New Mysteries Unveiled on Mercury

The Rembrandt impact crater basin on Mercury. Credit: Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Smithsonian Institution/Carnegie Institution of Washington

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Even though Mercury looks like the Moon at first glance, scientists from the MESSENGER mission say it’s becoming apparent that Mercury is an amazingly dynamic planet, and is actually more like Mars. For example, before this mission, scientists weren’t sure if volcanism even existed on Mercury, but from the spacecraft’s two flybys, they now know it is a very important part of the planet’s history. Additional new findings from the second flyby of Mercury in October 2008 show that the planet’s atmosphere, magnetosphere, and geological past are all characterized by much greater levels of activity than scientists first suspected.

And by the way, isn’t this a stunning picture of an impact basin? It’s one of the new discoveries from MESSENGER.

One of the most exciting results from the second flyby of Mercury is the discovery of a previously unknown large impact basin. The Rembrandt basin is more than 700 kilometers (430 miles) in diameter, and actually, to see the entire basin, it took combined images from both the first and second flyby to create the stunning picture above. Rembrandt is a relatively young impact basin, and forming about 3.9 billion years ago, is younger than any other known impact region on the planet. It shows pristine terrain on the outer portion of the crater, as well as unusual tectonic fault features, not found in any other big crater.

“This is the first time we’ve seen terrain exposed on the floor of an impact basin on Mercury that is preserved from when it formed” says MESSENGER scientist Thomas Watters. “Landforms such as those revealed on the floor of Rembrandt are usually completely buried by volcanic flows. We know that after Rembrandt formed, the planet was still contracting, so it is an exciting and unique new member of planetary craters we can study.”

MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer, or MASCS, detected significant amounts of magnesium clumped in the planet’s tenuous atmosphere, called the exosphere. Scientists had suspected magnesium would be present, but were surprised at its distribution and abundance.

“Detecting magnesium was not too surprising, but what is surprising is the distribution and amounts of magnesium that was recorded,” said Bill McClintock, a MESSENGER co- investigator.
The instrument also measured other exospheric constituents during the October 6 flyby, including calcium and sodium, and he suspects that additional metallic elements from the surface including aluminum, iron, and silicon also contribute to the exosphere.

The differences in Mercury's magnetosphere in the two flybys by MESSENGER. Credit: Image produced by NASA/Goddard Space Flight Center/Johns Hopkins University Applied Physics Laboratory//Carnegie Institution of Washington. Image reproduced courtesy of Science/AAAS.
The differences in Mercury's magnetosphere in the two flybys by MESSENGER. Credit: Image produced by NASA/Goddard Space Flight Center/Johns Hopkins University Applied Physics Laboratory//Carnegie Institution of Washington. Image reproduced courtesy of Science/AAAS.

MESSENGER observed a radically different magnetosphere at Mercury during its second flyby, compared with its earlier January 14, 2008 encounter. In the first flyby, no dynamic features were found. But the second flyby was a totally different situation, said James Slavin, MESSENGER Co-Investigator.

“MESSENGER measured large magnetic flux leakage through the dayside magnetopause, about a factor of 10 greater than even what is observed at the Earth during its most active intervals. The high rate of solar wind energy input was evident in the great amplitude of the plasma waves and the large magnetic structures measured by the Magnetometer throughout the encounter.”

Slavin said Mercury’s magnetic field bears a marked resemblance to what we have at earth, but it is about 100 times weaker, which implies interior of Mercury is in part molten. “There is a dynamo action that is ongoing which regenerates and maintains the planetary magnetic field,” he said.

A subsurface interpretation of an impact basin on Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institution of Washington.
A subsurface interpretation of an impact basin on Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institution of Washington.

Scientists are also learning more abour Mercury’s crustal evolution, and have now mapped about 90% of the planet’s surface. About 40% is covered by smooth plains which are now known to be of volcanic origna. “These plains are globally distributed (in contrast with the Moon, which has a nearside/farside asymmetry in the abundance of volcanic plains),” said Brett Denevi, MESSENGER team member.

