Star Escapes Black Hole with Minor Damage

Star Escapes Black Hole with Minor Damage

Scientia — Astronomers have gotten the closest look yet at what happens when a black hole takes a bite out of a star—and the star lives to tell the tale.

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We may think of black holes as swallowing entire stars—or any other object that wanders too close to their immense gravity. But sometimes, a star that is almost captured by a black hole escapes with only a portion of its mass torn off. Such was the case for a star some 650 million light years away toward Ursa Major, the constellation that contains the “Big Dipper,” where a supermassive black hole tore off a chunk of material from a star that got away.

Astronomers at The Ohio State University couldn’t see the star itself with their All-Sky Automated Survey for Supernovae (ASAS-SN, pronounced “assassin”). But they did see the light that flared as the black hole “ate” the material that it managed to capture.

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In a paper to appear in the Monthly Notices of the Royal Astronomical Society, they report that the star and the black hole are located in a galaxy outside of the newly dubbed Laniakea Supercluster, of which our home Milky Way Galaxy is a part.

If Laniakea is our galactic “city,” this event—called a “tidal disruption event,” or TDE— happened in our larger metropolitan area. Still, it’s the closest TDE ever spotted, and it gives astronomers the best chance yet of learning more about how supermassive black holes form and grow.

ASAS-SN has so far spotted more than 60 bright and nearby supernovae; one of the program’s other goals is to try to determine how often TDEs happen in the nearby universe. But study co-author Krzysztof Stanek, professor of astronomy at Ohio State, and his collaborators were surprised to find one in January 2014, just a few months after ASAS-SN’s four telescopes in Hawaii began gathering data.

To Stanek, the fact that the survey made such a rare find so quickly suggests that TDEs may be more common than astronomers realized.

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Star Escapes Black Hole with Minor Damage

Juno Spacecraft Crosses Jupiter/Sun Gravity Boundary

NASA’s Juno Spacecraft Crosses Jupiter/Sun Gravitational Boundary

Scientia — Since its launch five years ago, there have been three forces tugging at NASA’s Juno spacecraft as it speeds through the solar system. The sun, Earth and Jupiter have all been influential — a gravitational trifecta of sorts. At times, Earth was close enough to be the frontrunner. More recently, the sun has had the most clout when it comes to Juno’s trajectory. Today, it can be reported that Jupiter is now in the gravitational driver’s seat, and the basketball court-sized spacecraft is not looking back.

This artist’s rendering shows NASA’s Juno spacecraft making one of its close passes over Jupiter.
Credits: NASA/JPL-Caltech

“Today the gravitational influence of Jupiter is neck and neck with that of the sun,” said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “As of tomorrow, and for the rest of the mission, we project Jupiter’s gravity will dominate as the trajectory-perturbing effects by other celestial bodies are reduced to insignificant roles.”

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Juno was launched on Aug. 5, 2011. On July 4 of this year, it will perform a Jupiter orbit insertion maneuver — a 35-minute burn of its main engine, which will impart a mean change in velocity of 1,212 mph (542 meters per second) on the spacecraft. Once in orbit, the spacecraft will circle the Jovian world 37 times, skimming to within 3,100 miles (5,000 kilometers) above the planet’s cloud tops. During the flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.

Juno’s name comes from Greek and Roman mythology. The mythical god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife — the goddess Juno — was able to peer through the clouds and reveal Jupiter’s true nature.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. The California Institute of Technology in Pasadena manages JPL for NASA.

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– Credit and Resource –

NASA

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Juno Spacecraft Crosses Jupiter/Sun Gravity Boundary

Life on Ceres

Life on Ceres? Mysterious changes in the bright spots still baffle scientists

Scientia –Bright spots on the dwarf planet Ceres continue to puzzle researchers. When recently a team of astronomers led by Paolo Molaro of the Trieste Astronomical Observatory in Italy, conducted observations of these features, they found out something unexpected. The scientists were surprised to detect that the spots brighten during the day and also show other variations. This variability still remains a mystery.

The bright features have been discovered by NASA’s Dawn spacecraft which is orbiting this dwarf planet, constantly delivering substantial information about it. These spots reflect far more light than their much darker surroundings. The composition of these features is discussed as the scientists debate if they are made of water ice, of evaporated salts, or something else.

