enceladus moon

Magnetospheres: How Do They Work?

The sun, Earth, and many other planets are surrounded by giant magnetic bubbles.

Space may seem empty, but it’s actually a dynamic place, dominated by invisible forces, including those created by magnetic fields.  Magnetospheres – the areas around planets and stars dominated by their magnetic fields – are found throughout our solar system. They deflect high-energy, charged particles called cosmic rays that are mostly spewed out by the sun, but can also come from interstellar space. Along with atmospheres, they help protect the planets’ surfaces from this harmful radiation.

It’s possible that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, so finding magnetospheres around other planets is a big step toward determining if they could support life.

But not all magnetospheres are created equal – even in our own backyard, not all planets in our solar system have a magnetic field, and the ones we have observed are all surprisingly different.

Earth’s magnetosphere is created by the constantly moving molten metal inside Earth. This invisible “force field” around our planet has an ice cream cone-like shape, with a rounded front and a long, trailing tail that faces away from the sun. The magnetosphere is shaped that way because of the constant pressure from the solar wind and magnetic fields on the sun-facing side.

Earth’s magnetosphere deflects most charged particles away from our planet – but some do become trapped in the magnetic field and create auroras when they rain down into the atmosphere.

We have several missions that study Earth’s magnetosphere – including the Magnetospheric Multiscale mission, Van Allen Probes, and Time History of Events and Macroscale Interactions during Substorms (also known as THEMIS) – along with a host of other satellites that study other aspects of the sun-Earth connection.

Mercury, with a substantial iron-rich core, has a magnetic field that is only about 1% as strong as Earth’s. It is thought that the planet’s magnetosphere is stifled by the intense solar wind, limiting its strength, although even without this effect, it still would not be as strong as Earth’s. The MESSENGER satellite orbited Mercury from 2011 to 2015, helping us understand our tiny terrestrial neighbor.

After the sun, Jupiter has by far the biggest magnetosphere in our solar system – it stretches about 12 million miles from east to west, almost 15 times the width of the sun. (Earth’s, on the other hand, could easily fit inside the sun.) Jupiter does not have a molten metal core like Earth; instead, its magnetic field is created by a core of compressed liquid metallic hydrogen.

One of Jupiter’s moons, Io, has intense volcanic activity that spews particles into Jupiter’s magnetosphere. These particles create intense radiation belts and the large auroras around Jupiter’s poles.

Ganymede, Jupiter’s largest moon, also has its own magnetic field and magnetosphere – making it the only moon with one. Its weak field, nestled in Jupiter’s enormous shell, scarcely ruffles the planet’s magnetic field.

Our Juno mission orbits inside the Jovian magnetosphere sending back observations so we can better understand this region. Previous observations have been received from Pioneers 10 and 11, Voyagers 1 and 2, Ulysses, Galileo and Cassini in their flybys and orbits around Jupiter.

Saturn’s moon Enceladus transforms the shape of its magnetosphere. Active geysers on the moon’s south pole eject oxygen and water molecules into the space around the planet. These particles, much like Io’s volcanic emissions at Jupiter, generate the auroras around the planet’s poles. Our Cassini mission studies Saturn’s magnetic field and auroras, as well as its moon Enceladus.

Uranus’ magnetosphere wasn’t discovered until 1986 when data from Voyager 2’s flyby revealed weak, variable radio emissions. Uranus’ magnetic field and rotation axis are out of alignment by 59 degrees, unlike Earth’s, whose magnetic field and rotation axis differ by only 11 degrees. On top of that, the magnetic field axis does not go through the center of the planet, so the strength of the magnetic field varies dramatically across the surface. This misalignment also means that Uranus’ magnetotail – the part of the magnetosphere that trails away from the sun – is twisted into a long corkscrew.

Neptune’s magnetosphere is also tilted from its rotation axis, but only by 47. Just like on Uranus, Neptune’s magnetic field strength varies across the planet. This also means that auroras can be seen away from the planet’s poles – not just at high latitudes, like on Earth, Jupiter and Saturn.

Does Every Planet Have a Magnetosphere?

