Galileo's Flyby of Almathea

An anonymous reader writes "The spectacular Galileo flybys of Jupiter, Europa and Io are largely credited with the discovery of frozen water ice and some of the earliest examples of non-solar (tidal) heating anywhere in our solar system. For the next 10 days, Galileo scientists are preparing for their next target: probing one of Jupiter's moons, Almathea, at the close-up range of 100 miles. Almathea is one of the most unusual moons in the solar system, because it gives off more heat than it receives from the Sun."

Comments

frozen water ice?

[deaton]

is that anything like unfrozen ice water?

Re:frozen water ice?

[Alain Williams]

The point is that 'ice' can be made from all sorts of liquids - water is just one of them.

Re:frozen water ice?

[comic-not]

Well, ices can exist in the crystalline or amorphous phase. E.g. the water ice inside cometary nuclei is in amorphous form, and one can argue that it is technically not frozen, because it has originally been built from such tiny particles that there hasn't been a meaningful macrostate (BTW, did you ever create amorphous sulphur in the chemistry class?) to call it such. When amorphous ice is heated, it turns to the 'normal', crystalline phase, which more closely resembles our concept of 'frozen'. I don't know, however, whether the original poster tried to express this distinction.

Gives out more heat that it recieves.

[Anonymous Coward]

Lisa, In this house we obey the laws of thermodynamics.

Yes i know there are other explainations

Re:Gives out more heat that it recieves.

[verag]

The planet itself does this as well... "...Jupiter radiates nearly twice as much heat as it receives from the Sun." Found here

Jupiter is by far the most interesting planet (with it's moons) to me, other than the Earth. More information as well as pictures can be found on NASA's site for the planet itself.

Re:Gives out more heat that it recieves.

[Jugalator]

I think at least Io was so volcanic and active because of the extreme "tidal waves" from Jupiter. The "waves" are, due to the huge gravitation of Jupiter, so strong they pull solid matter and this of course cause quite a bit of friction. And friction cause heat. Not really surprising, since such a small object as our Moon does funny things to our seas. :-)

Anyway, to my point, perhaps the same applies to Amalthea?

heat generator

[scrod98]

because it gives off more heat than it receives from the Sun

And NASA releases a picture of the Intel Inside logo on the surface...

what are they hoping to find?

[Transient0]

a civilization of alien potheads who have hotboxed an entire atmosphere?

or maybe the worlds biggest overclocked processor.

I can't think of any other reasonable theory to account for this moon radiating so much heat.

Earth has Moon Envy

[Zech Harvey]

I mean, that's the only explanation I can come up with. Ours just...you know, sits there. We go there once, get bored and come back. So we spend our time looking at other planets' moons instead of making it back to ours. I mean really. Give our moon some lubbin'!

Re:Earth has Moon Envy

[edremy]

Nah. Ours is the biggest, at least in relation to our size. (Forget Pluto+Charon; they're just comets that took a wrong turn.)

It's not the number, it's the size, baby.

(And in seriousness, there's a fair number of theories that think life would not have come about without the large tides raised by the moon.)

Nice rendered pictures

[Dark Lord Seth]

For those of us who aren't very much at home in astronomy and it's terms and who just want to see (relatively) pretty pictures; Celestia also has Almathea available for your viewing pleasure, along with allot of different stuff in our solar system and even beyond there. Besides, it's a pretty proggy... :)

Almathea?

[CommandNotFound]

...isn't that the planet where they used to build luxury planets for the super-rich?

Re:Almathea?

[Tackhead]

> I thought the quote was "All these worlds are yours, except Europa. Attempt no landings there"

All these moon are belong to you.
Except Europa. Europa are belong to us.
You have no chance to survive, make your time.
Move "Discovery"! For great monolith!

Hmm, I think must've seen the Japanese translation...

For those looking for Earth like planets...

[MrFenty]

This sort of place is exactly the sort of reason I think, if we find life elsewhere in the universe (intelligent or otherwise) then it won't have to be on a planet that looks exactly like Earth and at roughly 1 AU from its local star. Here we have a moon that gives off heat, at a very large distance from its sun. There is no reason for us to be arrogant enough to assume that life can only exist on a place that looks identical to our place. This really bugs me, when I see people say "life can't exist there, that planet is twice Earth's distance from its star..." and rubbish like that. Aarrgghh !

