NASA’s MMS Delivers Promising Initial Results

NASA - MMS Mission logo.

Dec. 18, 2015

Just under four months into the science phase of the mission, NASA’s Magnetospheric Multiscale, or MMS, is delivering promising early results on a process called magnetic reconnection — a kind of magnetic explosion that’s related to everything from the northern lights to solar flares.

The unprecedented set of MMS measurements will open up our understanding of the space environment surrounding Earth, allowing us to better understand what drives magnetic reconnection events. These giant magnetic bursts can send particles hurtling at near the speed of light and create oscillations in Earth's magnetic fields, affecting technology in space and interfering with radio communications. Scientists from the Southwest Research Institute, NASA, the University of Colorado Boulder and the Johns Hopkins University Applied Physics Laboratory presented an overview of MMS science and early results on Dec. 17, 2015, at the American Geophysical Union’s Fall Meeting in San Francisco.

Image above: The four identical spacecraft of NASA’s Magnetospheric Multiscale, or MMS, mission (one of which is illustrated here) fly through the boundaries of Earth’s magnetic field to study an explosive process of magnetic reconnection. Thought to be the driver behind everything from solar flares to aurora, magnetic reconnection creates a sudden reconfiguration of magnetic fields, releasing huge amounts of energy in the process. Image Credits: NASA's Goddard Space Flight Center.

Planned for more than 10 years, the MMS mission started with the launch of four identical spacecraft on a single rocket in March 2015. Nine months later, the spacecraft are flying through the boundaries of Earth’s magnetic system, the magnetosphere. Their initial orbit is taking them through the dayside boundaries of the magnetosphere — known as the magnetopause — where the solar wind and other solar events drive magnetic reconnection. Eventually, their orbit will loop out farther to carry them through the farthest reaches of the magnetosphere on the night side, where magnetic reconnection is thought to be driven by the build-up of stored energy.

“We’ve recorded over 2,000 magnetopause crossings since our science phase began,” said Jim Burch, principal investigator for the MMS mission at Southwest Research Institute in San Antonio, Texas. “In that time, we’ve flown through hundreds of promising events.”

MMS’ four instrument suites and incredible measurement rates — a hundred times faster than ever before on certain instruments — is giving scientists their best look ever at magnetic reconnection. In fact, the mission's high resolution produces so much data it requires a scientist on duty during every MMS contact to prioritize which data is sent down from the spacecraft. 

One of the key features of MMS is its scaling ability. The four spacecraft fly in a four-sided, pyramid-shaped formation called a tetrahedron, allowing them to build up three-dimensional views of the regions and events they fly through. Because the four spacecraft are controlled independently, the scale of their formation — and their observations — can be zoomed in or out by a factor of ten.

Though many people think of space as a completely empty vacuum, it’s actually filled with electrically charged particles and electric and magnetic fields, which form a state of matter called plasma. All of this magnetic and electric energy means that magnetic reconnection plays a huge role in shaping the environment wherever plasma exists — whether that’s on the sun, in interplanetary space, or at the boundaries of Earth’s magnetic system.

“We can see the effects of reconnection on the sun in the form of coronal mass ejections and solar flares,” said Michael Hesse, lead co-investigator for theory and modeling on the MMS mission at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But with MMS, we’re finally able to observe the process of magnetic reconnection directly.”

Magnetic reconnection is a process in which magnetic fields reconfigure suddenly, releasing huge amounts of energy. When magnetic field lines snap and join back together in new formations, some of the energy that was stored in the magnetic field is converted to particle energy in the forms of heat and kinetic energy.

“Reconnection is a fundamental energy release process,” said Hesse. “It impacts both the temperature and speed of particles in a plasma, two of the defining characteristics.”

