Jupiter’s Great Red Spot Heats Planet’s Upper Atmosphere

Researchers from Boston University’s (BU) Center for Space Physics report today in Nature that Jupiter’s Great Red Spot may provide the mysterious source of energy required to heat the planet’s upper atmosphere to the unusually high values observed.

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Sunlight reaching Earth efficiently heats the terrestrial atmosphere at altitudes well above the sur-face—even at 250 miles high, for example, where the International Space Station orbits. Jupiter is over five times more distant from the Sun, and yet its upper atmosphere has temperatures, on av-erage, comparable to those found at Earth. The sources of the non-solar energy responsible for this extra heating have remained elusive to scientists studying processes in the outer solar system.

“With solar heating from above ruled out, we designed observations to map the heat distribution over the entire planet in search for any temperature anomalies that might yield clues as to where the energy is coming from,” explained Dr. James O’Donoghue, research scientist at BU, and lead author of the study.

Astronomers measure the temperature of a planet by observing the non-visible, infra-red (IR) light it emits. The visible cloud tops we see at Jupiter are about 30 miles above its rim; the IR emissions used by the BU team came from heights about 500 miles higher. When the BU observ-ers looked at their results, they found high altitude temperatures much larger than anticipated whenever their telescope looked at certain latitudes and longitudes in the planet’s southern hemi-sphere.

“We could see almost immediately that our maximum temperatures at high altitudes were above the Great Red Spot far below—a weird coincidence or a major clue?” O’Donoghue added.

Jupiter’s Great Red Spot (GRS) is one of the marvels of our solar system. Discovered within years of Galileo’s introduction of telescopic astronomy in the 17th Century, its swirling pattern of colorful gases is often called a “perpetual hurricane.” The GRS has varied is size and color over the centuries, spans a distance equal to three earth-diameters, and has winds that take six days to complete one spin. Jupiter itself spins very quickly, completing one revolution in only ten hours.

“The Great Red Spot is a terrific source of energy to heat the upper atmosphere at Jupiter, but we had no prior evidence of its actual effects upon observed temperatures at high altitudes,” ex-plained Dr. Luke Moore, a study co-author and research scientist in the Center for Space Physics at BU.

Solving an “energy crisis” on a distant planet has implications within our solar system, as well as for planets orbiting other stars. As the BU scientists point out, the unusually high temperatures far above Jupiter’s visible disk is not a unique aspect of our solar system. The dilemma also oc-curs at Saturn, Uranus and Neptune, and probably for all giant exoplanets outside our solar sys-tem.

“Energy transfer to the upper atmosphere from below has been simulated for planetary atmos-pheres, but not yet backed up by observations,” O’Donoghue said. “The extremely high tempera-tures observed above the storm appear to be the ‘smoking gun’ of this energy transfer, indicating that planet-wide heating is a plausible explanation for the ‘energy crisis.’ “

The Case Of The Missing Craters

When NASA’s Dawn spacecraft arrived to orbit the dwarf planet Ceres in March 2015, mission scientists expected to find a heavily cratered body generally resembling the protoplanet Vesta, Dawn’s previous port of call.

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Instead, as the spacecraft drew near to Ceres, a somewhat different picture began to emerge: Something has happened to Ceres to remove its biggest impact basins.

Now, writing in the online journal Nature Communications, a team of Dawn scientists led by Simone Marchi of the Southwest Research Institute in Boulder, Colorado, reports on their computer simulations of Ceres’ history. These suggest that Ceres has experienced significant geological evolution, possibly erasing the large basins.

The Dawn team includes Arizona State University’s David Williams, who is the director of the Ronald Greeley Center for Planetary Studies in ASU’s School of Earth and Space Exploration. Wiliams oversees a team of researchers using Dawn data to map the geology of Ceres.

He says, “When we first starting looking at Ceres images, we noticed that there weren’t any really large impact basins on the surface.” None are larger than 177 miles (285 kilometers) across. This presents a mystery, he says, because Ceres must have been struck by large asteroids many times over its 4.5-billion-year history.