Molaro and his colleagues studied the spots on Ceres in July and August 2015, using the High Accuracy Radial velocity Planet Searcher (HARPS), as was reported by the European Southern Observatory (ESO) earlier this year. This instrument, mounted on ESO’s 3.6m telescope at La Silla Observatory in Chile, enables measurements of radial velocities with the highest accuracy currently available.

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By utilizing HARPS, the researchers found out unexpected changes in the mysterious bright spots. However, at the beginning they thought that it was an instrumental problem. But after double checking, they had to conclude that the radial velocity anomalies were likely real. Then the team noticed that they were connected to periods of time when the bright spots in the Occator crater were visible from the Earth. So the scientists made an association between them.

However, these detected variations still continue to perplex the astronomers as they haven’t found a plausible explanation for their occurrence.

“We know nothing about these changes, really. And this increases the mystery of these spots,” Molaro told Astrowatch.net.

One of the proposed hypotheses is that the observed changes could be triggered by the presence of volatile substances that evaporate due to solar radiation. When the spots are on the side illuminated by the sun they form plumes that reflect sunlight very effectively. The scientists suggest that these plumes then evaporate quickly, lose reflectivity and produce the observed changes.

“It is already well known that a lot of water hides beneath the surface of Ceres, so water ice or clathrates hydrates are the most natural hypotheses. But a proper answer will be hopefully provided by scientists working in the Dawn team in the coming months,” Molaro said.

He noted that the indication of variability needs to be confirmed by direct imaging of Occator’s bright spot at the highest available spatial resolution.

“This kind of measurements are underway. I would say that the detection of a variability improves our ignorance rather than our understanding of this planetary body,” Molaro revealed.

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The team is currently applying for further observations by the end of this year to repeat in a more systematical way what they have done in their pilot project. An important aspect of their work is to have shown a new way to study Ceres from ground, which could turn out to be useful even after the end of the Dawn mission. However by now, they are eager to see the results from the Dawn spacecraft in the next months.

If the team’s theory is confirmed, Ceres would seem to be internally active. While this dwarf planet is known to be rich in water, it is unclear whether this is related to the bright spots. It is also still debated if Ceres due to its vast reservoir of water, could be a suitable place to host microbial life.

“Life as we know it on Earth needs liquid water, biogenic elements and a stable source of energy. Is Ceres a good place to have these things simultaneously and for a substantial amount of time, like billions of years? Nobody knows at the moment,” Molaro concluded.

A little about Ceres

• -Discovered: January 1,1801 by Giuseppe Piazzi of Italy (first asteroid/dwarf planet discovered)


• -Size: 975 by 909 kilometers (606 by 565 miles)


• -Shape: Spheroid


• -Rotation: Once every 9 hours, 4.5 minutes

The object is known by astronomers as “1 Ceres” because it was the very first minor planet discovered. As big across as Texas, Ceres’ nearly spherical body has a differentiated interior – meaning that, like Earth, it has denser material at the core and lighter minerals near the surface. Astronomers believe that water ice may be buried under Ceres’ crust because its density is less than that of the Earth’s crust, and because the dust-covered surface bears spectral evidence of water-bearing minerals. Ceres could even boast frost-covered polar caps.

Astronomers estimate that if Ceres were composed of 25 percent water, it may have more water than all the fresh water on Earth. Ceres’ water, unlike Earth’s, is expected to be in the form of water ice located in its mantle.

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– Credit and Resource –

NASA

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Life on Ceres

New Aspects of Pluto and its Moons

Science Papers Reveal New Aspects of Pluto and its Moons

This image of haze layers above Pluto’s limb was taken by the Ralph/Multispectral Visible Imaging Camera (MVIC) on NASA’s New Horizons spacecraft. About 20 haze layers are seen; the layers have been found to typically extend horizontally over hundreds of kilometers, but are not strictly parallel to the surface. For example, scientists note a haze layer about 3 miles (5 kilometers) above the surface (lower left area of the image), which descends to the surface at the right.
Credits: NASA/JHUAPL/SwRI/Gladstone et al./Science (2016)

Scientia — A year ago, Pluto was just a bright speck in the cameras of NASA’s approaching New Horizons spacecraft, not much different than its appearances in telescopes since Clyde Tombaugh discovered the then-ninth planet in 1930.

