NASA Cassini image of the swirling clouds on Saturn

Nature is an artist, and this time she seems to have let her paints swirl together a bit.

What the viewer might perceive to be Saturn's surface is really just the tops of its uppermost cloud layers.

Everything we see is the result of fluid dynamics.

Astronomers study Saturn's cloud dynamics in part to test and improve our understanding of fluid flows.

Hopefully, what we learn will be useful for understanding our own atmosphere and that of other planetary bodies.

This view looks toward the sunlit side of the rings from about 25 degrees above the ringplane.

The image was taken in red light with the NAC (Narrow Angle Camera) Cassini spacecraft on Aug. 23, 2014.

The view was acquired at a distance of approximately 1.1 million miles (1.8 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 127 degrees. Image scale is 7 miles (11 kilometers) per pixel.

NASA’s LRO Spacecraft Captures Images of LADEE’s Impact Crater

This image shows the area of the LADEE impact after spacecraft's planned impact into the eastern rim of Sundman V crater. 

Image Credit: NASA/Goddard/Arizona State University

NASA’S Lunar Reconnaissance Orbiter (LRO) spacecraft has spied a new crater on the lunar surface; one made from the impact of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) mission.

“The Lunar Reconnaissance Orbiter Camera (LROC) team recently developed a new computer tool to search Narrow Angle Camera (NAC) before and after image pairs for new craters, the LADEE impact event provided a fun test, said Mark Robinson, LROC principal investigator from Arizona State University in Tempe.

“As it turns there were several small surface changes found in the predicted area of the impact, the biggest and most distinctive was within 968 feet (295 meters) of the spot estimated by the LADEE operations team. What fun!”

The LADEE mission ended on April 18, 2014, with the spacecraft’s planned impact into the eastern rim of Sundman V crater on the far side of the moon.

LRO has taken an image of the LADEE impact site on the eastern rim of Sundman V crater.

The image was created by ratioing two images, one taken before the impact and another afterwards. 

The bright area highlights what has changed between the time of the two images, specifically the impact point and the ejecta.

Image Credit: NASA /Goddard /Arizona State University

LADEE's engines fired April 11, 2014, to perform a final orbital maintenance maneuver and adjust to guarantee it would impact on the farside of the moon and away from the Apollo landing sites.

Over a seven-day period, LADEE's orbit decreased and the spacecraft orbited very low to the surface and close to the walls of lunar craters and mountain ridges to give the team a chance to collect valuable science data.

Finally, LADEE impacted the eastern rim of Sundman V crater on April 18. The impact site is about half a mile (780 meters) from the crater rim with an altitude of about 8,497 feet (2,590 meters) and was only about two tenths of a mile (300 meters) north of the location mission controllers predicted based on tracking data.

The impact crater is small, less than ten feet (three meters) in diameter, barely resolvable by the LROC NAC.

The crater is small because the spacecraft, compared to most celestial impacts, was not traveling very fast, approximately 3,800 miles per hour (1,699 meters per second) and had a low mass and a low density.

The size of the impact crater made it hard to identify among the myriad of small fresh craters on the lunar surface. Images acquired of the impact region before the impact, were compared with images obtained after the impact to identify the crater.

Artist concept of the Lunar Reconnaissance Orbiter with Apollo mission imagery of the moon in the background.

Image Credit: NASA's Goddard Space Flight Center

Since the NAC images are so large (250 mega-pixels) and the new crater is so small, the LROC team co-registered the before and after images (called a temporal pair) and then divided the before image by the after image. By doing this, changes to the surface become evident.

The ejecta from the impact forms a triangular pattern primarily downrange to the west, extending about 656-984 feet (200-300 meters) from the impact site.

There is also a small triangular area of ejecta up range but it extends only about 66-98 feet (20-30 meters).

The ejecta pattern is oriented northwest, consistent with the direction the spacecraft was traveling when it impacted the surface.

"I'm happy that the LROC team was able to confirm the LADEE impact point," said Butler Hine, LADEE project manager at Ames Research Center in Moffett Field, California.

"It really helps the LADEE team to get closure and know exactly where the product of their hard work wound up."

NASA Messenger: Mercury Mission - 10 Years in Space

In celebration of the 10th anniversary of its launch, the MESSENGER team released this movie showing a flyover of Mercury. The movie is sped up by a factor of seven for ease of viewing.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory

Ten years ago, on August 3, 2004, NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft blasted off from Cape Canaveral, Florida, for a risky mission that would take the small satellite dangerously close to Mercury’s surface, paving the way for an ambitious study of the planet closest to the Sun.

The spacecraft traveled 4.9 billion miles (7.9 billion kilometers), a journey that included 15 trips around the Sun and flybys of Earth once, Venus twice, and Mercury three times, before it was inserted into orbit around its target planet in 2011.