Data shows an enhanced iron- and titanium content in an ancient basin studied by MESSENGER, which are exposed on the surface only through impact events, and may formed when dense minerals settled out as they crystallized from a cooling magma. “There are a complex series of events going on here, but we see it everywhere, so this is a microcosm of the entire planet” said Denevi.

These discoveries are more clues to the mystery of the creation of the rocky, bizarre planet that resides closest to the sun.

Source: NASA Press conference, MESSNEGER press release

The NASA Buzz: Shuttle Extension, Abandoning the Moon, and What About an Administrator?

Possible NASA lunar base. Credit: NASA

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The blogosphere and Twitterverse has been buzzing the past couple of days with NASA what-ifs and possibilities. But that usually happens whenever there are Congressional hearings about our favorite space agency. Here’s the run-down of what is really happening: No extra money has been given to extend the shuttle program as of yet but it is a possibility. NASA is not going to abandon going to the Moon. And no, President Obama hasn’t named a new NASA administrator yet. Want the details?

House and Senate leaders have agreed to authorize $2.5 billion to keep the U.S. space shuttle fleet flying through 2011. While no money has actually been appropriated for that yet, the extension would happen only if necessary to complete currently planned missions to the international space station. If another flight were added to the shuttle manifest, it’s possible the controversial Alpha Magnetic Spectrometer instrument would be brought to the station. AMS was mothballed after the Columbia accident in 2003 as a cost cutting move, but the because of the international scientific community’s outcry about cutting the one really exciting science experiment to fly on the space station (that was mostly paid for by other countries) last year Congress told NASA to reconsider. They are supposed to make a decision today.

Space shuttle Endeavour. Credit: NASA
Space shuttle Endeavour. Credit: NASA

But the shuttle retirement is controversial from a political point of view because it affects thousands of aerospace industry jobs, not only in Florida, but nationwide. Retiring the shuttle in 2010 would also give a five year gap (at least) until the Orion crew vehicle is ready to fly, making the US dependant on Russia for bringing humans and supplies to the ISS. This week House and Senate budget conferees agreed on “the strategic importance of uninterrupted human access to space” and said the extra $2.5 billion is provided “in anticipation that the funding is needed” to safely “complete the construction and equipping” of the space station.

But some NASA officials and contractors worry that giving more funding to the shuttle program would hamper the efforts for the Constellation program, funneling money away from the new rocket that will help return humans to the moon, hopefully by 2020. The Constellation program has already begun shifting gears and figuring out how to make flying by 2015 actually work. Ian reported last week that the Orion crew size would likely be decreased from six to four, which also makes the spacecraft lighter. One issue engineers have been facing has been excess weight. Other reports look like this is likely a done deal.

Speaking of returning to the Moon, Wednesday’s appropriation hearings created some buzz when Chris Scolese, the agency’s acting administrator, said he anticipates changes. Some reports said Scolese gave vague answers. Others had NASA abandoning the a base on the Moon, but that is likely an exaggeration.

Moon base. Credit: NASA
Moon base. Credit: NASA

“I just can’t tell you what those changes would be,” Scolese told members of the House Appropriations Subcommittee on Commerce, Justice, Science and Related Agencies. “We’re still looking at options for what do we mean by the moon. Do we mean a colony on the moon? That’s clearly very expensive. Are we looking at something along the lines of what we did with Apollo?” he said.

But that correlates completely with legislation passed in October, 2008 that says:

“As NASA works toward the establishment of a lunar outpost, NASA shall make no plans that would require a lunar outpost to be occupied to maintain its viability. Any such outpost shall be operable as a human-tended facility capable of remote or autonomous operation for extended periods.”

Scolese also pointed out that the budget overview released earlier this year by President Obama clearly backs the previous administration’s goal of sending astronauts to the moon by 2020, a decade after the scheduled retirement of the shuttle fleet.

“It will probably be less than an outpost on the moon, but where it fits between sorties — single trips to the moon to various parts — and an outpost is really going to be dependent on the studies that we’re going to be doing,” he said.

What will really end up happening on the Moon is likely to change over time, just as the Constellation program already appears to be changing.

And finally, the current administration has yet to name a new NASA administrator. One person whose name had been floating around recently, General Lester Lyles, withdrew himself from consideration Wednesday. Another name that has surfaced is Lori Garver, former NASA associate administrator who headed Obama’s space transition team.

