Ceres, More Fresh Water Than Earth!?, From Space.com Options

[Decepticon]

Fans of Ceres will find this article interesting.

The 200 Plus Images are something I would love to get my hands on. Rotation animation Anyone!?


http://www.space.com/scienceastronomy/0509...res_planet.html

[JRehling]

Fans of Ceres will find this article interesting.

The 200 Plus Images are something I would love to get my hands on. Rotation animation Anyone!?
http://www.space.com/scienceastronomy/0509...res_planet.html

HST raw images tend to eventually end up on the query-able release site... it depends on what is proprietary and for how long... I made a color composite from HST Ceres images as far back as '97.

[Decepticon]

Have you posted those yet? I would love to add that to my Ceres archive.

[David]

Interesting images. I've been comparing them with earlier telescopic images. The bright spot is definitely something new. It seems to me that Ceres is divided into lighter and darker colored halves, though the boundary is more irregular than the one on Iapetus (and the albedo differences are not so great). "Piazzi", presumed to be a crater, is a dark circular or oval formation somewhat more than half surrounded by lighter "arms" or lobes. I believe this formation is observable in the new pictures as well (though possibly it is simply a similar formation located on the opposite side of Ceres from the older images). In any case, the very bright spot is located approximately in the center of the light hemisphere and is definitely not seen on the older images. Possibly the region in which it occurs was not previously imaged, but I do not think so. I am wondering whether Ceres may, through some strange mechanism, be active. Enceladus is smaller, and yet turns out to be far more interesting than expected. Might not Ceres be more than an inert lump of ice and rock? Even if it turns out that Ceres is inactive, the composition of the bright spot should be very interesting.

[edstrick]

Ceres has long been suspected to be more than a totally undifferentiated ball of hydrated silicates. It's further out in the belt where things with water of hydration in minerals start to show up and S-types are declining or low in abundance, I can't recall if it has some in the infrared spectrum... stuff like Serpentine type minerals (hydrated olivine/pyroxene)

It continues to be astonishing how un-battered it looks. Pretty smooth circular limb and no obvious gouges and big-mother craters as it rotates. A planetino indeed!

We've been all hot about Vesta for years, with it's basaltic spectrum and probable pieces in meteorite collections, but what about the other "Big 2".. Juno and Pallas. One or both has very non-usual specta, not all that similar to other asteroids, though nothign really spectacularly unusual like Vesta. Juno, I think is in a very high inclination orbit.

[SigurRosFan]

Hubble Press Release Images: Largest Asteroid May Be 'Mini Planet' with Water Ice

http://hubblesite.org/newscenter/newsdesk/.../2005/27/image/

[Decepticon]

Looky Looky a great animation of Ceres rotation!

http://hubblesite.org/newscenter/newsdesk/...2005/27/video/a


I wonder how image stacking would help bring out more detail on Ceres.


EDIT: Opps! SigurRosFan Beat me to it.

[Jyril]

It continues to be astonishing how un-battered it looks.  Pretty smooth circular limb and no obvious gouges and big-mother craters as it rotates.  A planetino indeed!

Well, a body of its size is easily spherical, and with Hubble's resolution not much is visible anyway. It could be saturated with smaller craters.

Juno, I think is in a very high inclination orbit.

No, it's Pallas which has very inclined orbit. Juno is by far the smallest and the most irregular of the first four asteroids.

[tfisher]

http://hubblesite.org/newscenter/newsdesk/...2005/27/video/a
I wonder how image stacking would help bring out more detail on Ceres.

Unfortunately, I'm pretty sure this animation is *not* a series of Hubble images, but rather a simulation based on a surface map based on Hubble images. So its of no use. You need to get the original images to work with.

[dvandorn]

So, it's relatively obvious that the largest of the main-belt asteroids (Ceres, Vesta, Pallas) are differentiated objects. My curiosity is whether or not these objects must have differentiated "in place," in other words, only in the context of their current mass, size and position.

Could they have once been part of a larger differentiated body that was destroyed by a massive impact? I guess we need a lot more data about the large asteroids, but I'm wondering how small a body can be and still undergo differentiation. When you consider that the Moon apparently is still predominantly made up of undifferentiated chondritic material, sandwiched between a once-molten core and a differentiated mantle and crust, we know that a Moon-sized body does not completely differentiate... and we also suspect that the Moon was formed by a giant impact which completely destroyed a Mars-sized body (which would have to have contained a lot of chondritic material for the Moon to contain a lot of it), so 1) the Mars-sized impactor must not have completely differentiated, and 2) lunar differentiation may not fit into a model of differentiation for primarily-accreted bodies.

