New Horizons Crosses Neptune’s Orbit on Way to Pluto

neptune

Image Credit: NASA/JPL

Last week, NASA released this enhanced video of images Voyager 2 shot of Neptune’s moon Triton as it sailed past in 1989. Today, the New Horizons spacecraft crossed Neptune’s orbit on the way to its own flyby of now minor planet Pluto. The full NASA story is below.

NASA New Story

August 25, 2014

NASA’s Pluto-bound New Horizons spacecraft has traversed the orbit of Neptune. This is its last major crossing en route to becoming the first probe to make a close encounter with distant Pluto on July 14, 2015.

The sophisticated piano-sized spacecraft, which launched in January 2006, reached Neptune’s orbit — nearly 2.75 billion miles (4.4. billion kilometers) from Earth — in a record eight years and eight months. New Horizons’ milestone matches precisely the 25th anniversary of the historic encounter of NASA’s Voyager 2 spacecraft with Neptune on Aug. 25, 1989.

“It’s a cosmic coincidence that connects one of NASA’s iconic past outer solar system explorers, with our next outer solar system explorer,” said Jim Green, director of NASA’s Planetary Science Division, NASA Headquarters in Washington. “Exactly 25 years ago at Neptune, Voyager 2 delivered our ‘first’ look at an unexplored planet. Now it will be New Horizons’ turn to reveal the unexplored Pluto and its moons in stunning detail next summer on its way into the vast outer reaches of the solar system.”

New Horizons now is about 2.48 billion miles (nearly 4 billion kilometers) from Neptune — nearly 27 times the distance between Earth and our sun — as it crosses the giant planet’s orbit at 7:04 p.m. PDT (10:04 p.m. EDT) Monday. Although the spacecraft will be much farther from the planet than Voyager 2′s closest approach, New Horizons’ telescopic camera was able to obtain several long-distance “approach” shots of Neptune on July 10.

“NASA’s Voyager 1 and 2 explored the entire middle zone of the solar system where the giant planets orbit,” said Alan Stern, New Horizons principal investigator at the Southwest Research Institute in Boulder, Colorado. “Now we stand on Voyager’s broad shoulders to explore the even more distant and mysterious Pluto system.”

Several senior members of the New Horizons science team were young members of Voyager’s science team in 1989. Many remember how Voyager 2′s approach images of Neptune and its planet-sized moon Triton fueled anticipation of the discoveries to come. They share a similar, growing excitement as New Horizons begins its approach to Pluto.

“The feeling 25 years ago was that this was really cool, because we’re going to see Neptune and Triton up-close for the first time,” said Ralph McNutt of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, who leads the New Horizons energetic-particle investigation and served on the Voyager plasma-analysis team. “The same is happening for New Horizons. Even this summer, when we’re still a year out and our cameras can only spot Pluto and its largest moon as dots, we know we’re in for something incredible ahead.”

Voyager’s visit to the Neptune system revealed previously unseen features of Neptune itself, such as the Great Dark Spot, a massive storm similar to, but not as long-lived, as Jupiter’s Great Red Spot. Voyager also, for the first time, captured clear images of the ice giant’s ring system, too faint to be clearly viewed from Earth. “There were surprises at Neptune and there were surprises at Triton,” said Ed Stone, Voyager’s long-standing project scientist from the California Institute of Technology in Pasadena. “I’m sure that will continue at Pluto.”

Many researchers feel the 1989 Neptune flyby — Voyager’s final planetary encounter — might have offered a preview of what’s to come next summer. Scientists suggest that Triton, with its icy surface, bright poles, varied terrain and cryovolcanoes, is a Pluto-like object that Neptune pulled into orbit. Scientists recently restored Voyager’s footage of Triton and used it to construct the best global color map of that strange moon yet — further whetting appetites for a Pluto close-up.

“There is a lot of speculation over whether Pluto will look like Triton, and how well they’ll match up,” McNutt said. “That’s the great thing about first-time encounters like this — we don’t know exactly what we’ll see, but we know from decades of experience in first-time exploration of new planets that we will be very surprised.”

Similar to Voyager 1 and 2′s historic observations, New Horizons also is on a path toward potential discoveries in the Kuiper Belt, which is a disc-shaped region of icy objects past the orbit of Neptune, and other unexplored realms of the outer solar system and beyond.

