Gas giant question

[nightfisher]

So Jupiter and Saturn are classed as gas giants...........so this leaves a thicko like me wondering what would happen if a lander craft tried to land on one of these planets, would it just sink deeper and deeper into the gas layers?

[Floater]

From a fellow 'thicko', I think the answer has to be yes ... until the pressure got just a bit too much!

Not sure if we know for a fact what the cores of these planets are like.

[johnfosteruk]

6 minutes ago, Floater said:

Not sure if we know for a fact what the cores of these planets are like.

I think with the mass of them it doesn't really matter as it relates to Jules' question. The pressure would destroy the lander as you say, long before it reached the core.

[Alien 13]

It would be interesting to know, normal common sense physics would say the pressures lower down would turn the gas liquid then a solid but Jupiter is hot so is it a gas/liquid/solid at its core or something new?

Alan

[johnfosteruk]

1 minute ago, Alien 13 said:

so is it a gas/liquid/solid at its core

That's one of the things Juno is hoping to discover I believe, whether it's metallic hydrogen or something else unexpected. So we may know in due course.

[Alien 13]

Just now, johnfosteruk said:

That's one of the things Juno is hoping to discover I believe, whether it's metallic hydrogen or something else unexpected. So we may know in due course.

One thing we have learnt from these types of missions is to expect the unexpected.

Alan 

[Ibbo!]

IIRC they did crash one into jupiter some years ago and again if mem is working it lasted about 50 mins before being lost presumably crushed despite being made of titanium.

This i think gave us that jupiter's upper atmosphere is dry but has a fair amount of "lightning"

 

off to check NASA site and see if I can find the info.

 

Edit

Gallileo probe of course

Less helium, less lightning and less water but high winds

got pretty warm and was subjected to 23 atmospheres of pressure before it was destroyed.

[Alien 13]

A related question concerns the biggest gas giant in the solar system, does the Sun have a solid core?

Alan

[Floater]

Done a bit of homework now (having remembered a Report Card I once received saying I should have done it earlier! ?) and, apparently it is accepted that Saturn has a rock core, along with other solid stuff (check the scientific terminology, why doncha). The jury's still out on Jupiter's core.

I still guess the pressure would get you before you got 'in' enough to find out!

Fascinating stuff, though. What times we live in, eh?

[Floater]

11 minutes ago, Alien 13 said:

A related question concerns the biggest gas giant in the solar system, does the Sun have a solid core?

Alan

I think it doesn't have a solid core. It's plasma, a soup of ionised (ionized, if you feel that way ?) atoms/particles/photons(?).

[John]

Uranus and Neptune are also giants but interestingly seem to be referred to as ice giants.

 

[Alien 13]

3 minutes ago, Floater said:

I think it doesn't have a solid core. It's plasma, a soup of ionised (ionized, if you feel that way ?) atoms/particles/photons(?).

I wonder if Jupiter as a "failed star" is similar.

Alan

[Floater]

5 minutes ago, John said:

Uranus and Neptune are also giants but interestingly seem to be referred to as ice giants.

 

That seems to have something to do with the 'frost line', but the frost line itself is a matter of some conjecture as far as I can tell.

 

9 minutes ago, Alien 13 said:

I wonder if Jupiter as a "failed star" is similar.

Alan

Indeed. As earlier, what times we live in, eh? The sheer amount of data coming in from all sorts of areas is phenomenal. 

Can we cope with it? Time will tell ... ?

[Knight of Clear Skies]

15 hours ago, nightfisher said:

So Jupiter and Saturn are classed as gas giants...........so this leaves a thicko like me wondering what would happen if a lander craft tried to land on one of these planets, would it just sink deeper and deeper into the gas layers?

Here's a good XKCD What-If? that explains why interplanetary submariner isn't a safe career path.

 

[Astro Imp]

What a great thread, a seemingly simple question has produced a really interesting discussion.

[carastro]

Isn't Cassini going to be crashed in Saturn in September?  Maybe they will keep the link to/from the craft going as long as it lasts which might tell us something.

Watch this video, it explains all, if you can put up with the narrator:

https://www.usatoday.com/videos/news/world/2017/04/04/nasa-crash-cassini-into-saturn/83544058/

[Art Gecko]

4 hours ago, carastro said:

Isn't Cassini going to be crashed in Saturn in September?  Maybe they will keep the link to/from the craft going as long as it lasts which might tell us something.

Watch this video, it explains all, if you can put up with the narrator:

https://www.usatoday.com/videos/news/world/2017/04/04/nasa-crash-cassini-into-saturn/83544058/

Yes, but NASA are expecting to lose radio contact within about a minute of it entering the atmosphere, so what information we get from it will only really be the subject of the upper atmosphere... the interior will still be down to speculation.