Katherine Goodrich, a graduate student at the University of Colorado Boulder, is working with measurements from a suite of six instruments to characterize the behavior of electric and magnetic fields at magnetic reconnection sites. This suite of instruments, the FIELDS suite — duplicated on each of the four MMS spacecraft — contains six sensors that work together to form a three-dimensional picture of the electric and magnetic fields near the spacecraft. This suite has a very high accuracy, in part due to the very long booms on each sensor.

Animation above: The explosive realignment of magnetic fields — known as magnetic reconnection — is a thought to be a common process at the boundaries of Earth’s magnetic bubble. Magnetic reconnection can connect Earth’s magnetic field to the interplanetary magnetic field carried by the solar wind or coronal mass ejections. NASA’s Magnetospheric Multiscale, or MMS, mission studies magnetic reconnection by flying through the boundaries of Earth’s magnetic field. Animation Credits: NASA Goddard/SWRC/CCMC/SWMF.

“The long booms allow us to measure the fields with minimal contamination from the electronics aboard the spacecraft,” said Goodrich. Along the spin plane, the booms measure 400 feet from end to end — longer than a regulation soccer field. The booms on the axis of spin measure 100 feet from end to end.

Using FIELDS observations, Goodrich is looking for one of the smoking guns of magnetic reconnection, called a parallel electric field.

“What we’re looking for is an alignment of electric and magnetic fields,” said Goodrich. “This condition is impossible with a simplified understanding of plasma, but magnetic reconnection is anything but simple.”

In the simplest view of plasma — known as ideal plasma — the charged particles spinning along magnetic field lines carry enough current to instantaneously short out any electric field parallel to the magnetic field. But in actuality, plasma doesn't ever behave quite that simply, so scientists must consider a more detailed, complex version of the physics to understand how and why reconnection is able to occur. Such rigorous models — known as non-ideal plasmas — open up the possibility for the creation of gaps in these zooming charged particles, allowing parallel electric fields to form for an observable length of time.

“These events would have to combine energy dissipation, particle acceleration, and sudden changes in magnetic topology,” said Goodrich. “Magnetic reconnection fits the bill perfectly.”

Goodrich presented observations from MMS that showed how the FIELDS suite can spot examples of parallel electric fields at time scales down to half a second. Such observations show that MMS is flying directly through areas of interest that will help us better characterize the space environment around Earth.

Ian Cohen, a postdoctoral fellow at Johns Hopkins University Applied Physics Laboratory, or APL, uses a different instrument suite to identify and study the telltale particle behaviors that come with magnetic reconnection. Cohen works with two particle detectors aboard MMS: the Fly’s Eye Energetic Particle Sensor, or FEEPS, and the Energetic Ion Spectrometer. The measurements are providing evidence for a mechanism by which particles can escape the Earth system and join the interplanetary medium.

When magnetic reconnection happens on the day-side, magnetic field lines from the sun connect directly to Earth’s magnetic field.

“The linking of these magnetic fields means that particles can drift from within the magnetosphere to the boundary between Earth’s magnetic field and the solar wind,” said Cohen. “Once they get to that boundary, further reconnection events allow them to escape and float along the interplanetary magnetic field.”

This magnetic sun-Earth connection also means that particles disrupted by magnetic reconnection spiral along these newly linked magnetic field lines toward Earth, allowing the evidence of magnetic reconnection to be seen even from tens of thousands of miles away.

Cohen presented MMS observations that are clearly able to distinguish between the directions the particles are moving, which will help scientists better understand what mechanisms drive magnetic reconnection.

"All in all, the data we have gotten so far has just been astounding,” said Burch. “Now we're sifting through those observations and we’re going to be able to understand the drivers behind magnetic reconnection in a way never before possible."

MMS is the fourth NASA Solar Terrestrial Probes, or STP, program mission. Goddard built, integrated and tested the four MMS spacecraft and is responsible for overall mission management and mission operations. The Southwest Research Institute in San Antonio, Texas, leads the Instrument Suite Science Team, with the University of New Hampshire leading the FIELDS instrument suite. Science operations planning and instrument command sequence development will be performed at the MMS Science Operations Center at the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder.