“No country except the United States has the demonstrated capability to explore so far away,” said Stern. “The U.S. has led the exploration of the planets and space to a degree no other nation has, and continues to do so with New Horizons. We’re incredibly proud that New Horizons represents the nation again as NASA breaks records with its newest, farthest and very capable planetary exploration spacecraft.”

Voyager 1 and 2 were launched 16 days apart in 1977, and one of the spacecraft visited Jupiter, Saturn, Uranus and Neptune. Voyager 1 now is the most distant human-made object, about 12 billion miles (19 billion kilometers) away from the sun. In 2012, it became the first human-made object to venture into interstellar space. Voyager 2, the longest continuously operated spacecraft, is about 9 billion miles (15 billion kilometers) away from our sun.

New Horizons is the first mission in NASA’s New Frontiers program. APL manages the mission for NASA’s Science Mission Directorate at NASA Headquarters. APL also built and operates the New Horizons spacecraft.

The Voyager spacecraft were built and continue to be operated by NASA’s Jet Propulsion Laboratory in Pasadena, California. The Voyager missions are part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate.

To view the Neptune images taken by New Horizons and learn more about the mission, visit:

http://www.nasa.gov/newhorizons

For more information about the Voyager spacecraft, visit:

http://www.nasa.gov/voyager

A Decade of Discovery in Saturn’s System: The Great Cassini

cassini20140624b-full

It is sometimes difficult to attach an adequate number of superlatives to the Cassini probe, which is about to enter its second decade of operations in the Saturn system.  From launching the Huygens lander, to revealing Titan’s hydrocarbon seas and the ice geysers of Enceladus, Cassini has been much more than a probe.  In many ways, although it holds no crew, Cassini has been a ship of discovery which has earned a place alongside names Endeavour, Resolution and Beagle. Some of its many accomplishments are detailed in the NASA release included below.

There are two bittersweet items to this particular anniversary story.  The first is the simple fact that despite its myriad accomplishments, NASA has absolutely nothing  in the works in terms of a mission which compares favorably with Cassini, and could be considered a worthy successor to it.

Juno is on the way to Jupiter for a one year mission, and New Horizons is on the way to a flyby of Pluto next July, and after that, possibly a flyby of Kuiper belt object, but that is all it is, a flyby.  And, although NASA has received preliminary funding for a proposed “Europa Clipper” mission to Jupiter’s enigmatic moon, it likely would not launch until 2025, and even then not arriving until after a cruise of more than six years.  As of the moment, the Europa Clipper, which would in reality be orbiting Jupiter, is still likely to be a comparatively paltry solar powered spacecraft.  By comparison, Cassini is a veritable dreadnought. 

The second item is perhaps minor, possibly petty, certainly unlikely, and also probably not of great concern to many. At the end of its mission, Cassini will be sent in to a death plunge into Saturn’s atmosphere in order to prevent the extremely remote chance that it will instead crash into Titan, or perhaps another moon, and even more remotely, contaminate it with Earth borne organisms which have survived the long journey, longer stay and all that radiation.  While it will no doubt continue to send back useful data until the very last second, this ship deserves better.

NASA previously examined a number of End of Mission (EOM) options, from crashing into one of the icy Moons, to seeking a stable orbit around Titan or even a carefully engineered ejection from the Saturn system altogether with the slim possibility of a Jupiter flyby. Planetary protection issues are a noteworthy precaution, but sometimes it seems NASA has an altogether unholy fascination with destroying the objects it creates. Perhaps its the whole V’Ger thing.

One wishes NASA might have elected to leave Cassini in a stable orbit,  awaiting the day we can retrieve the history making craft and and provide her a proper home, either back on Earth, or in some yet to be envisioned orbital museum. Far fetched perhaps, but consider the implication. Is our confidence in humanity’s future in space so low that the certainty of destruction is preferable?

NASA News Story

It has been a decade since a robotic traveler from Earth first soared over rings of ice and fired its engine to fall forever into the embrace of Saturn. On June 30, the Cassini mission will celebrate 10 years of exploring the planet, its rings and moons.
The Cassini spacecraft, carrying the European Space Agency’s Huygens probe, arrived in the Saturn system on June 30, 2004, for a four-year primary mission. Since 2008, NASA has granted the mission three extensions, allowing scientists an unprecedented opportunity to observe seasonal changes as the planet and its retinue completed one-third of their nearly 30-year-long trek around the sun.