Sources: Florida Today, Lunar Network Blog, MSNBC, Wall Street Journal

Starbursts from Dwarf Galaxies Like Fireworks

These images, taken by NASA's Hubble Space Telescope, show myriad stars residing in the central regions of the three dwarf galaxies NGC 4163, NGC 4068, and IC 4662. Credit: NASA, ESA, K. McQuinn (University of Minnesota, Minneapolis), and I. Karachentsev (Special Astrophysical Observatory of the Russian Academy of Sciences, Russia)

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Fireworks in space? Astronomers are comparing “starbursts” from a galaxy that is in the throes of star formation to a Fourth of July fireworks display. And three particular galaxies are like my children’s favorite part of a fireworks display: the grand finale. These bursts occur at a fast and furious pace, lighting up a region for a short time before winking out. But that’s only part of the story. Archived data from the Hubble Space Telescope are showing that starbursts — intense regions of star formation — sweep across the whole galaxy and last 100 times longer than astronomers thought. The longer duration may affect how dwarf galaxies change over time, and therefore may shed light on galaxy evolution.

A group of astronomers studied three dwarf galaxies, NGC 4163, NGC 4068, and IC 4662. Their distances range from 8 million to 14 million light-years away. The trio is part of a survey of starbursts in 18 nearby dwarf galaxies.

“Our analysis shows that starburst activity in a dwarf galaxy happens on a global scale,” explains Kristen McQuinn of the University of Minnesota in Minneapolis and leader of the study. “There are pockets of intense star formation that propagate throughout the galaxy, like a string of firecrackers going off.” According to McQuinn, the duration of all the starburst events in a single dwarf galaxy would total 200 million to 400 million years.

These longer timescales are vastly more than the 5 million to 10 million years proposed by astronomers who have studied star formation in dwarf galaxies. “They were only looking at individual clusters and not the whole galaxy, so they assumed starbursts in galaxies lasted for a short time,” McQuinn says.

Hubble ACS image of NGC 4163.  Click for larger version.
Hubble ACS image of NGC 4163. Click for larger version.

Dwarf galaxies are considered by many astronomers to be the building blocks of the large galaxies seen today, so the length of starbursts is important for understanding how galaxies evolve.

“Astronomers are really interested to find out the steps of galaxy evolution,” McQuinn says. “Exploring these smaller galaxies is important because, according to popular theory, large galaxies are created from the merger of smaller, dwarf galaxies. So understanding these smaller pieces is an important part of filling in that scenario.”

With the high resolution Hubble data, McQuinn and her team were able to pick out individual stars in the galaxies and measure their brightness and color, two important characteristics astronomers use to determine stellar ages. By determining the ages of the stars, the astronomers could reconstruct the starburst history in each galaxy.

Two of the galaxies, NGC 4068 and IC 4662, show active, brilliant starburst regions in the Hubble images. The most recent starburst in the third galaxy, NGC 4163, occurred 200 million years ago and has faded from view.

The team looked at regions of high and low densities of stars, piecing together a picture of the starbursts. The galaxies were making a few stars, when something, perhaps an encounter with another galaxy, pushed them into high star-making mode. Instead of forming eight stars every thousand years, the galaxies started making 40 stars every thousand years, which is a lot for a small galaxy, McQuinn says. The typical dwarf is 10,000 to 30,000 light-years wide. By comparison, a normal-sized galaxy such as our Milky Way is about 100,000 light-years wide.

About 300 million to 400 million years ago star formation occurred in the outer areas of the galaxies. Then it began migrating inward as explosions of massive stars triggered new star formation in adjoining regions. Starbursts are still occurring in the inner parts of NGC 4068 and IC 4662.

The total duration of starburst activity depends on many factors, including the amount of gas in a galaxy, the distribution and density of the gas, and the event that triggered the starburst. A merger or an interaction with a large galaxy, for example, could create a longer starburst event than an interaction with a smaller system.

McQuinn plans to expand her study to another larger sample of more than 20 galaxies. “Studying nearby dwarf galaxies, where we can see the stars in great detail, will help us interpret observations of galaxies in the distant universe, where starbursts were much more common because galaxies had more gas with which to make stars,” McQuinn explains.