Sorry, I needed that rant.

Re:For those looking for Earth like planets...

[FortKnox]

To continue your rant philosophically...

We are ignorant when it comes to life. What exactly is life? We only know what life is within our world.
Astronomers get excited at the fact that we can find water on Mars and Europa, meaning they could have life, because our knowledge of life involves water. But, as far as we know, there could be life on the moon, we just aren't looking for it correctly.
If (or when, depending on your philosophy) we find extraterrestrial life, it will be when we aren't looking for it, IMHO.

Re:For those looking for Earth like planets...

[overunderunderdone]

This really bugs me, when I see people say "life can't exist there, that planet is twice Earth's distance from its star..." and rubbish like that. Aarrgghh !

If you are ranting about the "rare earth hypothesis" you should remember that the authors believe that life is MUCH more common than was previously believed. However they believe that advanced life and advanced civilizations are MUCH rarer than previously believed and do require conditions substantially similar to earths. Even you own post basically makes some of the same assumptions - you see the heat from this moon as promising because that heat is one of the prerequisites for life, the rare earth hypothesis adds additional prerequisites which must be present for *advanced* life. There are those that simply assume without thinking that life must evolve on a planet substantially similar to earth. The rare earth hypothesis arrived at pretty much the same conclusion through serious thought on the subject. They may be wrong (we simply don't have enough data) but their reasoning is sound and not based on simple prejudice or ignorance.

Looking at Jupiter and its moons

[igotmybfg]

Two summers ago, one of my friends in University here asked me to come outside with her and look at something which she described as 'cool'. Thinking I might get some :) I went with her, and we set up a tripod and telescope and ended up watching the stars all night long. For a time we focused on Jupiter, and though I couldn't see Almathea, I did see Jupiter, Callisto, Io, Europa, and Ganymede. The thought that there was nothing (well, almost nothing) in between me and those huge, huge objects that were so very far away still sends tingling down my spine whenever I think about it. It reminds me, when I think that there is pretty much nothing left to do or discover, that there is indeed a whole universe out there, waiting for (or perhaps indifferent to) us.

Cheers!

Re:Looking at Jupiter and its moons

[allanj]

Well, I think I speak (type?) for all of us here - did you, in fact, get some?

Re:Looking at Jupiter and its moons

[archen]

in between me and those huge, huge objects that were so very far away still sends tingling down my spine whenever I think about it.

I think so.

Re:Looking at Jupiter and its moons

[vinlud]

The thought that there was nothing (well, almost nothing) in between me and those huge, huge objects that were so very far away still sends tingling down my spine whenever I think about it. It reminds me, when I think that there is pretty much nothing left to do or discover, that there is indeed a whole universe out there, waiting for (or perhaps indifferent to) us.

You're talking 'bout the girl now right?

Re:I'm a little Confused

[apt142]

Haven't you read the Hitchhiker's Guide? Flying is easy. All you have to do is throw yourself at the ground and miss.

Monolith?

[alexc]

Did Galileo find a Black Monolith yet?

AmaLthea, not ALmathea

[Anonymous Coward]

Hell, has nobody noticed that the real name is Amalthea?
Where are your classics!?
She was the goat that nurtured baby Zeus = Jupiter!

Amalthea

[Blackneto]

The Correct spelling is Amalthea.
It says so on the JPL's website.
Also Amalthea was a nymph that nursed Jupiter in mythology. This fits in with the naming of the other moons.
It looks like it was only misspelled once on the astrobio site which may be the cause of the confusion.

Re:Shift the focus already

[ChuckDivine]

While I strongly support looking for close in objects, it's not like it's an either/or situation. The world has lots of astronomers (and other kinds of scientists as well). We also have resources sufficient to do research into a wide variety of astronomical phenomena.

Those of us who have actually done some political work in support of looking for earth approaching asteroids only ask for a few millions of dollars to finance such work. Focusing all of our attention on nearby objects would be foolish and wasteful in the extreme.

Leaves me feeling depressed...

[Anonymous Coward]

Every time I read stories on Galileo I get an incredable feeling of depression, not because the mission has been a failure, it has not. Rather that the craft never reached its full potentual. Early in the mission, the main arial to earth never opened meaning that the amount of pictures we get now are much lower then what we should have gotten, Sometimes I think that Galileo could have been the mission which found life on another planet besides earth. This would have changed everything, instead of planning wars today we would be planing probes to discover what the hell was out there.(a real long shot). Things like the pluto express would not have been cancelled, and millions would not be wasted on the ISS - a project which gets all its money just from the cool factor, and like the shuttle a complete waste of resources.

