Tag: Saturn
For an extraterrestrial skiing experience, Enceladus is the place to go.
Sponge in space
On August 25 Cassini did a close fly-by of the small Saturn moon Hyperion, getting as close as 15,500 miles. The mission has just released images from that fly-by.
Looks like a sponge, doesn’t it? This moon is small, only 168 miles across, which makes it about half the size of the asteroid Vesta that Dawn is presently orbiting. Why it is so peppered with craters is of course the big science question. I would guess this has something to do with the environment around Saturn, with its rings and the innumerable particles that come from it. Yet, other moons of Saturn are not as crater-filled, so there is obviously more to this than meets the eye.
This fly-by was the second closest of Hyperion that Cassini has done, the first passing over the the moon’s surface by only 310 miles. Because the irregularly-shaped moon’s rotation is more like a chaotic tumble, scientists could not predict what part of the surface they would see. To their luck the new images captured new territory.
Another fly-by is scheduled in only three weeks, on September 16, 2011. This time, however, the spacecraft won’t get as close, passing at a distance of about 36,000 miles.
Space Boat: A Nautical Mission to an Alien Sea
The Titan Mare Explorer: A nautical mission to an alien sea.
If [NASA] green-lights the mission, the capsule will lift off in 2016. By 2023, TiME will be about 800 million miles away in Titan’s north-polar region, home to its biggest lakes and seas. The capsule will take photographs, collect meteorological data, measure depth, and analyze samples. TiME will have no means of propulsion once it is on Titan, so it will float, carried by breezes across the sea’s surface. Then, by the mid-2020s, it will enter a decade-long winter of darkness as the moon’s orbit takes it to the dark side of Saturn, away from the sun and communication. It won’t have a line of sight to Earth to beam back more data until 2035.
The Titan Mare Explorer: A nautical mission to an alien sea.
If [NASA] green-lights the mission, the capsule will lift off in 2016. By 2023, TiME will be about 800 million miles away in Titan’s north-polar region, home to its biggest lakes and seas. The capsule will take photographs, collect meteorological data, measure depth, and analyze samples. TiME will have no means of propulsion once it is on Titan, so it will float, carried by breezes across the sea’s surface. Then, by the mid-2020s, it will enter a decade-long winter of darkness as the moon’s orbit takes it to the dark side of Saturn, away from the sun and communication. It won’t have a line of sight to Earth to beam back more data until 2035.
Enceladus rains water onto Saturn
The Herschel space telescope has discovered that the water expelled from the tiger stripes on Enceladus eventually rains down on Saturn.
Enceladus expels around 250 kg of water vapour every second, through a collection of jets from the south polar region known as the Tiger Stripes because of their distinctive surface markings. These crucial observations reveal that the water creates a doughnut-shaped torus of vapour surrounding the ringed planet. The total width of the torus is more than 10 times the radius of Saturn, yet it is only about one Saturn radius thick. Enceladus orbits the planet at a distance of about four Saturn radii, replenishing the torus with its jets of water.
The Herschel space telescope has discovered that the water expelled from the tiger stripes on Enceladus eventually rains down on Saturn.
Enceladus expels around 250 kg of water vapour every second, through a collection of jets from the south polar region known as the Tiger Stripes because of their distinctive surface markings. These crucial observations reveal that the water creates a doughnut-shaped torus of vapour surrounding the ringed planet. The total width of the torus is more than 10 times the radius of Saturn, yet it is only about one Saturn radius thick. Enceladus orbits the planet at a distance of about four Saturn radii, replenishing the torus with its jets of water.
Ethane lakes in a red haze: Titan’s uncanny moonscape
Titan’s ethane lakes in a red haze.
So far, there are no recognisable signs of organic life. That’s not surprising: by terrestrial standards, Titan is a deep freeze with surface temperatures at a chilly -180°C. Yet Titan is very much alive in the sense that its atmosphere and surface are changing before our eyes. Clouds drift through the haze and rain falls from them to erode stream-like channels draining into shallow lakes. Vast dune fields that look as if they were lifted from the Sahara sprawl along Titan’s equator, yet the dark grains resemble ground asphalt rather than sand. It is a bizarrely different world that looks eerily like home. Or as planetary scientist Ralph Lorenz puts it: “our prototype weird-world exoplanet”.
