New Mars map reveals history of a surface modified by water

A new geological map of part of the ancient Martian highlands produced by Scott C. Mest and David A. Crown of the Planetary Science Institute provides new insights into the planet's history of water modifying the planet's surface.

"This map depicts the complicated sequence of geologic processes that have served to modify ancient, rugged highland terrains surrounding the Hellas impact basin and shows evidence for the persistent effects of water and ice in degrading the Martian surface," Crown said.

The most prominent examples for the presence of water in this area are the canyon systems of Waikato Vallis in the north part of the map and Reull Vallis in the central part of the map.

These canyons are believed to have formed when underground water was released from plains materials to the surface, causing the ground to collapse.

The water could have been stored within the plains in localized aquifers or as ice, which could have melted due to the heat from nearby volcanoes.

"The canyon systems of Waikato Vallis and Reull Vallis are unlike anything we see here on Earth, so trying to understand how they formed requires us to be detectives," Mest said.

"We use images and topographic data from spacecraft to map the locations of these features, evaluate their relationships to each other, and estimate their ages from superposed impact craters, then we can begin to get a better understanding of the geologic processes that modified the surface and the sequences of events that present us with the surface we see today."

Based on Viking Orbiter images, Waikato and Reull Valles were thought to have been part of one long system.

However, by conducting detailed mapping using many of the newest and highest resolution data (e.g., MRO CTX, MRO HiRISE, Mars Odyssey THEMIS, and MOLA), Mest and Crown were able to show that these were two separate systems separated by an area of plains (Eridania Planitia).

Careful estimates of the ages of the canyons and the plains reveal a sequence of events starting with the water released from Waikato Vallis, which would have been stored for a time in the plains as a shallow lake.

As Reull Vallis was forming separately, the canyon breached a crater rim that was holding back the water in the lake; the lake drained gradually, which can be seen by many smaller channels incised on the floor of Reull Vallis.

In addition to these systems that dominate the landscape in this area, the plains and highland terrains contain many small channels that were carved by water flowing over the surface, likely around the same time that the canyons were forming.

Lastly, most highland peaks and the walls of many impact craters show evidence that ice-rich sediments flowed downhill, forming features that resemble rock glaciers on Earth; these features represent the most recent water-related activity in the area, and may be active today.

More information: "Geologic Map of MTM -30247, -35247 and -40247 Quadrangles, Reull Vallis Region of Mars" is published as a U.S. Geological Survey Scientific Investigations Map: pubs.usgs.gov/sim/3245/

Laboratory models suggest that stretching forces shaped Ganymede's surface

An image of a tabletop-size analogue model (left) shows details of fault systems created by extension that visually match an image by spacecraft Galileo of faulted terrain on Ganymede (right). 

Credit: Left Image: Courtesy of Southwest Research Institute; 

Right Image: Courtesy of NASA/JPL SSI

Processes that shaped the ridges and troughs on the surface of Jupiter's icy moon Ganymede are likely similar to tectonic processes seen on Earth, according to a team of researchers led by Southwest Research Institute (SwRI).

To arrive at this conclusion, the team subjected physical models made of clay to stretching forces that simulate tectonic action. The results were published in Geophysical Research Letters.

Physical analogue models simulate geologic structures in laboratory settings so that the developmental sequence of various phenomena can be studied as they occur.

The team, including researchers from SwRI, Wheaton College, NASA's Jet Propulsion Laboratory and NuStar Energy LP, created complex patterns of faults in their models, similar to the ridge and trough features seen in some regions of Ganymede.

The models consisted of a "wet clay cake" material possessing brittle characteristics to simulate how the icy moon's lithosphere, the outermost solid shell, responds to stresses by cracking.

The laboratory models suggest that characteristic patterns of ridges and troughs, called grooved terrain on Ganymede, result from its surface being stretched.

"The physical models showed a marked similarity to the surface features observed on Ganymede," said co-author Dr. Danielle Wyrick, a senior research scientist in the SwRI Space Science and Engineering Division.

"From the experiments, it appears that a process in which the crust breaks into separate blocks by large amounts of extension is the primary mechanism for creating these distinct features."

"Physical analogue modeling allows us to simulate the formation of complex three-dimensional geological structures on Ganymede, without actually going to Ganymede," said co-author Dr. David Ferrill, director of the Earth, Material and Planetary Sciences Department in the SwRI Geosciences and Engineering Division.

"These scaled models are able to reproduce the fine geometric details of geologic processes, such as faulting, and to develop and test hypotheses for landscape evolution on planetary bodies."