“Even Vesta, only about half of Ceres’ size, has two big basins at its south pole. But at Ceres, all we saw was the Kerwan Basin, just 177 miles in diameter,” Williams says. “That was a big red flag that something had happened to Ceres.”

The Kerwan Basin’s name was proposed by Williams, and it commemorates the Hopi Indian spirit of the sprouting corn.

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Dawn lead investigator Marchi notes, “We concluded that a significant population of large craters on Ceres has been obliterated beyond recognition over geological time scales, which is likely the result of Ceres’ peculiar composition and internal evolution.”

The team’s simulations of collisions with Ceres predicted that it should have 10 to 15 craters larger than 250 miles (400 kilometers) in diameter, and at least 40 craters larger than 60 miles (100 kilometers) wide. In reality, however, Dawn found that Ceres has only 16 craters larger than 60 miles, and none larger than the 177-mile Kerwan Basin.

Further study of Dawn’s images revealed that Ceres does have three large-scale depressions called “planitiae” that are up to 500 miles (800 kilometers) wide. These have craters within them that formed in more recent times, but the depressions could be left over from bigger impacts.
One of the depressions, called Vendimia Planitia, is a sprawling area just north of the Kerwan Basin. Vendimia Planitia must have formed much earlier than Kerwan.

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So what removed Ceres’ large craters and basins?

“If Ceres were highly rocky, we’d expect impact craters of all sizes to be preserved. Remote sensing from Earth, however, told us even before Dawn arrived that the crust of Ceres holds a significant fraction of ice in some form,” Williams explains.

If Ceres’ crust contained a large proportion of ice—especially if mixed with salts—that would weaken the crust and let the topography of a large basin relax and become smoother, perhaps even disappear.

In addition, says Williams, Ceres must have generated some internal heat from the decay of radioactive elements after it formed. This too could also have helped soften or erase large-scale topographic features.

He adds, “Plus we do see evidence of cryovolcanism—icy volcanism—in the bright spots found scattered over Ceres, especially in Occator Crater.” Cryovolcanism behaves like the rocky kind, only at much lower temperatures, where “molten ice”—water or brine—substitutes for molten rock.

“It’s possible that there are layers or pockets of briny water in the crust of Ceres,” says Williams. “Under the right conditions, these could migrate to the surface and be sources for the bright spots.”

For example, in Occator Crater, he points out, “the central bright spot is a domed feature which looks as if it has erupted or been pushed up from below.”
NASA plans for Dawn to continue orbiting Ceres as the dwarf planet makes its closest approach to the Sun in April 2018. Scientists want to see if the increasing solar warmth triggers any activity or produces detectable changes in Ceres’ surface.

“Ceres is revealing only slowly the answers to her many mysteries,” Williams says. “Completing the geological maps over the next year, and further analysis of the compositional and gravity data, will help us understand better Ceres’ geologic evolution.”

Ancient Temples In The Himalaya Reveal Signs Of Past Earthquakes

Tilted pillars, cracked steps, and sliding stone canopies in a number of 7th-century A.D. temples in northwest India are among the telltale signs that seismologists are using to reconstruct the extent of some of the region’s larger historic earthquakes.

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In their report published online July 27 in Seismological Research Letters, Mayank Joshi and V.C. Thakur of the Wadia Institute of Himalayan Geology show how the signs of destructive earthquakes are imprinted upon the ancient stone and wooden temples.

The temples in the Chamba district of Himachal Pradesh, India lie within the Kashmir “seismic gap” of the Northwest Himalaya range, an area that is thought to have the potential for earthquakes magnitude 7.5 or larger. The new analysis extends rupture zones for the 1905 Kangra earthquake (magnitude 7.8) and the 1555 Kashmir earthquake (possibly a magnitude 7.6 quake) within the Kashmir gap.

The type of damage sustained by temples clustered around two towns in the region—Chamba and Bharmour—suggests that the Chamba temples may have been affected by the 1555 earthquake, while the Bharmour temples were damaged by the 1905 quake, the seismologists conclude.