Titan’s ethane lakes in a red haze.
So far, there are no recognisable signs of organic life. That’s not surprising: by terrestrial standards, Titan is a deep freeze with surface temperatures at a chilly -180°C. Yet Titan is very much alive in the sense that its atmosphere and surface are changing before our eyes. Clouds drift through the haze and rain falls from them to erode stream-like channels draining into shallow lakes. Vast dune fields that look as if they were lifted from the Sahara sprawl along Titan’s equator, yet the dark grains resemble ground asphalt rather than sand. It is a bizarrely different world that looks eerily like home. Or as planetary scientist Ralph Lorenz puts it: “our prototype weird-world exoplanet”.
Cassini captures a truly huge storm on Saturn.
Cassini has captured an image of a truly huge storm on Saturn. Click on the image below to see the full image.
Cassini has captured an image of a truly huge storm on Saturn. Click on the image below to see the full image.
Cassini looks past one Saturn moon to another
The image below was taken on January 11, 2011 by the space probe Cassini, in orbit around Saturn. First we see the southern polar regions of the moon Rhea, 949 miles in diameter. Beyond is the moon Dione, 698 miles across, appearing to sit on the rings of Saturn.
As far as I am concerned, this image, as well as almost every other image from Cassini, proves that any hotel built in orbit around Saturn is unquestionably going to be one of the hottest tourist spots in the solar system.
Cassini directly samples the plumes from Enceladus and finds an ocean-like Spray
Cassini has directly sampled the plumes from Enceladus and discovered a salty ocean-like spray.
The new paper analyzes three Enceladus flybys in 2008 and 2009 with the same instrument, focusing on the composition of freshly ejected plume grains. The icy particles hit the detector target at speeds between 15,000 and 39,000 mph (23,000 and 63,000 kilometers per hour), vaporizing instantly. Electrical fields inside the cosmic dust analyzer separated the various constituents of the impact cloud.
The data suggest a layer of water between the moon’s rocky core and its icy mantle, possibly as deep as about 50 miles (80 kilometers) beneath the surface. As this water washes against the rocks, it dissolves salt compounds and rises through fractures in the overlying ice to form reserves nearer the surface. If the outermost layer cracks open, the decrease in pressure from these reserves to space causes a plume to shoot out. Roughly 400 pounds (200 kilograms) of water vapor is lost every second in the plumes, with smaller amounts being lost as ice grains. The team calculates the water reserves must have large evaporating surfaces, or they would freeze easily and stop the plumes.
Cassini has directly sampled the plumes from Enceladus and discovered a salty ocean-like spray.
The new paper analyzes three Enceladus flybys in 2008 and 2009 with the same instrument, focusing on the composition of freshly ejected plume grains. The icy particles hit the detector target at speeds between 15,000 and 39,000 mph (23,000 and 63,000 kilometers per hour), vaporizing instantly. Electrical fields inside the cosmic dust analyzer separated the various constituents of the impact cloud.
The data suggest a layer of water between the moon’s rocky core and its icy mantle, possibly as deep as about 50 miles (80 kilometers) beneath the surface. As this water washes against the rocks, it dissolves salt compounds and rises through fractures in the overlying ice to form reserves nearer the surface. If the outermost layer cracks open, the decrease in pressure from these reserves to space causes a plume to shoot out. Roughly 400 pounds (200 kilograms) of water vapor is lost every second in the plumes, with smaller amounts being lost as ice grains. The team calculates the water reserves must have large evaporating surfaces, or they would freeze easily and stop the plumes.
Evidence mounts for liquid water on Enceladus
Evidence mounts for liquid water on Enceladus.
Evidence mounts for liquid water on Enceladus.
A storm ten times bigger than Earth
A subsurface ocean of water on Titan
Scientists have found evidence that a subsurface ocean of water and ammonia exists within Saturn’s moon Titan.
Scientists have found evidence that a subsurface ocean of water and ammonia exists within Saturn’s moon Titan.
Saturn and Enceladus linked by electricity
Saturn and Enceladus linked by electricity.
Saturn and Enceladus linked by electricity.
The ripples in the rings of Saturn and Jupiter were caused by comets that hit them decades ago
The ripples in the rings of Saturn and Jupiter were caused by comet impacts decades ago.
