Category Archives: Space Science

Europa, Titan, & other deep space sites, Space Science

Hubble space telescope images show possible water plumes erupting from Europa

A team using the Hubble telescope spots possible water plumes erupting on Jupiter’s moon Europa. Here is the official NASA press release:

NASA’s Hubble Spots Possible Water Plumes Erupting on Europa

Astronomers using NASA’s Hubble Space Telescope have imaged what may be water vapor plumes erupting off the surface of Jupiter’s moon Europa. This finding bolsters other Hubble observations suggesting the icy moon erupts with high altitude water vapor plumes.

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This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The plumes, photographed by NASA’s Hubble’s Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. Hubble’s ultraviolet sensitivity allowed for the features, rising over 100 miles above Europa’s icy surface, to be discerned. The water is believed to come from a subsurface ocean on Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. [Larger images]
The observation increases the possibility that missions to Europa may be able to sample Europa’s ocean without having to drill through miles of ice.

“Europa’s ocean is considered to be one of the most promising places that could potentially harbor life in the solar system,” said Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “These plumes, if they do indeed exist, may provide another way to sample Europa’s subsurface.”

The plumes are estimated to rise about 125 miles (200 kilometers) before, presumably, raining material back down onto Europa’s surface. Europa has a huge global ocean containing twice as much water as Earth’s oceans, but it is protected by a layer of extremely cold and hard ice of unknown thickness. The plumes provide a tantalizing opportunity to gather samples originating from under the surface without having to land or drill through the ice.

 

The team, led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore observed these finger-like projections while viewing Europa’s limb as the moon passed in front of Jupiter.

The original goal of the team’s observing proposal was to determine whether Europa has a thin, extended atmosphere, or exosphere. Using the same observing method that detects atmospheres around planets orbiting other stars, the team realized if there was water vapor venting from Europa’s surface, this observation would be an excellent way to see it.

“The atmosphere of an extrasolar planet blocks some of the starlight that is behind it,” Sparks explained. “If there is a thin atmosphere around Europa, it has the potential to block some of the light of Jupiter, and we could see it as a silhouette. And so we were looking for absorption features around the limb of Europa as it transited the smooth face of Jupiter.”

In 10 separate occurrences spanning 15 months, the team observed Europa passing in front of Jupiter. They saw what could be plumes erupting on three of these occasions.

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This diagram shows how the plumes on Europa are seen in silhouette as the moon moves across the face of Jupiter. Europa makes a complete orbit of Jupiter in just 3.5 Earth days. [ Larger images]
This work provides supporting evidence for water plumes on Europa. In 2012, a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, detected evidence of water vapor erupting from the frigid south polar region of Europa and reaching more than 100 miles (160 kilometers) into space. Although both teams used Hubble’s Space Telescope Imaging Spectrograph instrument, each used a totally independent method to arrive at the same conclusion.

“When we calculate in a completely different way the amount of material that would be needed to create these absorption features, it’s pretty similar to what Roth and his team found,” Sparks said. “The estimates for the mass are similar, the estimates for the height of the plumes are similar. The latitude of two of the plume candidates we see corresponds to their earlier work.”

But as of yet, the two teams have not simultaneously detected the plumes using their independent techniques. Observations thus far have suggested the plumes could be highly variable, meaning that they may sporadically erupt for some time and then die down. For example, observations by Roth’s team within a week of one of the detections by Sparks’ team failed to detect any plumes.

If confirmed, Europa would be the second moon in the solar system known to have water vapor plumes. In 2005, NASA’s Cassini orbiter detected jets of water vapor and dust spewing off the surface of Saturn’s moon Enceladus.

Scientists may use the infrared vision of NASA’s James Webb Space Telescope, which is scheduled to launch in 2018, to confirm venting or plume activity on Europa. NASA also is formulating a mission to Europa with a payload that could confirm the presence of plumes and study them from close range during multiple flybys.

“Hubble’s unique capabilities enabled it to capture these plumes, once again demonstrating Hubble’s ability to make observations it was never designed to make,” said Paul Hertz, director of the Astrophysics Division at NASA Headquarters in Washington. “This observation opens up a world of possibilities, and we look forward to future missions — such as the James Webb Space Telescope — to follow up on this exciting discovery.”