Ceres lander/orbiter mission, anyone?

-the other Doug

[MizarKey]

Ceres lander/orbiter mission, anyone?

-the other Doug

Indeed -> DAWN mission to Ceres/Vista

Eric P / MizarKey

[SigurRosFan]

Basic data of the Dawn mission:

Launch - June 17, 2006

Vesta arrival - October 2011

Ceres arrival - August 2015

[gpurcell]

Killing the magentometer seems like a particularly bad idea right now....

[David]

Could they have once been part of a larger differentiated body that was destroyed by a massive impact?

That's the Good Old Theory, isn't it? I seem to recall that the "original fifth planet" played a role in some of the rollicking old space operas of the '40s and '50s. Then it was decided that any possible planet, even with the mass of the whole Main Belt, would have been pulled apart by Jupiter before it could ever form.
I'm not sure how reliable my logic on this is, but it seems to me that if Ceres is still spherical, it would have had to have formed in situ rather than as a result of a collision -- I don't think it's so big that, if it originated as an irregular fragment of a larger body, it would necessarily pull itself back into a sphere; compare the much larger Iapetus, which was evidently badly knocked about earlier in its history, and still shows the evident signs. Still, I suppose DAWN will tell us a lot more about Ceres' history; unfortunately we'll have to wait a long time for DAWN to get there!
Perhaps MER and Cassini will keep going long enough to keep me from getting bored. Ideally I'd like these missions to overlap enough that there will always be images coming back from some corner of the Solar System!

[ljk4-1]

I recall an illustrated story from a late 1970s graphic SF magazine about two astronauts who come upon a large smooth black sphere in the Planetoid Belt.

They can't figure out what it is and toss around all kinds of theories, until one of them thinks it may be the core of what was left of a gas giant planet that was somehow destroyed ages ago. They come to this conclusion just as the laser drill they placed on the black ball's surface starts cutting through....

[tedstryk]

Unfortunately, I'm pretty sure this animation is *not* a series of Hubble images, but rather a simulation based on a surface map based on Hubble images.  So its of no use.  You need to get the original images to work with.

If this was done like previous sets for targets that appear so small, the 200 images are probably sets of 50 at each of the four viewpoints shown in the image released possibly using different filters (but not always) and almost certainly multiple views at some or all wavelengths for a super-resolution effect. So the only way to make a movie would be to do what they did, or to make a four image animated gif, which could be done with what we have.

[Decepticon]

I can't believe the length of this mission.


Hardware failure possibilities goes up the longer the mission. What happens if something bad happens a week before Dawn arrives (*Knock On Wood*)??

[Marz]

I must say I found this article to be quite an eye-opener. I always thought of 'roids as boring lumps of rock, not this interesting! I wish ESA could launch a Ceres Express!

[tedstryk]

I can't believe the length of this mission.
Hardware failure possibilities goes up the longer the mission. What happens if something bad happens a week before Dawn arrives (*Knock On Wood*)??

The good thing that may come from this, according to what I have read, is that there may be multiple flybys of smaller asteroids along the way and in between the main targets.

[JRehling]

  Perhaps MER and Cassini will keep going long enough to keep me from getting bored.  Ideally I'd like these missions to overlap enough that there will always be images coming back from some corner of the Solar System!

There are currently three orbiters at Mars with one more cruising there now. In the meantime, Messenger will have flybys and a main mission returning images from much of the period between now and 2011, and Venus Express will have its mission in the meantime. Who knows how long Mars Smart Lander will last? And New Horizons will provide a quick flyby of the jovian system in 2007 before getting to Pluto in 2015. The Moon is sure to get still more attention (SMART is there now) from multiple countries by 2015. And a few small body missions are on the way.

Cassini may last decades, trumping all of this with a vast set of targets that will provide many discovery opportunities before we would become bored with the saturnian system.

The MERs won't last forever (moving parts are hell), but if left to stand and collect sunlight, with the occasional serendipitous cleaning event, they could last indefinitely, although their use will taper off if they lose mobility before something else gets them.