SwRI researchers previously have used physical analog models to examine the process by which pit crater chains, a series of linear pits, or depressions, develop on Mars, and how magma in the Martian subsurface deforms the surface of the Red Planet.

More information: The paper, "Physical models of grooved terrain tectonics on Ganymede," by D.W. Sims, D.Y. Wyrick, D.A. Ferrill, A.P. Morris, G.C. Collins, R.T. Pappalardo and S.L. Colton, was published by Geophysical Research Letters, 16 June 2014, Volume 41, Issue 11, pages 3774–3778, DOI: 10.1002/2014GL060359

Remarkable Features below the surface of the Moon

Mare Serenitatis / Sea of Serenity. 

Credit: Bruce Campbell (Smithsonian Institution, National Air and Space Museum); Arecibo /NAIC; NRAO /AUI /NSF

New images of Earth's Moon reveal more than can be seen with the naked eye, thanks to the combined efforts of the two largest radio telescopes of their kind, the National Radio Astronomy Observatory's Green Bank Telescope (GBT) in West Virginia and the Arecibo Observatory in Puerto Rico.

To make these images, radar signals beamed from Arecibo's powerful transmitter penetrated far below the Moon's dusty surface.

The signals then rebounded back and were picked up by the sensitive receivers on the GBT.

This observing technique, known as bistatic radar, has been used to study many objects in our solar system, including asteroids and other planets.

The first image reveals previously hidden features around an area known as Mare Serenitatis, or the Sea of Serenity, which is near the Apollo 17 landing site.

The radar observations were able to "see" approximately 10-15 meters (33-50 feet) below the lunar surface.

The light and dark features are the result of compositional changes in the lunar dust and differences in the abundance of rocks buried within the soil.

The second image is a similar observation of the lunar impact crater known as Aristillus.

The radar echoes reveal geologic features of the large debris field created by the force of the impact.

The dark "halo" surrounding the crater is due to pulverized debris beyond the rugged, radar-bright rim deposits.

The image also shows traces of lava-like features produced when lunar rock melted from the heat of the impact.

The crater is approximately 55 kilometers (34 miles) in diameter and 3.5 kilometers (2 miles) deep.

Aristillus Crater. 

Credit: Bruce Campbell (Smithsonian Institution, National Air and Space Museum); Arecibo/NAIC; NRAO/AUI/NSF

These images help planetary scientists interpret the complex history of the Moon, which is often obscured by dust layers built up over billions of years, better understand the geology of earlier landing sites, and plan for future lunar exploration.

Nasa Cassini Image: Surface of Titan Sea, Ligeia Mare, is mirror smooth

This false-colour image of the surface of Titan was made using radar measurements made by NASA's Cassini spacecraft. 

The spacecraft revealed that the surface of Ligeia Mare, Titan's second largest lake, is unusually still, most likely due to a lack of winds at the time of observation. 

Credit: Howard Zebker 

New radar measurements of an enormous sea on Titan offer insights into the weather patterns and landscape composition of the Saturn moon. 

The measurements, made in 2013 by NASA's Cassini spacecraft, reveal that the surface of Ligeia Mare, Titan's second largest sea, possesses a mirror-like smoothness, possibly due to a lack of winds.

"If you could look out on this sea, it would be really still. It would just be a totally glassy surface," said Howard Zebker, professor of geophysics and of electrical engineering at Stanford who is the lead author of a new study detailing the research.

Howard Zebker

The findings, recently published online in Geophysical Research Letters, also indicate that the solid terrain surrounding the sea is likely made of solid organic materials and not frozen water.

Saturn's second largest moon, Titan has a dense, planet-like atmosphere and large seas made of methane and ethane.

Measuring roughly 260 miles (420 km) by 217 miles (350 km), Ligeia Mare is larger than Lake Superior on Earth.

"Titan is the best analog that we have in the solar system to a body like the Earth because it is the only other body that we know of that has a complex cycle of solid, liquid, and gas constituents," Zebker said.

Titan's thick cloud cover makes it difficult for Cassini to obtain clear optical images of its surface, so scientists must rely on radar, which can see through the clouds, instead of a camera.

To paint a radar picture of Ligeia Mare, Cassini bounced radio waves off the sea's surface and then analyzed the echo.

The strength of the reflected signal indicated how much wave action was happening on the sea. To understand why, Zebker said, imagine sunlight reflecting off of a lake on Earth.

"If the lake were really flat, it would act as a perfect mirror and you would have an extremely bright image of the sun," he said.