Neither Venus nor Mars have global magnetic fields, although the interaction of the solar wind with their atmospheres does produce what scientists call an “induced magnetosphere.” Around these planets, the atmosphere deflects the solar wind particles, causing the solar wind’s magnetic field to wrap around the planet in a shape similar to Earth’s magnetosphere.

What About Beyond Our Solar System?

Outside of our solar system, auroras, which indicate the presence of a magnetosphere, have been spotted on brown dwarfs – objects that are bigger than planets but smaller than stars.

There’s also evidence to suggest that some giant exoplanets have magnetospheres. As scientists now believe that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, finding magnetospheres around exoplanets is a big step in finding habitable worlds.  

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Enceladus - Life in our solar system?

Enceladus is Saturns icy moon that measures approximately 504km in diameter, about a tenth of the size of Saturn’s largest moon Titan. Almost completely covered in ice, this moon could potentially harbour the same type of life-sustaining chemical reactions found in deep sea hydrothermal vents here on Earth.

In 2005, NASA’s Saturn orbiting Cassini spacecraft spotted geysers of water and ice erupting fro fissures near Enceladus’ South Pole. Scientists believe they originate from a great ocean beneath the shell of ice. This ocean manages to stay liquid because the gravitational force exerted by Saturn is so intense that it twists and stretches the moon generating internal heat.

In October 2015, Cassini went on a dive through one of the plumes passing within just 39km of Enceladus’ surface. A team of scientists led by Hunter Waite analysed the observations made by the spacecraft. They discovered that the geysers contain between 0.4%-1.4% molecular hydrogen (H2) and 0.3%-0.8% carbon dioxide (CO2). These are being produced continuously by reactions between hot water and rock near the core of the moon. Some of the most primitive metabolic pathways found in microbes at deep ocean hydrothermal vents involve the reduction of CO2 with H2 to form methane (CH4) by a process known as methanogenesis.

Solar System: Things to Know This Week

Our solar system is a jewel box filled with a glittering variety of beautiful worlds–and not all of them are planets. This week, we present our solar system’s most marvelous moons.

1. Weird Weather: Titan

Saturn’s hazy moon Titan is larger than Mercury, but its size is not the only way it’s like a planet. Titan has a thick atmosphere, complete with its own “water cycle” – except that it’s way too cold on Titan for liquid water. Instead, rains of liquid hydrocarbons like ethane and methane fall onto icy mountains, run into rivers, and gather into great seas. Our Cassini spacecraft mapped the methane seas with radar, and its cameras even caught a glimpse of sunlight reflecting off the seas’ surface. Learn more about Titan: saturn.jpl.nasa.gov/science/titan/

2. Icy Giant: Ganymede

Jupiter’s moon Ganymede is the largest in the solar system. It’s bigger than Mercury and Pluto, and three-quarters the size of Mars. It’s also the only moon known to have its own magnetic field. Details: solarsystem.nasa.gov/planets/ganymede/indepth

3. Retrograde Rebel: Triton

Triton is Neptune’s largest moon, and the only one in the solar system to orbit in the opposite direction of its planet’s rotation, a retrograde orbit. It may have been captured from the Kuiper Belt, where Pluto orbits. Despite the frigid temperatures there, Triton has cryovolcanic activity – frozen nitrogen sometimes sublimates directly to gas and erupts from geysers on the surface. More on Triton: solarsystem.nasa.gov/planets/triton/indepth

4. Cold Faithful: Enceladus

The most famous geysers in our solar system (outside of those on Earth) belong to Saturn’s moon Enceladus. It’s a small, icy body, but Cassini revealed this world to be one of the solar system’s most scientifically interesting destinations. Geyser-like jets spew water vapor and ice particles from an underground ocean beneath the icy crust of Enceladus. With its global ocean, unique chemistry and internal heat, Enceladus has become a promising lead in our search for worlds where life could exist. Get the details: saturn.jpl.nasa.gov/science/enceladus/

5. Volcano World: Io

Jupiter’s moon Io is subjected to tremendous gravitational forces that cause its surface to bulge up and down by as much as 330 feet (100 m). The result? Io is the most volcanically active body in the Solar System, with hundreds of volcanoes, some erupting lava fountains dozens of miles high. More on Io’s volcanoes: solarsystem.nasa.gov/planets/io/indepth