[edstrick]

I'm wondering...

If Ceres is differentiated into a rocky core and water-ice mantle with a dirt-layer on top...

Since it's closer to the sun, it's warmer inside than Callisto. Temperature is relatively high since the dirt is black.

The water ice, protected from 4 1/2 billion years of sunlight <more or less> by thickness and a dirt-layer, may be pretty damn soft, especially if small amounts of salts are present, leached out of the rock as it differentiated.

Ceres may not preserve craters ... even with low isotope heating and heat flow from inside, the ice may be so warm and soft that even in the low gravity, it just flows, turning craters into palimpsests, like craters on Enceladus, Ganymede and Callisto are relaxed. Very very interesting....

[SigurRosFan]

Back in August 2003:

--- Ceres apparently retains considerable volatile material. The latest gross properties indicate that Ceres has a density of about 2100 kilograms per cubic meter, suggesting that the body's composition may be half water (). Its density is similar to that of Ganymede (1940 kg/m3) and Callisto (1860 kg/m3). ---

http://www-ssc.igpp.ucla.edu/dawn/newslett..._evolution.html

[David]

Juno is by far the smallest and the most irregular of the first four asteroids.

Was it pure happenstance that Juno was the third asteroid discovered? It's only the thirteenth or fourteenth largest Main Belt asteroid, it's not particularly bright, and I can't really see that there's anything remarkable about it; why was it discovered before. say, Hebe, Iris, or Hygiea?

[SigurRosFan]

This article shows a limb profile.

HST Mapping of the Shape and Rotation Pole of Ceres

http://www-ssc.igpp.ucla.edu/dawn/newslett...df/20040831.pdf

[Decepticon]

Great Links Everyone! I'm also looking forward to next earth telescopes that will become operational over the next 10yrs. That way Ceres mapping will improve and help with the dawn mission.

I really do hope Ceres has more in common with the Jupiter moons.

[AndyG]

One big advantage of Ceres is that the opportunity for getting there repeats every 15.5 months - more often than Mars. Meanwhile the Hohmann flight time is about 470 days - not seriously worse than Mars. Indeed, it's almost weird that the asteroids haven't been better covered by missions before the ion-age. After all, it's still bright out there - a couple of hundred watts per square metre - and the low local gravities mean that multiple targets becomes an attractive option. Or is it all too O'Neillian? Finding accessible and potentially useful resources just a few thousand m/s of delta-V from cislunar space?

Andy G

[antoniseb]

One big advantage of Ceres is that the opportunity for getting there repeats every 15.5 months

I agree that it is strange that we haven't already made more missions to these places, but hey, we've only launched a few probes per year that escape Earth orbit, and that seems to be the budget. What an interesting coincidence that this giant water resource is already named after the Earth goddess.

[David]

One big advantage of Ceres is that the opportunity for getting there repeats every 15.5 months - more often than Mars. Meanwhile the Hohmann flight time is about 470 days - not seriously worse than Mars.

Huh. So as late as 2011 or 2012 we could launch a "Ceres Express" probe, and it would get to Ceres before DAWN?

[Bob Shaw]

Huh. So as late as 2011 or 2012 we could launch a "Ceres Express" probe, and it would get to Ceres before DAWN? 

David:

True, but... ...half the story.

Firstly, 'Ceres Express' wouldn't visit Vesta as well. Secondly, it might not be able to orbit Ceres except at great expense in terms of launch mass. And thirdly, it ain't funded!

Have a look at the attached trajectory diagram - in effect, Dawn carries out two missions for the price of one - and orbit insertion around two mini-planets, as well!

The asteroid size comparisons are also fascinating! These are *worlds*!

Bob Shaw

Attached thumbnail(s)

 

[David]

The asteroid size comparisons are also fascinating! These are *worlds*!

It's funny that at about the same time we find ourselves talking about how small Pluto is, and how big Ceres is.

[tedstryk]

It's funny that at about the same time we find ourselves talking about how small Pluto is, and how big Ceres is. 

Originally they called Ceres a planet and then demoted it for being too small. I always wonder if it had tipped the other way, and everything not a comet orbiting the sun was called a planet. It would have made the way the solar system is presented in school unrecognizable, but given the fact that there is apparently no great size gap that we once thought existed, it might actually have been a more realistic conception of our solar system than the one we were taught with nine planets neatly orbiting the sun.

