Here’s the May 3, 2012 edition of the Weekly Space Hangout, where we were joined by our usual cast of space journalists, including Alan Boyle, Nicole Gugliucci, Ian O’Neill, Jason Major, Emily Lakdawalla and Fraser Cain. We were then joined by two new people, Amy Shira Teitel from Vintage Space and Sawyer Rosenstein from the Talking Space Podcast.
Want to watch an episode live? We record the Weekly Space Hangout every Thursday at 10:00am PDT, 1:00pm EDT. The live show will appear in Fraser’s Google+ stream, or on our YouTube Channel. You can also watch it live over on Cosmoquest.org.
Venus 34 Days Before 2012 Transit - Credit: John Chumack
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Head outside on any clear night this week and you won’t be able to miss brilliant Venus decorating the western horizon. Right now it’s surrounded by a host of bright winter stars like Capella, Betelgeuse, Aldebaran and the Pleiades. But, don’t stop there. Use any type of optical aid and you’ll see the planet is in the crescent phase right now and bigger than Jupiter in apparent size!
There’s a lot of things to know about viewing Venus. Oddly enough, the smaller the phase, the more brightly it shines. If you cannot see its slender form for the glare, simply try wearing sunglasses while using your binoculars… or stacking dark filters, such as green and blue, for the telescope eyepiece. While you’d think that something which sparkles and shines like Venus would be very exciting to see magnified, it’s actually pretty bland. However, don’t let rather ordinary appearances fool you. Behind that “girl next door” exterior is a really radical chick. Beneath the bland clouds runaway greenhouse gases heat things up to 860 degrees Fahrenheit (460 degrees Celsius) and volcanoes rule.
Keep on watching Venus. Right now she’s headed towards Earth and the pinnacle of observing excitement – the Transit. It will continue to grow larger in apparent size and the crescent phase will narrow even more. On June 5 (June 6 in Australia and Asia), it will pass between the Earth and Sun… an event which only happens about twice in a century and won’t happen again until the year 2117!
The clock is ticking and now is the time to begin your preparations to view the transit of Venus. Do not wait until just a few days before the event to choose a location for your observations. If you do, you might find yourself faced with clouds… an obstruction you hadn’t planned on… getting permission to be in a certain area… or many other things. Knowing exactly where the Sun will be during the transit means a relaxed experience!
As of now, you’re going to find it will be very difficult to locate solar filters for particular telescopes – and waiting any longer may mean not having one at all. Because the transit of Venus is such a rare event, many retailers are carrying special eclipse/transit viewing glasses. They will appear much like the cardboard 3D glasses you get at the movie theatre, but instead of red and blue lenses, they will have either black mylar or Baader filter film. These glasses are safe for solar viewing, but there are a few things you must understand about them. Before you view, please inspect the edges carefully to make sure they are sealed and no sunlight can enter. Even more importantly, do not use them in conjunction with binoculars or a telescope. Eclipse glasses were meant strictly for use with your eyes. Concentrating sunlight with an optical aid and hoping the glasses will be enough to block the Sun’s harmful rays is taking a chance at blinding yourself. Always use approved solar filter material when viewing with telescopes or binoculars and always supervise when children are present.
Venus Transit 2004 - Credit: John Chumack
The next tip for viewing the Venus transit has to do with photography. If you plan on filming or photographing the event through a telescope, now is the time to practice. Do not wait until just a few days before the event to be sure your video equipment is working properly – or that your camera is prepared. Start now by taking practice pictures of the Sun and make sure you have spare batteries or a power supply on hand for the day of the event. Nothing is more disappointing than being ready to photograph an astronomical event and having your equipment fail at the last second. It’s always wise to have a back-up option… such as a cell phone camera, spare pocket camera, or even a camcorder handy just in case. All of these will work afocally. If you practice in advance, you’ll find you can take quite satisfactory photos by just holding the camera to a properly filtered telescope eyepiece.
The last tip for viewing the Venus transit is time. Make sure well in advance of exactly what time the transit starts in your area! The local transit times page by Steven van Roode and Francois Mignard is an excellent resource. But don’t forget… the times are given on an astronomical standard – Universal Time. If you are unsure of how to convert, try the Time Zone Converter to assist you.
Greenland ice breakup seen from NASA ER-2 cockpit during a MABEL flight (NASA)
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NASA researchers have just completed science mission flights over Greenland and the surrounding seas, gathering data on ice distribution and thickness with the MABEL (Multiple Altimeter Beam Experimental Lidar) laser altimeter instrument mounted in the nose of an ER-2 aircraft. WIth MABEL’s unprecedented ability to detect individual photons, researchers will be able to even more accurately determine how Arctic ice sheets are behaving in today’s changing climate.
