupiter. What if we were to tow a few of them to Mars, and shave them,
> and put them into the atmosphere? Do you think it might begin to rain on
> Mars? I do.
Using Trojan globs of ice from Jupiter-sun L4 and L5 points, you
wouldn't have to escape Jupiter's gravity well.
Hop
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