Venus also has a similarly thick atmosphere, yet radar observations have mapped the rocky surface even though the atmosphere is at surface level equal to being submerged a kilometre underwater...  so far we have no radar evidence of a rocky surface on Jupiter or Saturn, which suggests either there is no solid surface or gases, liquids and solids react differently in such an extreme and alien environment.

[Floater]

1 hour ago, Art Gecko said:

... so far we have no radar evidence of a rocky surface on Jupiter or Saturn, which suggests either there is no solid surface or gases, liquids and solids react differently in such an extreme and alien environment.

And this is where it gets even trickier. I quote this from Space.com: 

Like Jupiter, Saturn is suspected to have a rocky core surrounded by hydrogen and helium. However, the question of how solid the core might be is still up for debate. Though composed of rocky material, the core itself may be liquid.

From the same piece I learned that scientists deem the 'surface' of a gas giant is decided to be at the point of one bar pressure, regardless of whether it's 'solid' or not.

It makes the head spin a bit, doesn't it!

[Guest]

Will Cassini  send images of Saturn when it begins to plunge into it's atmosphere I wonder?

Also,how much bigger would Jupiter of Saturn have to be to be classed as a star?

[johnfosteruk]

17 minutes ago, Grumpy Martian said:

Will Cassini  send images of Saturn when it begins to plunge into it's atmosphere I wonder?

No, they'll be turning the cameras off on the final descent and mostly recording non image data.

So they'll take images of the northern storm/hexagon, Enceledus setting, some ring shots, Titan, and some other stuff until about 3 hours from impact. Then the spacecraft will go into near realtime transmit mode. During this phase they'll be nearly live streaming data from (mainly) the spectrometers, fields and particles instrument and dust analysers running as it descends towards the atmosphere.

As it enters the atmosphere they'll keep that running while inertial thrusters correct attitude adjustment as long as possible until they lose contact. That's assuming she doesn't take a nasty hit from a ring particle during these ring dives of course. Either way, what an amazing mission it's been.

Can't wait.

Meanwhile, my favourite of all the spectacular images Cassini has sent us

[Guest]

Thank you for this info. It has been fantastic.This image is beautiful. Do you think that we will see a return mission in our lifetime given the time gap between Pioneer and Voyager?

[Knight of Clear Skies]

10 hours ago, Grumpy Martian said:

Also,how much bigger would Jupiter of Saturn have to be to be classed as a star?

The lowest mass Brown Dwarfs weigh in at about 13 times the mass of Jupiter, but they only go through a short deuterium-burning phase before cooling for the rest of their life. You'd need 80 Jupiters to make a low-mass Red Dwarf. Jupiter is a 'failed star' in the same sense that Johnny Vegas is a 'failed elephant'.

On 26/04/2017 at 20:51, Floater said:

That seems to have something to do with the 'frost line', but the frost line itself is a matter of some conjecture as far as I can tell.

I don't believe the existence of the frost line is in any doubt but its location certainly is. We understand the broad strokes of planetary formation but the details are devilishly complicated, where Earth's water came from is a another mystery.

On 26/04/2017 at 20:39, John said:

Uranus and Neptune are also giants but interestingly seem to be referred to as ice giants.

It's thought that they didn't grow large enough early enough to feed heavily on the hydrogen and helium present in the Sun's protoplanetary disc. As the Sun began to shine its solar wind expelled the remaining gas into space. As a result the ice giants are only composed of about 20% hydrogen and helium (by mass) compared to 90% for Jupiter and Saturn, who got an earlier start.

Confusingly, although they are referred to as 'ice giants' the ices in their mantles are in a hot fluid state. They formed largely by capturing icy planetesimals.

Things get very odd down towards the interior - it's thought that diamonds may form and rain down like hailstones. 

[Floater]

1 hour ago, Knight of Clear Skies said:

I don't believe the existence of the frost line is in any doubt but its location certainly is. We understand the broad strokes of planetary formation but the details are devilishly complicated, where Earth's water came from is a another mystery.

... the ice giants are only composed of about 20% hydrogen and helium ... Confusingly, although they are referred to as 'ice giants' the ices in their mantles are in a hot fluid state. They formed largely by capturing icy planetesimals.

Things get very odd down towards the interior

I'm hanging on the edges here (aren't we all?!) but this is correct as far as I understand - and, indeed, it is devilishly complicated! ? The frost line separates the terrestrial planets from the ice giants in our solar system but giants have been detected much closer to their host star in other systems. The suggestion is these 'hot Jupiters' formed outside the frost line then migrated inwards.

Just to add to the fun different volatile substances, or gases, have different frost lines ...

I believe the idiom is 'Go figure'.

Meanwhile, I remain fascinated and eager to learn more. And when the number crunchers, analysts and theorists get their heads round the Cassini data we should definitely learn more. The mission is a triumph and is testimony to the technological ability of our species. Would that we could do as well in some other areas.