At the same time, news has come in from researchers with the University of Washington, who have completed a NASA- and NSF-funded study of the enormous island’s glaciers spanning a ten-year period. What they have found is that the glaciers have been increasing in speed about 30% over the past ten years — which is actually less than earlier studies had anticipated.
“In some sense, this raises as many questions as it answers. It shows there’s a lot of variability,” said Ian Joughin, a glaciologist in the UW’s Applied Physics Laboratory and coauthor of the paper, published May 4 in Science.
Previous research had suggested that Greenland’s melting glaciers could contribute up to 19 inches to global sea level rise by 2100. But the behavior of Greenland’s vast ice fields and ocean-draining glaciers was not yet thoroughly researched. Based on this new study, the outlet glaciers have not sped up as much as expected.
Still, ocean-draining (a.k.a. marine-terminating) glaciers move much faster than their land-based counterparts, and the UW researchers have found that their speeds are increasing on average — up to 32% in some areas.
The team realizes that the study may just not have observed a long enough period of time. (These are glaciers, after all!)
Icebergs calve from the edge of Greenland's Gyldenlove glacier in April 2011. (NASA/GSFC/Michael Studinger)
“There’s the caveat that this 10-year time series is too short to really understand long-term behavior, so there still may be future events – tipping points – that could cause large increases in glacier speed to continue,” said Ian Howat, an assistant professor of earth sciences at Ohio State University and a co-author of the paper. “Or perhaps some of the big glaciers in the north of Greenland that haven’t yet exhibited any changes may begin to speed up, which would greatly increase the rate of sea level rise.”
What the researchers didn’t find was any evidence that the rate of flow is slowing down. Though the true extent of the effect of Greenland’s ice on future sea level rise may not be unerringly predictable down to the inch or centimeter, even at the currently observed rate a contribution of 4 or more inches by the end of the century is still very much a possibility.
Meanwhile, the data gathered from the MABEL science flights over the past four weeks will be used to calibrate NASA’s next-generation ice-observing satellite, IceSat-2, planned for launch in 2016. Once in orbit, IceSat-2 will provide even more detailed insight to the complex behavior of our planet’s ice sheets.
Artist concept of the Curiosity Rover on Mars. Credit: NASA
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After 36 years of debate, confusion, and failed attempts by other space agencies to answer a basic question, NASA’s Mars Science Laboratory (MSL) is on its way to repeat the search for organic matter that eluded the two Viking probes.
With 96 days left until landing, MSL will touch down at the Gale Crater this August. The rover, called Curiosity, will be the largest vehicle delivered to our neighboring planet thus far. Weighing in at 900 kg, Curiosity is nearly five times as large as the Spirit and Opportunity rovers that landed eight years ago, and more than 1.5 times as large as each Viking lander that arrived on planet in 1976.
Like the Vikings and Mars Exploration Rovers, Curiosity was conceived and launched, largely to gather information that may tell us whether the Red Planet harbors microbial life. Instrumentation launched for in situ analysis has been advancing steadily since the Viking era, yet each chapter in the story of the search for Martian life builds upon the previous ones.
Though usually mentioned only briefly in the days when Spirit and Opportunity were making headlines, the twin Viking landers were amazing craft, not only for their time, but even for today. The instrument suite of each Viking lander included a suite of three biology experiments, instruments designed for the direct detection of microbes, should the regolith at either of the two Viking landing sites contain any. While subsequent landing craft have carried instruments designed to assess Mars’ potential for life, none since the Project Viking has been built to look for Martian life forms directly.
According to Viking investigator Gilbert Levin, the Viking landers already discovered Martian life. Back in 1976-1977, Levin’s instrument, known as the Labeled Release (LR) experiment, yielded positive results at Chryse Planitia and Utopia Planitia, the two Viking landing sites. When treated with a solution containing small, organic chemicals labeled with radioactive carbon, regolith samples taken at the landing sites released a gas, indicated by an increase in radioactivity in the space above the sample.
While Levin believes the gas is carbon dioxide resulting from the oxidation of the organic chemicals, it’s also conceivable that the chemicals were reduced to another gas, methane. Either way, since heating the samples to a temperature high enough to kill most of the microbes that we know on Earth prevented the gas release, the Viking science team concluded initially that the LR had detected life.