But this week, in the journal Science, New Horizons scientists have authored the first comprehensive set of papers describing results from last summer’s Pluto system flyby. “These five detailed papers completely transform our view of Pluto – revealing the former ‘astronomer’s planet’ to be a real world with diverse and active geology, exotic surface chemistry, a complex atmosphere, puzzling interaction with the sun and an intriguing system of small moons,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute (SwRI), Boulder, Colorado.

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Above are New Horizons’ views of the informally named Sputnik Planum on Pluto (top) and the informally named Vulcan Planum on Charon (bottom). The Sputnik Planum strip measures 228 miles (367 kilometers) long, and the Vulcan Planum strip measures 194 miles (312 kilometers) long. Illumination is from the left. The bright, nitrogen-ice plains are defined by a network of crisscrossing troughs. This observation was obtained by the Ralph/Multispectral Visible Imaging Camera (MVIC) at a resolution of 1,050 feet (320 meters) per pixel. The Vulcan Planum view in the bottom panel includes the “moated mountain” Clarke Mons just above the center of the image. The water ice-rich plains display a range of surface textures, from smooth and grooved at left, to pitted and hummocky at right. This observation was obtained by the Long Range Reconnaissance Imager (LORRI) at a resolution of 525 feet (160 meters) per pixel.
Credits: NASA/JHUAPL/SwRI

After a 9.5-year, 3-billion-mile journey – launching faster and traveling farther than any spacecraft to reach its primary target – New Horizons zipped by Pluto on July 14, 2015. New Horizons’ seven science instruments collected about 50 gigabits of data on the spacecraft’s digital recorders, most of it coming over nine busy days surrounding the encounter.

The first close-up pictures revealed a large heart-shaped feature carved into Pluto’s surface, telling scientists that this “new” type of planetary world – the largest, brightest and first-explored in the mysterious, distant “third zone” of our solar system known as the Kuiper Belt – would be even more interesting and puzzling than models predicted.

The newly published Science papers bear that out; click here for a list of top results.

“Observing Pluto and Charon up close has caused us to completely reassess thinking on what sort of geological activity can be sustained on isolated planetary bodies in this distant region of the solar system, worlds that formerly had been thought to be relics little changed since the Kuiper Belt’s formation,” said Jeff Moore, lead author of the geology paper from NASA’s Ames Research Center, Moffett Field, California.

Scientists studying Pluto’s composition say the diversity of its landscape stems from eons of interaction between highly volatile and mobile methane, nitrogen and carbon monoxide ices with inert and sturdy water ice. “We see variations in the distribution of Pluto’s volatile ices that point to fascinating cycles of evaporation and condensation,” said Will Grundy of the Lowell Observatory, Flagstaff, Arizona, lead author of the composition paper. “These cycles are a lot richer than those on Earth, where there’s really only one material that condenses and evaporates – water. On Pluto, there are at least three materials, and while they interact in ways we don’t yet fully understand, we definitely see their effects all across Pluto’s surface.”

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This enhanced color view of Pluto’s surface diversity was created by merging Ralph/Multispectral Visible Imaging Camera (MVIC) color imagery (650 meters or 2,132 feet per pixel) with Long Range Reconnaissance Imager panchromatic imagery (230 meters or 755 feet per pixel). At lower right, ancient, heavily cratered terrain is coated with dark, reddish tholins. At upper right, volatile ices filling the informally named Sputnik Planum have modified the surface, creating a chaos-like array of blocky mountains. Volatile ice also occupies a few nearby deep craters, and in some areas the volatile ice is pocked with arrays of small sublimation pits. At left, and across the bottom of the scene, gray-white methane ice deposits modify tectonic ridges, the rims of craters, and north-facing slopes. The scene in this image is 260 miles (420 kilometers) wide and 140 miles (225 kilometers) from top to bottom; north is to the upper left.
Credits: NASA/JHUAPL/SwRI

Above the surface, scientists discovered Pluto’s atmosphere contains layered hazes, and is both cooler and more compact than expected. This affects how Pluto’s upper atmosphere is lost to space, and how it interacts with the stream of charged particles from the sun known as the solar wind. “We’ve discovered that pre-New Horizons estimates wildly overestimated the loss of material from Pluto’s atmosphere,” said Fran Bagenal, from the University of Colorado, Boulder, and lead author of the particles and plasma paper. “The thought was that Pluto’s atmosphere was escaping like a comet, but it is actually escaping at a rate much more like Earth’s atmosphere.”

