Tag: Jupiter

A possible impact on Jupiter?

5:26 pm

On March 17 two different amateur astronomers have taken videos of a bright flash on Jupiter which suggests something had crashed into the gas giant.

March 17th’s impact, if the evidence for it holds up, becomes the fourth such event in the past decade. The largest of these occurred July 19, 2009, and it left a distinctly dark “powder burn” in Jupiter’s upper atmosphere first spotted by Australian astro-imager Anthony Wesley. That was followed by three lesser strikes on June 3, 2010 (recorded independently by Wesley and Christopher Go); on August 10, 2010 (independently seen by Masayuki Tachikawa and Kazuo Aoki); and on September 10, 2012 (seen visually by Dan Petersen and independently recorded by George Hall).

Counting the historic multiple-hit crash of Comet Shoemaker-Levy 9 in July 1994, that’s a grand total of six impacts on Jupiter in the past 22 years.

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Cosmic rays cause the red in Jupiter’s Great Red Spot

10:07 am

New ground-based chemistry research suggests that the bombardment of cosmic rays in Jupiter’s upper atmosphere could be the cause of the red color of the gas giant’s Great Red Spot.

They found that one of the spot’s major components, ammonium hydrosulfide, breaks down when exposed to that radiation in such a way that it turns red. They also think that ultraviolet radiation, also prevalent in space, will do the same.

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Juno becomes most distant solar-powered mission

9:34 am

Scheduled to enter orbit around Jupiter in July 2016, the American space probe Juno has now broken the record as the most distant solar-powered interplanetary spacecraft ever to operate.

The previous record had been held by Rosetta. In the past most missions beyond Mars used nuclear-generated power plants, since the amount of sunlight is insufficient. However, improvements to the efficiency of solar power, combined with a lack of nuclear fuel in the U.S., has made it possible to fly missions using solar power farther from the sun.

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New weather maps of Jupiter

1:27 pm

Using the Hubble Space Telescope astronomers have compiled a new set of maps of Jupiter, showing changes in the gas giant’s bands and spots, including the Giant Red Spot.

The scientists behind the new images took pictures of Jupiter using Hubble’s Wide Field Camera 3 over a ten-hour period and have produced two maps of the entire planet from the observations. These maps make it possible to determine the speeds of Jupiter’s winds, to identify different phenomena in its atmosphere and to track changes in its most famous features.

The new images confirm that the huge storm, which has raged on Jupiter’s surface for at least three hundred years, continues to shrink, but that it may not go out without a fight. The storm, known as the Great Red Spot, is seen here swirling at the centre of the image of the planet. It has been decreasing in size at a noticeably faster rate from year to year for some time. But now, the rate of shrinkage seems to be slowing again, even though the spot is still about 240 kilometres smaller than it was in 2014.

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Juno flight plan at Jupiter revised

10:16 am

In preparation for its arrival in orbit around Jupiter in about a year, engineers for the unmanned probe Juno have revised their planned orbital maneuvers.

Following a detailed analysis by the Juno team, NASA recently approved changes to the mission’s flight plan at Jupiter. Instead of taking 11 days to orbit the planet, Juno will now complete one revolution every 14 days. The difference in orbit period will be accomplished by having Juno execute a slightly shorter engine burn than originally planned.

The revised cadence will allow Juno to build maps of the planet’s magnetic and gravity fields in a way that will provide a global look at the planet earlier in the mission than the original plan. Over successive orbits, Juno will build a virtual web around Jupiter, making its gravity and magnetic field maps as it passes over different longitudes from north to south. The original plan would have required 15 orbits to map these forces globally, with 15 more orbits filling in gaps to make the map complete. In the revised plan, Juno will get very basic mapping coverage in just eight orbits. A new level of detail will be added with each successive doubling of the number, at 16 and 32 orbits.

The change will extend the official mission from 15 to 20 months, though I expect that even this will be extended if the spacecraft’s fuel holds out.

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Is the dark material along Europa’s long surface fissures sea salt?

11:02 am

The uncertainty of science: By creating what they call “Europa in a can” here on Earth, scientists have determined that the dark material that appears to have seeped out of Europa’s long linear fractures might be sea salt from the underground ocean, turned brown by the harsh radiation hitting the moon’s surface.

This result is quite intriguing, but the only thing certain about it is its uncertainty. The only way we will know what this brown material really is will be to go there again with much better equipment and study the material itself

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Ganymede’s underground salt water ocean

9:33 am

By measuring the interaction of Jupiter and Ganymede’s magnetic fields, scientists have been able to estimate the size of the salt water ocean in Ganymede’s interior.

A team of scientists led by Joachim Saur of the University of Cologne in Germany came up with the idea of using Hubble to learn more about the inside of the moon. “I was always brainstorming how we could use a telescope in other ways,” said Saur. “Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”

If a saltwater ocean were present, Jupiter’s magnetic field would create a secondary magnetic field in the ocean that would counter Jupiter’s field. This “magnetic friction” would suppress the rocking of the aurorae. This ocean fights Jupiter’s magnetic field so strongly that it reduces the rocking of the aurorae to 2 degrees, instead of 6 degrees if the ocean were not present. Scientists estimate the ocean is 60 miles (100 kilometers) thick — 10 times deeper than Earth’s oceans — and is buried under a 95-mile (150-kilometer) crust of mostly ice.

That’s more water than contained in all of Earth’s oceans.

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Jupiter’s shrinking Great Red Spot.

9:34 am

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.

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Two days after its flyby of Earth, Jupiter probe Juno remains in safe mode.

10:38 am

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.

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Engineers hope Juno’s Earth flyby yesterday will help solve a mystery seen in previous flybys by unmanned probes.

5:32 am

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.

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Is a natural rain of diamonds occurring on Jupiter and Saturn? Two scientists say yes!

5:07 am

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.

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After the unmanned probe Juno zipped past the Earth on its way to Jupiter today, it unexpectedly went into safe mode.

9:28 pm

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.

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The lingering echo of Comet Shoemaker-Levy in the atmosphere of Jupiter.

7:32 pm

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.”

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The location of the volcanoes on Titan are not where scientists had expected them to be.

9:30 am

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.

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The discovery of volcanoes on Io

12:39 pm

discovery image

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:
» Read more

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After postponing Juno’s second midcourse correction burn, engineers have now successfully completed that burn.

6:03 pm

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.

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