6. Yin and Yang Moon: Iapetus

When Giovanni Cassini discovered Iapetus in 1671, he observed that one side of this moon of Saturn was bright and the other dark. He noted that he could only see Iapetus on the west side of Saturn, and correctly concluded that Iapetus had one side much darker than the other side. Why? Three centuries later, the Cassini spacecraft solved the puzzle. Dark, reddish dust in Iapetus’s orbital path is swept up and lands on the leading face of the moon. The dark areas absorb energy and become warmer, while uncontaminated areas remain cooler. Learn more: saturn.jpl.nasa.gov/news/2892/cassini-10-years-at-saturn-top-10-discoveries/#nine

7. A Double World: Charon and Pluto

At half the size of Pluto, Charon is the largest of Pluto’s moons and the largest known satellite relative to its parent body. The moon is so big compared to Pluto that Pluto and Charon are sometimes referred to as a double planet system. Charon’s orbit around Pluto takes 6.4 Earth days, and one Pluto rotation (a Pluto day) takes 6.4 Earth days. So from Pluto’s point of view Charon neither rises nor sets, but hovers over the same spot on Pluto’s surface, and the same side of Charon always faces Pluto. Get the details: www.nasa.gov/feature/pluto-and-charon-new-horizons-dynamic-duo

8. “Death Star” Moon: Mimas

Saturn’s moon Mimas has one feature that draws more attention than any other: the crater Herschel, which formed in an impact that nearly shattered the little world. Herschel gives Mimas a distinctive look that prompts an oft-repeated joke. But, yes, it’s a moon. More: olarsystem.nasa.gov/planets/mimas

9. Don’t Be Afraid, It’s Just Phobos

In mythology, Mars is a the god of war, so it’s fitting that its two small moons are called Phobos, “fear,” and Deimos, “terror.” Our Mars Reconnaissance Orbiter caught this look at Phobos, which is roughly 17 miles (27 km) wide. In recent years, NASA scientists have come to think that Phobos will be torn apart by its host planet’s gravity. Details: www.nasa.gov/feature/goddard/phobos-is-falling-apart

Learn more about Phobos: solarsystem.nasa.gov/planets/phobos/indepth

10. The Moon We Know Best

Although decades have passed since astronauts last set foot on its surface, Earth’s moon is far from abandoned. Several robotic missions have continued the exploration. For example, this stunning view of the moon’s famous Tycho crater was captured by our Lunar Reconnaissance Orbiter, which continues to map the surface in fine detail today. More: www.lroc.asu.edu/posts/902

Discover more lists of 10 things to know about our solar system HERE.

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Saturn’s Moon, Enceladus, Is Our Closest Great Hope For Life Beyond Earth

“Cassini provided scientists with a wealth of data about Enceladus’ surface and the composition of its powerful plumes. This data showed evidence of a deep saltwater ocean with an energy source beneath Enceladus’ surface. The presence of water, warmth, and organic molecules are the necessary requirements for sustaining life as we know it. Water is proven to exist, while the tidal forces from Saturn provide the necessary heat. Based on observations of other bodies in the Solar System, Enceladus likely contains the raw ingredients for life as well. The suspected existence of all three hints at the possible presence of the precursors to amino acids in this vast subsurface ocean. Should we find extraterrestrial life on Enceladus – or in the geyser-like plumes erupting into space – the implications are almost incomprehensible.”

When you think about life beyond Earth, you likely think of it occurring on a somewhat Earth-like planet. A rocky world, with either a past or present liquid ocean atop the surface, seems ideal. But that might not even be where life on Earth originated! Deep beneath the Earth’s surface, geologically active hydrothermal vents currently support diverse colonies of life without any energy from the Sun. Saturn’s icy moon, Enceladus, has a subsurface ocean unlike any other world we’ve yet discovered. The tidal forces of Saturn itself provide the necessary heat, and also create cracks in the Enceladean surface, enabling massive geysers. This subsurface ocean rises hundreds of kilometers high, regularly resurfaces the world with a coat of fresh ice, and even creates the E-ring of Saturn. But most spectacularly, it may house actively living organisms, and could be the next-best world for life, after Earth, in the Solar System today.