The epicenter of the 1555 earthquake is thought to be in the Srinagar Valley, about 200 kilometers northwest of Chamba. If the 1555 earthquake did extend all the way to Chamba, Joshi said, “this further implies that the eastern Kashmir Himalaya segment between Srinagar and Chamba has not been struck by a major earthquake for the last 451 years.”

The stress built up in this section of the fault, Joshi added, “may be able to generate an earthquake of similar magnitude to that of the 2005 Kashmir earthquake that devastated the eastern Kashmir.”

That magnitude 7.6 earthquake killed more than 85,000 people, mostly in north Pakistan, and caused massive infrastructure damage.

To better understand the historical earthquake record in the region, Joshi and Thakur examined several temples in the region to look for telltale signs of earthquake damage. It can be difficult at first to distinguish whether a tilted pillar, for example, is due to centuries of aging or to earthquake deformation.
But Joshi noted that archaeoseismologists are trained to look for regular kinds of deformation to a structure—damages “that have some consistency in their pattern and orientation,” said Joshi. “In the cases of aging and ground subsidence, there is no regular pattern of damage.”

At the temples, the researchers measured the tilt direction, the amount of inclination on pillars and the full temple structures, and cracks in building stones, among other types of damage. They then compared this damage to historic accounts of earthquakes and information about area faults to determine which earthquakes were most likely to have caused the damage.

“In the Chamba-area temples, there are some marker features that indicate that the body of the temple structure has suffered some internal deformation,” said Joshi. “The pillars and temple structures are tilted with respect to their original positions. The rooftop portions show tilting or displacement.”
Other earthquake damage uncovered by the researchers included upwarping of stone floors, cracked walls, and a precariously leaning fort wall.

“The deformation features also give some clues about the intensity of an earthquake,” Joshi explained. “For example if a structure experiences a higher intensity XI or X, then the structure could collapse. But if the structure is not collapsed but it tilts only, then it indicates that the structure experienced lower intensity of IX and VIII.”

The Mercalli intensity scale is a measurement of the observed effects of an earthquake, such as its impact on buildings and other infrastructure. Scale measurements of VIII (“severe”) and IX (“violent”) would indicate significant damage, while higher scale measurements indicate partial to complete destruction of buildings, roads, and other infrastructure.

Comet Lovejoy Shows Asymmetric Behavior At Perihelion

Indian astronomers have recently conducted spectrographic observations of long-period Comet Lovejoy to study its gas emission. They found that this comet showcases an asymmetric behavior at perihelion and an increase in the activity during the post-perihelion phase. The findings were detailed in a paper published July 22 on the arXiv pre-print server.

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Comet Lovejoy, formally designated C/2014 Q2, is an Oort cloud comet, discovered by Terry Lovejoy in August 2014. Its perihelion was on January 30, 2015 at a heliocentric distance of 1.29 AU, offering astronomers an excellent opportunity to observe its activity—in particular, the emission of numerous organic molecules in gas.

The scientists, led by Kumar Venkataramani of the Physical Research Laboratory in Ahmedabad, India, utilized the LISA spectrograph to obtain spectra of the comet. LISA is a low-resolution, high luminosity spectrograph, designed for the spectroscopic study of faint and extended objects. The instrument is installed on the 0.5 m telescope at the Mount Abu Infra-Red Observatory (MIRO), Mount Abu, India.

The observation campaign lasted from January to May 2015. It covered the period during which the comet’s heliocentric distance varied from 1.29 AU, just prior to perihelion, to around 2.05 AU post perihelion. The spectra obtained by the researchers show strong molecular emission bands of diatomic carbon, tricarbon, cyanide, amidogen, hydridocarbon and neutral oxygen.

“Various molecular emission lines like C2, C3, CN, NH2, CH, O were clearly seen in the comet spectrum throughout this range. The most prominent of them being the C2 molecule, which was quite dominant throughout the time that we have followed the comet. Apart from the C2 emission band, those of CN and C3 were also quite prominent,” the scientist wrote in the paper.