McQuinn’s results appeared in the April 10 issue of The Astrophysical Journal.

Source: HubbleSite

Where In The Universe #52



Its time once again for another Where In The Universe Challenge. The goal of this challenge is to test your skills and knowledge of the cosmos. Guess where in the Universe this image is from, and give yourself extra points if you can guess which spacecraft is responsible for the image. Post your guess in the comment section (no links to hints please!) and check back tomorrow for the answer. Good luck!

UPDATE: The answer has now been posted below.

As many of you said, this is an image from the Mars Pathfinder rover, Sojouner. The rock was named “Yogi” and is a meter-size rock located about 5 meters northwest of the Mars Pathfinder lander and was the second rock visited by the Sojourner Rover’s alpha proton X-ray spectrometer (APXS) instrument. To get one picture of the entire rock, it took several pictures stitched together in a mosaic, combining four “Super Pan” frames taken with the Sojouner’s camera. This composite color mosaic consists of 7 frames from the right eye, taken with different color filters that were enlarged by 500% and then co-added using Adobe Photoshop to produce, in effect, a super-resolution panchromatic frame that is sharper than an individual frame would be.

Doing this, scientists were able to address questions about the texture of this rock and what it might tell us about its mode of origin.

This is the approximate the true color of Mars. The shadow around Yogi looks a little funny, because shadows were processed separately from the rest of the rock and combined with the rest of the scene to bring out details in the shadow of Yogi that would be too dark to view at the same time as the sunlit surfaces. This resulted in the unusual color fringing at the edges of the shadow.

So, there you have it, a little blast from the past from Pathfinder. I hope you enjoyed this image, and check back next week for another WITU challenge.

Opportunity Finds Young Crater on Mars

A brand new bouncing baby crater. Opportunity Rover, portion of Navcam mosaic (Sol 1825; PIA 1185). Image credit: NASA/JPL-Caltech

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The two Mars Exploration Rovers have both seen their fair share of craters in their five years on Mars. Opportunity is currently booking it across Meridiani Planum on her way to Endeavour Crater, an ancient, huge hole in the ground (22 kilometers (13.7 miles across). But recently she came across the youngest crater either rover has ever seen. This crater is “young,” in relative terms; scientists say this small crater called “Resolution” formed sometime in the past 100,000 years. Most features studied by Opportunity are much older, including rocks over 3 billion years old. In contrast to these seniors, Resolution is just a baby.

Unlike a baby’s soft skin, a newborn crater starts out sharp, and only softens over time. As craters age, the “sandblasting” action of the Martian wind erodes rocks ejected during crater formation and fills its bowl with sand. Signs of this crater’s youth are fresh rocks on the crater rim and an empty bowl. The newer crater also drapes over older surrounding dunes. Finding youth pays off: scientists can compare Resolution to older craters to learn how fast wind changes the Martian surface over time.

Von Braun hill on Mars. Credit: NASA/JPL
Von Braun hill on Mars. Credit: NASA/JPL

In other rover news, Spirit has received a boost of power from a wind cleaning event. Rover driver Scott Maxwell shared via Twitter that Spirit’s current energy output is up to 371 watts/hour per sol. This is up from less than 250watts/hour in January. Maxwell said Spirit’s solar panels are the cleanest they’ve been in 550 sols. That’s good news, because Spirit needs all the energy she can get, with trying to battle some recent issues with memory problems.

The image above is Spirit’s current view, with a mound in the upper left called “Von Braun” that is the rover’s possible investigation site in future months. From the location where Spirit was when the image was taken, Von Braun is about 160 meters (525 feet) away.

Source: JPL

IYA Live Telescope Today – Messier 10

We certainly hope you had the opportunity to keep an eye on our remote telescope! Despite the weather changes in the southern hemisphere causing a little rain delay, we’ve been looking forward to a clear night and firing the telescope back up. I know it’s certainly fascinating to watch and don’t be disappointed if you log on and get an error message. (That just means the scope is not operating at the moment or you need to refresh.) If you didn’t get a chance to watch the IYA telescope “live” on Galactic TV today, don’t worry. We took a video capture for you. Step inside to enjoy today’s view of Messier Object 10. We do it all for you…

The following information is a direct quotation from Wikipedia:

M10 Globular Cluster: Constellation – OPHIUCHUS

Messier 10 or M10 (also designated NGC 6254) is a globular cluster in the constellation of Ophiuchus.