Come get the full story on Enceladus, and welcome Starts With A Bang’s newest contributor, the remarkable Jesse Shanahan!

Solar System: Things to Know This Week

We’ve been up close and personal with Saturn for 13 years now, thanks to the Cassini mission

From a tour of Saturn’s many enthralling moons to an incredible view of Earth through its rings, the planet continues to captivate the imagination. This week, here are 10 things you need to know about our fascinating ringed neighbor.

1. Strange Sighting

When Galileo Galilei was observing Saturn in the 1600s, he noticed strange objects on each side of the planet. He drew in his notes a triple-bodied planet system with ears. These “ears” were later discovered to be the rings of Saturn.

2. Solar System Status

Saturn orbits our sun and is the sixth planet from the sun at an average distance of about 886 million miles or 9.5 AU.

3. Short Days

Time flies when you’re on Saturn. One day on Saturn takes just 10.7 hours (the time it takes for Saturn to rotate or spin once). The planet makes a complete orbit around the sun (a year in Saturnian time) in 29 Earth years, or 10,756 Earth days. saturn.jpl.nasa.gov/news/2955/measuring-a-day

4. No Shoes Necessary

That’s because you can’t stand on Saturn—it’s a gas-giant planet and doesn’t have a solid surface. But you might want a jacket. The planet’s temperatures can dip to -220 degrees F.

5. Few visitors

Only a handful of missions have made their way to Saturn: Pioneer 11, Voyager 1 and 2, and Cassini-Huygens, which is there now. Since 2004, Cassini has been exploring Saturn and its moons and rings—but will complete its journey on Sept. 15, 2017.

6. Saturn’s Close-Up

This month is a great time to observe Saturn from Earth. Check out June’s “What’s Up?” video for a how-to guide.

7. Daring Dives

Saturn’s spectacular ring system is made up of seven rings with several gaps and divisions between them. From now until September, the Cassini spacecraft is performing a set of daring dives every week between the planet and the rings. No other mission has ever explored this unique region before, and what we learn from these final orbits will help us understand of how giant planets—and planetary systems everywhere—form and evolve.

8. Many, Many Moons 

Saturn has a total of 62 moons: 53 known moons, with an additional nine moons awaiting confirmation.

9. Curious Shapes 

Saturn’s moon Atlas looks like a flying saucer. See for yourself.

10. Would You Live on a Moon? 

Saturn can’t support life as we know it, but some of its moons have conditions that might support life. Ocean worlds could be the answer to life in space and two of Saturn’s moons—Titan and Enceladus—are on that list.

Want to learn more? Read our full list of the 10 things to know this week about the solar system HERE.

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It’s May the 4th: Are Star Wars Planets Real?

Look at what we’ve found so far.

Is your favorite Star Wars planet a desert world or an ice planet or a jungle moon?

It’s possible that your favorite planet exists right here in our galaxy. Astronomers have found over 3,400 planets around other stars, called “exoplanets.”

Some of these alien worlds could be very similar to arid Tatooine, watery Scarif and even frozen Hoth, according to NASA scientists.

Find out if your planet exists in a galaxy far, far away or all around you. And May the Fourth be with you!

Planets With Two Suns

From Luke Skywalker’s home world Tatooine, you can stand in the orange glow of a double sunset. The same could said for Kepler-16b, a cold gas giant roughly the size of Saturn, that orbits two stars. Kepler-16b was the Kepler telescopes’s first discovery of a planet in a “circumbinary” orbit (that is, circling both stars, as opposed to just one, in a double star system). 

The best part is that Tatooine aka Kepler-16b was just the first. It has family. A LOT of family. Half the stars in our galaxy are pairs, rather than single stars like our sun. If every star has at least one planet, that’s billions of worlds with two suns. Billions! Maybe waiting for life to be found on them.

Desert Worlds

Mars is a cold desert planet in our solar system, and we have plenty of examples of scorching hot planets in our galaxy (like Kepler-10b), which orbits its star in less than a day)! Scientists think that if there are other habitable planets in the galaxy, they’re more likely to be desert planets than ocean worlds. That’s because ocean worlds freeze when they’re too far from their star, or boil off their water if they’re too close, potentially making them unlivable. Perhaps, it’s not so weird that both Luke Skywalker and Rey grew up on planets that look a lot alike.