The work by Sparks and his colleagues will be published in the Sept. 29 issue of the Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (the European Space Agency.) NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. STScI, which is operated for NASA by the Association of Universities for Research in Astronomy in Washington, conducts Hubble science operations.

For images and more information about Europa and Hubble, visit:

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Mars, Multiple media, Space Science

Mars Curiosity rover sends remarkable images of layered rocket formations

Lots of wonderful new pictures from the Curiosity rover on Mars:

Mars Rover Views Spectacular Layered Rock Formations

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This view [larger image] from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows an outcrop with finely layered rocks within the “Murray Buttes” region on lower Mount Sharp. The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer — called the “Stimson formation” — during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes. The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.
The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA’s Curiosity Mars rover, which is currently exploring the “Murray Buttes” region of lower Mount Sharp. The new images arguably rival photos taken in U.S. National Parks.

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This view [see larger image] from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows a sloping hillside within the “Murray Buttes” region on lower Mount Sharp. The rim of Gale Crater, where the rover has been active since landing in 2012, is visible in the distance, through the dusty haze. The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.
Curiosity took the images with its Mast Camera (Mastcam) on Sept. 8. The rover team plans to assemble several large, color mosaics from the multitude of images taken at this location in the near future.

“Curiosity’s science team has been just thrilled to go on this road trip through a bit of the American desert Southwest on Mars,” said Curiosity Project Scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory, Pasadena, California.

The Martian buttes and mesas rising above the surface are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed.

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This view [see larger image]  from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows sloping buttes and layered outcrops within the “Murray Buttes” region on lower Mount Sharp. The buttes and mesas rising above the surface are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer — called the “Stimson formation” — during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.

“Studying these buttes up close has given us a better understanding of ancient sand dunes that formed and were buried, chemically changed by groundwater, exhumed and eroded to form the landscape that we see today,” Vasavada said.

The new images represent Curiosity’s last stop in the Murray Buttes, where the rover has been driving for just over one month. As of this week, Curiosity has exited these buttes toward the south, driving up to the base of the final butte on its way out. In this location, the rover began its latest drilling campaign (on Sept. 9). After this drilling is completed, Curiosity will continue farther south and higher up Mount Sharp, leaving behind these spectacular formations.

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This view [see larger image] from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows finely layered rocks within the “Murray Buttes” region on lower Mount Sharp. The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer — called the “Stimson formation” — during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes. The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.
Curiosity landed near Mount Sharp in 2012. It reached the base of the mountain in 2014 after successfully finding evidence on the surrounding plains that ancient Martian lakes offered conditions that would have been favorable for microbes if Mars has ever hosted life. Rock layers forming the base of Mount Sharp accumulated as sediment within ancient lakes billions of years ago.

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This view [see larger image]  from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows a hillside outcrop with layered rocks within the “Murray Buttes” region on lower Mount Sharp.
On Mount Sharp, Curiosity is investigating how and when the habitable ancient conditions known from the mission’s earlier findings evolved into conditions drier and less favorable for life.

For more information about Curiosity, visit: http://mars.jpl.nasa.gov/msl

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Europa, Titan, & other deep space sites, Gas giants Saturn, Jupiter, et al, Space Science

Video: Cassini radar images dunes on Saturn’s moon Titan

The Cassini spacecraft orbiting Saturn has returned radar imagery of dunes on the moon Titan, the only moon in our solar system to have an atmosphere. Radar allows a view of what is hidden by the atmospheric haze: Titan’s Dunes and Other Features Emerge in New Images – Cassini/NASA

xanaduannexontitanThis synthetic-aperture radar (SAR) image was obtained by
NASA’s Cassini spacecraft on July 25, 2016, during its “T-121”
pass over Titan’s southern latitudes.

The video shows some of the radar imagery.

This video focuses on Shangri-la, a large, dark area on Titan filled with dunes. The long, linear dunes are thought to be comprised of grains derived from hydrocarbons that have settled out of Titan’s atmosphere. Cassini has shown that dunes of this sort encircle most of Titan’s equator. Scientists can use the dunes to learn about winds, the sands they’re composed of, and highs and lows in the landscape.

The radar image was obtained by the Cassini Synthetic Aperture radar (SAR) on July 25, 2016, during the mission’s 122nd targeted Titan encounter.

