NASA Dawn, What will it discover about Ceres?

originally posted by: Tardacus
What`s really interesting is that it has an ION engine propelling it. I thought that was interesting because it was built about 15 years ago.We had the technology to build ION engines 15 years ago I wonder how much more advanced they are now and what other things are using ION engines that we don`t know about yet?

The reason the ion engine (or some sort of similar electric propulsion) was necessary for the Dawn mission was that it had two targets (the asteroid Vesta and the dwarf planet Ceres), and the mission called for the spacecraft to spend a lot of time orbiting each target.

To do so, the spacecraft needed an engine that could be shut down once it reached orbit around Vesta, then restarted again months later to the fly off to Ceres, and to enter orbit around Ceres.

The usual type of chemically-fueled engines (such as the on the Cassini spacecraft around Saturn, and the thrusters used on the cruise stage of the Rovers sent to Mars) would not be able to accomplish this. Those chemical thruster spend 95% to 99% of their fuel in the first 20 minutes after launch. After that, those rockets basically coasted their way to Mars or Saturn, nonpowered, except for a little fuel left to fine-tune their course along the way.

For example, the New Horizons probe that has been heading towards Pluto for the past 14 years has been coasting without thrust for those 14 years since launch, except for some minor course corrections (although it received a gravity-assist slingshot boost from Jupiter as it flew by the giant planet).

The ion engine is different. It has very little thrust compared to a chemically-fueled engine, but that thrust can be continuous for days, weeks, months, or maybe even years. That continuous thrust may be only a little, but over time it all adds up. As I mentioned above, it can also be used to make major course changes, such as first going to Vesta, spending a few months there, then re-igniting that thruster to set a new course to Ceres.

a reply to: ukmicky1980

Well, Ceres is full of water, it exists right outside the "goldilocks zone" yet we're already finding life in some of the coldest places in the world. Given the discovered water vapor emissions, it looks as if the inside of the planet may be oceanic.

My guess is there's about a 30% chance of some type of basic life there.

A picture:

a reply to: Ross 54

The ice on Europa does not sublime into space...Well, maybe it does, but the surface ice can also be continually fed from the sub-surface ocean.

Ceres also has a sub-surface water ice. If there is some mechanism by where that water is kept warm (radioactive decay?) then maybe that water may be feeding the surface ice (if that really is what the white patch is).

So, we have now four theories:

-Ice patch

-Impact event showing light-coloured material underneath

-extraterrestrial civilisation technology or settlement

-And, the one I proposed, light-coloured boulder or rocks.

Hm, good news is, one of us is bound to guess it right.

originally posted by: Aliensun
a reply to: ukmicky1980

The have covered up for several decades details that point to intelligent manipulation of Phobos, one of the tiny moons of Mars. They have taken decades to even admit that Mars once had water. Slowly, they are creeping toward telling us that there WAS life on Mars. But even that must wait. In retrospect, there is no reason to expect any shocking news about Ceres.

NASA is a propaganda factory as much as anything else. They have their schedule and they are keeping to it. That schedule seems to be to find evidence far away from Earth and then let that realization slowly circle back to our solar system to eventually acknowledge all of the phenomena that they have been ignoring for over half a century is really alien craft working at our planet.

If I was a smarter guy I'd find a gif of that wild haired guy who always say it's aliens and he'd be nodding his head vigorously!

But seriously, I don't think NASA is just there to blur or omit UFOs from official media. Do you really think that's all it amounts to? Those people are a LOT smarter than that. They're there for the real deal, doing science, like anyone who commits their life to something important to them. Maybe there's an instance here or there of someone being hushed or pushed along, but I doubt it. More than likely, they're both dumb and yet a lot smarter than the rest of us - which is why I'm at my computer and not at SpaceX or working for Eion Musk. My hope is we eventually find signatures of ET bacterial or fungal or otherwise living materials out there somewhere, indicating life is more ubiquitous, but I'm sure there're a lot of other exciting revelations which might come out of our exploration of the nearby cosmos. Maybe all we'll find is extinct life? That's a sad thought, but on the other hand, we won't have aany competitors when the Eion Musks' or Steve Fossetts' desire to colonize the cosmos in a >million year adventure.

originally posted by: projectvxn

originally posted by: Tardacus
I never heard of Dawn until a about a week ago when I stumbled across this mission purely by chance.

What`s really interesting is that it has an ION engine propelling it. I thought that was interesting because it was built about 15 years ago.We had the technology to build ION engines 15 years ago I wonder how much more advanced they are now and what other things are using ION engines that we don`t know about yet?

We had the tech in the 50s. There just wasn't a practical application for them until recent decades.

Not sure why ion propulsion hasn't taken off.

It has taken off; many spacecraft and satellites use ion propulsion. Key thing to remember is that it provides a very weak thrust. You can't launch a rocket off Earth using it. This also means that ion thrusters are used to either very slowly accelerate a spacecraft over many days / weeks / months, or for occasional course adjustments.

The thrust provided by an ion engine is approximately the same as someone gently blowing on your skin.

a reply to: jonnywhite

Ah! You are speaking of Giorgio Tsoukalos:



But yeah, I agree. There is so much competition out there in the science community (both gov-funded and independent)... If alien life is found, there would be not much point covering it up, everyone will actually be rushing to be the first to make the announcement and get down in history.

a reply to: swanne

And also the possibility I speculated, an exposed bed of some kind of reflective mineral.

Your right though, one of us will be right, or close! lol

originally posted by: Soylent Green Is People
a reply to: Ross 54

The ice on Europa does not sublime into space...Well, maybe it does, but the surface ice can also be continually fed from the sub-surface ocean.