Probes are the way to go, its just a pity that for every one sent few manage to survive the trip, the payoff is so great.

Re:Leaves me feeling depressed...

[raduga]

With the primary arial undeployed the primary effect has been a reduction in the total number of pictures, and the frequency at which they are captured and returned; since the low-gain antenna / tape recorder are still capable of bringing back images of the same quality, just not nearly as many.

It's disappointing, sure, but even had the arial been fully deployed, we wouldn't have significantly greater resolution, and might not see substantially more detail of Europa's surface. Also, the change in mission priorities might (?) have meant fewer resources spent on magnetometric observations. Events don't seem to change frequently enough on Europa's surface that a few missing frames would have changed our view much.

(Contrast with Io! What if we'd missed that eruption?)

Jupiter's mass is the cause of the heating

[Big Mark]

Jupiter is so heavy that it's inner reigions are incredibly hot - some think it's actually a star that just wasn't big enough to have it's own mass crush it's innards to the point where nuclear fusion occurs and the star is born. It's big enough, though, that the innards are squished to to superheat. It's this heat from the inside that makes Jupiter warm up.

The moon's heating is accounted for by tidal forces - Jupiter is just so flippin' MASSIVE that it's gravity stretches and squeezes the moon, and these tidal forces make it heat up.

The surface of Amalthea (sp.?) will be interesting to look at. I think it will have pronounced cracks on the surface where aeons of tidal forces have had their way.

Re:Jupiter's mass is the cause of the heating

[LMCBoy]

It's this heat from the inside that makes Jupiter warm up.

This parses to "Jupiter is hot because it is hot."

You're correct that Jupiter's core is not hot enough for nuclear reactions (core temperature is about 20,000 K).

Just to clarify, Jupiter gives off more heat than it receives because it is still collapsing! Sounds incredible, but the "heavier" elements are still slowly settling out toward its core. As they do, they release gravitational potential energy in the form of heat. This settling process must be incredibly slow, since it's presumably been happening steadily for the past 4.6 Gyr; the fact that it still produces a significant amount of heat demonstrates how damn BIG Jupiter is.

See SEDS.org for more information (about halfway down the page, right after the section on the Great Red Spot).

It's *Amalthea*

[notfancy]

Sorry to pick nits, but the name is Amalthea (ah-mal-THEH-ah), it means "the Goddess Amal" (IIRC a Babylonian name for Astarte, the Moon goddess). She was the goat that nursed Jupiter (Zeus, actually) in Mount Ida, and whose horn the baby god pulled with his mighty force while playing with her. That horn is called the Cornucopia, or the Horn of Plenty, after Jupiter, ashamed at his own clumsiness, bestowed that gift on the goat as an apology.

Spacecraft dimensions

[teridon]

From the article:

Dimensions: The length of the spacecraft is 9 m and, with the high-gain antenna (HGA) deployed, is 4.6 m in diameter.

Ha! That's great! Except that the high-gain antenna failed to deploy. Fortunately, with some spacecraft reprogramming, Galileo will still acheive about 70% of its original science goals using the low-gain antenna.

Mr. Armchair Science butts in.

[erik_fredricks]

Almathea is one of the most unusual moons in the solar system, because it gives off more heat than it receives from the Sun."

Actually, Triton (Neptune's largest) does, too, IIRC. All the gas giants do as well.

In Amalthea's case (as well as Europa and Io), the moon is constantly being contracted and stretched by Jupiter's gravity, and those tidal forces generate heat in the moon's core. You can duplicate this effect by squeezing a piece of styrofoam in your hand and feeling it heat up.

Of course, all the gas giants have internal heat sources due to the immense gravity in their highly contracted solid cores. Neptune gives off way more heat and light than it receives from the Sun.

A sneak peak at Almathea

[mraymer]

Celestia is a 3D space simulator much like OpenUniverse. It's avaible for both Windows and *nix OSes. In it, you can view all the planets, some moons, asteroids, and a fair number of stars. Here's a shot of Almathea. They release add-ons every now and then-- you can even download the recently discovered Quaoar!