Ice Planets

An icy super-Earth named OGLE-200-BLG-390Lb reminded scientists so much of the frozen Rebel base they nicknamed it “Hoth,” after its frozen temperature of minus 364 degrees Fahrenheit. Another Hoth-like planet was discovered last month; an Earth-mass icy world orbiting its star at the same distance as Earth orbits the sun. But its star is so faint, the surface of OGLE-2016-BLG-1195Lb is probably colder than Pluto.

Forest worlds

Both the forest moon of Endor and Takodana, the home of Han Solo’s favorite cantina in “Force Awakens,” are green like our home planet. But astrobiologists think that plant life on other worlds could be red, black, or even rainbow-colored!

In February 2017, the Spitzer Space Telescope discovered seven Earth-sized planets in the same system, orbiting the tiny red star TRAPPIST-1.

The light from a red star, also known as an M dwarf, is dim and mostly in the infrared spectrum (as opposed to the visible spectrum we see with our sun). And that could mean plants with wildly different colors than what we’re used to seeing on Earth. Or, it could mean animals that see in the near-infrared.

What About Moons?

In Star Wars, Endor, the planet with the cute Ewoks, is actually a habitable moon of a gas giant. Now, we’re looking for life on the moons of our own gas giants. Saturn’s moon Enceladus or Jupiter’s moon Europa are ocean worlds that may well support life. Our Cassini spacecraft has explored the Saturn system and its moons. Watch the video and learn more about the missions’s findings.

And Beyond

The next few years will see the launch of a new generation of spacecraft to search for planets around other stars. TESS and the James Webb Telescope are slated to launch in 2018, and WFIRST in the mid-2020s. That’s one step closer to finding life.

You might want to take our ‘Star Wars: Fact or Fiction?’ quiz. Try it! Based on your score you may obtain the title of Padawan, Jedi Knight, or even Jedi Master! 

You don’t need to visit a galaxy far, far away to find wondrous worlds. Just visit this one … there’s plenty to see.

Discover more about exoplanets here: https://exoplanets.nasa.gov/

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Ocean Worlds: The Story of Seas on Earth and Other Planets

So far, every volume signed Jan Zalasiewicz had proved a geological pleasure (as indeed have all the others in the series on Earth Systems Science that OUP have been releasing), and this latest instalment (the second book he’s co written with Mark Williams) did not disappoint my high expectations. While it isn’t an overview of the current state of oceanography, it provides a pleasant and fascinating romp through all things ocean, from the origin of the water in comets, through their role in the great cycles of the elements to the current ecological catastrophe shaping up in the planet’s seas.

Keep reading


Countdown to Cassini’s Grand Finale

After nearly 13 years in orbit around Saturn, the international Cassini–Huygens mission is about to begin its final chapter: the spacecraft will perform a series of daring dives between the planet and its rings, leading to a dramatic final plunge into Saturn’s atmosphere on 15 September.

On 22 April, Cassini successfully executed its 127th and final close flyby of Saturn’s largest moon, Titan.

The manoeuvre put the spacecraft onto its ’grand finale’ trajectory: a series of 22 orbits, each lasting about a week, drawing closer to Saturn and passing between the planet’s innermost rings and its outer atmosphere. The first crossing of the ring plane will occur on 26 April.

With the repeated dives in this yet unvisited region, the mission will conclude its journey of exploration by collecting unprecedented data to address fundamental questions about the origin of Saturn and its ring system.

Launched in 1997, the Cassini-Huygens spacecraft embarked on a seven-year voyage across the Solar System, eventually reaching Saturn in July 2004. Several months later, the Cassini orbiter released ESA’s Huygens probe, which landed on Titan on 14 January 2005 – the first landing in the outer Solar System.

The mission has greatly contributed to our understanding of the Saturnian environment, including the giant planet’s system of rings and moons.
Combining the data collected in situ by Huygens and the observations performed by Cassini during flybys of Titan, the mission revealed the atmospheric processes of this moon and their seasonal evolution, as well as the surface morphology and interior structure, which may include a liquid water ocean.