[tedstryk]

Check out this version of the rotation movie. It is much more natural.

http://www.swri.org/press/2005/Images/ceres_movie.html

http://www.swri.org/press/2005/ceres.htm

[deglr6328]

I wonder if we are missing any other potential internal heating mechanisms possible besides tidal flexing and radioactive decay which could create a liquid ocean on small ice worlds like this......can't think of any though...

[alan]

When the bright spot is near the right limb it appears to be the central peak of a crater. A patch of ice poking through the darker crust perhaps?

[Decepticon]

Nice link tedstryk!

Its intresting to see so much detail on such a small body.

[Guest_Myran_*]

Its three different gif animations for the three frequency bands, and so the rotation for the three version may not be syncronised, its rather unlikely it will be in fact.

[SigurRosFan]

--- Its density is similar to that of Ganymede (1940 kg/m3) and Callisto (1860 kg/m3). ---

Ceres: The missing fifth galilean moon??

http://xs45.xs.to/pics/05360/Ceres_Jupiter_System.gif

[alan]

Wow, that makes Ceres look puny.

[Bob Shaw]

--- Its density is similar to that of Ganymede (1940 kg/m3) and Callisto (1860 kg/m3). ---

Ceres: The missing fifth galilean moon??

http://xs45.xs.to/pics/05360/Ceres_Jupiter_System.gif

Without wishing to labour the point, the Galilean moons *are* planets! Well, they would be if they were anywhere other than orbiting Jupiter (unless they were in the Kuiper Belt, when of course they'd be, er, you know, thingies. Wossernames...). And Ceres is a mini-planet at best...

[Decepticon]

Proto Planet

[SigurRosFan]

Well, they would be if they were anywhere other than orbiting Jupiter ...

Thus, Ceres is a mini-planet or a "embryonic planet"?

And the layered jupiter moons are capture-planets.

p.s. Er, what is a planet??

[Bob Shaw]

Thus, Ceres is a mini-planet or a "embryonic planet"?

And the layered jupiter moons are capture-planets.

p.s. Er, what is a planet??

Shhsh! If I tell you that, I must kill you...

[SigurRosFan]

...

Are there specifications for the maximal thickness of Ceres' ice layer somewhere?

[tedstryk]

This all makes me wonder...Is Vesta, being basaltic, part of the core/mantle of a destroyed planet in the asteroid belt, and is Ceres the largest attempted planet, with similar ratios to proto-Vesta, not to be destroyed. It would indeed be cool to find out that Ceres was an ejected galilean moon. But it is hard for me to see how it ended up in its current orbit in such a case.

Bob: The idea that the galileans are planets is an interesting idea....I have always thought that it would be a cool idea to define planet as worlds large enough to be reasonably spherical (nonwithstanding elongation from ultra-fast rotation) and possible sustain internal activity (maybe Enceladus be around the cutoff there). Otherwise I support abandoning the term. Many suggest keeping it narrow despite the lack of a cut off so that we have a reasonable number of planets to teach schoolchildren. I say that we can't define the solar system's nature based on what would be easier for school children, because this is, in actuality, giving the children a severely distorted view of the solar system, not a better one.

[Guest_BruceMoomaw_*]

... 

Are there specifications for the maximal thickness of Ceres' ice layer somewhere?

If -- as suggested in the press release -- Ceres may be as much as 25% water ice, then the ice layer would be about 10% as deep as Ceres' total radius.

[Guest_BruceMoomaw_*]

Has anyone noticed what an attractive living place Ceres starts to look like? Brimming over with easily accessible water and organic compounds; nice low gravity, making landings and takeoffs easier; far enough from the Sun that the intensity of solar radiation outbursts is considerably weakened (and water ice makes a good shield against that in any case)... maybe it's time to consider buying real estate there.

[David]

Brimming over with easily accessible water and organic compounds; nice low gravity, making landings and takeoffs easier; far enough from the Sun that the intensity of solar radiation outbursts is considerably weakened

I'm sold! Where do I pick up my tickets??!

[dvandorn]

I've been saying for a while that the asteroids are the logical next place for humans to visit. They're pieces of the ancient accretion phase of the solar system and hence scientifically interesting, and they also offer literally tons of resources that make them far more exploitable than smelly, rusty, salty old Mars down there at the bottom of that gravity well.