Related Link:

- NASA’s MMS mission website: http://www.nasa.gov/mms

Image (mentioned), Animation (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Sarah Frazier/Rob Garner.

Greetings, Orbiter.ch

Unscheduled Spacewalk Likely on Monday

ISS - Expedition 46 Mission patch.

December 18, 2015

ISS - International Space Station (STS-134 image)

The International Space Station’s mission managers are preparing for a likely unplanned spacewalk by Astronauts Scott Kelly and Tim Kopra no earlier than Monday, Dec. 21.

Late Wednesday, the Mobile Transporter rail car on the station’s truss was being moved by robotic flight controllers at Mission Control, Houston, to a different worksite near the center of the truss for payload operations when it stopped moving. The cause of the stall is being evaluated, but experts believe it may be related to a stuck brake handle, said ISS Mission Integration and Operations Manager Kenny Todd. Flight controllers had planned to move the transporter away from the center of the truss to worksite 2. The cause of the stall that halted its movement just four inches (10 centimeters) away from where it began is still being evaluated. Progress 62 is scheduled to launch at 3:44 a.m. EST Monday, and dock on Wednesday to the Pirs docking compartment at 5:31 a.m. Wednesday.

Image above: NASA Astronaut Joe Acaba, in the broken red striped spacesuit, and Astronaut Ricky Arnold, in the white striped suit, work to relocate Crew and Equipment Translation Aid (CETA) near the Mobile Transporter (MT) during an STS-119 spacewalk in March 2009.

The ISS Mission Management Team met Friday morning and is targeting Monday for the spacewalk, but will meet again in a readiness review Sunday morning. Managers could elect to press ahead for Monday, or take an extra day and conduct the spacewalk Tuesday.

ISS Expedition 46 Commander Scott Kelly and Flight Engineer Tim Kopra of NASA will conduct the spacewalk. It will be the 191st spacewalk in support of space station assembly and maintenance, the third in Kelly’s career and the second for Kopra. Kelly will be designated Extravehicular Activity crew member 1 (EV1) wearing the suit bearing the red stripes, and Kopra will be Extravehicular Activity crew member 2 (EV2) wearing the suit with no stripes.

A start time for the spacewalk either Monday or Tuesday has not yet been set, but NASA TV coverage will begin 90 minutes prior to the start of the spacewalk.

Related links:

ISS - Mobile Transporter: http://www.nasa.gov/missions/shuttle/f_slowtrain.html

International Space Station (ISS): http://www.nasa.gov/mission_pages/station/main/index.html

Images, Text, Credit: NASA.

Greetings, Orbiter.ch

Hubble Checks out a Home for Old Stars

NASA - Hubble Space Telescope patch.


Dec. 18, 2015

This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the globular cluster Terzan 1. Lying around 20,000 light-years from us in the constellation of Scorpius (The Scorpion), it is one of about 150 globular clusters belonging to our galaxy, the Milky Way.

Typical globular clusters are collections of around a hundred thousand stars, held together by their mutual gravitational attraction in a spherical shape a few hundred light-years across. It is thought that every galaxy has a population of globular clusters. Some, like the Milky Way, have a few hundred, while giant elliptical galaxies can have several thousand.

They contain some of the oldest stars in a galaxy, hence the reddish colors of the stars in this image — the bright blue ones are foreground stars, not part of the cluster. The ages of the stars in the globular cluster tell us that they were formed during the early stages of galaxy formation! Studying them can also help us to understand how galaxies formed.

Terzan 1, like many globular clusters, is a source of X-rays. It is likely that these X-rays come from binary star systems that contain a dense neutron star and a normal star. The neutron star drags material from the companion star, causing a burst of X-ray emission. The system then enters a quiescent phase in which the neutron star cools, giving off X-ray emission with different characteristics, before enough material from the companion builds up to trigger another outburst.