Enshrouded by a thick nitrogen-dominated atmosphere and partly covered by lakes and rivers, Titan has a weather and hydrological cycle that bears some interesting similarities to Earth. However, there are important differences: the key component there is not water, like on our planet, but methane, and the temperature is very low, around –180°C at the surface.

Over its 13-year mission, Cassini will have covered about half of Saturn’s orbit, in which the planet takes 29 years to circle the Sun. This means that the spacecraft has monitored two seasons on Titan, an object that can teach us much on the past and the future of Earth.

Another of Cassini’s breakthroughs was the detection of a towering plume of water vapour and organic material spraying into space from warm fractures near the south pole of Saturn’s icy moon, Enceladus. These salt-rich jets indicate that an underground sea of liquid water is lurking only a few kilometres below the moon’s icy surface, as confirmed by gravity and rotation measurements.

A recent analysis of data collected during flybys of Enceladus with the Cassini Ion Neutral Mass Spectrometer also revealed hydrogen gas in the plume, suggesting that rock might be reacting with warm water on the seafloor of the moon’s subsurface ocean. This hydrothermal activity could provide a chemical energy source for life, enabling non-photosynthetic biological processes similar to the ones found near the hydrothermal vents on the Earth’s ocean floor and pointing to the potential habitability of Enceladus’ underground ocean.

Following over a decade of ground-breaking discoveries, Cassini is now approaching its end. With little fuel left to correct the spacecraft trajectory, it has been decided to end the mission by plunging it into Saturn’s atmosphere on 15 September 2017. In the process, Cassini will burn up, satisfying planetary protection requirements to avoid possible contamination of any moons of Saturn that could have conditions suitable for life.

The grand finale is not only a spectacular way to complete this extraordinary mission, but will also return a bounty of unique scientific data that was not possible to collect during the previous phases of the mission.

Cassini has never ventured into the area between Saturn and its rings before, so the new set of orbits is almost like a whole new mission.
These close orbits will be inclined 63 degrees with respect to Saturn’s equator and will provide the highest resolution observations ever achieved of the inner rings and the planet’s clouds. The orbits will also give the chance to examine in situ the material in the rings and plasma environment of Saturn.

With its radio science investigation, Cassini will measure Saturn’s gravitational field as close as 3000 km from Saturn’s upper cloud layers, greatly improving the current models of the planet’s internal structure and winds in its atmosphere. Scientists expect the new data will also allow them to disentangle the gravity of the planet from the tiny pull exerted on the spacecraft by the rings, estimating the total mass of the rings to unprecedented accuracy. ESA ground stations in Argentina and Australia will help receive Cassini’s radio science data, providing a series of 22 tracking passes during the grand finale.

The grand finale orbits will also probe the planet’s magnetic field at similarly close distances. Previous observations have shown that the magnetic field is weaker than expected, with the magnetic axis surprisingly well aligned with the planet’s rotation. New data to be collected by the Cassini magnetometer will provide insights to understand why this is so and where the sources of magnetic field are located, or whether something in Saturn’s atmosphere has been obscuring the true magnetic field from Cassini until now.

While crossing the ring plane, Cassini’s Cosmic Dust Analyzer will directly sample the composition of dust particles from different parts of the ring system, whereas the Ion Neutral Mass Spectrometer will sniff the upper atmosphere layers of Saturn to analyse molecules escaping from the atmosphere as well as water-based molecules that originate from the rings.
“At last, we have now reached the final and most audacious phase of this pioneering mission, pushing the spacecraft once again into unexplored territory,” says Nicolas Altobelli, ESA Cassini project scientist.
“We are looking forward to the flow of exciting new data that Cassini will send back in the coming months.”

Ocean Worlds Beyond Earth

We’re incredibly lucky to live on a planet drenched in water, nestled in a perfect distance from our sun and wrapped with magnetic fields keeping our atmosphere intact against harsh radiation and space weather.

We know from recent research that life can persist in the cruelest of environments here on Earth, which gives us hope to finding life thriving on other worlds. While we have yet to find life outside of Earth, we are optimistic about the possibilities, especially on other ocean worlds right here in our solar system.  

So…What’s the News?!