Does anyone have the stat for the surface gravity of Ceres? If it's enough that you could firmly root heavy machinery without extreme measures, I think we may have a winner there...

-the other Doug

[alan]

wikipedia lists it as 0.27 m/s^2

[David]

Divide Earth weights by 36 and you'll have approximately the correct number. An M-1 tank (by way of example) would weigh 1750 kg (about 4000 pounds) on Ceres. So no, you couldn't imitate Superman and lift a tank one-handed... but maybe a gang of Cereans drunk on Vestan ale could tip one over after a night of carousing.

[SigurRosFan]

Thanks Bruce!

Thus, the ice crust is roughly 50 kilometers thick.

[helvick]

Divide Earth weights by 36 and you'll have approximately the correct number.  An M-1 tank (by way of example) would weigh 1750 kg (about 4000 pounds) on Ceres.  So no, you couldn't imitate Superman and lift a tank one-handed... but maybe a gang of Cereans drunk on Vestan ale could tip one over after a night of carousing. 

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

[Ames]

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

Pedantic...

~600,000N - Newtons if we are talking mass

[Guest_BruceMoomaw_*]

The full "Nature" paper is now available at http://oposite.stsci.edu/pubinfo/pr/2005/27/pdf.pdf . (That double "pdf" at the end is no mistake.)

It turns out I made a dumb mistake by assuming that the "25% ice" figure was a reference to Ceres' volume, rather than its mass. Since ice is much lower density than rock, if that figure is for ice then the water-ice mantle on Ceres would have a bigger volume and thus be thicker than I had calculated. Sure enough:

"Assuming the densest core materials and the nominal mean density of 2,077 kgm23, ice mantles are 110–124km thick and constitute 24–26% of the body mass. The lighter core material requires a mantle thickness of 66 km and a 16% ice mass."

[Marz]

Thanks for the link and info, Bruce!

From reading, it almost sounds like Ceres is in its own class of 'roid, since it's the only one truly "relaxed". It's interesting that they expect the denser materials to have sunk to the core, and yet Ceres still maintains a spectral class of "C". Is there perhaps a layer of dusty "regolith" that is leftover from ice-sublimation that maybe lends it this spectral class, despite the fact that it is likely a "differentiated CM-chondrite"?

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense. A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day").

Perhaps most exciting in terms of human exploration potential is from the Nature letter: "Even the minimum mantle thickness is greater than the likely
excavation depths of craters a few hundred km across." So even if the crust is a nasty jumble of pebbles n' dust, a large crater would provide easy access to the water-rich mantle. A nice RTG rover could maybe scratch the bottom of the crater rim and begin melting a hole through the dirty-ice and begin excavating a nice cavern. Spray the walls with ice to make it air-tight, insulate with foam, pressurize and presto! Instant-igloo!

Before I rush out in my covered wagon to stake my claim in the land-rush:

1. is solar-power economically viable from Ceres? How much panels would be needed to crank out the equivelent of the ISS? (ISS = 110kW using 2,500 square metres of solar-panels).

2. is the low gravity a problem for long-term residents? would a gravity-centerfuge be required to keep folks healthy enough for return to earth?

3. is nitrogen available anywhere near the belt?

4. what would be the raison d'etree for a Ceres Base? Watching 'roids? Fuel-depot for outer-solar-system missions?

5. how hard would it be to move nearby small 'roids into orbit for material's processing?

Exciting stuff to dream about!

[tedstryk]

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

Not only are pounds and kilograms measures for the same thing (the newton correction is right), but the original point is using the right measure for what it is supposed to show - how hard something would be to support on Ceres under its gravity. So there is nothing to be picky about here....

[ljk4-1]

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense.  A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day"). 

Future generations who spend their whole lives on worlds like Ceres will probably have no issues with a 9-hour day whatsoever, having never been on Earth. Of course the colonies may be set up inside these rocks, so daylight can be an entirely artificial and controlled affair.

And we are assuming that future space colonists will be humans and not AI machines, who likely would have no concerns about day-night awake-sleep cycles.

[helvick]

1. is solar-power economically viable from Ceres?  How much panels would be needed to crank out the equivelent of the ISS?  (ISS = 110kW using 2,500 square metres of solar-panels).