When a cold icy body like the Comet Lovejoy passes by the sun near perihelion, its ices start sublimating, releasing a mixture of gas and dust, which form the coma. Studying these emissions is crucial for scientists as comets could hold the key to our understanding of the solar system’s evolution and the origin of life in the universe. Therefore, the abundance of volatile material in comets is the target of many scientific studies that seek to reveal the secrets of planet formation and demonstrate the conditions that occurred when our solar system was born.

According to the study, the gas production rate increased after perihelion and exhibited a decreasing trend only after February 2015. The researchers also noted a simultaneous increase in gas and dust, indicating an increase in the overall activity of the comet after its perihelion passage.

“This kind of asymmetry has been seen in many comets. (…) Although we do not have data points at exactly the same distance for pre- and post-perihelion passages, we can, perhaps, say that this comet may have a large positive asymmetry,” the paper reads.

The scientists concluded that this asymmetry suggests that there might be volatile material present beneath the surface of the comet. It is also possible that the surface of the comet’s nucleus consists of layers of ice that have different vaporization rates.

However, as the team noted, more exhaustive study is required to confirm their conclusions.

NASA To Map The Surface Of An Asteroid

NASA’s OSIRIS-REx spacecraft will launch September 2016 and travel to a near-Earth asteroid known as Bennu to harvest a sample of surface material and return it to Earth for study. The science team will be looking for something special. Ideally, the sample will come from a region in which the building blocks of life may be found.

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To identify these regions on Bennu, the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) team equipped the spacecraft with an instrument that will measure the spectral signatures of Bennu’s mineralogical and molecular components.

Known as OVIRS (short for the OSIRIS-REx Visible and Infrared Spectrometer), the instrument will measure visible and near-infrared light reflected and emitted from the asteroid and split the light into its component wavelengths, much like a prism that splits sunlight into a rainbow.

“OVIRS is key to our search for organics on Bennu,” said Dante Lauretta, principal investigator for the OSIRIS-REx mission at the University of Arizona in Tucson. “In particular, we will rely on it to find the areas of Bennu rich in organic molecules to identify possible sample sites of high science value, as well as the asteroid’s general composition.”

OVIRS will work in tandem with another OSIRIS-REx instrument—the Thermal Emission Spectrometer, or OTES. While OVIRS maps the asteroid in the visible and near infrared, OTES picks up in the thermal infrared. This allows the science team to map the entire asteroid over a range of wavelengths that are most interesting to scientists searching for organics and water, and help them to select the best site for retrieving a sample.

In the visible and infrared spectrum, minerals and other materials have unique signatures like fingerprints. These fingerprints allow scientists to identify various organic materials, as well as carbonates, silicates and absorbed water, on the surface of the asteroid. The data returned by OVIRS and OTES will actually allow scientists to make a map of the relative abundance of various materials across Bennu’s surface.

“I can’t think of a spectral payload that has been quite this comprehensive before,” said Dennis Reuter, OVIRS instrument scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

OVIRS will be active during key phases throughout the mission. As the OSIRIS-REx spacecraft approaches Bennu, OVIRS will view one entire hemisphere at a time to measure how the spectrum changes as the asteroid rotates, allowing scientists to compare ground-based observations to those from the spacecraft. Once at the asteroid, OVIRS will gather spectral data and create detailed maps of the surface and help in the selection of a sample site.

Using information gathered by OVIRS and OTES from the visible to the thermal infrared, the science team will also study the Yarkovsky Effect, or how Bennu’s orbit is affected by surface heating and cooling throughout its day. The asteroid is warmed by sunlight and re-emits thermal radiation in different directions as it rotates. This asymmetric thermal emission gives Bennu a small but steady push, thus changing its orbit over time. Understanding this effect will help scientists study Bennu’s orbital path, improve our understanding of the Yarkovsky effect, and improve our predictions of its influence on the orbits of other asteroids.

But despite its capabilities to perform complex science, OVIRS is surprisingly inexpensive and compact in its design. The entire spectrometer operates at 10 watts, requiring less power than a standard household light bulb.