The object was discovered by Charles Messier on May 29, 1764, who cataloged it as number 10 in his list. He described it as a “nebula without stars”, but later study revealed it as a globular cluster of thousands of stars.

M10 has an apparent diameter of some 20 arcminutes, about two-thirds of the apparent diameter of the Moon. Viewed through medium-sized telescopes it appears about half that size (8′ to 9′), as its bright core is only 35 light-years across. M10 has a spatial diameter of 83 light-years and is estimated to be 14,300 light-years away from Earth.

Four variable stars have been discovered in this cluster.

As always, you can visit the remote telescope by clicking on the IYA “LIVE Remote Cam” Logo to your right. We’ll be broadcasting whenever skies are clear and dark in Central Victoria! Enjoy…

Factual information is copied from: Wikipedia. Thank you so much!

Russia Considering Rocket-Powered Precision Landing for Next Generation Spacecraft

The future Russian capsule could land on a bright rocket plume. Credit: Anatoly Zak, Russianspaceweb.com

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Engineers for Russia’s next-generation manned space vehicle are considering a rocket-powered landing system which would provide precision landing on Earth. Currently, the Soyuz uses small solid propellant motors to soften its touchdown, but the ship’s parachute plays the main role in providing the vehicle and crew with a safe landing. Russia is developing a new spacecraft to replace the Soyuz which has been used for nearly forty years. If the rocket-powered landing system is approved, this would be the first time in history that a manned vehicle relied solely on rocket engines for touchdown.

All previous Russian/USSR manned missions have landed on Earth using a parachute, except for the Russian shuttle, Buran, which was never flown to space. made one unmanned spaceflight in 1988. (Early US missions used parachutes, while the shuttle uses wings and wheels to land.)

This change in landing architecture is being considered because Russia is building a spaceport in eastern part of the country that has only a narrow strip of land where spacecraft could land, approximately 2 by 5 kilometers. The new spaceport is a highly political decision, as the current spaceport in Baikonur is located in the newly independent republic of Kazakhstan, and Russian politicians would like to end their dependence and on Kazakhstan for spaceflight.

Artist concept of the new capsule in flight. Credit: Anatoly Zak, Russianspaceweb.com
Artist concept of the new capsule in flight. Credit: Anatoly Zak, Russianspaceweb.com

Therefore, Russian engineers found themselves under political pressure to improve the maneuverability of the next generation spacecraft, so it could guide itself into a relatively small landing area.

Last July, Korolev-based RKK Energia released the first drawings of a multi-purpose transport ship, known as the Advanced Crew Transportation System (ACTS), which, at the time, Russia had hoped to develop in co-operation with Europe.

Combined with retractable landing legs and a re-usable thermal protection system, landing rockets provides the possibility of a reusable capsule as well.

According to the presentation made by Nikolai Bryukhanov, the leading designer at RKK Energia, at the 26th International Symposium on Space Technology and Science in Hamamatsu, Japan, the spacecraft would fire its engines at an altitude of just 600-800m, as the capsule is streaking toward Earth after re-entering the atmosphere at the end of its mission.

After a vertical descent, the precision landing would be initiated at the altitude of 30m above the surface.

The concept looks similar to the US’s experimental DC-X vehicle, tested in the 1990s, which was abandoned at the end of the Cold War.

Source: BBC

Confirmed: Chocolate and Astronomy Go Together

Chocolate astronomy sculpture. Credit: Museo de Chocolate.

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Two of my greatest loves are coming together at the Museo de Chocolate (Chocolate Museum) of Barcelona. To celebrate the International Year of Astronomy 2009, this year’s International Contest of Chocolate Figures has chosen astronomy as its theme. And the fourteen sculptures that are part of the competition –in which the designers use chocolate to embody creative astronomical interpretations, as the one seen here — will be on display at the Museo de Chocolate starting on May 7 in a new temporary exhibition, “Los Mundos Celestes-400 años del descubrimiento del sistema solar” (Celestial Worlds – 400 years since the discovery of the Solar System). I understand the exhibition as being temporary, but my question is, who gets to eat them?