SwRI’s Randy Gladstone of San Antonio is the lead author of the Science paper on atmospheric findings. He added, “We’ve also discovered that methane, rather than nitrogen, is Pluto’s primary escaping gas. This is pretty surprising, since near Pluto’s surface the atmosphere is more than 99 percent nitrogen.”

Scientists also are analyzing the first close-up images of Pluto’s small moons—Styx, Nix, Kerberos and Hydra. Discovered between 2005 and 2012, the four moons range in diameter from about 25 miles (40 kilometers) for Nix and Hydra to about six miles (10 kilometers) for Styx and Kerberos. Mission scientists further observed that the small satellites have highly anomalous rotation rates and uniformly unusual pole orientations, as well as icy surfaces with brightness and colors distinctly different from those of Pluto and Charon.

They’ve found evidence that some of the moons resulted from mergers of even smaller bodies, and that their surface ages date back at least 4 billion years. “These latter two results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary system,” said Hal Weaver, New Horizons project scientist from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and lead author of the Science paper on Pluto’s small moons.

About half of New Horizons’ flyby data has now been transmitted home – from distances where radio signals at light speed need nearly five hours to reach Earth – with all of it expected back by the end of 2016.

“This is why we explore,” said Curt Niebur, New Horizons program scientist at NASA Headquarters in Washington. “The many discoveries from New Horizons represent the best of humankind and inspire us to continue the journey of exploration to the solar system and beyond.”

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– Credit and Resource –

NASA

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New Aspects of Pluto and its Moons

Top New Horizons Findings Reported in Science

This high-resolution image captured by NASA’s New Horizons spacecraft combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). The bright expanse is the western lobe of the “heart,” informally called Sputnik Planum, which has been found to be rich in nitrogen, carbon monoxide and methane ices.
Credits: NASA/JHUAPL/SwRI

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1. The age-dating of Pluto’s surface through crater counts has revealed that Pluto has been geologically active throughout the past 4 billion years. Further, the surface of Pluto’s informally-named Sputnik Planum, a massive ice plain larger than Texas, is devoid of any detectable craters and estimated to be geologically young – no more than 10 million years old.


2. Pluto’s moon Charon has been discovered to have an ancient surface. As an example, the great equatorial expanse of smooth plains on Charon informally named Vulcan Planum (home of the “moated mountains” informally named Kubrick and Clarke Mons) is likely a vast cryovolcanic flow or flows that erupted onto Charon’s surface about 4 billion years ago. These flows are likely related to the freezing of an internal ocean that globally ruptured Charon’s crust.


3. The distribution of compositional units on Pluto’s surface – from nitrogen-rich, to methane-rich, to water-rich – has been found to be surprisingly complex, creating puzzles for understanding Pluto’s climate and geologic history. The variations in surface composition on Pluto are unprecedented elsewhere in the outer solar system.


4. Pluto’s upper atmospheric temperature has been found to be much colder (by about 70 degrees Fahrenheit) than had been thought from Earth-based studies, with important implications for its atmospheric escape rate. Why the atmosphere is colder is a mystery.


5. Composition profiles for numerous important species in Pluto’s atmosphere (including molecular nitrogen, methane, acetylene, ethylene and ethane) have been measured as a function of altitude for the first time.


6. Also for the first time, a plausible mechanism for forming Pluto’s atmospheric haze layers has been found. This mechanism involves the concentration of haze particles by atmospheric buoyancy waves (called “gravity waves” by atmospheric scientists), created by winds blowing over Pluto’s mountainous topography.


7. Before the flyby, the presence of Pluto’s four small moons raised concerns about debris hazards in the system. But the Venetia Burney Student Dust Counter only counted a single dust particle within five days of the flyby. This is similar to the density of dust particles in free space in the outer solar system — about 6 particles per cubic mile — showing that the region around Pluto is, in fact, not filled with debris.


8. New Horizons’ charged-particle instruments revealed that the interaction region between the solar wind and Pluto’s atmosphere is confined on the dayside of Pluto to within 6 Pluto radii, about 4,500 miles (7,000 kilometers). This is much smaller than expected before the flyby, and is likely due to the reduced atmospheric escape rate found from modeling of ultraviolet atmospheric occultation data.