“When you put it into that perspective, you can see just how efficient this instrument is, even though it is taking extremely complicated science measurements,” said Amy Simon, deputy instrument scientist for OVIRS at Goddard. “We’ve put a big job in a compact instrument.”
Unlike most spectrometers, OVIRS has no moving parts, reducing the risk of a malfunction.

“We designed OVIRS to be robust and capable of lasting a long time in space,” Reuter said. “Think of how many times you turn on your computer and something doesn’t work right or it just won’t start up. We can’t have that type of thing happen during the mission.”

Drastic temperature changes in space will put the instrument’s robust design to the test. OVIRS is a cryogenic instrument, meaning that it must be at very low temperatures to produce the best data. Generally, it doesn’t take much for something to stay cool in space. That is, until it comes in contact with direct sunlight.
Heat inside OVIRS would increase the amount of thermal radiation and scattered light, interfering with the infrared data. To avoid this risk, the scientists anodized the spectrometer’s interior coating. Anodizing increases a metal’s resistance to corrosion and wear. Anodized coatings can also help reduce scattered light, lowering the risk of compromising OVIRS’ observations.

The team also had to plan for another major threat: water. The scientists will search for traces of water when they scout the surface for a sample site. Because the team will be searching for tiny water levels on Bennu’s surface, any water inside OVIRS would skew the results. And while the scientists don’t have to worry about a torrential downpour in space, the OSIRIS-REx spacecraft may accumulate moisture while resting on its launch pad in Florida’s humid environment.

Immediately after launch, the team will turn on heaters on the instrument to bake off any water. The heat will not be intense enough to cause any damage to OVIRS, and the team will turn the heaters off once all of the water has evaporated.

“There are always challenges that we don’t know about until we get there, but we try to plan for the ones that we know about ahead of time,” said Simon.
OVIRS will be essential for helping the team choose the best sample site. Its data and maps will give the scientists a picture of what is present on Bennu’s surface.

In addition to OVIRS, Goddard will provide overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Dante Lauretta is the mission’s principal investigator at the University of Arizona. Lockheed Martin Space Systems in Denver built the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency’s Science Mission Directorate in Washington.

Digging Deeper Into Mars

Water is the key to life on Earth. Scientists continue to unravel the mystery of life on Mars by investigating evidence of water in the planet’s soil. Previous observations of soil observed along crater slopes on Mars showed a significant amount of perchlorate salts, which tend to be associated with brines with a moderate pH level.

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However, researchers have stepped back to look at the bigger picture through data collected from the 2001: Mars Odyssey, named in reference to the science fiction novel by Arthur C. Clarke, “2001: A Space Odyssey,” and found a different chemical on Mars may be key. The researchers found that the bulk soil on Mars, across regional scales the size of the U.S. or larger, likely contains iron sulfates bearing chemically bound water, which typically result in acidic brines. This new observation suggests that iron sulfates may play a major role in hydrating martian soil.

This finding was made from data collected by the 2001: Mars Odyssey Gamma Ray Spectrometer, or GRS, which is sensitive enough to detect the composition of Mars soil up to one-half meter deep. This is generally deeper than other missions either on the ground or in orbit, and it informs the nature of bulk soil on Mars. This research was published recently in the Journal of Geophysical Research: Planets.

“This is exciting because it’s contributing to the story of water on Mars, which we’ve used as a path for our search for life on Mars,” said Nicole Button, LSU Department of Geology and Geophysics doctoral candidate and co-author in this study.

The authors expanded on previous work, which explored the chemical association of water with sulfur on Mars globally. They also characterized how, based on the association between hydrogen and sulfur, the soil hydration changes at finer regional scales. The study revealed that the older ancient southern hemisphere is more likely to contain chemically bound water while the sulfates and any chemically bound water are unlikely to be associated in the northerly regions of Mars.

The signature of strong association is strengthened in the southern hemisphere relative to previous work, even though sulfates become less hydrated heading southwards. In addition, the water concentration may affect the degree of sulfate hydration more than the sulfur concentration. Limited water availability in soil-atmosphere exchange and in any fluid movement from deeper soil layers could explain how salt hydration is water-limited on Mars. Differences in soil thickness, depth to any ground ice table, atmospheric circulation and sunshine may contribute to hemispheric differences in the progression of hydration along latitudes.