Source: Pasteleria.com

Nearsighted No More: Astronomers Resolve Milky Way’s Mysterious X-Ray Glow

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The map above details the Galactic ridge X-ray emission, first detected 25 years ago and observed recently by NASA’s Rossi X-ray Timing Explorer (RXTE) observatory. The inset shows the zoomed Chandra image of the region, close to the center of the galaxy. 

The mysterious — and formerly blurry — X-ray source puzzled astronomers for a quarter century, but a new paper release today by the journal Nature has helped to clear the air.

spitzer_region
Region close to the Galactic Center obtained by Spitzer infrared telescope in three spectral band. The field of view of CHANDRA is shown by the white square. Credit: M. Revnivtsev

 

Lead author Mikhail Revnivtsev, of Munich Technical University in Garching, Germany, and his colleagues report that the formerly unresolved X-ray glow has a spectrum characteristic of a hot (100 million degrees Kelvin) optically thin plasma, with a prominent iron emission line.

But the gravitational well of the Galactic disk is far too shallow to confine such a hot interstellar medium; it would flow away at a velocity of a few thousand kilometers per second, exceeding the speed of sound in the gas.

Replenishing such energy losses would require a source that exceeds all plausible energy sources in the Milky Way — including supernovae — by orders of magnitude, they write.

Based on their observations, the team is proposing that the hot plasma is instead bound to many faint sources: plain old stars.

“Here we report that at energies of 6–7 keV, more than 80 percent of the seemingly diffuse X-ray emission is resolved into discrete sources, probably accreting white dwarfs and coronally active stars,” they write.

“Such stellar X-ray sources are of the common ‘garden variety’ in the Sun’s neighbourhood,” writes Michael Shull, an astrophysicist at the University of Colorado at Boulder, in an accompanying editorial. “However, at the distance of the Galactic ridge from Earth, their combined light becomes a diffuse blur, the X-ray equivalent of the many stars that make up the Milky Way, as Galileo first saw with his telescope in visible light.”

Shull notes that the results are a testament to the increased power of telescopes like Chandra, which de-mystified the source of the X-ray glow — and he cautions astronomers about describing faint backgrounds at all wavelengths, before getting a good look.

“As Revnivtsev and colleagues’ work demonstrates, sometimes the exotic explanation can be set aside by more accurate imaging and spectroscopy,” he writes.

LOWER IMAGE CAPTION: Region close to the Galactic Center obtained by Spitzer infrared telescope in three spectral band. The field of view of CHANDRA is shown by the white square. Credit: M. Revnivtsev

Source: Nature

Salt in Enceladus’ Geysers Hints at Subsurface Liquid Ocean

Enceladus Ice Geysers Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

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Planetary scientists say the geysers shooting from Saturn’s moon Enceladus are likely to come from a subsurface sea of liquid water. During the Cassini spacecraft’s fly-through of the geyser’s plume on October 9, 2008, the instruments on board were able to measure the molecular weight of the chemicals in the ice. Detected were traces of sodium in the form of salt and sodium bicarbonate. The chemicals would have originated in the rocky core of Enceladus, so to reach a plume they must have leached from the core via liquid water.

Frank Postberg of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and colleagues, are presenting their findings at the European Geophysical Union meeting in Vienna this week.

Although the salt could have been leached out by an ancient ocean which since been frozen solid, that freezing process would concentrate most of the salt very far from the surface of the moon’s ice, says Julie Castillo of NASA’s Jet Propulsion Laboratory in Pasadena, California, quoted in New Scientist. “It is easier to imagine that the salts are present in a liquid ocean below the surface,” she says. “That’s why this detection, if confirmed, is very important.”

Observations of the plumes from Earth in 2007 detected no sign of sodium, casting doubt on such a subsurface sea. But the new in-situ detection may change our understanding of Enceladus’ geysers.

Source: New Scientist