“Having a healthy, long-lived spacecraft at Saturn has afforded us a precious opportunity,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “By having a decade there with Cassini, we have been privileged to witness never-before-seen events that are changing our understanding of how planetary systems form and what conditions might lead to habitats for life.”

After 10 years at Saturn, the stalwart spacecraft has beamed back to Earth hundreds of gigabytes of scientific data, enabling the publication of more than 3,000 scientific reports. Representing just a sampling, 10 of Cassini’s top accomplishments and discoveries are:

– The Huygens probe makes first landing on a moon in the outer solar system (Titan)

– Discovery of active, icy plumes on the Saturnian moon Enceladus

– Saturn’s rings revealed as active and dynamic — a laboratory for how planets form

– Titan revealed as an Earth-like world with rain, rivers, lakes and seas

– Studies of Saturn’s great northern storm of 2010-2011

– Studies reveal radio-wave patterns are not tied to Saturn’s interior rotation, as previously thought

– Vertical structures in the rings imaged for the first time

– Study of prebiotic chemistry on Titan

– Mystery of the dual, bright-dark surface of the moon Iapetus solved

– First complete view of the north polar hexagon and discovery of giant hurricanes at both of Saturn’s poles

“It’s incredibly difficult to sum up 10 extraordinary years of discovery in a short list, but it’s an interesting exercise to think about what the mission will be best remembered for many years in the future,” Spilker said.

Further details about each of these top-10 discoveries are available at:

http://saturn.jpl.nasa.gov/news/cassinifeatures/10thannivdiscoveries/

In celebration of the 10th anniversary, members of the Cassini team selected some of their favorite images for a gallery, describing in their own words what makes the images special to them. The gallery is available at:

http://saturn.jpl.nasa.gov/news/cassinifeatures/10thannivimages/

While Cassini was originally approved for a four-year study of the Saturn system, the project’s engineers and scientists had high hopes that the mission might carry on longer, and designed the system for endurance. The spacecraft has been remarkably trouble-free, and from an engineering standpoint, the main limiting factor for Cassini’s lifetime now is how much propellant is left in its tanks. The mission owes a great deal of its longevity to skillful and efficient piloting by the mission’s navigation and operations teams.

“Our team has done a fantastic job optimizing trajectories to save propellant, and we’ve learned to operate the spacecraft to get the most out of it that we possibly can,” said Earl Maize, Cassini project manager at JPL. “We’re proud to celebrate a decade of exploring Saturn, and we look forward to many discoveries still to come.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington.

A Glowing Red Nebula and Uranus Seen Through Saturn’s Rings

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Image Credit: ESO

The European Southern Observatory at La Silla released this image of a glowing hydrogen cloud, or nebula, Gum 41. The glow is caused by the searing radiation emitted by young, very hot stars which excites the hydrogen gas left over from star formation.

This nebula is in the constellation Centaurus in the southern sky, approximately 7,300 light years away.

According to ESO, GUM 41 is actually quite faint, and the image was aided by the use of a filter to pick out the red glow against the background of space.

Much closer to home, there was this, Uranus as seen from the Cassini spacecraft orbiting Saturn

Uranus

From the JPL story:

“When this view was obtained, Uranus was nearly on the opposite side of the sun as seen from Saturn, at a distance of approximately 28.6 astronomical units from Cassini and Saturn. An astronomical unit is the average distance from Earth to the sun, equal to 93 million miles (150 million kilometers). At their closest – once during each Saturn orbit of nearly 30 years – the two planets approach to within about 10 astronomical units of each other.”

A rather beautiful galaxy we’ve got here.

A Multi-Layered Ocean on Ganymede

ganymede

Image credit: JPL

A fascinating news release out of JPL suggests once more just how weird and wonderful our own solar system is turning out to be. Today’s story offers speculation that Jupiter’s moon  Ganymede may have “layered” oceans in which water alternates with different tiers of ice, depending on the relative salt content. Furthermore, as with Europa, the presence of microbial life is not out of the question.

A copy of the full news release is include below, and as it reminds us at the end, Ganymede is but one of five moons in our solar system thought to have its own, very substantial ocean.  While sending astronauts to the outer planets and their moon is well outside of what we can achieve with present technology, sending robotic craft are limited by one thing…money.

