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Dawn at Ceres Thread

Frida Space

By Frida Space
in Science & Spaceflight

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lajoswinkler

lajoswinkler

Posted
Posted

Some of the animations from that thread.

92iruXN.gif

l1tj16W.gif

I'm still convinced these are just patches of terrain with higher albedo. Someone there mentioned Phoebe.

phoebe.jpg

Others are talking about very high albedo. People constantly forget that most of bodies looking like this are VERY VERY VERY dark, and when you take a photo and want to see a nice feature rich surface, you cause washing out of the grayish surfaces.

Those white spots are not white. They are gray. We have exact same things on the Moon.

s11_813223RE.jpg

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baggers

baggers

Posted
Posted

Others are talking about very high albedo. People constantly forget that most of bodies looking like this are VERY VERY VERY dark, and when you take a photo and want to see a nice feature rich surface, you cause washing out of the grayish surfaces.

Those white spots are not white. They are gray. We have exact same things on the Moon.

Hello.

I agree Ceres is very dark(0.09 albedo), but theses spots have an albedo >0.5. Remember that they have been spoted far away and are very small. The contrast is very high. We still don't know the "final" albedo of all these spots. Could be 1 in some cases.

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lajoswinkler

lajoswinkler

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Hello.

I agree Ceres is very dark(0.09 albedo), but theses spots have an albedo >0.5. Remember that they have been spoted far away and are very small. The contrast is very high. We still don't know the "final" albedo of all these spots. Could be 1 in some cases.

It can't be 1.

But it could be a pile of office papers, too, but that's highly unlikely.

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K^2

K^2

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Posted
It can't be 1.

I can think of at least three absolutely implausible scenarios under which it can.

Also, your office papers hypothesis is intriguing. We might be able to explain low albedo of the rest of the surface if it's covered in toner. What if the entire thing is just a storage closet for some interstellar office supplies, which happened to drift out of its way?

You can't prove it's wrong! But you can prove it to be very unlikely.

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Linear

Linear

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Posted
I can think of at least three absolutely implausible scenarios under which it can.

Also, your office papers hypothesis is intriguing. We might be able to explain low albedo of the rest of the surface if it's covered in toner. What if the entire thing is just a storage closet for some interstellar office supplies, which happened to drift out of its way?

You can't prove it's wrong! But you can prove it to be very unlikely.

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worir4

worir4

Posted
Posted (edited)
Didn't realise it was getting that low! You'll be able to see the colour of the alien's shorts.

...The white dots are an alien colony, right?

Defiantly aliens... But not kerbals or else we would not be able to see them until we got to <22.5km

Edited by worir4
Much bad grammer
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Esme

Esme

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Posted

Sorry! that was me making a bad landing ...again. Main white dot is where the lander hit and the fuel tanks ruptured - the two smaller dots to the right are where the command capsule landed then bounced, and the rest of the white is due to debris sputtering off in all directions. Blew the coal-black dust covering most of the surface right off the ice underneath, see?

Anyway, I hope you'll excuse me, must dash, I've got another lander to launch, CeresLander IX...

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Streetwind

Streetwind

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Starting to resolve more and more details, I see. What started as one spot became two, and now has become a whole set of spots.

And what's fun about this: the more fragmented into small individual spots this bright region is, the brighter each individual spot must be on its own. :)

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Nikolai

Nikolai

Posted
Posted (edited)
Could it be a comet or asteroid that broke apart shortly before impact? Like Shoemaker-Levy 9 and Jupiter?

My BOTE calculations indicate that anything impacting Ceres has a minimum specific energy of 132 joules per gram. That's not even enough to boil cold water. So maybe?

(mu of Ceres is 63.1 km^3 s^-2, radius of Ceres is 476.2 km; this gives a minimum impact speed of about 515 m/s, which is a specific energy of 132 joules, or 31.7 calories, per gram)

Edited by Nikolai
slipped on escape velocity calculations, but results unchanged
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Slam_Jones

Slam_Jones

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Could it be a comet or asteroid that broke apart shortly before impact? Like Shoemaker-Levy 9 and Jupiter?

That's kinda what I was imagining. Basically a space-geode (looks like boring rock on the outside, while the inside is filled with colorful crystal-like stuff) that whacked into it and split open, spilling some of it out.

Then again, what do I know :)

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-Velocity-

-Velocity-

Posted
Posted (edited)
Some of the animations from that thread.

I'm still convinced these are just patches of terrain with higher albedo. Someone there mentioned Phoebe.

Others are talking about very high albedo. People constantly forget that most of bodies looking like this are VERY VERY VERY dark, and when you take a photo and want to see a nice feature rich surface, you cause washing out of the grayish surfaces.

Those white spots are not white. They are gray. We have exact same things on the Moon.

"Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice,"- http://www.nasa.gov/jpl/dawn/ceres-bright-spots-seen-closer-than-ever

"highly reflective material"- that doesn't sound like grey dust, Lajos. You keep forgetting/ignoring that they estimated an albedo of 0.4 with the spots not even resolved yet, so the actual albedo has to be much higher than that.

One can look up light curves for Ceres. It is reasonably variable, like 0.04 magnitudes or something like that. IF that 0.04 magnitude change is entirely due to the spots, we should be able to estimate their albedo from this variability, the albedo of the rest of the surface and now the known area of the spots.

How in the world could it be ice? Who knows. Maybe it really is salt or some kind of white clay or sand or something.

WHEN are we actually going to be able to know for sure what it is? CAN Dawn distinguish between salt and ice? Will we just get better and better pictures of it and but never be able to tell what it is? Don't they have some kind of neutron spectroscopy crap or something?

I suppose if its sublimating into space, you might be able to detect water vapor/oxygen/hydroxyl/hydrogen when you flew over the spots, but does Dawn even have instruments to detect that? Hopefully the other instruments on board aren't as weak as its visible light camera (the Fischer-Price plastic toy telescope I got for my fifth birthday has higher resolution...).

Edited by |Velocity|
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