Hubble and the sunrise over Earth

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

Related links:

Wide Field Planetary Camera 2: https://www.spacetelescope.org/about/general/instruments/wfpc2/

Hubble Space Telescope websites:

    http://www.nasa.gov/hubble
    http://hubblesite.org/
    http://www.spacetelescope.org/

Image, Video,  Credits: NASA & ESA, Acknowledgement: Judy Schmidt/Text Credits: European Space Agency/NASA/Ashley Morrow.

Best regards, Orbiter.ch

NASA Releases New High-Resolution Earthrise Image

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

Dec. 18, 2015

NASA's Lunar Reconnaissance Orbiter (LRO) recently captured a unique view of Earth from the spacecraft's vantage point in orbit around the moon.

"The image is simply stunning," said Noah Petro, Deputy Project Scientist for LRO at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The image of the Earth evokes the famous 'Blue Marble' image taken by Astronaut Harrison Schmitt during Apollo 17, 43 years ago, which also showed Africa prominently in the picture."

In this composite image we see Earth appear to rise over the lunar horizon from the viewpoint of the spacecraft, with the center of the Earth just off the coast of Liberia (at 4.04 degrees North, 12.44 degrees West). The large tan area in the upper right is the Sahara Desert, and just beyond is Saudi Arabia. The Atlantic and Pacific coasts of South America are visible to the left. On the moon, we get a glimpse of the crater Compton, which is located just beyond the eastern limb of the moon, on the lunar farside.

LRO was launched on June 18, 2009, and has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. LRO experiences 12 earthrises every day; however the spacecraft is almost always busy imaging the lunar surface so only rarely does an opportunity arise such that its camera instrument can capture a view of Earth. Occasionally LRO points off into space to acquire observations of the extremely thin lunar atmosphere and perform instrument calibration measurements. During these movements sometimes Earth (and other planets) pass through the camera's field of view and dramatic images such as the one shown here are acquired.

This image was composed from a series of images taken Oct. 12, when LRO was about 83 miles (134 kilometers) above the moon's farside crater Compton. Capturing an image of the Earth and moon with LRO's Lunar Reconnaissance Orbiter Camera (LROC) instrument is a complicated task. First the spacecraft must be rolled to the side (in this case 67 degrees), then the spacecraft slews with the direction of travel to maximize the width of the lunar horizon in LROC's Narrow Angle Camera image. All this takes place while LRO is traveling faster than 3,580 miles per hour (over 1,600 meters per second) relative to the lunar surface below the spacecraft!

The high-resolution Narrow Angle Camera (NAC) on LRO takes black-and-white images, while the lower resolution Wide Angle Camera (WAC) takes color images, so you might wonder how we got a high-resolution picture of the Earth in color. Since the spacecraft, Earth, and moon are all in motion, we had to do some special processing to create an image that represents the view of the Earth and moon at one particular time. The final Earth image contains both WAC and NAC information. WAC provides the color, and the NAC provides high-resolution detail.

Artist's view of Lunar Reconnaissance Orbiter (LRO) spacecraft

"From the Earth, the daily moonrise and moonset are always inspiring moments," said Mark Robinson of Arizona State University in Tempe, principal investigator for LROC. "However, lunar astronauts will see something very different: viewed from the lunar surface, the Earth never rises or sets. Since the moon is tidally locked, Earth is always in the same spot above the horizon, varying only a small amount with the slight wobble of the moon. The Earth may not move across the 'sky', but the view is not static. Future astronauts will see the continents rotate in and out of view and the ever-changing pattern of clouds will always catch one's eye, at least on the nearside. The Earth is never visible from the farside; imagine a sky with no Earth or moon - what will farside explorers think with no Earth overhead?"

NASA's first Earthrise image was taken with the Lunar Orbiter 1 spacecraft in 1966. Perhaps NASA's most iconic Earthrise photo was taken by the crew of the Apollo 8 mission as the spacecraft entered lunar orbit on Christmas Eve Dec. 24, 1968. That evening, the astronauts -- Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot William Anders -- held a live broadcast from lunar orbit, in which they showed pictures of the Earth and moon as seen from their spacecraft. Said Lovell, "The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth."