Ceres is at ~ 2.77 AU on average, solar panels in orbit around Ceres would produce about 18% of the power of an equivalent array in Earth orbit. On the surface that would be reduced by a further 50 to 75% depending on whether they were Sun tracking or not.

The numbers you quote for ISS are interesting - the Solar constant in Earth orbit (the amount of radiation incident per m^2) is 1.37 kW. Most Solar panels in orbit are >16% efficient on average (the MER type are very good at ~26%) which means that the ISS panels are only generating 40% of their capacity even after accounting for a 12 hour night cycle. I assume this is due to layout and mechanical difficulties keeping them perfectly normal to the sun.

[ljk4-1]

Asteroid or miniplanet? Cornell astronomer finds Ceres appears to have shape and interior similar to terrestrial planets

http://www.news.cornell.edu/stories/Sept05/Ceres.to.html

Sept. 15, 2005

By Thomas Oberst
cunews@cornell.edu


ITHACA, N.Y. -- When is a space rock more than just a space rock?

Ceres 1 was already holding the title of the solar system's largest asteroid. Now new observations show the space rock may be more worthy of the appellation "miniplanet."

On Sept. 7 NASA released photographs of Ceres that show the rock is a smooth ellipsoid, or oblong sphere, with an average diameter of approximately 590 miles -- about the size of Texas. A scientific paper on the findings, by a group led by Peter C. Thomas, senior research associate at Cornell University's Center for Radiophysics and Space Research, appeared in the Sept. 9 issue of the journal Nature.

Co-author Joel Parker, an astronomer at the Southwest Research Institute in Boulder, Colo., used the Hubble Space Telescope's Advanced Camera for Surveys to snap 267 images of Ceres on Dec. 28, 2003, during a nine-hour period -- one Ceres "day."

[tfisher]

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense.  A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day"). 

I would think it would be more natural to push 3 hours longer to a 27 hour day rather than compress by 6 hours to an 18 hour day. So maybe it would be like:

[ dark ][light ][ dark ][light ][ dark ][ light]
---- )( morning )(nap)( - evening - )( sleeptime

This gives you around 9 hours of sleeptime each 'night' with another 2-3 hour midday
nap. That leaves 15-16 hours of uptime split into a morning and evening period.

There have been studies putting people into such an environment: here, for instance, is a report from a 28-hour day study. The circadian rhythm doesn't stretch so far -- it ends up cycling around 24 hours 11 minutes -- but apparantly people function without major problems on such a cycle.

[Bob Shaw]

I would think it would be more natural to push 3 hours longer to a 27 hour day rather than compress by 6 hours to an 18 hour day.  So maybe it would be like:

[ dark ][light ][ dark ][light ][ dark ][ light]
---- )( morning  )(nap)( - evening - )( sleeptime

This gives you around 9 hours of sleeptime each 'night' with another 2-3 hour midday
nap.  That leaves 15-16 hours of uptime split into a morning and evening period. 

There have been studies putting people into such an environment: here, for instance, is a report from a 28-hour day study.  The circadian rhythm doesn't stretch so far -- it ends up cycling around 24 hours 11 minutes -- but apparantly people function without major problems on such a cycle.

If Ceres has much in the way of axial tilt, then that might also cause the length of day to vary...

[Guest_BruceMoomaw_*]

The new "Nature" article confirms that its obliquity (axial tilt relative to its orbital plane) is only about 3 degrees. But this dosn't make much difference in any case -- for any future inhabitants of Ceres, after all, are going to spend most of the time UNDERGROUND, where they will be perfectly free to stick to the old 24-hour circadian cycle. Ditto for the Moon. (Any surface work teams will, of course, have to consider whether the Sun is shining on the surface at the moment or not.)

A more serious obstacle: Ceres' very low gravity will leave its inhabitants susceptible to the same harmful health effects that weightlessness does. But then, the same thing is true of dwellers on the Moon, and maybe even on Mars. As Poul Anderson points out, regular hours-long exercise sessions on a centrifuge will be an annoying necessity of life elsewhere in the Solar System.

[dvandorn]

The problem is, we don't have any real data on how much gravity the human body needs to stay healthy, and for how many hours in a day it needs that gravity.

Some astronauts who suffered mild SAS symptoms on their way out to the Moon felt much better after landing on the Moon. It only took 1/6G for them to feel completely normal and comfortable.