Asteroids & Comets, Space Science, Space Systems

Dawn Mission: Latest research results shows Ceres is an icy world with a “cryovolcano”

The Dawn probe orbiting Ceres in the Asteroid Belt has returned new information  about the dwarf planet. Below are summaries of several new findings:

Ceres’ Geological Activity, Ice Revealed in New Research 

A lonely 3-mile-high (5-kilometer-high) mountain on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere. These are just two of many new insights about Ceres from NASA’s Dawn mission published this week in six papers in the journal Science.

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Ceres’ lonely mountain, Ahuna Mons, is seen in this simulated perspective view. The elevation has been exaggerated by a factor of two. The view was made using enhanced-color images from NASA’s Dawn mission. Images taken using blue (440 nanometers), green (750 nanometers) and infrared (960 nanometers) spectral filters were combined to create the view. The spacecraft’s framing camera took the images from Dawn’s low-altitude mapping orbit, from an altitude of 240 miles (385 kilometers) in August 2016. The resolution of the component images is 120 feet (35 meters) per pixel.
Chris Russell, principal investigator of the Dawn mission, based at the University of California, Los Angeles, said

“Dawn has revealed that Ceres is a diverse world that clearly had geological activity in its recent past”

 

Ahuna Mons as a Cryovolcano

Ahuna Mons is a volcanic dome unlike any seen elsewhere in the solar system, according to a new analysis led by Ottaviano Ruesch of NASA’s Goddard Space Flight Center, Greenbelt, Maryland, and the Universities Space Research Association. Ruesch and colleagues studied formation models of volcanic domes, 3-D terrain maps and images from Dawn, as well as analogous geological features elsewhere in our solar system. This led to the conclusion that the lonely mountain is likely volcanic in nature. Specifically, it would be a cryovolcano — a volcano that erupts a liquid made of volatiles such as water, instead of silicates.

“This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past,” Ruesch said.

For more details on this study, see: http://www.nasa.gov/feature/goddard/2016/ceres-cryo-volcano

A Temporary Atmosphere

A surprising finding emerged in the paper led by Russell: Dawn may have detected a weak, temporary atmosphere. Dawn’s gamma ray and neutron (GRaND) detector observed evidence that Ceres had accelerated electrons from the solar wind to very high energies over a period of about six days. In theory, the interaction between the solar wind’s energetic particles and atmospheric molecules could explain the GRaND observations.

A temporary atmosphere would be consistent with the water vapor the Herschel Space Observatory detected at Ceres in 2012-2013. The electrons that GRaND detected could have been produced by the solar wind hitting the water molecules that Herschel observed, but scientists are also looking into alternative explanations.

“We’re very excited to follow up on this and the other discoveries about this fascinating world,” Russell said.

Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn’s visible and infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

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The small, bright crater Oxo (6 miles, 10 kilometers wide) on Ceres is seen in this perspective view. The elevation has been exaggerated by a factor of two. The view was made using enhanced-color images from NASA’s Dawn mission. Dawn’s visible and infrared mapping spectrometer (VIR) has found evidence of water ice at this crater. The results were published in the journal Science in Sept. 2016. Images taken using blue (440 nanometers), green (750 nanometers) and infrared (960 nanometers) spectral filters were combined to create the view. The spacecraft’s framing camera took the images from Dawn’s low-altitude mapping orbit, from an altitude of 240 miles (385 kilometers) in August 2016. The resolution of the component images is 120 feet (35 meters) per pixel.
Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres’ crust does contain a significant component of water-ice. This is consistent with a study of Ceres’ diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres’ past. Craters that are roughly polygonal — that is, shapes bounded by straight lines — hint that Ceres’ crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet’s various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both — a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters’ depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

“The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution,” Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres’ crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet’s crust indicates Ceres’ surface material has been altered by a global process involving water.

Although Ceres’ phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, “pancake”-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

“In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu,” Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres’ surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission

More information about Dawn is available at the following sites:

Asteroids & Comets, Space Science, Space Systems

Philae lander on Comet 67P/C-G has been found

The European Space Agency (ESA) announced today that the Philae spacecraft, deployed from the Rosetta mother ship on November 14, 2014 to land on Comet 67P/Churyumov–Gerasimenko has finally been found. After several bounces it had ended up in a shadowed area. After a short time it went silent since the solar panels could not replenish its battery and before its location could be determined.

Philae found!

Less than a month before the end of the mission, Rosetta’s high-resolution camera has revealed the Philae lander wedged into a dark crack on Comet 67P/Churyumov–Gerasimenko.