“We have operated successfully in orbit for more than three Earth years and more than 14 Mercury years as we celebrate this amazing 10th anniversary milestone,” said MESSENGER Mission Operations Manager Andy Calloway, of the Johns Hopkins University Applied Physics Laboratory (APL).

“The MESSENGER spacecraft operates in one of the most challenging and demanding space environments in our Solar System, and we have met that challenge directly through innovation and hard work, as exemplified by the stunning discoveries and data return achievements.

Our only regret is that we have insufficient propellant to operate another 10 years, but we look forward to the incredible science returns planned for the final eight months of the mission.”

MESSENGER captured the images in the flyover movie during this flight path over Mercury's north polar region.

Image Credit: NASA

MESSENGER is only the second spacecraft sent to Mercury. Mariner 10 flew past it three times in 1974 and 1975 and gathered detailed data on less than half the surface.

MESSENGER took advantage of an ingenious trajectory design, lightweight materials, and miniaturisation of electronics, all developed in the three decades since Mariner 10 flew past Mercury.

“It was quite challenging to design and execute a trajectory that could culminate in Mercury orbit,” said Mission and Spacecraft Systems Engineer Dan O’Shaughnessy, of APL.

“Designing an attendant spacecraft that was light enough to carry the necessary propellant to execute such a trajectory with enough room left over for a payload capable of global characterisation of the planet is an impressive accomplishment.”

Additionally, he said, “the team’s concept of operations that streamlines planning while optimizing the use of our payload. despite substantial thermal and power constraints, is an amazing feat.”

MESSENGER Deputy Principal Investigator Larry Nittler, of the Carnegie Institution of Washington, said that the mission has rewritten scientists’ understanding of the planet “and given us plenty of surprises.”

“Geochemical measurements have revealed a surface poor in iron, but rich in moderately volatile elements such as sulphur and sodium,” said Nittler.

“These results rule out some long-standing theories put forward to explain Mercury’s anomalously high density compared with the other planets in the inner solar system,” he explained.

“Maps of elemental abundances show that the interior is highly chemically heterogeneous, providing important clues to the early geological history of the planet.”

“MESSENGER observations have also shown that Mercury’s surface was shaped by volcanic activity, identified unique landforms shaped by loss of volatile materials, and confirmed the presence of large amounts of water ice protected from the Sun’s heat within permanently shadowed impact craters near the planet’s poles, said Nittler

Infographic with statistics on the MESSENGER mission.

Image Credit: NASA

“We have found that the complex interplay of the interplanetary magnetic field with that of Mercury results in a remarkably dynamic electromagnetic environment surrounding the planet, including unexplained bursts of electrons and highly variable distributions of different elements in the thin exosphere,” Nittler added.

“Over the next few months, MESSENGER will observe Mercury at lower altitudes and thus smaller spatial scales than ever before, and this is sure to result both in exciting scientific discoveries and new puzzles about our solar system’s enigmatic innermost planet.”

In celebration of the 10th anniversary of its launch, the MESSENGER team has released a movie acquired during an early stage of MESSENGER’s low-altitude campaign.

Messenger narrow-angle camera (NAC)

The movie provides a bird’s-eye view of what the spacecraft sees as it flies over the planet at close range and was assembled from 214 images taken by the narrow-angle camera (NAC) on June 8, 2014.

The NAC’s field of view looked toward the horizon along the direction of MESSENGER's motion as the probe crossed the terminator into night.

Scott Murchie

“This view is what a traveller on the MESSENGER spacecraft might see during low-altitude operations in the coming year,” noted MESSENGER Co-Investigator Scott Murchie of APL.

“During the final phase of its mission, MESSENGER's science instruments will use low-altitude operations like this to explore the surface and subsurface of Mercury at unprecedented resolution.”

The image frames were taken once per second while MESSENGER was at altitudes ranging from 115 to 165 kilometers, traveling at a speed of 3.7 kilometers per second relative to the surface. The movie is sped up by a factor of six for ease of viewing.

Read the full article here

NASA LRO Images: Lunar Pits Could Shelter Astronauts

This video shows images from NASA's LRO spacecraft of various lunar pits. Since 2009, NASA's Lunar Reconnaissance Orbiter (LRO) has spotted hundreds of conspicuous holes on the Moon. 

These steep-walled "pits" might lead to underground environments sheltered from radiation, meteorite impacts, and extreme temperatures, making them valuable sites for future exploration.

This is a spectacular high-Sun view of the Mare Tranquillitatis pit crater revealing boulders on an otherwise smooth floor. 

This image from LRO's NAC is 400 meters (1,312 feet) wide, north is up. 

Image Credit: NASA /GSFC /Arizona State University.

While the moon's surface is battered by millions of craters, it also has over 200 holes; steep-walled pits that in some cases might lead to caves that future astronauts could explore and use for shelter, according to new observations from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft.

The pits range in size from about 5 meters (~5 yards) across to more than 900 meters (~984 yards) in diameter, and three of them were first identified using images from the Japanese Kaguya spacecraft.

