Skydiving on Saturn

May 20, 2011 By Pete Wilton
Skydiving on Saturn
Illustration of Saturn skydiving. Lower image: Observation of the 2010 Saturn storm in infrared. Credit: OU/ESO/Fletcher/Barry.

Daredevils regularly bail out at high altitude to skydive through Earth’s atmosphere but what would it be like to skydive on Saturn?

Would you jump in summer into an atmosphere shrouded in a yellow-ochre haze, aim for winter when the planet is tinged blue, or maybe leap into the shadow of those famous rings?

These thoughts were prompted by new research from an international team led by Oxford University scientists into a powerful storm on Saturn first spotted in December 2010. 

"What we see when we look at Saturn in visible light is the top of the cloud decks – that’s near the top of the troposphere or ‘weather zone’ – made up of ammonia clouds and other hazy materials," Leigh Fletcher of Oxford University’s Department of Physics, who led the work, tells us.

"This top layer of cloud is a bit like the skin of an apple, it stops us seeing the body and ‘core’ of the planet underneath." What lies beneath is a mystery, but Saturn sometimes shows its true colours in spectacular fashion.

Seeing (infra)red

As the team report in this week’s Science, for the first time scientists have been able to study a major storm on Saturn using both observations from an orbiting spacecraft (NASA's Cassini) and ground-based telescope (ESO's VLT) at thermal infrared wavelengths.

These wavelengths are longer than the visible light we normally see reflected from Saturn’s clouds and enable researchers to figure out the temperatures, winds and composition of the atmosphere, helping them to build up a picture of its weather in 3D.

So the first question when imagining a Saturn skydive is: where do you start?

Like the Earth, Saturn’s upper atmosphere – its stratosphere – is relatively stable. This stratosphere extends way above the troposphere and the visible cloud deck, radiating energy generated within the planet out into space. 

But whilst Earth’s stratosphere starts around 10km above the surface of our planet (a few kilometres above the clouds) on Saturn the stratosphere extends hundreds of kilometres above the clouds.

Saturn’s stratosphere should be a ‘weather-free’ zone, relatively unaffected by the turmoil of storm clouds churning deep below, "but this turns out to be completely wrong" Leigh explains.

Instead, the new observations spotted ‘beacons’ in the stratosphere that, at 15-20 degrees Kelvin hotter than their surroundings (120-140 Kelvin), stand out like the beacons of a lighthouse. In fact, the spectacular effects of Saturn’s giant storm were being felt in the stratosphere almost 300km above the visible clouds, "that’s almost as far as the International Space Station orbits above the surface of the Earth’ Leigh adds."

"It’s as if the storms in the troposphere are giving the normally stable stratosphere a punch – hitting it and causing the hotspots we’ve been able to pick up in infrared.’

Light the beacons

These beacons are thought to be created when ‘air’ (87% hydrogen, 12% helium, 1% other trace gases) wells up and then descends; becoming compressed and heating up like the air in a bicycle pump. It’s the emission from the other 1%, gases such as methane, ethane, and acetylene, which makes the beacons visible.

Our skydiver would have to plummet some 300kms from the stratospheric beacons to reach the troposphere where convection rules and energy is turned into powerful air currents. Here, at the topmost layer of the clouds, the bright white areas we see in visible light are plumes of fresh material as yet untainted by Saturn ‘smog’.

But of course, this being Saturn, these aren’t ordinary storm clouds: instead they are clouds mostly made up of crystals of ammonia ice and other exotic materials.

"It’s as if, by injecting these plumes of fresh material up into the troposphere, the planet is doing a gigantic experiment for us; injecting a visible tracer that we are then able to use to track Saturn’s jet streams as they travel from east to west around the planet," Leigh tells us.

These top layers of clouds that ‘cloak’ the planet - shielding the lower reaches of the atmosphere from view - vary in colour from the pristine, bright and new, to old, dark clumps that have accumulated ‘dirt’ or contaminate as they circulate in the turbulent currents of the giant storm.

Yet the journey of our intrepid skydiver is nowhere near over even now she’s reached the top of the visible clouds. She would have to plunge even deeper, into cloud decks normally hidden from telescopes and orbiting spacecraft, to find the source of the powerful storms and beacons observed by the team.