Two of our veteran missions are providing tantalizing new details about icy, ocean-bearing moons of Jupiter and Saturn, further enhancing the scientific interest of these and other “ocean worlds” in our solar system and beyond!

Cassini scientists announce that a form of energy for life appears to exist in Saturn’s moon Enceladus, and Hubble researchers report additional evidence of plumes erupting from Jupiter’s moon Europa.

The Two Missions: Cassini and Hubble


Our Cassini spacecraft has found that hydrothermal vents in the ocean of Saturn’s icy moon Enceladus are producing hydrogen gas, which could potentially provide a chemical energy source for life.

Cassini discovered that this little moon of Saturn was active in 2005. The discovery that Enceladus has jets of gas and icy particles coming out of its south polar region surprised the world. Later we determined that plumes of material are coming from a global ocean under the icy crust, through large cracks known as “tiger stripes.” 

We have more evidence now – this time sampled straight from the plume itself – of hydrothermal activity, and we now know the water is chemically interacting with the rock beneath the ocean and producing the kind of chemistry that could be used by microbes IF they happened to be there.

This is the culmination of 12 years of investigations by Cassini and a capstone finding for the mission. We now know Enceladus has nearly all the ingredients needed for life as we know it.

The Cassini spacecraft made its deepest dive through the plume on Oct. 28, 2015. From previous flybys, Cassini determined that nearly 98% of the gas in the plume is water and the rest is a mixture of other molecules, including carbon dioxide, methane and ammonia. 

Cassini’s other instruments provided evidence of hydrothermal activity in the ocean. What we really wanted to know was…Is there hydrogen being produced that microbes could use to make energy? And that’s exactly what we found!

To be clear…we haven’t discovered microbes at Enceladus, but vents of this type at Earth host these kinds of life. We’re cautiously excited at the prospect that there might be something like this at Enceladus too!


The Hubble Space Telescope has also been studying another ocean world in our solar system: Europa!

Europa is one of the four major moons of Jupiter, about the size of our own moon but very different in appearance. It’s a cold, icy world with a relatively smooth, bright surface crisscrossed with dark cracks and patches of reddish material.

What makes Europa interesting is that it’s believed to have a global ocean, underneath a thick crust of ice. In fact, it’s got about twice as much ocean as planet Earth!

In 2014, we detected evidence of intermittent water plumes on the surface of Europa, which is interesting because they may provide us with easier access to subsurface liquid water without having to drill through miles of ice.

And now, in 2016, we’ve found one particular plume candidate that appears to be at the same location that it was seen in 2014. 

This is exciting because if we can establish that a particular feature does repeat, then it is much more likely to be real and we can attempt to study and understand the processes that cause it to turn on or off. 

This plume also happens to coincide with an area where Europa is unusually warm as compared to the surrounding terrain. The plume candidates are about 30 to 60 miles (50 to 100 kilometers) in height and are well-positioned for observation, being in a relatively equatorial and well-determined location.

What Does All This Mean and What’s Next?

Hubble and Cassini are inherently different missions, but their complementary scientific discoveries, along with the synergy between our current and planned missions, will help us in finding out whether we are alone in the universe. 

Hubble will continue to observe Europa. If you’re wondering how we might be able to get more information on the Europa plume, the upcoming Europa Clipper mission will be carrying a suite of 9 instruments to investigate whether the mysterious icy moon could harbor conditions favorable for life. Europa Clipper is slated to launch in the 2020s.

This future mission will be able to study the surface of Europa in great detail and assess the habitability of this moon. Whether there’s life there or not is a question for this future mission to discover!

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Could We Find Alien Life on Saturn’s Moon Enceladus?
Saturn’s icy moon, Enceladus, is one of the most beautiful moons in our solar system, and it may also be the best place to discover extraterrestrial life!

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Solar System: Things to Know This Week

Earth is the ultimate ocean planet (that we know of), but it turns out that our solar system has water in some surprising places, with five ocean-bearing moons and potentially several more worlds with their own oceans. 

1. The Original “Alien Ocean”

Our Galileo spacecraft (1989-2003) detected the first evidence of an ocean beyond Earth under the ice of Jupiter’s icy moon Europa.