Hundreds more were found using a new computer algorithm that automatically scanned thousands of high-resolution images of the lunar surface from LRO's Narrow Angle Camera (NAC).

"Pits would be useful in a support role for human activity on the lunar surface," said Robert Wagner of Arizona State University, Tempe, Arizona.

"A habitat placed in a pit, ideally several dozen meters back under an overhang, would provide a very safe location for astronauts: no radiation, no micrometeorites, possibly very little dust, and no wild day-night temperature swings."

Wagner developed the computer algorithm, and is lead author of a paper on this research now available online in the journal Icarus.

Most pits were found either in large craters with impact melt ponds, areas of lava that formed from the heat of the impact and later solidified, or in the lunar maria, dark areas on the moon that are extensive solidified lava flows hundreds of miles across. In ancient times, the maria were thought to be oceans; "maria" is the Latin word for "seas."

Various cultures have interpreted the patterns formed by the maria features in different ways; for example, some saw the face of a man, while others saw a rabbit or a boy carrying a bundle of sticks on his back.

These images from NASA's LRO spacecraft show all of the known mare pits and highland pits. Each image is 222 meters (about 728 feet) wide.

Image Credit: NASA /GSFC /Arizona State University

The pits could form when the roof of a void or cave collapses, perhaps from the vibrations generated by a nearby meteorite impact, according to Wagner.

However, he noted that from their appearance in the LRO photos alone, there is little evidence to point to any particular cause.

The voids could be created when molten rock flowed under the lunar surface; on Earth, lava tubes form when magma flows beneath a solidified crust and later drains away.

The same process could happen on the moon, especially in a large impact crater, the interior of which can take hundreds of thousands of years to cool, according to Wagner.

After an impact crater forms, the sides slump under lunar gravity, pushing up the crater's floor and perhaps causing magma to flow under the surface, forming voids in places where it drains away.

Exploring impact melt pits would pin down the nature of the voids in which they form. "They are likely due to melt flow within the pond from uplift after the surface has solidified, but before the interior has cooled," said Wagner.

"Exploring impact melt pits would help determine the magnitude of this uplift, and the amount of melt flow after the pond is in place."

Exploring the pits could also reveal how oceans of lava formed the lunar maria.

"The mare pits in particular would be very useful for understanding how the lunar maria formed. We've taken images from orbit looking at the walls of these pits, which show that they cut through dozens of layers, confirming that the maria formed from lots of thin flows, rather than a few big ones."

"Ground-level exploration could determine the ages of these layers, and might even find solar wind particles that were trapped in the lunar surface billions of years ago," said Wagner.

To date, the team has found over 200 pits spread across the melt ponds of 29 craters, which are considered geologically young "Copernican" craters at less than a billion years old; eight pits in the lunar maria, three of which were previously known from images from the Japanese Kaguya orbiter; and two pits in highlands terrain.

The general age sequence matches well with the pit distributions, according to Wagner.

"Impact melt ponds of Copernican craters are some of the younger terrains on the moon, and while the maria are much older at around three billion years old, they are still younger and less battered than the highlands."

"It's possible that there's a 'sweet spot' age for pits, where enough impacts have occurred to create a lot of pits, but not enough to destroy them," said Wagner.

A ghostly 'ladder' in Saturn's F ring

A ladder-like structure in Saturn’s F ring seen by Cassini on Feb. 13, 2013. 

Credit: NASA/JPL-Caltech/SSI

Saturn's F ring is certainly a curious structure.

Orbiting the giant planet 82,000 kilometers above its equatorial cloud tops, the F ring is a ropy, twisted belt of bright ice particles anywhere from 30-500 km wide.

It can appear as a solid band or a series of braided cords surrounded by a misty haze, and often exhibits clumps and streamers created by the gravitational influence of embedded moonlets or passing shepherd moons.

In the picture above, acquired by the Cassini spacecraft on Feb. 13, 2013 and released on May 27, we see a section of the F ring separated into long ropes and spanned by connecting bands of bright material—the "ladder" structure suggested in the title.

Scientists believe that interactions between the F ring and the moons Prometheus and Pandora cause the dynamic structure of the F ring.

Made of particles of water ice finer than cigarette smoke, the F ring orbits Saturn beyond the outer edge of the A ring across the expanse of the 2,600-km-wide Roche Division. In these images, Saturn and the main ring systems are off frame to the left.

Animation of Saturn’s F ring and shepherd moons.

This view looks toward the unilluminated side of the rings from about 32 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft's narrow-angle camera (NAC).

The view was obtained at a distance of approximately 426,000 miles (686,000 kilometers) from Saturn and at a phase angle of 162 degrees.

Image scale is 2 miles (4 kilometers) per pixel.

Esa Rosetta Osiris NAC Images: landslide and boulders

Rosetta pics of landslide and boulders at the highest resolution