The ripples in the rings of Saturn and Jupiter were caused by comet impacts decades ago.
The spring rains (of methane) have arrived on Titan
The spring rains (of methane) have arrived on Titan.
The spring rains (of methane) have arrived on Titan.
Enceladus’s hotspot is far hotter than predicted
The tiger stripe fissures on Saturn’s moon Enceladus have turned out to be far hotter than predicted.
The tiger stripe fissures on Saturn’s moon Enceladus have turned out to be far hotter than predicted.
The sponge-like Saturn moon
The sponge-like Saturn moon. Key quote:
Hyperion measures about 250kms across; it rotates chaotically and has a density so low that it might house a vast system of caverns inside.
The sponge-like Saturn moon. Key quote:
Hyperion measures about 250kms across; it rotates chaotically and has a density so low that it might house a vast system of caverns inside.
A Fizzy Ocean on Enceladus
A fizzy ocean on Enceladus? Key quote:
[Scientists believe] that gasses dissolved in water deep below the surface [of Enceladus] form bubbles. Since the density of the resulting “sparkling water” is less than that of the ice, the liquid ascends quickly up through the ice to the surface. “Most of the water spreads out sideways and ‘warms’ a thin surface ice lid, which is about 300 feet thick,” explains Matson. “But some of it collects in subsurface chambers, builds up pressure, and then blasts out through small holes in the ground, like soda spewing out of that can you opened.”
A fizzy ocean on Enceladus? Key quote:
[Scientists believe] that gasses dissolved in water deep below the surface [of Enceladus] form bubbles. Since the density of the resulting “sparkling water” is less than that of the ice, the liquid ascends quickly up through the ice to the surface. “Most of the water spreads out sideways and ‘warms’ a thin surface ice lid, which is about 300 feet thick,” explains Matson. “But some of it collects in subsurface chambers, builds up pressure, and then blasts out through small holes in the ground, like soda spewing out of that can you opened.”
Vast Storm Rampages Across Saturn
A vast storm rages across the face of Saturn.
A vast storm rages across the face of Saturn.
Cyclone lasting more than 5 years is detected on Saturn
A cyclone on Saturn has now lasted more than five years, since scientists started tracking it closely in 2004 with the arrival of Cassini in orbit around Saturn.
A cyclone on Saturn has now lasted more than five years, since scientists started tracking it closely in 2004 with the arrival of Cassini in orbit around Saturn.
Cassini Spots Potential Ice Volcano on Saturn Moon
Scientists have used data from Cassini to identify what they think are ice volcanoes on Titan. The two volcanoes, each about 3000 feet high, are located near the equator and appear to resemble the volcanoes on Earth, with a central crater on top of cone-like peak and finger-like flows coming down the sides from the crater. The lava here, however, is not molten rock, but water.
Scientists have used data from Cassini to identify what they think are ice volcanoes on Titan. The two volcanoes, each about 3000 feet high, are located near the equator and appear to resemble the volcanoes on Earth, with a central crater on top of cone-like peak and finger-like flows coming down the sides from the crater. The lava here, however, is not molten rock, but water.
the violent origin of Saturn’s rings
Scientists have created a computer simulation describing the violent origin of Saturn’s rings, with moons being stripped of their ice as they death spiral into Saturn.
Note that this is only a theory, illustrated by a computer model. Though it is fascinating however!
Scientists have created a computer simulation describing the violent origin of Saturn’s rings, with moons being stripped of their ice as they death spiral into Saturn.
Note that this is only a theory, illustrated by a computer model. Though it is fascinating however!
Cassini Finds Warm Cracks on Enceladus
Cassini pinpoints the hot spots in the cracks on Enceladus.
Cassini pinpoints the hot spots in the cracks on Enceladus.
Saturn moon has thin oxygen and carbon dioxide atmosphere
Saturn moon has a thin oxygen and carbon dioxide atmosphere. Key quote:
“The major implication of this finding at Rhea is that oxygen atmospheres at icy moons, until now only detected at Europa and Ganymede, may in fact be commonplace around those irradiated icy moons throughout the universe with sufficient mass to hold an atmosphere,” said study leader Ben Teolis of the Southwest Research Institute in San Antonio, Texas.