"But if you ruffle up the surface of the sea, the light gets scattered in a lot of directions, and the reflection would be much dimmer. We did the same thing with radar on Titan."

The radar measurements suggest the surface of Ligeia Mare is eerily still. "Cassini's radar sensitivity in this experiment is one millimeter, so that means if there are waves on Ligeia Mare, they're smaller than one millimeter. That's really, really smooth," Zebker said.

One possible explanation for the sea's calmness is that no winds happened to be blowing across that region of the moon when Cassini made its flyby.

Another possibility is that a thin layer of some material is suppressing wave action. "For example, on Earth, if you put oil on top of a sea, you suppress a lot of small waves," Zebker said.

Cassini also measured microwave radiation emitted by the materials that make up Titan's surface.

By analyzing those measurements, and accounting for factors such as temperature and pressure, Zebker's team confirmed previous findings that the terrain around Ligeia Mare is composed of solid organic material, likely the same methane and ethane that make up the sea.

"Like water on Earth, methane on Titan can exists as a solid, a liquid, and a gas all at once," Zebker said.

Titan's similarities to Earth make it a good model for our own planet's early evolution, Zebker said. "Titan is different in the details from Earth, but because there is global circulation happening, the big picture is the same," he added.

"Seeing something in two very different environments could help reveal the overall guiding principles for the evolution of planetary bodies, and help explain why Earth developed life and Titan didn't."

More Information: "Surface of Ligeia Mare, Titan, from Cassini altimeter and radiometer analysis" H.Zebler et al.: 30 JAN 2014 - DOI: 10.1002/2013GL058877

NASA SDO: Giant sunspot making third rotation across surface of the sun

A massive and significantly strong sunspot is currently making its third pass across a “complex region” of the Sun, according to NASA.

Sunspots like the one currently being tracked by NASA and NOAA, are part of the active Sun regions which typically produce large solar flares and coronal mass ejections.

Sunspot AR1990 was previously labeled AR1967 while on its second rotation around the Sun, and AR1944, during its initial trip around the face of the Sun.

As previously reported by NASA, the largest solar flare of 2014 was unleashed by the Sun late last week.

The huge X Class solar flare erupted from sunspot AR1990, according to NASA’s Solar Dynamics Observatory (SDO).

The agency’s spacecraft recorder captured the gigantic bursts of plasma from the coronal mass ejection – CME.

X Class solar flares are the strongest type of solar storms. The massive solar flare was not Earth-directed, so the power grid was not in jeopardy.

If the 4.9 X Class solar flare had been directed towards Earth, the CME could have likely prompted a significant geomagnetic storm.

During such a storm charged particles smash against the Earth’s magnetic field. The Sun is currently in the most active phase of its 11-year solar cycle.

NASA Messenger: Mercury’s surface showing a high-reflectance area

MESSENGER spacecraft obtained this image of Mercury’s surface showing a high-reflectance area seemingly confined to a region of lower elevation bounded by linear scarp (cliff) segments. 

Such diffuse bright areas sometimes relate to the deposition of small secondary craters and ray segments by a relatively recent impact crater. 

However, regional images show no rayed craters in the immediate vicinity (except Han Kan).

So a compositional difference might account for the difference in the albedo (brightness) of the material in the low-lying area. 

Are the scarps the result of vertical movement along faults, or were they formed by secondary crater chains? 

Researchers also have yet to explain the hollows on the central peak of the crater at upper left, and the smooth impact melt on the floor of the terrace-walled crater just below center.

ESA GlobAlbedo Project: The reflecting power of a surface

The ‘V’ in its name stands for Vegetation: Proba-V will fly a reduced-mass version of the Vegetation instrument currently on board the Spot satellites to provide a daily overview of global vegetation growth. 

The Proba satellites are part of ESA’s In‑orbit Technology Demonstration Programme: missions dedicated to flying innovative technologies. 

Credit: ESA-P.Carril

The amount of sunlight being absorbed or reflected by Earth is one of the driving forces for weather and climate. Satellites are providing this information with unprecedented accuracy.

The reflecting power of a surface is known as 'albedo'. Bright snow and ice have a high albedo, meaning they reflect solar radiation back into space, while green areas like forests and fields have a much lower albedo.

The lower the albedo, the more energy from the Sun is absorbed.

Changes in Earth's surfaces can therefore affect how much of the Sun's energy is absorbed – such as a decrease in snow cover or an increase in the area used for agriculture.

If the amount of energy absorbed changes, this has an effect on Earth's energy budget and ultimately affects our weather and climate.