While that's anecdotal information at best, there is still, as of right now, *zero* research data on micro-gravity deterioration effects at 1/6G, or 1/3G, or even 1/20G.

And physiology, like most things in the real world, doesn't follow nice, clean curves. A body can take some conditions a fairly wide degree out of "normal" for quite some time without showing any real degradation. But change the degree just slightly, or change another parameter in addition, and the body hits a "trigger" and starts reacting in ways that are ultimately destructive (loss of bone mass and minerals, etc.).

It's possible that 1/6G might be more than enough gravity for the body to retain normal bone density levels indefinitely. Maybe, though less likely, 1/20G will be enough to do the trick.

It seems to me the *only* way to get this data is by flying spacecraft (in LEO, for ease of the commute) which can be spun at different rates to create different gravity levels (via momentum / centripetal force). Heck you could create different levels at different distances from the rotational center.

Then put people aboard those spacecraft for three months, then six months, then nine months, then a year... do direct observational science on physiological reactions to spending extended periods at whatever gravity strength you want to create.

It wouldn't be all that hard to put together -- just build a central control bus and attach two TransHabs to it. Balance the weight in the TransHabs properly, set the whole thing spinning on the ends of a truss. Put solar panels near the center of the control bus, and keep your consumables down at the ends of the Habs. Cheap (relatively speaking), easy (relatively speaking) little station, which can support (with refurbishment/resupply) a crew of 3 to 6 for up to a year.

Run it for a year at a 1/3G speed, then for a year at 1/6G speed, and then for a year at 1/20G speed. Test crews in all three modes. Get your baseline data.

THEN start planning what kind of spacecraft you need for really long journeys.

-the other Doug

[mike]

If the idea of using people is deemed somehow unfeasible, rabbits or rats or even monkeys could always be used, too.

It is a good idea - someone will do it eventually. If not NASA or ESA or whoever, then a corporation who wants to see just what their space miners can handle..

[Rob Pinnegar]

I vaguely remember reading a paper once in which the size distribution of main belt asteroids was studied. The number of asteroids with radii of 1 km, 10 km, 100 km and all the radii in between was graphed as a function of radius.

The curve fitted to this graph predicted that the largest asteroid should have a radius considerably smaller than Ceres' (but still larger than Pallas or Vesta). The authors took this as an indication that Ceres might have experienced a small amount of runaway accretion late in its formation. Thus it could really be considered as a "mini-planet", distinct from the other asteroids, but not in the class of the major planets.

Wish I could remember where this came from.

[tedstryk]

Thus, Ceres is a mini-planet or a "embryonic planet"?

And the layered jupiter moons are capture-planets.

p.s. Er, what is a planet??

Well, probably not. It is generally thought that the Galileans formed in Jovian orbit.

[tedstryk]

I vaguely remember reading a paper once in which the size distribution of main belt asteroids was studied. The number of asteroids with radii of 1 km, 10 km, 100 km and all the radii in between was graphed as a function of radius.

The curve fitted to this graph predicted that the largest asteroid should have a radius considerably smaller than Ceres' (but still larger than Pallas or Vesta). The authors took this as an indication that Ceres might have experienced a small amount of runaway accretion late in its formation. Thus it could really be considered as a "mini-planet", distinct from the other asteroids, but not in the class of the major planets.

Wish I could remember where this came from.

Vesta, of course, may turn out to be a piece of an embryonic planet destroyed in an impact. If so, it might provide us a great window on a planetary interior.

[Marz]

Has anyone noticed what an attractive living place Ceres starts to look like?  ... maybe it's time to consider buying real estate there.

I'm still trying to decide if I need to stake out my claim...

1. While the low gravity well sure simplifies landing and takeoff, doesn't it also mean there is a correspondingly high cost for being captured in orbit? Most mars probes save gobs of fuel by aerobraking, but for wimpy Ceres, how much fuel would be burned to allow for a fast-route Hoffman xfer?

1-A. Could a Mars flyby be used to slow-down (instead of speed up) the wagon? Even if possible, is it stupid because you're only ~25% of the distance, so instead Mars should be used to gain velocity instead of loose it?

1-B. Assuming sufficient electrical power, could water and carbon in the dust grains be used to manufacture rocket fuel? What would be the fuel of choice?