9. The high albedos (reflectiveness) of Pluto’s small satellites – about 50 to 80 percent – are entirely different from the much lower albedos of the small bodies in the general Kuiper Belt population, which range from about 5 to 20 percent. This difference lends further support to the idea that these satellites were not captured from the general Kuiper Belt population, but instead formed by agglomeration in a disk of material produced in the aftermath of the giant collision that created the entire Pluto satellite system.

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– Credit and Resource –

NASA

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Top New Horizons Findings Reported in Science

Cassini"s Enceladus Final Flyby

Scientia — In late 2015, NASA’s Cassini spacecraft is making its final three flybys of Enceladus, the little moon that stunned scientists with the revelation it harbors a global ocean under its icy shell, active geysers of water-ice feeding one of Saturn’s rings and the first tantalizing signs of hydrothermal activity beyond Earth. All these discoveries have vaulted Enceladus to one of the top future destinations for exploration and the search for signs of potential life beyond Earth.

• 14 October 2015: Cassini aligned it self to get some of the best shots of Saturn’s Moon Enceladus. Cassini was looking at the moon’s north polar region at an altitude of just 1,142 miles (1,839 kilometers).
  
  

  This high-resolution Cassini image shows a landscape of stark contrasts on Saturn’s moon Enceladus. Thin cracks cross over the pole — the northernmost extent of a global system of such fractures. Credit: NASA/JPL/Space Science Institute – Provided by NASA

  
  
  Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. “The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters,” said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. “These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well.”
  
  
  
  



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  28 October 2015: Cassini will make a daring flight through the moon’s famous plume only 30 miles (48 kilometers) above Enceladus’ south pole. The flyby is Cassini’s deepest-ever dive through the jets. The encounter will allow Cassini to obtain the most accurate measurements yet of the plume’s composition, and new insights into the ocean world beneath the ice.
  

  NASA’s Cassini spacecraft will sample the ocean of Saturn’s moon Enceladus on Wednesday, Oct. 28, when it flies through the moon’s plume of icy spray.

  
  

  Cassini launched in 1997 and entered orbit around Saturn in 2004. Since then, it has been studying the huge planet, its rings and its magnetic field. Here are some things to know about the mission’s upcoming close flyby of Enceladus:

  
  
  1. Enceladus is an icy moon of Saturn. Early in its mission, Cassini discovered Enceladus has remarkable geologic activity, including a towering plume of ice, water vapor and organic molecules spraying from its south polar region. Cassini later determined the moon has a global ocean and likely hydrothermal activity, meaning it could have the ingredients needed to support simple life.
  
  
  2. The flyby will be Cassini’s deepest-ever dive through the Enceladus plume, which is thought to come from the ocean below. The spacecraft has flown closer to the surface of Enceladus before, but never this low directly through the active plume.
  
  
  3. The flyby is not intended to detect life, but it will provide powerful new insights about how habitable the ocean environment is within Enceladus.
  
  
  4. Cassini scientists are hopeful the flyby will provide insights about how much hydrothermal activity — that is, chemistry involving rock and hot water — is occurring within Enceladus. This activity could have important implications for the potential habitability of the ocean for simple forms of life. The critical measurement for these questions is the detection of molecular hydrogen by the spacecraft.
  
  
  5. Scientists also expect to better understand the chemistry of the plume as a result of the flyby. The low altitude of the encounter is, in part, intended to afford Cassini greater sensitivity to heavier, more massive molecules, including organics, than the spacecraft has observed during previous, higher-altitude passes through the plume.
  
  
  6. The flyby will help solve the mystery of whether the plume is composed of column-like, individual jets, or sinuous, icy curtain eruptions — or a combination of both. The answer would make clearer how material is getting to the surface from the ocean below.
  
  
  7. Researchers are not sure how much icy material the plumes are actually spraying into space. The amount of activity has major implications for how long Enceladus might have been active.
  
  
  
  


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  19 December 2015: Cassini’s final targeted flyby will allow the spacecraft to measure heat flow from the moon’s interior at an altitude of 3,106 miles, or 4,999 kilometers.

  
  
  
  

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NASA

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Cassini"s Enceladus Final Flyby

Cassini Reveals Global Ocean in Saturn’s Moon Enceladus

Scientia — NASA’s Cassini Mission reveals a global ocean beneath the icy crust of Saturn’s moon Enceladus.