Most of the science team, but not Levin, decided that the gas release in the LR must have resulted from a non-biological chemical reaction. This rethinking was due to variety of factors, but the most important of which was that the gas chromatograph-mass spectrometer (GC-MS) of each lander failed to detect organic matter in the samples. As the late Carl Sagan explained it on his television series, Cosmos, “If there is life on Mars, where are the dead bodies?”
While most astrobiologists and planetary scientists do not agree with Levin that the results of his 36 year-old experiment constitute conclusive evidence for Martian life, there is a growing number of Mars scientists who are equivocal on the issue. According to Levin, Sagan moved into the equivocal category in 1996, after astrobiologist David McKay and colleagues published a paper in the journal Science describing fossilized life in meteorite ALH84001, one of a handful of meteorites known to be from Mars.
The SAM experiment.
Traveling within Curiosity’s enormous instrument package is a suite of machines called SAM, which stands for “Sample Analysis at Mars”. After all of these years, SAM represents NASA’s first attempt to repeat Viking’s search for Martian organics, but with more advanced technology.
This is not to say that other attempts were not made during the intervening years. In 1996, the Russian Federal Space Agency launched a Mars-bound probe carrying not only organic chemistry equipment but an upgraded version of Levin’s experiment. Rather than treating regolith samples with a mixture of “right-handed” and “left-handed” forms of organic substrates (known in chemistry as racemic mixtures), the new LR would have treated some samples with a left-handed substrate (L-cysteine) and others with the substrate’s mirror image (D-cysteine).
Had results been the same for L- and D-cysteine, a non-biological mechanism would have seemed all the more likely. However, if the active agent in the Martian regolith favored one compound at the expense of the other, this would indicate life. Even more intriguing: if the active agent favored D-cysteine, it would have suggested an origin of life on Mars separate from the origin of life on Earth, since terrestrial life forms use mostly left-handed amino acids. Such a result would suggest that life originates fairly easily, implying a cosmos teaming with living forms.
But Russia’s Mars ’96 probe crashed in the Pacific Ocean shortly after liftoff. A few years later, the European Space Agency sent Beagle 2 to Mars, carrying an advanced organic detection package, but this probe too was lost.
While Curiosity’s SAM does not include an LR experiment of any sort, it does have organic matter detection capability that can operate in mass spectrometry (MS), or gas chromatography-mass spectrometry (GS-MS) mode. In addition to being able to detect certain classes of organic compounds that the Viking GCMS would have missed in surface material, SAM also is designed to look for methane in the Martian atmosphere. Though atmospheric methane already has been detected already from orbit, detailed measurements of its concentration and fluctuations will help astrobiologists to determine whether the source is methane-producing microorganisms.
Astronomers have found four nearby white dwarf stars surrounded by disks of material that could be the remains of rocky planets much like Earth — and one star in particular appears to be in the act of swallowing up what’s left of an Earthlike planet’s core.
The research, announced today by the Royal Astronomical Society, gives a chilling look at the eventual fate that may await our own planet.
Astronomers from the University of Warwick used Hubble to identify the composition of four white dwarfs’ atmospheres, found during a survey of over 80 such stars located within 100 light-years of the Sun. What they found was a majority of the material was composed of elements found in our own Solar System: oxygen, magnesium, silicon and iron. Together these elements make up 93% of our planet.
In addition, a curiously low ratio of carbon was identified, indicating that rocky planets were at one time in orbit around the stars.
Since white dwarfs are the leftover cores of stellar-mass stars that have burnt through all their fuel, the material in their atmosphere is likely the leftover bits of planets. Once held in safe, stable orbits, when their stars neared the ends of their lives they expanded, possibly engulfing the innermost planets and disrupting the orbits of others, triggering a runaway collision effect that eventually shattered them all, forming an orbiting cloud of debris.
This could very well be what happens to our Solar System in four or five billion years.
“What we are seeing today in these white dwarfs several hundred light years away could well be a snapshot of the very distant future of the Earth,” said Professor Boris Gänsicke of the Department of Physics at the University of Warwick, who led the study. “During the transformation of the Sun into a white dwarf, it will lose a large amount of mass, and all the planets will move further out. This may destabilise the orbits and lead to collisions between planetary bodies as happened in the unstable early days of our solar systems.”
One of the white dwarfs studied, labeled PG0843+516, may even be actively eating the remains of an once-Earthlike world’s core.
The researchers identified an abundance of heavier elements like iron, nickel and sulphur in the atmosphere surrounding PG0843+516. These elements are found in the cores of terrestrial planets, having sunk into their interiors during the early stages of planetary formation. Finding them out in the open attests to the destruction of a rocky world like ours.