More images and information from ASU's Lunar Reconnaissance Orbiter Camera website:
http://lroc.sese.asu.edu/posts/895

For more information about Lunar Reconnaissance Orbiter (LRO). visit:
http://www.nasa.gov/mission_pages/LRO/main/index.html

Images, Text, Credits: NASA/Goddard/Arizona State University/Bill Steigerwald.

Greetings, Orbiter.ch

CERN - ATLAS and CMS present their 2015 LHC results

CERN - European Organization for Nuclear Research logo.

Dec. 17, 2015

Image above: A 13 TeV collision recorded by ATLAS. The yellow and green bars indicate the presence of particle jets, which leave behind lots of energy in the calorimeters. (Image: ATLAS).

Particles circulated in the Large Hadron Collider (LHC) on Sunday for the last time in 2015, and, two days later, the two large general-purpose experiments, ATLAS and CMS, took centre stage to present their results from LHC Run 2. These results were based on the analysis of proton collisions at the previously unattained energy of 13 TeV, compared with the maximum of 8 TeV attained during LHC Run 1 from 2010 to 2012.  

The amount of data on which the two experiments’ analyses are based is still limited – around eight times less than that collected during Run 1 – and physicists need large volumes of data to be able to detect new phenomena. Nonetheless, the experimentalists have already succeeded in producing numerous results. Each of the two experiments has presented around 30 analyses, about half of which relate to Beyond-Standard-Model research. The Standard Model is the theory that describes elementary particles and their interactions, but it leaves many questions unanswered. Physicists are therefore searching for signs of Beyond-Standard-Model physics that might help them to answer some of those questions.

The new ATLAS and CMS results do not show any significant excesses that could indicate the presence of particles predicted by alternative models such as supersymmetry. The two experiments have therefore established new limits for the masses of these hypothetical new particles. Advances in particle physics often come from pushing back these limits. For example, CMS and ATLAS have established new restrictions for the mass of the gluino, a particle predicted by the theory of supersymmetry. This is just one of the many results that were presented on 15 December.

Image above: A 13 TeV proton collision recorded by CMS. The two green lines show two photons generated by the collision. (Image: CMS).

The two experiments have also observed a slight excess in the diphoton decay channel. Physicists calculate the mass of hypothetical particles that decay to form a pair of photons, and look at how often different masses are seen. If the distribution does not exactly match that expected from known processes, or in other words a bump appears at a specific mass not corresponding to any known particle, it may indicate a new particle being produced and decaying. However, the excess is too small at this stage to draw such a conclusion. We will have to wait for more data in 2016 to find out whether this slight excess is an inconsequential statistical fluctuation or, alternatively, a sign of the existence of a new phenomenon. Find out next time: season 2 is only just beginning.

The presentations by ATLAS and CMS are available here:
https://indico.cern.ch/event/442432/

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related article:

LHC experiments back in business at record energy ( LHC Run 2):
http://orbiterchspacenews.blogspot.ch/2015/06/lhc-experiments-back-in-business-at.html

Related links:

Large Hadron Collider (LHC): http://home.cern/topics/large-hadron-collider

ATLAS experiments: http://home.cern/about/experiments/atlas

CMS experiments: http://home.cern/about/experiments/cms

For more information about European Organization for Nuclear Research (CERN), visit: http://home.cern/

Images (mentioned), Text, Credits: CERN/Corinne Pralavorio.

Best regards, Orbiter.ch

New Findings from NASA’s New Horizons Shape Understanding of Pluto and its Moons

NASA - New Horizons Mission logo.

Dec. 17, 2015

Five months after NASA’s New Horizons spacecraft flew past Pluto to take the first images and measurements of this icy world and its system of satellites, knowledge about this distant system continues to unfold.