Researchers found the magnitude of the moon’s very slight wobble, as it orbits Saturn, can only be accounted for if its outer ice shell is not frozen solid to its interior, meaning a global ocean must be present.

The finding implies the fine spray of water vapor, icy particles and simple organic molecules Cassini has observed coming from fractures near the moon’s south pole is being fed by this vast liquid water reservoir. The research will be presented in a paper published online this week in the journal Icarus.

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Previous analysis of Cassini data suggested the presence of a lens-shaped body of water, or sea, underlying the moon’s south polar region. However, gravity data collected during the spacecraft’s several close passes over the south polar region lent support to the possibility the sea might be global. The new results — derived using an independent line of evidence based on Cassini’s images — confirm this to be the case.

“This was a hard problem that required years of observations, and calculations involving a diverse collection of disciplines, but we are confident we finally got it right,” said Peter Thomas, a Cassini imaging team member at Cornell University, Ithaca, New York, and lead author of the paper.

Cassini scientists analyzed more than seven years’ worth of images of Enceladus taken by the spacecraft, which has been orbiting Saturn since mid-2004. They carefully mapped the positions of features on Enceladus — mostly craters — across hundreds of images, in order to measure changes in the moon’s rotation with extreme precision.

Illustration of the interior of Saturn’s moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. Thickness of layers shown here is not to scale. Credits: NASA/JPL-Caltech

As a result, they found Enceladus has a tiny, but measurable wobble as it orbits Saturn. Because the icy moon is not perfectly spherical — and because it goes slightly faster and slower during different portions of its orbit around Saturn — the giant planet subtly rocks Enceladus back and forth as it rotates.

The team plugged their measurement of the wobble, called a libration, into different models for how Enceladus might be arranged on the inside, including ones in which the moon was frozen from surface to core.

“If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be,” said Matthew Tiscareno, a Cassini participating scientist at the SETI Institute, Mountain View, California, and a co-author of the paper. “This proves that there must be a global layer of liquid separating the surface from the core,” he said.

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The mechanisms that might have prevented Enceladus’ ocean from freezing remain a mystery. Thomas and his colleagues suggest a few ideas for future study that might help resolve the question, including the surprising possibility that tidal forces due to Saturn’s gravity could be generating much more heat within Enceladus than previously thought.

“This is a major step beyond what we understood about this moon before, and it demonstrates the kind of deep-dive discoveries we can make with long-lived orbiter missions to other planets,” said co-author Carolyn Porco, Cassini imaging team lead at Space Science Institute (SSI), Boulder, Colorado, and visiting scholar at the University of California, Berkeley. “Cassini has been exemplary in this regard.”

The unfolding story of Enceladus has been one of the great triumphs of Cassini’s long mission at Saturn. Scientists first detected signs of the moon’s icy plume in early 2005, and followed up with a series of discoveries about the material gushing from warm fractures near its south pole. They announced strong evidence for a regional sea in 2014, and more recently, in 2015, they shared results that suggest hydrothermal activity is taking place on the ocean floor.

Cassini is scheduled to make a close flyby of Enceladus on October 28, in the mission’s deepest-ever dive through the moon’s active plume of icy material. The spacecraft will pass a mere 30 miles (49 kilometers) above the moon’s surface.

Some Amazingly Awesome Pictures of Enceladus

envira-gallery slug=”enceladus”

 

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Cassini Reveals Global Ocean in Saturn’s Moon Enceladus

Pluto, Majestic Mountains, Frozen Plains and Foggy Hazes

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named icy plain Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. To the right, east of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights over a dozen layers of haze in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 780 miles (1,250 kilometers) wide. (Image credit: NASA/JHUAPL/SwRI)

 

Image of Pluto’s Vast, Icy Plain Informally Called Sputnik Planum

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Last Updated: Sep. 16, 2015
Editor: Tricia Talbert

In the center of this 300-mile (470-kilometer) wide image of Pluto from NASA’s New Horizons spacecraft is a large region of jumbled, broken terrain on the northwestern edge of the vast, icy plain informally called Sputnik Planum, to the right. The smallest visible features are 0.5 miles (0.8 kilometers) in size. This image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers).

