Scientists produce the first global geologic map of Jupiter’s moon Ganymede.
A very useful start to the geological study of the solar system’s largest moon.
Jupiter’s shrinking Great Red Spot.
In the 1880s the GRS resembled a huge blimp gliding high above white crystalline clouds of ammonia and spanned 40,000 km (25, 000 miles) across. You couldn’t miss it even in those small brass refractors that were the standard amateur observing gear back in the day. Nearly one hundred years later in 1979, the Spot’s north-south extent has remained virtually unchanged, but it’s girth had shrunk to 25,000 km (15,535 miles) or just shy of two Earth diameters. Recent work done by expert astrophotographer Damian Peach using the WINJUPOS program to precisely measure the GRS in high resolution photos over the past 10 years indicates a continued steady shrinkage.
Lots more fascinating information at the link. Read it all.
Hubble discovers water vapor venting from Europa’s south pole.
It is not yet known if this water is coming from the interior or from the surface.
Be warned: None of the images from this press release are real. They are all artist’s impressions, but done in such a way as to look like actual Hubble images.
Scientists detect evidence of the splash of clay material left by an asteroid or comet after it impacted Europa.
Juno, on its way to Jupiter, flew past the Earth on October 9 and made a movie.
The link has details. The video is below the fold.
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Juno has exited safe mode and is now functioning normally.
Two days after its flyby of Earth, Jupiter probe Juno remains in safe mode.
The Juno spacecraft is in a healthy and stable state, with its tractor-trailer-size solar panels pointed toward the sun. The mission team is in communication with Juno and has seen no sign of any failures in the probe’s subsystems or components, said project manager Rick Nybakken of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. So Juno’s handlers plan to take their time and do a thorough investigation before attempting to bring all of the spacecraft’s systems back online.
In other words, there is no rush to take the spacecraft out of safe mode. It is far better to figure out exactly what is going on first.
The uncertainty of science: Engineers hope Juno’s Earth flyby yesterday will help solve a mystery seen in previous flybys by unmanned probes.
Since 1990, mission controllers at ESA and NASA have noticed that their spacecraft sometimes experience a strange variation in the amount of orbital energy they pick up from Earth during flybys, a technique routinely used to fling satellites deep into our Solar System. The unexplained variation is noticed as a tiny difference in the expected speed gained (or lost) during the passage.
The variations are extremely small: NASA’s Jupiter probe ended up just 3.9 mm/s faster than expected when it swung past Earth in December 1990. The largest variation– a boost of 13.0 mm/s – was seen with NASA’s NEAR asteroid craft in January 1998. Conversely, the differences during swingbys of NASA’s Cassini in 1999 and Messenger in 2005 were so small that they could not be confirmed.
The experts are stumped.
It is likely that these small variations are related in some way with simple engineering and not some unknown feature of gravity. Nonetheless, it remains a mystery.
Is a natural rain of diamonds occurring on Jupiter and Saturn? Two scientists say yes!
In their scenario, lightning zaps molecules of methane in the upper atmospheres of Saturn and Jupiter, liberating carbon atoms. These atoms then stick onto each other, forming larger particles of carbon soot, which the Cassini spacecraft may have spotted in dark storm clouds on Saturn3. As the soot particles slowly float down through ever-denser layers of gaseous and liquid hydrogen towards the planets’ rocky cores, they experience ever greater pressures and temperatures. The soot is compressed into graphite, and then into solid diamonds before reaching a temperature of about 8,000 °C, when the diamond melts, forming liquid diamond raindrops, they say. Inside Saturn, the conditions are right for diamond ‘hail’ to form, beginning at a depth of about 6,000 kilometres into the atmosphere and extending for another 30,000 km below that, says Baines. He estimates that Saturn may harbour about 10 million tonnes of diamond produced this way, with most of it made up of rocks no bigger than a millimetre and perhaps some chunks spanning 10 centimeters.
But don’t invest your money yet in a diamond gathering expedition. This is only a theory, which many scientists dispute.
After the unmanned probe Juno zipped past the Earth on its way to Jupiter today, it unexpectedly went into safe mode.
Engineers continued to diagnose the issue, which occurred after Juno whipped around Earth in a momentum-gathering flyby. Up until Wednesday, Juno had been in excellent health. While in safe mode, it can communicate with ground controllers, but its activities are limited.
It is unclear at the moment why this happened.
The lingering echo of Comet Shoemaker-Levy in the atmosphere of Jupiter.
The Herschel observations, together with heat maps provided by NASA’s Infrared Telescope Facility on Mauna Kea, showed the researchers that the Jovian stratosphere was 20° to 30°F (10° to 15°C) warmer than it would be if completely dry. One question is whether the stratospheric warming results from the gentle, continuous infall of interplanetary dust particles, which would be warmed by sunlight as they linger high up. Cavalié and his colleagues believe IDPs create some of the infrared emission but cannot explain it all. Further, a continuously supplied source would migrate to lower depths, yet most of the emission is too high up, at pressures less than 2 millibars. And while the amount of water is roughly constant across the southern hemisphere, the emission gradually weakens northward until it’s less than half as strong. It’s not simply that Jupiter’s bottom half is hotter — there’s just more water down there. As the researchers note, “At least 95% of the observed water comes from the SL9 comet and subsequent (photo)-chemistry in Jupiter’s stratosphere according to our models, as of today.