To help scientists build better simulations of weather and climate, ESA's GlobAlbedo project is using satellite data to map changes in Earth's reflectivity.

Led by University College London, the team used readings from the Envisat and Spot-Vegetation satellites to produce global surface albedo maps from 1998 to 2011.

The maps, available for free online, provide the most accurate measure of Earth's reflectivity to date.

"GlobAlbedo is the first gap-free, 1 km-resolution map of Earth's land surface with an uncertainty estimate for every pixel. This could only have been produced from satellite data," said Professor Jan-Peter Muller of University College London, leader of the GlobAlbedo project.

By combining data from different satellite sensors, scientists have maximised the coverage and created a time series that can be extended to include historical as well as future satellite measurements.

The maps have proven useful to a variety of users, including the UK Met Office. Scientists there have been using them to update the land surface albedo information in the Met Office's operational Global Atmosphere weather model, resulting in more accurate weather predictions and climate forecasts.

"Tests show that they help to give more accurate temperature forecasts over the United States and Asia, especially in summer," said Dr Malcolm Brooks from the Met Office.

"We expect to be producing operational forecasts using these data in the spring of 2014."

Mars Surface: Fit for human habitation?

NASA's Hubble Space Telescope snapped this shot of Mars on Aug. 26, 2003, when the Red Planet was 34.7 million miles from Earth.

The picture was taken just 11 hours before Mars made its closest approach to us in 60,000 years.

CREDIT: NASA/ESA

While Mars was likely a more hospitable place in its wetter, warmer past, the Red Planet may still be capable of supporting microbial life today, some scientists say.

Ongoing research in Mars-like places such as Antarctica and Chile's Atacama Desert shows that microbes can eke out a living in extremely cold and dry environments, several researchers stressed at "The Present-Day Habitability of Mars" conference held here at the University of California Los Angeles this month.

And not all parts of the Red Planet's surface may be arid currently — at least not all the time. Evidence is building that liquid water might flow seasonally at some Martian sites, potentially providing a haven for life as we know it.

"We certainly can't rule out the possibility that it's habitable today," said Alfred McEwen of the University of Arizona, principal investigator for the HiRise camera aboard NASA's Mars Reconnaissance Orbiter spacecraft.

Surface water on Mars
McEwen discussed some intriguing observations by HiRise, which suggest that briny water may flow down steep Martian slopes during the local spring and summer.

Sixteen such sites have been identified to date, mostly on the slopes of the huge Valles Marineris canyon complex, McEwen said.

The tracks seem to repeat seasonally as the syrupy fluids descend along weather-worn pathways.

While the brines may originate underground, Caltech's Edwin Kite noted, there is an increasing suspicion that a process known as deliquescence — in which moisture present in the atmosphere is gathered by compounds on the ground, allowing it to become a liquid — may be responsible.

Astrobiologists are keen to learn more about these brines, for not much is known about them at the moment.

"Briny water on Mars may or may not be habitable to microbes, either from Earth or from Mars," McEwen said.

Valles Marineris on Mars

Magnetic Flux Loops on the Sun Surface

This is an image of magnetic loops on the sun, captured by NASA's Solar Dynamics Observatory (SDO).

It has been processed to highlight the edges of each loop to make the structure more clear.

A series of loops such as this is known as a flux rope, and these lie at the heart of eruptions on the sun known as coronal mass ejections (CMEs.) 

This is the first time scientists were able to discern the timing of a flux rope's formation. (Blended 131 Angstrom and 171 Angstrom images of July 19, 2012 flare and CME.)

Image Credit: NASA/Goddard Space Flight Center/SDO

ESA Huygens Probe's bounce-landing reveals Titan's surface - YouTube

The Huygens probe, brought to Saturn's moon Titan by NASA's Cassini spacecraft, bounced, slid, and wobbled to rest in the 10 seconds after it touched down on Titan.

The first 10 seconds of Huygens' touchdown on Titan in January 2005 are relived in this animation.

The motion was reconstructed by combining accelerometer data from the Huygens Atmospheric Structure Instrument and the Surface Science Package with photometry data from the Descent Imager/Spectral Radiometer.

After descending through the thick atmosphere, the probe landed on the moon's surface, creating a hole around 12 cm deep.

It then bounced out onto a flat surface and slid 30-40 cm to its final resting place, before wobbling back and forth at least five times.

Vibrations in the probe's instruments were recorded for nearly 10 seconds after impact.