Of course, being heavier elements, they will be the first to be accreted by their star.
“It is entirely feasible that in PG0843+516 we see the accretion of such fragments made from the core material of what was once a terrestrial exoplanet,” Prof. Gänsicke said.
It’s an eerie look into a distant future, when Earth and the inner planets could become just some elements in a cloud.
Noctilucent clouds taken from the ISS Image Credit: NASA
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Astronomers usually curse and shake their fist at clouds for obscuring the sky and spoiling their observations. This month however, we enter the season when, after dark, thin veils of clouds appear to glow with an eerie blue light and are eagerly awaited and sought after.
Polar mesospheric, noctilucent or night shining clouds (NLC) form at the edge of space, between 76 and 85 kilometers up in the arid atmosphere, where there is one hundred millionth the amount of moisture found in the air at the Sahara Desert! Here temperatures can fall below -100 degrees Celsius, so what little water vapour is present freezes directly or forms on dust particles from micrometeors or volcanic eruptions.
During the Summer months, as the Sun stays close to the horizon, its rays illuminate these layers of ice crystals, producing a fine network of tenuous, incandescent filaments. They appear, in the Northern hemisphere, from mid May to mid August (mid November to mid February in the South) in latitudes between 50º and 70º, when the Sun is 6 to 16 degrees below the horizon. Look for them low in the Northwestern sky from an hour after sunset, or low in the Northeast before dawn.
They were first noted in 1885, two years after the eruption of Krakatoa when people were accustomed to looking at the spectacular sunsets and the glowing clouds were thought to be produced by the ash from the volcano in our atmosphere. Eventually the ash disappeared, but the clouds remained. In fact throughout the twentieth century noctilucent clouds have been occurring more frequently and across a wider area, as well as becoming brighter, perhaps due to climate change as increased greenhouse gases cool the mesosphere. The clouds also vary with the solar cycle, as ultraviolet radiation from the Sun splits the water molecules and so the clouds decrease in brightness during solar maximum. Changes in brightness seem to follow fluctuations in solar radiation but about a year later, though nobody knows the reason for this time delay.
The clouds have been found to be highly reflective to radar, possibly due to sodium and iron atoms, stripped from micrometeors, forming a thin metal coating on the ice grains. In 2006 Mars Express discovered similar clouds, forming from carbon dioxide 100 kilometers up in the Martian atmosphere, that were also only observed when the Sun was below the horizon. In 2009 the Charged Aerosol Release Experiment (CARE) created artificial noctilucent clouds using rocket exhaust that were observed for several weeks. In July 2008 the crew aboard the ISS were treated to a noctilucent cloud display over Mongolia and were able to capture the image above.
So over the Summer months, keep an eye on the northern horizon after dark for a chance to catch these beautiful and unusually welcome clouds.
Enceladus' southern ice geysers are brilliant in backlit sunlight (NASA/JPL/SSI/J. Major)
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The latest images are in from Saturn’s very own personal paparazzi, NASA’s Cassini spacecraft, fresh from its early morning flyby of the ice-spewing moon Enceladus. And, being its last closeup for the next three years, the little moon didn’t disappoint!
The image above is a composite I made from two raw images (this one and this one) assembled to show Enceladus in its crescent-lit entirety with jets in full force. The images were rotated to orient the moon’s southern pole — where the jets originate — toward the bottom.
Cassini was between 72,090 miles (116,000 km) and 90,000 miles (140,000 km) from Enceladus when these images were acquired.
This morning’s E-19 flyby completed a trio of recent close passes by Cassini of the 318-mile (511-km) -wide moon, bringing the spacecraft as low as 46 miles (74 km) above its frozen surface. The goal of the maneuver was to gather data about Enceladus’ internal mass — particularly in the region around its southern pole, where a reservoir of liquid water is thought to reside — and also to look for “hot spots” on its surface that would give more information about its overall energy distribution.
Cassini had previously discovered that Enceladus radiates a surprising amount of heat from its surface, mostly along the “tiger stripe” features — long, deep furrows (sulcae) that gouge its southern hemisphere, they are the source of the water-ice geysers.
Cassini also used the flyby opportunity to study Enceladus’ gravitational field.
By imaging the moon with backlit lighting from the Sun the highly-reflective ice particles in the jets become visible. More direct lighting reduces the jets’ visibility in images, which must be exposed for the natural light of the scene or risk “blowing out” due to Enceladus’ natural high reflectivity.