Taken together, they conclude, these observations offer “clear evidence that a recent comet … is the principal source of water in Jupiter. What we observe today is a remnant of the oxygen delivery by the comet at 44°S in July 1994.”
The uncertainty of science: The location of the volcanoes on Titan are not where scientists had expected them to be.
As Io moves closer to Jupiter, the planet’s powerful gravity pulls hard on the moon, deforming it. This force decreases as Io retreats, and the moon bounces back. This cycle of flexing creates friction in Io’s interior, which in turn generates enormous amounts of volcano-driving tidal heat. Common sense suggests that Io’s volcanoes would be located above the spots with the most dramatic internal heating. But Hamilton and his colleagues found that the volcanoes are significantly farther to the east than expected.
Many of the news headlines, including the article above, have trumpeted how the volcanoes on Io are in the wrong place. (See also this article.) Not. The theories were wrong, not the volcanoes. Nature does what it wants to do. It is our job to figure out why.
Touching the underground ocean of Europa, from Earth.
On March 8, 1979, as Voyager 1 was speeding away from Jupiter after its historic flyby of the gas giant three days earlier, it looked back at the planet and took some navigational images. Linda Morabito, one of the engineers in charge of using these navigational images to make sure the spacecraft was on its planned course, took one look at the image on the right, an overexposed image of the moon Io, and decided that it had captured something very unusual. On the limb of the moon was this strange shape that at first glance looked like another moon partly hidden behind Io. She and her fellow engineers immediately realized that this was not possible, and that the object was probably a plume coming up from the surface of Io. To their glee, they had taken the first image of an eruption of active volcano on another world!
Today, on the astro-ph preprint website, Morabito has published a minute-by-minute account of that discovery. It makes for fascinating reading, partly because the discovery was so exciting and unique, partly because it illustrated starkly the human nature of science research, and partly because of the amazing circumstances of that discovery. Only one week before, scientists has predicted active volcanism on Io in a paper published in the journal Science. To quote her abstract:
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Jupiter’s Great Red Spot continues to shrink.
After postponing Juno’s second midcourse correction burn last month, engineers have now successfully completed that burn.
NASA’s Juno spacecraft successfully executed a second Deep Space Maneuver, called DSM-2 last Friday, Sept. 14. The 30 minute firing of its main engine refined the Jupiter-bound spacecraft’s trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.
Amateurs astronomers have once again captured images of a major impact of something on Jupiter.
NASA engineers had postponed a planned midcourse maneuver of its Jupiter-bound Juno spacecraft due to unexpectedly high pressures seen in the previous engine burn.
Europe has decided to build a probe to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.
Known as JUICE, the Jupiter Icy Moons Explorer, the probe will enter orbit around the gas giant planet in 2030 for a series of flybys of Ganymede, Callisto and Europa. JUICE will brake into orbit around Ganymede, Jupiter’s largest moon, in 2032 for at least one year of close-up research.
Scientists have published the first complete global geological map of the Jupiter moon Io.
The highly detailed, colorful map reveals a number of volcanic features, including: paterae (caldera-like depressions), lava flow fields, tholi (volcanic domes), and plume deposits, in various shapes, sizes and colors, as well as high mountains and large expanses of sulfur- and sulfur dioxide-rich plains. The mapping identified 425 paterae, or individual volcanic centers. One feature you will not see on the geologic map is impact craters. “Io has no impact craters; it is the only object in the Solar System where we have not seen any impact craters, testifying to Io’s very active volcanic resurfacing,” says Williams.
You can download the map here.
Scientists have found evidence for the existence of great shallow lakes below the surface of Europa.
Juno, on its way to Jupiter, took a look back and snapped this picture of the Earth/Moon double planet.
The image was taken by the spacecraft’s camera, JunoCam, on Aug. 26 when the spacecraft was about 6 million miles (9.66 million kilometers) away.
Gives us a glimpse at what our home planet will really look like to future spacefarers, either on they way out or on their way home.
Things are so good on Juno ten days after launch that mission controllers have canceled a rocket burn to adjust the spacecraft’s course.
After a delay slightly under one hour, the Jupiter probe Juno has lifted off. Check here for updates on its status.
Juno, the U.S.’s next Jupiter probe, headed to the launchpad on Friday for a planned August 5 launch.
The ripples in the rings of Saturn and Jupiter were caused by comet impacts decades ago.
Jupiter’s south equatorial stripe appears to be reappearing.
Steve Squyres of Cornell University and the project scientist of the Mars rovers Spirit and Opportunity spoke today at an astrobiology symposium in Arlington, Virginia. He described several spectacular planetary missions that might be flown in the coming decade. All are being considered. None have yet been chosen or funded.
Squyres is the co-chair of a committee of the National Science Foundation that is right now putting together a decadal survey for outlining unmanned planetary research for the next decade. This survey is expected to be released in March, which is when we will find out which of the above missions the planetary science community prefers.
The detection in June by two different amateur astronomers of an impact on Jupiter bodes well for asteroid/comet research. You can read the actual paper here. [pdf] Key quote from the abstract:
A systematic study of the impact rate and size of these bolides can enable an empirical determination of the flux of meteoroids in Jupiter with implications for the populations of small bodies in the outer Solar System and may allow a better quantification of the threat of impacting bodies to Earth. The serendipitous recording of this optical flash opens a new window in the observation of Jupiter with small telescopes.
More information on the recently discovered fireball that impacted Jupiter on August 20, including images.