New Horizons science team members are highlighting the latest findings from the Pluto flyby at this week’s American Geophysical Union (AGU) fall meeting in San Francisco. Among the highlights are insights into Pluto’s geology and composition, as well as new details about the unexpected haze in Pluto’s atmosphere and its interaction with the solar wind.

“We’re much less than halfway through transmitting data about the Pluto system to Earth, but a wide variety of new scientific results are already emerging,” said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado.

Geological evidence has been found for widespread past and present glacial activity, including the formation of networks of eroded valleys, some of which are “hanging valleys,” much like those in Yellowstone National Park, Wyoming. “Pluto has greatly exceeded our expectations in diversity of landforms and processes — processes that continue to the present,” said Alan Howard of the University of Virginia, Charlottesville, a scientific collaborator with the New Horizons’ Geology, Geophysics and Imaging team.

Key to understanding activity on Pluto is the role of the deep layer of solid nitrogen and other volatile ices that fill the left side of Pluto’s ‘heart’—a vast, 620-mile (1,000-kilometer) -wide basin, informally named Sputnik Planum. New numerical models of thermal convection within this ice layer not only explain the numerous polygonal ice features seen on Sputnik Planum’s surface, but indicate this layer may be up to a few miles thick. Evaporation of this nitrogen and condensation on higher surrounding terrain leads to glacial flow back toward the basin; additional numerical models of nitrogen ice flow show how Pluto’s landscape has been and is still being transformed.

In the last few months, New Horizons has also returned a multitude of color and phase-angle data on the remarkable atmospheric haze that surrounds Pluto, rising hundreds of miles or kilometers above the surface. In addition to assessing its optical properties, the science team is examining several important questions about Pluto’s extensive haze: where it originates, why it forms layers, and how it varies spatially around Pluto.

“Pluto has greatly exceeded our expectations in diversity of landforms and processes — processes that continue to the present,” - Alan Howard, University of Virginia, Charlottesville.

“Like almost everything on Pluto, the haze is much more complicated than we thought,” said Andy Cheng, New Horizons co-investigator with the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. “But with the excellent New Horizons data currently in hand, we soon expect to have a much better understanding.”

New Horizons has also found new and more stringent limits for an atmosphere on Pluto’s largest moon, Charon. Moreover, scientists studying infrared spectral observations of Charon from the LEISA instrument aboard New Horizons are reporting evidence that ammonia (NH3) absorption occurs at a low level across a large portion of Charon's surface, not just the high local concentrations that had been previously detected in a few locations. One of those, the informally named Organa Crater, had been noted as being especially rich in NH3. It’s not yet known what controls the distribution of Charon’s NH3, or if it comes from Charon’s interior or an external source.

New Horizons scientists are also presenting findings about how Pluto and its moons interact with the solar wind, a constant stream of particles and plasma that flows from the sun and is still traveling at 900,000 miles per hour (1.4 million kilometers per hour) at Pluto. Pluto’s outflowing atmosphere provides a source of neutral atoms that can exchange electrons with the solar wind’s positively charged atoms of oxygen (O), carbon (C), and nitrogen (N). Observations from the Earth-orbiting Chandra X-ray Observatory during closest approach contributed to scientists’ understanding of the processes at work. Team members searched for X-ray emissions near Pluto to help determine the rate at which Pluto’s atmosphere is being lost to space, in much the same way X-ray emissions are used to characterize the outflow of material from comets.