Credits: ESA--C. Carreau)

NASA Messenger: Mercury's Surface Resembles Rare Meteorites

These image of Mercury by NASA's Messenger probe show the distinctive colour of the planet's northern plains and their surrounding terrain. 

The top image is as Messenger saw the scene, with the bottom image enhanced to bring out features. Image released June 16, 2011. 

CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 

Mercury has a surface unlike any other planet's in the solar system, instead resembling a rare type of meteorite, researchers say.

The finding, based on an analysis of data from NASA's Messenger probe, sheds new light on the formation and history of the mysterious innermost planet, scientists add.

Mercury, the smallest planet in the solar system, is also one of the least understood, having received much less attention from scientific missions than Mars, Jupiter and Saturn.

NASA set out to change that when it launched the Messenger probe a little more than eight years ago. Messenger became the first spacecraft to orbit Mercury.

Past research based on Messenger data suggested a vast part of Mercury is covered with hardened lava, enough to bury the state of Texas under 4 miles (6.4 kilometers) of once-molten rock, scientists said.

All in all, these mammoth floods of lava cover 6 percent of the planet's surface, an area equal to nearly 60 percent of the continental United States.

They created Mercury's smooth northern plains between 3.5 billion to 4 billion years ago.

Credit: NASA/JHUAPL/CIW-DTM/GSFC/MIT/Brown University. Rendering by James Dickson and Jim Head.

Perspective view of ancient volcanic plains in the northern high latitudes of Mercury revealed by NASA's Messenger spacecraft.

Purple colours are low and white is high, spanning a range of about 2.3 km.

Width of area spans about 1200 km. Each line is 5 degrees in latitude and longitude.

Lava plains are common in the solar system.

For instance, young Mars spewed lava all across its surface, and it still has the largest volcano in the solar system: Olympus Mons is about 370 miles (600 km) in diameter, wide enough to cover the entire state of New Mexico, and 16 miles (25 km) high, three times taller than Mount Everest.

Now, 205 measurements of Mercury's surface composition, made by the X-ray spectrometer onboard Messenger, reveal how much Mercury's surface differs from those of other planets in the solar system.

"Being the closest planet to the sun does mean its formation history would be different and more extreme than the other terrestrial planets, with hotter temperatures and exposure to a stronger gravitational field," says lead study author Shoshana Weider, a planetary geologist at the Carnegie Institution of Washington.

The surface is dominated by minerals high in magnesium and enriched in sulfur, making it similar to partially melted versions of an enstatite chondrite, a rare type of meteorite that formed at high temperatures in low-oxygen conditions in the inner solar system.

"The similarity between the constituents of these meteorites and Mercury's surface leads us to believe that either Mercury formed via the accretion of materials somewhat like the enstatite chondrites, or that both enstatite chondrites and the Mercury precursors were built from common ancestors," Weider said.

JAXA: Mysteries of Venus Targeted by New Japanese Probe

SPACE.com -- Mysteries of Venus Targeted by New Japanese Probe

A new Japanese space probe is poised to launch toward Venus today to help solve the enduring mysteries of the hellish, cloud-covered world, which has been often described as Earth's twin.

The Venus Climate Orbiter Akatsuki, which means "Dawn" in Japanese, is set to launch from Tanegashima Space Center in Japan today on a 2-year mission to study the weather and surface of Venus in unprecedented detail. Liftoff is set for 5:44 p.m. EDT today, though it will be early Tuesday morning local time at the launch site.

"Once we can explain the structure of Venus, we will be able to better understand Earth," said Akatsuki project scientist Takeshi Imamura in a statement released by the Japan Aerospace Exploration Agency (JAXA). "For example, we may discover the reasons that only Earth has been able to sustain oceans, and why only Earth is abundant in life."

Imamura has called Akatsuki "the world's first interplanetary probe that deserves to be called a meteorological satellite."

The probe carries five different cameras to study Venus' clouds as well as map the planet's weather and peer through its thick atmosphere to view the surface. It will join Europe's Venus Express already in orbit around the planet, and has scientists on that mission eager as well.

"Venus somehow transformed from a more Earth-like place to the alien place it is today, and what's fascinating about the world is figuring out how it diverges from the Earth and the history behind why that happened," said David Grinspoon, curator of astrobiology at the Denver Museum of Nature and Science and an interdisciplinary scientist on the Venus Express mission. "It could help us understand how things here might change."

Akatsuki will launch atop a Japanese H-2A rocket and won't be alone during blastoff. JAXA is launching several smaller satellite experiments with the mission, including an ambitious solar sail designed to tag along on the trip to Venus. [More on Japan's solar sail mission.]