One might think that a true space faring society would be hard at work figuring out a way to send probes to all of these destinations, but we are not. Instead, Alabama Senator Richard Shelby is complaining that NASA isn’t spending enough money on SLS, while continuing to rage against Commercial Crew, and in particular SpaceX.  Apparently for saving NASA too much money.

JPL New Release:

The largest moon in our solar system, a companion to Jupiter named Ganymede, might have ice and oceans stacked up in several layers like a club sandwich, according to new NASA-funded research that models the moon’s makeup.

Previously, the moon was thought to harbor a thick ocean sandwiched between just two layers of ice, one on top and one on bottom.

“Ganymede’s ocean might be organized like a Dagwood sandwich,” said Steve Vance of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., explaining the moon’s resemblance to the “Blondie” cartoon character’s multi-tiered sandwiches. The study, led by Vance, provides new theoretical evidence for the team’s “club sandwich” model, first proposed last year. The research appears in the journal Planetary and Space Science.

The results support the idea that primitive life might have possibly arisen on the icy moon. Scientists say that places where water and rock interact are important for the development of life; for example, it’s possible life began on Earth in bubbling vents on our sea floor. Prior to the new study, Ganymede’s rocky sea bottom was thought to be coated with ice, not liquid — a problem for the emergence of life. The “club sandwich” findings suggest otherwise: the first layer on top of the rocky core might be salty water.

“This is good news for Ganymede,” said Vance. “Its ocean is huge, with enormous pressures, so it was thought that dense ice had to form at the bottom of the ocean. When we added salts to our models, we came up with liquids dense enough to sink to the sea floor.”

NASA scientists first suspected an ocean in Ganymede in the 1970s, based on models of the large moon, which is bigger than Mercury. In the 1990s, NASA’s Galileo mission flew by Ganymede, confirming the moon’s ocean, and showing it extends to depths of hundreds of miles. The spacecraft also found evidence for salty seas, likely containing the salt magnesium sulfate.

Previous models of Ganymede’s oceans assumed that salt didn’t change the properties of liquid very much with pressure. Vance and his team showed, through laboratory experiments, how much salt really increases the density of liquids under the extreme conditions inside Ganymede and similar moons. It may seem strange that salt can make the ocean denser, but you can see for yourself how this works by adding plain old table salt to a glass of water. Rather than increasing in volume, the liquid shrinks and becomes denser. This is because the salt ions attract water molecules.

The models get more complicated when the different forms of ice are taken into account. The ice that floats in your drinks is called “Ice I.” It’s the least dense form of ice and lighter than water. But at high pressures, like those in crushingly deep oceans like Ganymede’s, the ice crystal structures become more compact. “It’s like finding a better arrangement of shoes in your luggage — the ice molecules become packed together more tightly,” said Vance. The ice can become so dense that it is heavier than water and falls to the bottom of the sea. The densest and heaviest ice thought to persist in Ganymede is called “Ice VI.”

By modeling these processes using computers, the team came up with an ocean sandwiched between up to three ice layers, in addition to the rocky seafloor. The lightest ice is on top, and the saltiest liquid is heavy enough to sink to the bottom. What’s more, the results demonstrate a possible bizarre phenomenon that causes the oceans to “snow upwards.” As the oceans churn and cold plumes snake around, ice in the uppermost ocean layer, called “Ice III,” could form in the seawater. When ice forms, salts precipitate out. The heavier salts would thus fall downward, and the lighter ice, or “snow,” would float upward. This “snow” melts again before reaching the top of the ocean, possibly leaving slush in the middle of the moon sandwich.

“We don’t know how long the Dagwood-sandwich structure would exist,” said Christophe Sotin of JPL. “This structure represents a stable state, but various factors could mean the moon doesn’t reach this stable state.

Sotin and Vance are both members of the Icy Worlds team at JPL, part of the multi-institutional NASA Astrobiology Institute based at the Ames Research Center in Moffett Field, Calif.

The results can be applied to exoplanets too, planets that circle stars beyond our sun. Some super-Earths, rocky planets more massive than Earth, have been proposed as “water worlds” covered in oceans. Could they have life? Vance and his team think laboratory experiments and more detailed modeling of exotic oceans might help find answers.

Ganymede is one of five moons in our solar system thought to support vast oceans beneath icy crusts. The other moons are Jupiter’s Europa and Callisto and Saturn’s Titan and Enceladus. The European Space Agency is developing a space mission, called JUpiter ICy moons Explorer or JUICE, to visit Europa, Callisto and Ganymede in the 2030s. NASA and JPL are contributing to three instruments on the mission, which is scheduled to launch in 2022 (see http://www.jpl.nasa.gov/news/news.php?release=2013-069).