Image: Zigzagging across Pluto

This high-resolution swath of Pluto (right) sweeps over the cratered plains at the west of the New Horizons’ encounter hemisphere and across numerous prominent faults, skimming the eastern margin of the dark, forbidding region informally known as Cthulhu Regio, and finally passing over the mysterious, possibly cryovolcanic edifice Wright Mons, before reaching the terminator or day-night line. Among the many notable details shown are the overlapping and infilling relationships between units of the relatively smooth, bright volatile ices from Sputnik Planum (at the edge of the mosaic) and the dark edge or “shore” of Cthulhu. The pictures in this mosaic were taken by the Long-Range Reconnaissance Imager (LORRI) in “ride-along” mode with the LEISA spectrometer, which accounts for the ‘zigzag’ or step pattern. Taken shortly before New Horizons’ July 14 closest approach to Pluto, details as small as 500 yards (500 meters) can be seen. NOTE: Click on the image and ZOOM IN for optimal viewing.

For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images, Text, Credits: NASA/JHUAPL/SwRI/Bill Keeter.

Best regards, Orbiter.ch

Rocks Rich in Silica Present Puzzles for Mars Rover Team

NASA - Mars Science Laboratory (MSL) logo.

Dec. 17, 2015

In detective stories, as the plot thickens, an unexpected clue often delivers more questions than answers. In this case, the scene is a mountain on Mars. The clue: the chemical compound silica. Lots of silica. The sleuths: a savvy band of Earthbound researchers whose agent on Mars is NASA's laser-flashing, one-armed mobile laboratory, Curiosity.

Image above: This May 22, 2015, view from the Mast Camera (Mastcam) in NASA's Curiosity Mars rover shows the "Marias Pass" area where a lower and older geological unit of mudstone -- the pale zone in the center of the image -- lies in contact with an overlying geological unit of sandstone. Image Credits: NASA/JPL-Caltech/MSSS.

NASA's Curiosity rover has found much higher concentrations of silica at some sites it has investigated in the past seven months than anywhere else it has visited since landing on Mars 40 months ago. Silica makes up nine-tenths of the composition of some of the rocks. It is a rock-forming chemical combining the elements silicon and oxygen, commonly seen on Earth as quartz, but also in many other minerals.

"These high-silica compositions are a puzzle. You can boost the concentration of silica either by leaching away other ingredients while leaving the silica behind, or by bringing in silica from somewhere else," said Albert Yen, a Curiosity science team member at NASA's Jet Propulsion Laboratory, Pasadena, California. "Either of those processes involve water. If we can determine which happened, we'll learn more about other conditions in those ancient wet environments."

Image above: This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover covers an area in "Bridger Basin" that includes the locations where the rover drilled a target called "Big Sky" on the mission's Sol 1119 (Sept. 29, 2015) and a target called "Greenhorn" on Sol 1137 (Oct. 18, 2015). Image Credits: NASA/JPL-Caltech/MSSS.

Water that is acidic would tend to carry other ingredients away and leave silica behind. Alkaline or neutral water could bring in dissolved silica that would be deposited from the solution. Apart from presenting a puzzle about the history of the region where Curiosity is working, the recent findings on Mount Sharp have intriguing threads linked to what an earlier NASA rover, Spirit, found halfway around Mars. There, signs of sulfuric acidity were observed, but Curiosity's science team is still considering both scenarios -- and others -- to explain the findings on Mount Sharp.

Adding to the puzzle, some silica at one rock Curiosity drilled, called "Buckskin," is in a mineral named tridymite, rare on Earth and never seen before on Mars. The usual origin of tridymite on Earth involves high temperatures in igneous or metamorphic rocks, but the finely layered sedimentary rocks examined by Curiosity have been interpreted as lakebed deposits. Furthermore, tridymite is found in volcanic deposits with high silica content. Rocks on Mars' surface generally have less silica, like basalts in Hawaii, though some silica-rich (silicic) rocks have been found by Mars rovers and orbiters. Magma, the molten source material of volcanoes, can evolve on Earth to become silicic. Tridymite found at Buckskin may be evidence for magmatic evolution on Mars.

Image above: This map shows the route on lower Mount Sharp that NASA's Curiosity followed between April 19, 2015, and Nov. 5, 2015. During this period the mission investigated silica-rich rock targets including "Buckskin," in the "Maria Pass" area, and "Greenhorn," in the "Bridger Basin" area. Image Credits: NASA/JPL-Caltech/Univ. of Arizona.