The images below are raw spacecraft downloads right from the Cassini’s imaging headquarters in Boulder, CO.
Enceladus' geysers in action on May 2, 2012. (NASA/JPL/SSI)Enceladus sprays ice into the hazy E ring, which orbits Saturn (NASA/JPL/SSI)
Cassini also swung closely by Dione during this morning’s flyby but the images from that encounter aren’t available yet. Stay tuned to Universe Today for more postcards from Saturn!
As always, you can follow along with the ongoing Cassini mission on JPL’s dedicated site here, as well as on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site.
A 'side by side' comparison of 4 different shots taken over the period of 30 hours before the March 19, 2011 'SuperMoon'. It shows the progression of Moon in it's orbit until the closest point. Credit: Ramiz Qureshi, from Karachi, Pakistan.
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This weekend will provide the full Moon’s closest approach of the year to Earth. On Saturday, May 5, 2012 the Moon could appear as much as 14% bigger and 30% brighter than other full Moons of 2012, according to some calculations. Will you notice it? Not if you haven’t really been paying attention, or have a reference point to compare it to other full Moons. And it certainly won’t have any adverse effects on Earth, as this closest approach happens every year — just a fact of orbital mechanics. But perhaps a great way to celebrate Cinco de Mayo is to spend the evening gazing at the Moon!
Every month, as the Moon circles the Earth in its elongated orbit, its distance from the Earth varies. This weekend, the Moon is reaching what’s known as its perigee, the closest point to Earth in its orbit. It will be about 356,953 kilometers (221,802 miles) from Earth on Saturday. Apogee — when the Moon is farthest away — varies, but is around 405,000 km (252,000 miles) away.
What is most interesting is that the timing of the perigee and full Moon is really, really close: The full moon occurs at 03:34 UTC on May 6 (11:34 p.m. EDT on May 5 )eastern and perigee follows at 03:35 UTC (11:35 p.m. EDT)
David Morrison, from NASA says “supermoon” is not an astronomical term and he confirms a supermoon has no effect on Earth, and that the change in size is hardly noticeable to the average person. If you miss it, the Moon will be very nearly as close at the next full Moon, and very nearly as close as it was at the last full Moon.
But even better is that two weeks after the “supermoon” on May 5th, the Moon will be at apogee as it lines up in front of the Sun for an amazing annular eclipse on May 20th. An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.
If you’re a photographer, take a picture of the Moon and send it to us. If we get a some good images, we’ll share them. Join our Flickr group, or send us your images by email (this means you’re giving us permission to post them). Please explain a little about it such as when you took it, the equipment you used, etc.
These images, taken with NASA's Galaxy Evolution Explorer (GALEX) and the Pan-STARRS1 telescope in Hawaii, show a galaxy that brightened suddenly, caused by a flare from its nucleus. Credit: NASA, S. Gezari (JHU), A. Rest (STScI), and R. Chornock (Harvard-Smithsonian CfA)
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I’m going to try and say this before the Bad Astronomer does: Holy Haleakala! A team of astronomers using the Pan-STARRS1 telescope on Mount Haleakala in Hawaii have found evidence of a black hole ripping a star to shreds. While this isn’t the first time this type of activity has been detected, these new observations are the best views so far of what happens to objects that are consumed by a black hole. Plus, astronomers, for the first time, know what kind of star was destroyed and watched as it happened. This all helps in providing more insight into how black holes behave: They aren’t enormous vacuum cleaners that suck up and destroy everything around them, or sharks that seek out and consume their victims. Instead, like Venus Fly Traps, they wait for objects to come to them.
“Black holes, like sharks, suffer from a popular misconception that they are perpetual killing machines,” said Ryan Chornock of the Harvard-Smithsonian Center for Astrophysics (CfA). “Actually, they’re quiet for most of their lives. Occasionally a star wanders too close, and that’s when a feeding frenzy begins.”
If a star passes too close to a black hole, tidal forces can rip it apart. The remaining gases then swirl in toward the black hole. But just a small fraction of the material near a black hole falls in, while most of it just circles for a while – sometimes forever. The material close the black hole gets superheated, causing it to glow. By searching for newly glowing supermassive black holes, astronomers can spot them in the midst of a feast.
So, kind of like with Junior, the giant Venus Fly Trap in the movie “Little Shop of Horrors,” the feast is evident from what doesn’t get eaten.