"The storms don’t begin in the troposphere with these ammonia clouds, we think that they start around 200-300km below the top of the troposphere, possibly within clouds of water hidden deep within Saturn’s atmosphere," explains Leigh.

Stormy weather

Here, over 500km below the beacons in Saturn’s stratosphere, is where bad weather is brewed. An injection of energy into this cloud deck can form giant bubbles or plumes which rise upwards. These drag with them material that will eventually form the visible tropospheric clouds, and it’s the response to this powerful convection that is likely to be generating those hot beacons which show up in infrared in Saturn’s stratosphere.

If our skydiver has made it this far, she’s reached the part of the atmosphere scientists would really like to study – one possible source of the incredible phenomena seen on giant planets.

These latest observations are just the beginning of the story of Saturn’s stormy weather. Since the work reported in Science the team have been continuing to monitor the behaviour of the beacons and hope that they can reveal much more about the planet’s atmosphere.

Leigh comments: "We’ve taken what people think of as a serene and beautiful astronomical object and moved it into the messy and volatile realm of meteorology. It’s a nice thought when you look up at a blue sky on Earth filled with fluffy of water vapour that the same physics of weather is driving vast storms on another, very different, planet."

Our imaginary skydiver has taken us on a wild ride deep into the heart of this gas giant but she’s still only scratched the surface. ’s deep churning atmosphere extends another 58,000km to the core – that’s 3.5 times the diameter of the . Assuming she survived the incredible heat, pressure, and poisonous fumes she’d still be faced by one final problem: how do you land on a planet that has no solid surface?

Explore further: NASA's Maven explorer arrives at Mars after year

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spectator
3.8 / 5 (5) May 20, 2011
how do you land on a planet that has no solid surface?


You don't really believe something that massive and that cold has no solid surface, do you?

What? You think in the alleged 4.567 billion years you people claim the solar system has been here, no asteroids or comets have hit saturn? That would automatically make a solid core "somewhere" in there. Even if the asteroids which have hit Saturn disintegrated upon impact, the metals from them would eventually settle to the core as they cooled.

Saturn is probably has a core rock dust and metals, covered in dirty methane-ice, much like a comet.

To believe something at 95 earth masses has been sitting in space allegedly for billions of years, or even a few thousand years, and not picked up a rocky core is ridiculous. Even the earth, with it's gravitational footprint being 95 times weaker, picks up tremendous amount of dirt each year from micro meteors and daily basketball sized impactors.
spectator
3 / 5 (2) May 20, 2011
Saturn even has rocky moons.

You don't think it maybe ate a few dozen rocky moons and even dwarf planets or asteroids, such as it's trojans, or one of Jupiter's trojans over the ages?
eachus
not rated yet May 20, 2011
Um, maybe you look at the energy reaching the cloud tops and the insulating effect of thousands of kilometers of atmosphere, and conclude that any rocky or metallic core is also molten?

You could argue for a much larger core, but you run into the elemental numbers game. Earth is mostly solid, since the (early) solar wind blew most hydrogen and helium into the outer solar system. But even if you add carbon, nitrogen, and oxygen, it is hard to get anything other than organic compounds which would be liquid or gas at a thousand degrees Kelvin or so.
yyz
not rated yet May 20, 2011
Hey, what happened to pix of the storm on Saturn. UT has Cassini(!) & ESO images of this rare event: http://www.univer...r-storm/

Quite a view for amateur astronomers too. Storms this intense (& visible in scopes as small as 4-6 inches) are quite rare, so I've been visually following this event for a bit. Blue or green filters can help with the contrast, but go and check it out for yourself if you have an opportunity.
yyz
not rated yet May 20, 2011
Doh! I missed the link to the PO story with the VLT-VISIR pix in this article. Still......my link has a good look at this storm from Saturn orbit(by Cassini).
spectator
1 / 5 (1) May 20, 2011
eachus:

The truth is I don't think anyone knows a lot about the interior of gas giants.

We know from experiments on Earth that many materials experience their phase changes at different temperatures when under different pressures.

Liquid water under extreme pressure phase changes to Ice 7.