Other authors of the study are Mathieu Bouffard of Ecole Normale Supérieure de Lyon, France, and Mathieu Choukroun, also of JPL and the Icy World team of the NASA Astrobiology Institute. JPL is managed by the California Institute of Technology in Pasadena for NASA.

 

Cassini Data Suggests Enceladus Has a Subsurface Ocean

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Image Credit: NASA/JPL-Caltech

The treasure trove which is the Cassini spacecraft orbiting the Saturn system continues to produce fascinating discoveries. Now it appears that Saturn’s moon Enceladus has a subsurface ocean, one which is likely responsible for the geysers which Enceladus is jetting into space.

It is important to note that after the end of the Cassini mission, NASA has nothing else planned for this amazing system, one which offers an ever widening number of targets worthy of further exploration. Much the same could be said for Jupiter’s system as well, which will at least be visited by the short lived Juno orbiter, even as notional funding for a Europa mission is barely enough to keep the lights on.

One wonders what it would take to inspire a new major outer planets mission.

The full text of the NASA press release is below:

NASA’s Cassini spacecraft and Deep Space Network have uncovered evidence Saturn’s moon Enceladus harbors a large underground ocean of liquid water, furthering scientific interest in the moon as a potential home to extraterrestrial microbes.

Researchers theorized the presence of an interior reservoir of water in 2005 when Cassini discovered water vapor and ice spewing from vents near the moon’s south pole. The new data provide the first geophysical measurements of the internal structure of Enceladus, consistent with the existence of a hidden ocean inside the moon. Findings from the gravity measurements are in the Friday April 4 edition of the journal Science.

“The way we deduce gravity variations is a concept in physics called the Doppler Effect, the same principle used with a speed-measuring radar gun,” said Sami Asmar of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., a coauthor of the paper. “As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we’re trying to measure. We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system.”

The gravity measurements suggest a large, possibly regional, ocean about 6 miles (10 kilometers) deep, beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick. The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our solar system to host microbial life. Before Cassini reached Saturn in July 2004, no version of that short list included this icy moon, barely 300 miles (500 kilometers) in diameter.

“This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole,” said David Stevenson of the California Institute of Technology, Pasadena, one of the paper’s co-authors.

Cassini has flown near Enceladus 19 times. Three flybys, from 2010 to 2012, yielded precise trajectory measurements. The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft’s flight path. Variations in the gravity field, such as those caused by mountains on the surface or differences in underground composition, can be detected as changes in the spacecraft’s velocity, measured from Earth.

The technique of analyzing a radio signal between Cassini and the Deep Space Network can detect changes in velocity as small as less than one foot per hour (90 microns per second). With this precision, the flyby data yielded evidence of a zone inside the southern end of the moon with higher density than other portions of the interior.

The south pole area has a surface depression that causes a dip in the local tug of gravity. However, the magnitude of the dip is less than expected given the size of the depression, leading researchers to conclude the depression’s effect is partially offset by a high-density feature in the region, beneath the surface.

“The Cassini gravity measurements show a negative gravity anomaly at the south pole that however is not as large as expected from the deep depression detected by the onboard camera,” said the paper’s lead author, Luciano Iess of Sapienza University of Rome. “Hence the conclusion that there must be a denser material at depth that compensates the missing mass: very likely liquid water, which is seven percent denser than ice. The magnitude of the anomaly gave us the size of the water reservoir.”

There is no certainty the subsurface ocean supplies the water plume spraying out of surface fractures near the south pole of Enceladus, however, scientists reason it is a real possibility. The fractures may lead down to a part of the moon that is tidally heated by the moon’s repeated flexing, as it follows an eccentric orbit around Saturn.

Much of the excitement about the Cassini mission’s discovery of the Enceladus water plume stems from the possibility that it originates from a wet environment that could be a favorable environment for microbial life.