The researchers considered several existing hypotheses in the context of their overall observations, which suggest a meaningful presence of iron-sulfate rich soils, which are wet compared to Mars’ typically desiccated soil. This type of wet soil was uncovered serendipitously by the Spirit Rover while dragging a broken wheel across the soil in the Paso Robles area of Columbia Hills at Gusev Crater. Key hypotheses of the origin of this soil include hydrothermal activity generating sulfate-rich, hydrated deposits on early Mars similar to what is found along the flanks of active Hawaiian volcanoes on Earth.
Alternatively, efflorescence, which creates the odd salt deposits on basement walls on Earth, may have contributed trace amounts of iron-sulfates over geologic time. A third key hypothesis involves acidic aerosols released at volcanic sites, such as acid fog, dispersed throughout the atmosphere, and interacting subsequently with the finer components of soil as a source of widespread hydrated iron-sulfate salts.

Among these hypotheses, the researchers identify acid fog and hydrothermal processes as more consistent with their observations than efflorescence, even though the sensitivity of GRS to elements, but not minerals, prevents a decisive inference. Hydrothermal sites, in particular, are increasingly recognized as important places where the exchange between the surface and deep parts of Earth’s biosphere are possible. This hypothesis is significant to the question of martian habitability.

“Our story narrows it to two hypotheses, but emphasizes the significance of all of them,” said LSU Department of Geology and Geophysics Assistant Professor Suniti Karunatillake, who is a fellow lead author. “The depth and breadth of these observation methods tell us about global significance, which can inform the big question of what happened to the hydrologic cycle on Mars.”

Astronomers Discover Dizzying Spin Of The Milky Way Galaxy’s ‘Halo’

Astronomers at the University of Michigan’s College of Literature, Science, and the Arts (LSA) discovered for the first time that the hot gas in the halo of the Milky Way galaxy is spinning in the same direction and at comparable speed as the galaxy’s disk, which contains our stars, planets, gas, and dust.

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This new knowledge sheds light on how individual atoms have assembled into stars, planets, and galaxies like our own, and what the future holds for these galaxies.

“This flies in the face of expectations,” says Edmund Hodges-Kluck, assistant research scientist. “People just assumed that the disk of the Milky Way spins while this enormous reservoir of hot gas is stationary – but that is wrong. This hot gas reservoir is rotating as well, just not quite as fast as the disk.”

The new NASA-funded research using the archival data obtained by XMM-Newton, a European Space Agency telescope, was recently published in the Astrophysical Journal. The study focuses on our galaxy’s hot gaseous halo, which is several times larger than the Milky Way disk and composed of ionized plasma.

Because motion produces a shift in the wavelength of light, the U-M researchers measured such shifts around the sky using lines of very hot oxygen. What they found was groundbreaking: The line shifts measured by the researchers show that the galaxy’s halo spins in the same direction as the disk of the Milky Way and at a similar speed—about 400,000 mph for the halo versus 540,000 mph for the disk.

“The rotation of the hot halo is an incredible clue to how the Milky Way formed,” said Hodges Kluck. “It tells us that this hot atmosphere is the original source of a lot of the matter in the disk.”

Scientists have long puzzled over why almost all galaxies, including the Milky Way, seem to lack most of the matter that they otherwise would expect to find. Astronomers believe that about 80% of the matter in the universe is the mysterious “dark matter” that, so far, can only be detected by its gravitational pull. But even most of the remaining 20% of “normal” matter is missing from galaxy disks. More recently, some of the “missing” matter has been discovered in the halo. The U-M researchers say that learning about the direction and speed of the spinning halo can help us learn both how the material got there in the first place, and the rate at which we expect the matter to settle into the galaxy.

“Now that we know about the rotation, theorists will begin to use this to learn how our Milky Way galaxy formed – and its eventual destiny,” says Joel Bregman, a U-M LSA professor of astronomy.

“We can use this discovery to learn so much more – the rotation of this hot halo will be a big topic of future X-ray spectrographs,” Bregman says.