Saturn moon has a thin oxygen and carbon dioxide atmosphere. Key quote:
“The major implication of this finding at Rhea is that oxygen atmospheres at icy moons, until now only detected at Europa and Ganymede, may in fact be commonplace around those irradiated icy moons throughout the universe with sufficient mass to hold an atmosphere,” said study leader Ben Teolis of the Southwest Research Institute in San Antonio, Texas.
Cassini back in operation
Cassini back in operation.
Cassini back in operation.
Cassini to be back in operation by November 24
Engineers expect to get Cassini, which went into safe mode on November 2, back in operation by next week.
Engineers expect to get Cassini, which went into safe mode on November 2, back in operation by next week.
Cassini goes into safe mode
Cassini went into safe mode on Tuesday, November 2nd. At the moment engineers expect it to take at least another week to get the spacecraft back to normal.
Cassini went into safe mode on Tuesday, November 2nd. At the moment engineers expect it to take at least another week to get the spacecraft back to normal.
A wish list of spectacular future planetary missions
Steve Squyres of Cornell University and the project scientist of the Mars rovers Spirit and Opportunity spoke today at an astrobiology symposium in Arlington, Virginia. He described several spectacular planetary missions that might be flown in the coming decade. All are being considered. None have yet been chosen or funded.
- A mission to grab a sample from a comet and return it to Earth.
- A mission to put a rover or lander on one of the poles of Mars to study the frozen layers of water under the icecap.
- Mars sample return mission. This mission is so difficult and expensive that it probably would be broken down into three parts:
- Two rovers on the surface to gather and cache sample material.
- A lander/rover mission to grab the samples and bring them up to Mars orbit. “Putting into orbit a precious cargo the size of a coconut,” Squyres said.
- A mission to grab the sample cargo in Martian orbit and return it to Earth.
- An orbiter to study both Jupiter and its moon Europa.
- An orbiter to Enceladus, the moon of Saturn, to study the water and organic chemistry in its mysterious plumes.
- An orbiter to Titan, with balloon to probe the atmosphere as well as a “lake lander, a boat” to study Titan’s lakes.
- A variety of landers and rovers to go to Venus. One of the more astonishing mission concepts would land, then take off again to visit different places on the surface.
Squyres is the co-chair of a committee of the National Science Foundation that is right now putting together a decadal survey for outlining unmanned planetary research for the next decade. This survey is expected to be released in March, which is when we will find out which of the above missions the planetary science community prefers.
The basic ingredients of life might exist in Titan’s atmosphere
Big news! In a simulation of the upper atmosphere of Titan at about 600 miles altitude, scientists have discovered the basic ingredients of life are quickly synthesized when exposed to the kind of hard radiation found there. Key quote from the press release, issued today at the 42nd meeting of the AAS Division for Planetary Sciences:
The molecules discovered include the five nucleotide bases used by life on Earth (cytosine, adenine, thymine, guanine and uracil) and the two smallest amino acids, glycine and alanine.
For those who don’t remember their high school biology, these nucleotides are the building blocks of DNA.
The abstract of the scientist’s work can be found here.
What the scientists did was recreate the basic ingredients of Titan’s upper atmosphere, comprised of nitrogen, methane and carbon monoxide. Cassini data has shown that within this atmosphere are very large molecules, as yet unidentified.
The scientists then bathed their recreation in the kind of intense radiation expected at that altitude, and amazingly produced the complex organic molecules that are basic to life. Moreover, the experiment was the first to produce these complex molecules without the presence of water, something that scientists have previously thought was required. These results suggest that in addition to forming in the oceans, life could also form in the upper atmospheres of planets.
This result also suggests strongly that it is incredibly easy to produce the basic building blocks of life, almost anywhere in the universe where organic molecules are present.
It’s only a seltzer moon
Plumes from Saturn’s Enceladus may be carbonated
The plumes that come out of the tiger stripe cracks on Saturn’s moon Enceladus may be carbonated!
The plumes that come out of the tiger stripe cracks on Saturn’s moon Enceladus may be carbonated!
Liquid on Titan
The Cassini image below, released today at the 42nd meeting of the AAS Division for Planetary Sciences, shows light reflecting off a lake on Titan’s northern hemisphere. According to the scientists who took the image, this is the first definitive confirmation of the presence of liquid in those lakes.