2. What are some reasons to send people to Ceres? Would it make sense to park space-telescopes on either pole as a huge inferometer, with astronauts required to install and commission them? Are the organic compounds worth the risk of sending people to collect the samples? Would it make sense to setup Ceres as a communication hub between earth-mars so we don't have those crappy opposition blackouts?

[Bob Shaw]

I'm still trying to decide if I need to stake out my claim... 

1. While the low gravity well sure simplifies landing and takeoff, doesn't it also mean there is a correspondingly high cost for being captured in orbit?  Most mars probes save gobs of fuel by aerobraking, but for wimpy Ceres, how much fuel would be burned to allow for a fast-route Hoffman xfer?

1-A.  Could a Mars flyby be used to slow-down (instead of speed up) the wagon?  Even if possible, is it stupid because you're only ~25% of the distance, so instead Mars should be used to gain velocity instead of loose it?

1-B.  Assuming sufficient electrical power, could water and carbon in the dust grains be used to manufacture rocket fuel?  What would be the fuel of choice?

2.  What are some reasons to send people to Ceres?  Would it make sense to park space-telescopes on either pole as a huge inferometer, with astronauts required to install and commission them?  Are the organic compounds worth the risk of sending people to collect the samples?  Would it make sense to setup Ceres as a communication hub between earth-mars so we don't have those crappy opposition blackouts?

Marz:

1. No, it'd be pointless, not least because Mars might be in entirely the wrong place - and Hohmann transfers are, er, the slow jobs. That's the point of them...

1-B. There's fuel, and there's oxidiser - anything that burns is fuel, anything that oxidises is, er, well, oxidiser. The big hope would be water ice, which breaks down into both very nicely - but look at the in-situ fuel generation on Mars discussions for a whole range of alternative, lower energy, chemistries.

2. George O Smith's 'Venus Equilateral' described such a system, but really, it's hardly an economic solution. As for the astronomy, why bother with an asteroid?

In short, Ceres may well be a world in it's own right, with it's own imperatives. Personally, I can hardly wait - if Earth is to Mars as Mars is to Ceres, then it will shed so much light on the other Terrestrial planets (oops!).

Bob Shaw

[Decepticon]

http://www.swri.org/press/2005/Images/ceres_movie.html

I was looking at the above animated Gifs of Ceres rotation and I think I see a hint of a Massive crater right in the middle of the little body.

Does anyone else see it?

[tedstryk]

http://www.swri.org/press/2005/Images/ceres_movie.html

I was looking at the above animated Gifs of Ceres rotation and I think I see a hint of a Massive crater right in the middle of the little body.

Does anyone else see it?

I see something that looks like it. But it may be an illusion. Better imagery will tell.

[Guest_BruceMoomaw_*]

I noted in the "Dawn" thread the excellent Keck photos of Ceres taken in 2003 ( http://www.cfht.hawaii.edu/Instruments/Ima...pueo-nui-ss.pdf , pg. 13), which clearly show what looks like a big dark circular patch with a big lighter-colored patch smack in its middle (feature "B"). When these were shown at the 2003 DPS meeting, that feature's continued existence as Ceres rotated -- and its resemblance to a dark crater with a big light central peak region, like Tsiolkovsky on the Moon's farside -- was much clearer than in the published photos, for some reason.

Apparently that light-colored central patch is the same as the (relatively) bright spot in the Hubble photos, where they massively cranked up the contrast (the "light spot" is actually only about 5% higher albedo than its surroundings, and so the Keck photos showed it much more realistically).

[Decepticon]

Heres another map. Forgot where I found this.

[tedstryk]

Things like this really make me mad...Here is space.com's map of Ceres...

http://www.space.com/reference/debris/maps.html



Clearly a bunch of cloned crap from Gaileo's images of Gaspra, a world not even on a similar scale. And no disclaimer....

[Decepticon]

How sad.

[David]

What's even worse is that they put it under the heading of "space debris".

I realize that there is room for argument over definitions, but I do not think that anybody can look at Ceres and call it "debris".

[jamescanvin]

If the idea of using people is deemed somehow unfeasible, rabbits or rats or even monkeys could always be used, too.

It is a good idea - someone will do it eventually.  If not NASA or ESA or whoever, then a corporation who wants to see just what their space miners can handle..

You mean like this?

Link

James

[mike]

Yeah. Cool stuff. If I had an infinite amount of money, well, I'd fund everything, but this would be one of the first.