“Material from Enceladus’ south polar jets contains salty water and organic molecules, the basic chemical ingredients for life,” said Linda Spilker, Cassini’s project scientist at JPL. “Their discovery expanded our view of the ‘habitable zone’ within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA’s Science Mission Directorate in Washington. For more information about Cassini, visit:

http://www.nasa.gov/cassini

New Discovery at the Edge of Solar System Suggest Planet X May Still Be Out There

Image Credit: Scott Sheppard/Carnegie Institution for Science

Image Credit: Scott Sheppard/Carnegie Institution for Science

Time lapse photo showing movement

On the third episode of the re-tooled COSMOS, Neil deGrasse Tyson took his ship of the imagination to the Oort cloud to discover the origin of comets. He may have to go back.

Astronomers have discovered a second dwarf planet orbiting in the far reaches of the solar system, well beyond the boundary of the Kuiper Belt, where poor Pluto orbits,  demoted to minor planet status in part by Tyson himself.  The new object, designated 2012 VP113,  is estimated to have a diameter of 450 km, and makes its closest approach to the sun at a very distant 80 astronomical units.   Its only known companion is the dwarf planet Sedna.

The interesting part is that it quite likely has a great deal of company, as many as a thousand more celestial bodies, including some according to the team which discovered 2012 VP113, that “could rival the size of Mars or even Earth.”

And that’s not all, not by a long shot.  The similarity in orbits displayed by 2012 VP113 and Sedna suggests that the long hypothesized Planet X, sometimes called Nemesis, could still be a possibility. Rather than a very dim red dwarf star, or a Jupiter sized object, it could be roughly 10 times the size of Earth,  orbiting so far out and radiating so little heat, that nothing in the current tool box is capable of detecting it.

The timing is almost comical. Earlier this month, results of a search by NASA’s Wide-Field Infrared Survey Explorer were interpreted to suggest Planet X did not exist.

The NASA report on the new Dwarf Planet is here, and a Sky and Telescope article on the implications for Planet X is here.

We really need to start cranking out the PU-238, there is an awful lot of solar system to explore.

Cassini Looks at Saturn’s Moon Dione

Dione as imaged by Cassini Credit: NASA

Dione as imaged by Cassini
Credit: NASA

With at least 53 confirmed Moons, it’s a little difficult to keep track of everything going on in Saturn’s system, but the amazing Cassini probe which has been on duty there since 2004 is still doing a remarkable job. Overshadowed by methane rich and surprisingly Earth-like Titan, and showy Enceladus, which is jetting ice crystals into space in a plume three higher than its diameter, Dione got a chance to shine this week.

In this image released by NASA,  and taken on September 10th, Dione reveals long geologic fault lines caused by fractures in its icy outer surface.  Dione is 698 miles in diameter, tidally locked to Saturn, and has two smaller moons, Helene and Polydeuces,  phase locked in its orbit, at 60 degrees ahead and behind respectively.

The Water Geysers of Enceladus

Fries with That? Credit : JPL

Fries with That?
Credit : JPL

Forget about the Bellagio,  the best dancing water fountain in this solar system isn’t in Vegas, its in orbit around Saturn’s moon Enceladus.  In the latest series of a series of images released by JPL from the remarkable Cassini spacecraft still on duty in the Saturn system, NASA has captured the simply stunning spectacle of water ice  being  shot from the Moon’s subsurface ocean into space.  Based on observations, it appears the phenomenon occurs due to regular variation in its orbits as it reaches a peak distance from Saturn. The full press release from JPL is here.

There is another aspect to this story which almost beggars belief.  Thanks to this historic mission, we now have documented evidence of water from another planetary body, including apparently organics, being shot out of a gravity well and into space. It is the solar system’s equivalent of a drive through window for a scientific treasure trove. And Enceladus isn’t even the most interesting moon in the system, a distinction which clearly goes to Titan. However, as NASA’s Planetary Division Director Jim Green glumly  assessed earlier this year,  despite all that has been learned about both the Saturnian and Jovian systems in recent years, there is no room in the budget for new Flagship missions to either of these two destinations.

While the U.S. is participating in the European Space Agency’s JUICE, Jupiter Icy Moon’s Explorer Mission, the total contribution of $100 million, or about the rolling 38 day average for the Orion capsule.

Europa: A Salty Piece of Land?

Europa: A Salty Piece of Land?Credit : JPL

Europa: A Salty Piece of Land?
Credit : JPL

 

A team of scientists working at NASA’s JPL and Cal-Tech studying Jupiter’s moon Europa, have found evidence of a chemical exchange between the frozen, radiation swept surface and a liquid ocean which is believed to exist beneath an ice pack nearly 60 miles thick.