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Rosetta’s lander Philae has been identified in OSIRIS narrow-angle camera images taken on 2 September 2016 from a distance of 2.7 km. The image scale is about 5 cm/pixel. Philae’s 1 m-wide body and two of its three legs can be seen extended from the body. The images also provide proof of Philae’s orientation. A Rosetta Navigation Camera image taken on 16 April 2015 is shown at top right for context, with the approximate location of Philae on the small lobe of Comet Churyumov-Gerasimenko marked.
The images were taken on 2 September by the OSIRIS narrow-angle camera as the orbiter came within 2.7 km of the surface and clearly show the main body of the lander, along with two of its three legs.

The images also provide proof of Philae’s orientation, making it clear why establishing communications was so difficult following its landing on 12 November 2014.

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Close-up of the Philae lander, imaged by Rosetta’s OSIRIS narrow-angle camera on 2 September 2016 from a distance of 2.7 km. The image scale is about 5 cm/pixel. Philae’s 1 m-wide body and two of its three legs can be seen extended from the body. The images also provide proof of Philae’s orientation. The image is a zoom from a wider-scene, and has been interpolated.

“With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,”

says Cecilia Tubiana of the OSIRIS camera team, the first person to see the images when they were downlinked from Rosetta yesterday.

“After months of work, with the focus and the evidence pointing more and more to this lander candidate, I’m very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos,”

says ESA’s Laurence O’Rourke, who has been coordinating the search efforts over the last months at ESA, with the OSIRIS and SONC/CNES teams.

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An OSIRIS narrow-angle camera image taken on 2 September 2016 from a distance of 2.7 km in which Philae was definitively identified. The image has been processed to adjust the dynamic range in order to see Philae while maintaining the details of the comet’s surface. Philae is located at the far right of the image, just above centre. The image scale is about 5 cm/pixel.
Philae was last seen when it first touched down at Agilkia, bounced and then flew for another two hours before ending up at a location later named Abydos, on the comet’s smaller lobe.

After three days, Philae’s primary battery was exhausted and the lander went into hibernation, only to wake up again and communicate briefly with Rosetta in June and July 2015 as the comet came closer to the Sun and more power was available.

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A number of Philae’s features can be made out in this image taken by Rosetta’s OSIRIS narrow-angle camera image on 2 September 2016. The images were taken from a distance of 2.7 km, and have a scale of about 5 cm/pixel. Philae’s 1 m wide body and two of its three legs can be seen extended from the body. Several of the lander’s instruments are also identified, including one of the CIVA panoramic imaging cameras, the SD2 drill and SESAME-DIM (Surface Electric Sounding and Acoustic Monitoring Experiment Dust Impact Monitor).
However, until today, the precise location was not known. Radio ranging data tied its location down to an area spanning a few tens of metres, but a number of potential candidate objects identified in relatively low-resolution images taken from larger distances could not be analysed in detail until recently.

While most candidates could be discarded from analysis of the imagery and other techniques, evidence continued to build towards one particular target, which is now confirmed in images taken unprecedentedly close to the surface of the comet.

At 2.7 km, the resolution of the OSIRIS narrow-angle camera is about 5 cm/pixel, sufficient to reveal characteristic features of Philae’s 1 m-sized body and its legs, as seen in these definitive pictures.

“This remarkable discovery comes at the end of a long, painstaking search,” says Patrick Martin, ESA’s Rosetta Mission Manager. “We were beginning to think that Philae would remain lost forever. It is incredible we have captured this at the final hour.”

[ Matt Taylor, ESA’s Rosetta project scientist says,]

“This wonderful news means that we now have the missing ‘ground-truth’ information needed to put Philae’s three days of science into proper context, now that we know where that ground actually is!” …

[ Holger Sierks, principal investigator of the OSIRIS camera adds,]

“Now that the lander search is finished we feel ready for Rosetta’s landing, and look forward to capturing even closer images of Rosetta’s touchdown site,” …

The discovery comes less than a month before Rosetta descends to the comet’s surface. On 30 September, the orbiter will be sent on a final one-way mission to investigate the comet from close up, including the open pits in the Ma’at region, where it is hoped that critical observations will help to reveal secrets of the body’s interior structure.

Further information on the search that led to the discovery of Philae, along with additional images, will be made available soon.