Ceres also has a sub-surface water ice. If there is some mechanism by where that water is kept warm (radioactive decay?) then maybe that water may be feeding the surface ice (if that really is what the white patch is).

Yes, ice does sublime directly to water vapor on Ceres. A subsurface ocean on Ceres is still highly speculative. The Hershel Space Telescope detected water vapor plumes from two dark areas of low latitude. More water vapor was detected when Ceres was near the Sun. This supports the idea of small, comet-like ice deposits, rather than a subsurface ocean. The bright spot is at high latitude, and does not seem to figure in the reports of water vapor plumes.

originally posted by: projectvxn

originally posted by: Tardacus
I never heard of Dawn until a about a week ago when I stumbled across this mission purely by chance.

What`s really interesting is that it has an ION engine propelling it. I thought that was interesting because it was built about 15 years ago.We had the technology to build ION engines 15 years ago I wonder how much more advanced they are now and what other things are using ION engines that we don`t know about yet?

We had the tech in the 50s. There just wasn't a practical application for them until recent decades.

Not sure why ion propulsion hasn't taken off.

I'm still waiting for the NNPT to be amended to allow research and testing into nuclear propulsion.

Frankly NASA has a vested interest in chemical propulsion. that is changing as the old fossils die off. but NASA is finally putting more priority on ion drives for more than satellite station keeping. they are even venturing into their first plasma rocket VASIMR trying desperately to find funding to get the thing a launch carrier to get it to the ISS for testing, a Fusion rocket and even EM drives and stuff with an even higher "kook" factor as defined by the old guard.

NASA's fusion rocket development program based on John Slough's civilian fusion reactor: www.nasa.gov...

Dr Chang Diaz (former shuttle astronaut) Ad Astra VASIMIR

www.adastrarocket.com...

a reply to: ukmicky1980

It's Heavens lil light !



What! You don't recognize?

Too bad all we get is a blurry cell phone pic...

I think the answer is going to be quite unique in that it being so bright at such a distance. The image released was observed 238,000 miles away from Ceres. To compare, our Moon is 238,900 miles away from Earth. I'm not sure why the pic is so blurry, hopefully in a couple months there will be much clearer ones. I'm guessing an impact crater from an asteroid made up of highly reflective elements that interacted with Cere's surface to create this very bright spot. S+F

originally posted by: game over man
The image released was observed 238,000 miles away from Ceres. To compare, our Moon is 238,900 miles away from Earth. I'm not sure why the pic is so blurry

Actually Dawn has no telescopes on board, its main observation tool is the framing cameras with 20mm apertures.

Furthermore, Ceres is rather small a planet:



Ever tried taking a pic of the moon without magnification and with such a small aperture? Now imagine trying to take a pic of a rock some 3.6 times smaller than the Moon at approximately the same distance with that very same gear. Give poor Dawn some credit, mate!

originally posted by: swanne
Ever tried taking a pic of the moon without magnification and with such a small aperture? Now imagine trying to take a pic of a rock some 3.6 times smaller than the Moon at approximately the same distance with that very same gear. Give poor Dawn some credit, mate!

Indeed.

The Moon also looks so much bigger when a person is looking at it with their eyes than it does in normal pictures (non-cropped, non-zoomed, non-telephoto pictures) taken with normal cameras. It looks surprisingly small:



Image Source, Plus Additional Images

originally posted by: game over man
I'm guessing an impact crater from an asteroid made up of highly reflective elements that interacted with Cere's surface to create this very bright spot. S+F

Many researchers think that Ceres may have a deep layer of water-ice covering it, just below a relatively thin crust of dust. It should be noted that this diagram is only one possibility for the internal structure of Ceres. The differentiated water-ice layer has not yet been confirmed



NASA Image -- Ceres' Interior

Perhaps the bright spot is some of the ice showing through for some reason (crater? something else?). The question then becomes why is that ice still exposed, rather that that portion of the ice sublimating into space, or that section being re-coated in dust. There are indications of the presence of volatile materials in the mantle of Ceres; maybe these volatile materials are lowering the freezing point of the water, and helping to keep the water-ice a little soft or slushy. Maybe that is helping to feed the patch of ice in the bright spot from beneath.

If we say this is ice, then do we have a definite explanation for the presence and persistence of that ice on the surface? No, not yet. However, that does not mean that it isn't ice; it simply means we don't yet have an explanation if it is ice. It does look like ice, from the limited photographic information that we have.

An interesting scenario. Essentially an ice lake, about 30 miles across, it appears, subliming away at the top, and fed by enough water seeping up from below to maintain itself.
Since water would immediately boil away as vapor, once it reached the surface, which is essentially in a vacuum, it's hard to see it even beginning to form ice, though.
Perhaps this thing is a seething, bubbling cauldron of water boiling away. This would presumably require a large number of seeps, distributed over a 30 mile area. That's a lot, but it's conceivable. This would also explain the dynamic, flickering appearance of the bright spot.
Another problem is that ESA's Herschel Space Telescope found a couple of water vapor plumes at low latitudes on Ceres, but apparently none at the high latitude of the bright spot. I should imagine that a thirty-mile-wide field of furiously boiling water would have been detected.

originally posted by: Ross 54
Since water would immediately boil away as vapor, once it reached the surface, which is essentially in a vacuum, it's hard to see it even beginning to form ice, though.

Water (or urine) dumps from various manned spacecraft show the dumped water turn into ice particles straight away. On Ceres, perhaps some of them settled back down due to gravity.

www.youtube.com...