2. Lost Oceans

There are signs that Mars and Venus once had oceans, but something catastrophic may have wiped them out. Earth’s natural force field – our magnetosphere – acts like shield against the erosive force of the solar wind.

3. Earth, the Original Ocean World

The search for life beyond Earth relies, in large part, on understanding our home planet. Among the newest Earth ocean explorers us the Cyclone Global Navigation Satellite System, or CYGNSS–a constellation of microsatellites that will make detailed measurements of wind speeds over Earth’s oceans to help understand hurricanes. The spacecraft have moved into their science operations phase.

4. Sister Ships

It’s fitting the first mission to explore an alien ocean is named in honor of fast-sailing clipper ships of old. Our Europa Clipper spacecraft will seek signs of habitability on Jupiter’s moon Europa.

5. Game Changer

Scientists expected Saturn’s moon Enceladus to be a tiny, solid chunk of ice and rock. But, not long after arriving at Saturn, our Cassini spacecraft made a series of incremental discoveries, eventually confirming that a global subsurface ocean is venting into space, with signs of hydrothermal activity.

6. Why Ocean Worlds Matter

“The question of whether or not life exists beyond Earth, the question of whether or not biology works beyond our home planet, is one of humanity’s oldest and yet unanswered questions. And for the first time in the history of humanity, we have the tools and technology and capability to potentially answer this question. And, we know where to go to find it. Jupiter’s ocean world Europa.” - Kevin Hand, NASA Astrobiologist

7. More Alien Oceans

Scientists think Jupiter’s giant moons Ganymede and Callisto also hide oceans beneath their surfaces. Elsewhere in the solar system, scientists hope to look for hidden oceans on far-flung worlds from Ceres in the main asteroid belt to Pluto in the Kuiper Belt.

8. Cold Faithful(s)?

Thanks to our Cassini orbiter we know the tiny moon Enceladus is venting its ocean into space in a towering, beautiful plume. The Hubble Space Telescope also has seen tantalizing hints of plumes on Jupiter’s moon Europa. Plumes are useful because they provide samples of ocean chemistry for oceans that could be miles below the surface and difficult for spacecraft to reach. It’s like they’re giving out free samples!

9. Titanic Seas and Ocean

Saturn’s moon Titan not only has liquid hydrocarbon seas on its surface. It also shows signs of a global, subsurface saltwater ocean–making the giant moon a place to possibly look for life as we know it and life as we don’t know it … yet.

10. Oceans Beyond

Several of the thousands of planets discovered beyond our solar system orbit their stars in zones where liquid surface water is possible–including Proxima-b, a rocky planet orbiting the star nearest to our own.

BONUS: Adopt a bit of YOUR Ocean World

We invite everyone to help us celebrate Earth Day 2017 by virtually adopting a piece of Earth as seen from space. Your personalized adoption certificate will feature data from our Earth-observing satellites for a randomly assigned location, much of it ocean (it is 70 percent of the Earth’s surface after all!). Print it and share it, then explore other locations with our interactive map and get even more Earth science data from NASA’s Worldview website.

Visit go.nasa.gov/adopt to adopt your piece of the planet today!

Discover more lists of 10 things to know about our solar system HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


NASA’s Cassini reveals the full glory of Saturn’s rings

“Composed of 99.9% water-ice, the ring system has thousands of thin gaps, and was thicker and more varied in the past. The once-rocky material has coalesced into moons, but the watery rings will remain for as long as our Solar System exists.”

In the 1600s, the earliest telescopes saw that Saturn had “ears,” while later observers all the way back then finally saw their true nature: a ringed system with complex gaps, bands and colorations throughout. Since then, Saturn’s rings have been a source of wonder and puzzlement to skywatchers everywhere. The only ring system visible through most telescopes from Earth, Saturn’s main rings measure more than 70,000 km long, yet are no more than 1 km in thickness. Once thought to have only two gaps in them, the Cassini spacecraft has revealed over a thousand, teaching us that Saturn’s rings are ancient – likely as old as the planet itself – and will likely continue to exist for as long as our Sun shines.

Go get the full story in a glorious set of pictures from Cassini and no more than 200 words on today’s Mostly Mute Monday!