This computer simulation shows a star being shredded by the gravity of a massive black hole. Some of the stellar debris falls into the black hole and some of it is ejected into space at high speeds. The areas in white are regions of highest density, with progressively redder colors corresponding to lower-density regions. The blue dot pinpoints the black hole’s location. The elapsed time corresponds to the amount of time it takes for a Sun-like star to be ripped apart by a black hole a million times more massive than the Sun.
The team discovered this type of glow on May 31, 2010, with Pan-STARRS1 and also with NASA’s Galaxy Evolution Explorer (GALEX). The flare brightened to a peak on July 12th before fading away over the course of a year. The event took place in a galaxy 2.7 billion light-years away, and the black hole contains as much mass as 3 million Suns, making it about the same size as the Milky Way’s central black hole.
“We observed the demise of a star and its digestion by the black hole in real time,” said Harvard co-author Edo Berger.
“We’re also witnessing the spectral signature of the ejected gas, said Suvi Gezari of The Johns Hopkins University who lead the research, “which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas we detect from the carnage, we know that the slaughtered star had to have been the helium-rich core of a stripped star.”
Follow-up observations with the MMT Observatory in Arizona showed that the black hole was consuming large amounts of helium. Therefore, the shredded star likely was the core of a red giant star. The lack of hydrogen showed this is likely not the first time the star had encountered the same black hole, and that it lost its outer atmosphere on a previous pass.
The star may have been near the end of its life, the astronomers say. After consuming most of its hydrogen fuel, it had probably ballooned in size, becoming a red giant. The astronomers think the bloated star was looping around the black hole in a highly elliptical orbit, similar to a comet’s elongated orbit around the Sun.
This computer-simulated image shows gas from a tidally shredded star falling into a black hole. Some of the gas also is being ejected at high speeds into space. Astronomers observed a flare in ultraviolet and optical light from the gas falling into the black hole and glowing helium from the stars's helium-rich gas expelled from the system. Credit: NASA, S. Gezari (The Johns Hopkins University), and J. Guillochon (University of California, Santa Cruz)
“This is the first time where we have so many pieces of evidence, and now we can put them all together to weigh the perpetrator (the black hole) and determine the identity of the unlucky star that fell victim to it,” Gezari said. “These observations also give us clues to what evidence to look for in the future to find this type of event.”
The team’s results were published today in the online edition of the journal Nature.
Galileo image of Ganymede, Jupiter's - and the Solar System's - largest moon. (Ted Stryk)
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The European Space Agency has given the go-ahead for an exciting mission to explore the icy moons of Jupiter, as well as the giant planet itself.
JUICE — JUpiter ICy moons Explorer — will consist of a solar-powered spacecraft that will spend 3.5 years within the Jovian system, investigating Ganymede, Europa and the upper atmosphere of Jupiter. Anticipated to launch in June 2022, JUICE would arrive at Jupiter in early 2030.
As its name implies, JUICE’s main targets are Jupiter’s largest icy moons — Ganymede and Europa — which are thought to have liquid oceans concealed beneath their frozen surfaces.
The largest moon in the Solar System, Ganymede is also thought to have a molten iron core generating a magnetic field much like Earth’s. The internal heat from this core may help keep Ganymede’s underground ocean liquid, but the dynamics of how it all works are not quite understood.
JUICE will also study the ice-coated Europa, whose cueball-smooth surface lined with cracks and jumbled mounds of frozen material seem to be sure indicators of a subsurface ocean, although how deep and how extensive is might be are still unknown — not to mention its composition and whether or not it could be hospitable to life.
The rust-colored cracks lining Europa's otherwise smooth surface hint at a subsurface ocean. (Ted Stryk)
“JUICE will give us better insight into how gas giants and their orbiting worlds form, and their potential for hosting life,” said Professor Alvaro Giménez Cañete, ESA’s Director of Science and Robotic Exploration.
The JUICE spacecraft was originally supposed to join a NASA mission dedicated to the investigation of Europa, but NASA deemed their proposed mission too costly and it was cancelled. According to Robert Pappalardo, study scientist for the Europa mission based at JPL, NASA may still supply some instruments for the spacecraft “assuming that the funding situation in the United States can bear it.”
Artist's rendering of JUICE at Jupiter. (ESA/AOES)
JUICE will also capture images of Jupiter’s moon Callisto and search for aurorae in the gas giant’s upper atmosphere, as well as measure the planet’s powerful magnetic field. Once arriving in 2030, it will spend at least three years exploring the Jovian worlds.
Read more in today’s news release from Nature, and stay tuned to ESA’s JUICE mission page here.