Methane under extreme pressure (i.e. at gulf oil well depths,) phase changes to Methan Hydrate ice in the pressence of water.

Within a few dozen miles down into a gas giant, under that super gravity and all that mass above you, the pressure would quickly climb to produce exotic phase changes, even at high temperatures.

Saturn is called a "gas giant", as is jupiter, but that is a relative term. It's density is less than water, but just barely, at 0.68g/cm^3. That's the mean density of a liquid.

It's not like this thing is made of "air". The mean density is exactly half way between liquid water and liquid methane, and FAR more dense than ordinary liquid hydrogen.
panorama
not rated yet May 20, 2011
The truth is I don't think anyone knows a lot about the interior of gas giants.

I'm glad and warmed by the supposition that what you think is "The truth". Truly warming.
that_guy
5 / 5 (3) May 20, 2011
I'd like to point out that the supposition that saturn does not have a solid surface to land on is a good one. i think it's a good assumption that it has some kind of solid or semi solid core, but it is doubtlessly covered in liquid, such as liquid hydrogen from the compression. That said, Saturn is the least dense of all the planets (less dense than water), so presumably, and solid/liquid portion of it would be small.
that_guy
5 / 5 (2) May 20, 2011
The great virgin galactic saturn skydive:
"Make your last skydive the best skydive!"
"The most extreme thing you'll never survive!"
"Wait until you tell you friends about...nevermind..."
"Euthanasia...made EXTREME"
sstritt
1 / 5 (3) May 20, 2011
The great virgin galactic saturn skydive:
"Make your last skydive the best skydive!"
"The most extreme thing you'll never survive!"
"Wait until you tell you friends about...nevermind..."
"Euthanasia...made EXTREME"
Maybe a better option is a carbon nanotube bungee jump into Saturn. That way its not a guaranteed one-way trip.
that_guy
not rated yet May 20, 2011
The great virgin galactic saturn skydive:
"Make your last skydive the best skydive!"
"The most extreme thing you'll never survive!"
"Wait until you tell you friends about...nevermind..."
"Euthanasia...made EXTREME"
Maybe a better option is a carbon nanotube bungee jump into Saturn. That way its not a guaranteed one-way trip.

But then how would you find out if it has a surface or not?
MarkyMark
5 / 5 (2) May 21, 2011
The great virgin galactic saturn skydive:
"Make your last skydive the best skydive!"
"The most extreme thing you'll never survive!"
"Wait until you tell you friends about...nevermind..."
"Euthanasia...made EXTREME"
Maybe a better option is a carbon nanotube bungee jump into Saturn. That way its not a guaranteed one-way trip.

But then how would you find out if it has a surface or not?

Make the bungee cord really long.
plasticpower
3 / 5 (1) May 22, 2011
I agree with the very first post, there is a crap-load (millions of metric tons) of space crap (asteroids, big solid rocks) falling into these planets. The metals these objects are composed of are most definitely not gases at such high pressures. However, "gas giant" is a fitting name because no matter how much you argue about the contents at the center, most of the planet is made up of gas. Chances are, the temperatures at the center are so hot that even the metal/rocky middle is liquid. Think about Earth.. nobody really knows if the core is solid. It might be. Or it might be liquid rock. There certainly IS liquid rock below Earth's crust. And the pressures on Earth aren't nearly as great as on Saturn or Jupiter.
technicalengeneering
5 / 5 (1) May 22, 2011
You guys should really check out:
http://en.wikiped...i/Saturn
and:
http://en.wikiped...ki/Earth

You might just learn something.
Bob_Kob
2 / 5 (4) May 29, 2011
Saturn: 9 times larger than earth, but apparently theres enough asteroids out there to 'fill it up'.
Sinister1811
1 / 5 (4) May 29, 2011
I don't agree with the first post at all. Considering the enormous sizes of Jupiter and Saturn, daily bombardments of meteorites or asteroids would have to take forever to produce a solid surface. The size of the asteroids compared to the planets is miniscule. Given the thick atmospheres - the meteorites (and what have you) would burn up upon impact. A planet having a solid core isn't nearly the same as having a solid surface. Most of the planet consists of Gaseous atmosphere, so to say that the name "Gas Giant" isn't a fitting description doesn't make any sense.