Using spectrographic analysis of surface ice taken from the Keck II telescope in Hawaii, the pair found a clear signature of magnesium sulfate, believed to be formed from a combination of sulfur emanating from Jupiter’s innermost moon Io, and magnesium chloride salt welling up from the Europan ocean below. The find is significant because if the exchange is actually taking place it is a sign that the subsurface ocean is richer and more diverse than it otherwise would be, and could in fact be quite similar to Earth’s own oceans, and thus an ideal candidate for life. But then again if you read Arthur C. Clarke’s 2010: Odyssey Two, you already know that, and are probably smart enough to stay away, heeding the warning ” All these world are yours except Europa, attempt no landing there”

The full story (not the book) can be found here.

Epilogue:  Apparently following advice for once, Russia announced today that it is planning a landing mission for Europa’s sister moon, Ganymede in 2023,  which may or may not be part of the European Space Agency’s  Jucy Icy Moon Explorer (Juice) mission scheduled for 2022. The JUICE mission will spend several years in orbit around the gas giant before finally settling into an orbit (wisely) around Ganymede.

On Titan: Icebergs Really Could Be Dead Ahead

Artists Impression of "Titanic" IcebergsCredit : JPL

Artists Impression of “Titanic” Icebergs
Credit : JPL

Source: JPL

One of the most promising potential locations for eventual human settlement in the outer solar system is Saturn’s fascinating moon, Titan.

Bigger than innermost planet Mercury, half again as large as our own Moon, and second only to Ganymede in total size,  Titan possesses a thick nitrogen atmosphere, which blankets a bizarre frigid landscape  dominated by the hydrocarbons  methane and ethane.  Perhaps the most unusual feature however, is that the hydrocarbons exist in the form of a vast network of seas and large lakes, making it the only other planetary body in our solar system known to have stable liquids on its surface.

Eight years ago, on January 14, 2005, the European Space Agency built Huygens probe, carried to Titan by the Cassini spacecraft, became the first man-made spacecraft to land on a planetary body in the outer solar system.   Based on descent analysis and some of the 350 pictures send back to Earth, it apparently landed in a dry area not far from the shoreline of one of the many seas.

Now,  scientists studying data from the Cassini probe orbiting the Saturnian system have concluded that many of those seas likely contain floating “icebergs” of  methane and ethane made buoyant by a small percentage of nitrogen “air” in their composition. According to the theory,  the hydrocarbon ice could float or sink depending on seasonal variations in temperature.  As Titan’s northern lakes warm slighty with the coming spring, Cassini’s radar should be able to detect first increased reflection as submerged ice comes to the surface, followed by a decrease as it melts into the seas.

While it is a truly cold world,  -179 degrees Centigrade,  the organic components comprising the surface  environment  mean it is a possible abode of microbial life. It is also a veritable planetary filling station for rocket fuel, which though far too distant to have any bearing on an Earth-Moon-Mars   transportation infrastructure, at least offers a ready-made supply for local operations, particularly ascent and descent from Titan itself.  Titan’s greatest asset however, may be what it doesn’t have,  which is an abundance of fatal radiation due to both its thick atmosphere, as well as the overall weaker magnetic field of Saturn, meaning the entire system is  not constantly awash in high doses of radiation like that found around  Jupiter.

As compelling as Saturn’s system is, which contains at last 62 moons, most of which are tiny, but also the brilliantly reflective water ice world of Enceladus which is dominated by ice geysers shooting into space, it may be quite some time before we can build on the fantastical knowledge base provided by Cassini.  Besides limited budgets and two very expensive flagship programs in SLS and JWST, the U.S. has allowed its capacity to produce nuclear fuel for space reactors, of the type which powers Cassini,  and critical for missions beyond Mars, to fade to essentially nothing.

For all the talk of the importance of STEM education initiatives, it is difficult to reconcile the lack of any follow-up on a major success story such as provided by Cassini with the potential for engaging successive generations of engineers and scientists to dig deeper into the mysteries being revealed, particularly given the long time frame between any project start, transit time, and the arrival of the first bits of data.

While both NASA and the Department of Energy are working to develop a more efficient type of space reactor, the Advanced Stirling Radioisotope Generator,   which would require fewer PU- 238 pellets but provide a higher yield, the need for renewed production is a real problem which is being studiously ignored by Congress.