 

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Pluto’s ‘Heart’

(Image credit: NASA/JHUAPL/SwRI)
Last Updated: Sep. 17, 2015
Editor: Tricia Talbert

Sputnik Planum is the informal name of the smooth, light-bulb shaped region on the left of this composite of several New Horizons images of Pluto. The brilliantly white upland region to the right may be coated by nitrogen ice that has been transported through the atmosphere from the surface of Sputnik Planum, and deposited on these uplands. The box shows the location of the glacier detail images below.

 

Mosaic of High-Resolution Images of Pluto

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Last Updated: Sep. 16, 2015
Editor: Tricia Talbert

Mosaic of high-resolution images of Pluto, sent back from NASA’s New Horizons spacecraft from Sept. 5 to 7, 2015. The image is dominated by the informally-named icy plain Sputnik Planum, the smooth, bright region across the center. This image also features a tremendous variety of other landscapes surrounding Sputnik. The smallest visible features are 0.5 miles (0.8 kilometers) in size, and the mosaic covers a region roughly 1,000 miles (1600 kilometers) wide. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers).

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– Credit and Resource –

NASA

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Pluto, Majestic Mountains, Frozen Plains and Foggy Hazes

Mars Orbiter Preparing for 2016 Arrival

With its biggest orbit maneuver since 2006, NASA’s Mars Orbiter will prepare this week for the arrival of NASA’s next Mars lander, InSight, next year.

A planned 77-second firing of six intermediate-size thrusters on July 29 will adjust the orbit timing of the veteran spacecraft so it will be in position to receive radio transmissions from InSight as the newcomer descends through the Martian atmosphere and touches down on Sept. 28, 2016. These six rocket engines, which were used for trajectory corrections during the spacecraft’s flight from Earth to Mars, can each produce about 22 newtons, or five pounds, of thrust.

“Without making this orbit change maneuver, Mars Reconnaissance Orbiter would be unable to hear from InSight during the landing, but this will put us in the right place at the right time,” said MRO Project Manager Dan Johnston of NASA’s Jet Propulsion Laboratory, Pasadena, California.

NASA’s Mars Reconnaissance Orbiter passes above a portion of the planet called Nilosyrtis Mensae in this artist’s concept illustration.
Credits: NASA/JPL-Caltech

The orbiter will record InSight’s transmissions for later playback to Earth as a record of each event during the critical minutes of InSight’s arrival at Mars, just as MRO did for the landings of NASA’s Curiosity Mars rover three years ago, and NASA’s Phoenix Mars lander in 2008.

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InSight will examine the deep interior of Mars for clues about the formation and early evolution of all rocky planets, including Earth.

MRO will continue its studies of Mars while preparing for the InSight arrival. MRO collects high-resolution imaging and spectral data, as well as atmospheric and sub-surface profiles. It has returned several times more data about the Red Planet than all other deep-space missions combined. It will also continue providing communication relay support for Mars rovers and making observations for analysis of candidate landing sites for future missions.

After the InSight landing, plans call for MRO to perform a pair of even larger maneuvers in October 2016 and April 2017 — each using the six intermediate-size thrusters longer than three minutes. These will return it to the orbit timing it has used since 2006, crossing the equator at about 3 a.m. and 3 p.m., local solar time, during each near-polar loop around the planet. To observe the InSight arrival, MRO will be in an orbit that crosses the equator at about 2:30 p.m. local solar mean time.

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The last time the mission performed a maneuver larger than this week’s was on November 15, 2006. That maneuver fired the intermediate-size thrusters for 76 seconds to establish the original 3 p.m. Local Mean Solar Time (LMST) sun-synchronous condition after a six-month period of using dips into the upper atmosphere to alter the orbit’s shape. The spacecraft has three sets of thrusters. It used its most powerful set — six thrusters, each with 170 newtons, or 39 pounds of force — for about 27 minutes to first enter orbit when it arrived at Mars on March 10, 2006. It uses eight smaller thrusters most frequently, for small adjustments to course or orientation.

Even after the planned 2017 maneuver, the spacecraft’s remaining supply of hydrazine propellant is projected to be more than 413 pounds (about 187 kilograms), equivalent to about 19 years of consumption in normal operations.

– Credit and Resource –

provided by: NASA

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Mars Orbiter Preparing for 2016 Arrival