Curiosity has been studying geological layers of Mount Sharp, going uphill, since 2014, after two years of productive work on the plains surrounding the mountain. The mission delivered evidence in its first year that lakes in the area billions of years ago offered favorable conditions for life, if microbes ever lived on Mars. As Curiosity reaches successively younger layers up Mount Sharp's slopes, the mission is investigating how ancient environmental conditions evolved from lakes, rivers and deltas to the harsh aridity of today's Mars.

Seven months ago, Curiosity approached "Marias Pass," where two geological layers are exposed in contact with each other. The rover's laser-firing instrument for examining compositions from a distance, Chemistry and Camera (ChemCam), detected bountiful silica in some targets the rover passed on its way to the contact zone. The rover's Dynamic Albedo of Neutrons instrument simultaneously detected that the rock composition was unique in this area.

"The high silica was a surprise -- so interesting that we backtracked to investigate it with more of Curiosity's instruments," said Jens Frydenvang of Los Alamos National Laboratory in New Mexico and the University of Copenhagen, Denmark.

Image above: This image from the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity Mars rover shows detailed texture of a rock target called "Elk" on Mars' Mount Sharp, revealing laminations that are present in much of the Murray Formation geological unit of lower Mount Sharp. Image Credits: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS.

Gathering clues about silica was a major emphasis in rover operations over a span of four months and a distance of about one-third of a mile (half a kilometer).

The investigations included many more readings from ChemCam, plus elemental composition measurements by the Alpha Particle X-ray Spectrometer (APXS) on the rover's arm and mineral identification of rock-powder samples by the Chemistry and Mineralogy (CheMin) instrument inside the rover.

Buckskin was the first of three rocks where drilled samples were collected during that period. The CheMin identification of tridymite prompted the team to look at possible explanations: "We could solve this by determining whether trydymite in the sediment comes from a volcanic source or has another origin," said Liz Rampe, of Aerodyne Industries at NASA's Johnson Space Center, Houston. "A lot of us are in our labs trying to see if there's a way to make tridymite without such a high temperature."

Image above: This view from NASA's Curiosity Mars rover shows an example of discoloration closely linked to fractures in the Stimson formation sandstone on lower Mount Sharp. The pattern is evident along two perpendicular fractures.Curiosity's Navigation Camera (Navcam) acquired the component images of this mosaic on Aug. 23, 2015, during the 1.083rd Martian day, or sol, of the mission. The location is along the rover's path between "Marias Pass" and "Bridger Basin." In this region, the rover has found fracture zones to be associated with rock compositions enriched in silica, relative to surrounding bedrock. Image Credits: NASA/JPL-Caltech.

Beyond Marias Pass, ChemCam and APXS found a pattern of high silica in pale zones along fractures in the bedrock, linking the silica enrichment there to alteration by fluids that flowed through the fractures and permeated into bedrock. CheMin analyzed drilled material from a target called "Big Sky" in bedrock away from a fracture and from a fracture-zone target called "Greenhorn." Greenhorn indeed has much more silica, but not any in the form of tridymite. Much of it is in the form of noncrystalline opal, which can form in many types of environments, including soils, sediments, hot spring deposits and acid-leached rocks.

"What we're seeing on Mount Sharp is dramatically different from what we saw in the first two years of the mission," said Curiosity Project Scientist Ashwin Vasavada of JPL. "There's so much variability within relatively short distances. The silica is one indicator of how the chemistry changed. It's such a multifaceted and curious discovery, we're going to take a while figuring it out."

For more about Curiosity, which is examining sand dunes this month, visit: http://mars.jpl.nasa.gov/msl/

Additional images can be seen here: http://www.jpl.nasa.gov/news/news.php?release=2015-377

Images (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/JPL/Guy Webster/Tony Greicius.

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