samedi 13 décembre 2014

MESSENGER Data Suggest Recurring Meteor Shower on Mercury












NASA - MESSENGER Mission to Mercury logo.

December 13, 2014

The closest planet to the sun appears to get hit by a periodic meteor shower, possibly associated with a comet that produces multiple events annually on Earth.

The clues pointing to Mercury’s shower were discovered in the very thin halo of gases that make up the planet’s exosphere, which is under study by NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft.

“The possible discovery of a meteor shower at Mercury is really exciting and especially important because the plasma and dust environment around Mercury is relatively unexplored,” said Rosemary Killen, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study, available online in Icarus.


Image above: Mercury appears to undergo a recurring meteor shower, perhaps when its orbit crosses the debris trail left by comet Encke. (Artist's concept.) Image Credit: NASA's Goddard Space Flight Center.

A meteor shower occurs when a planet passes through a swath of debris shed by a comet, or sometimes an asteroid. The smallest bits of dust, rock and ice feel the force of solar radiation, which pushes them away from the sun, creating the comet’s sometimes-dazzling tail. The larger chunks get deposited like a trail of breadcrumbs along the comet’s orbit – a field of tiny meteoroids in the making.

Earth experiences multiple meteor showers each year, including northern summer’s Perseids, the calling card of comet Swift–Tuttle, and December’s reliable Geminids, one of the few events associated with an asteroid. Comet Encke has left several debris fields in the inner solar system, giving rise to the Southern and Northern Taurids, meteor showers that peak in October and November, and the Beta Taurids in June and July.

The suggested hallmark of a meteor shower on Mercury is a regular surge of calcium in the exosphere. Measurements taken by MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer have revealed seasonal surges of calcium that occurred regularly over the first nine Mercury years since MESSENGER began orbiting the planet in March 2011.

The suspected cause of these spiking calcium levels is a shower of small dust particles hitting the planet and knocking calcium-bearing molecules free from the surface. This process, called impact vaporization, continually renews the gases in Mercury’s exosphere as interplanetary dust and meteoroids rain down on the planet. However, the general background of interplanetary dust in the inner solar system cannot, by itself, account for the periodic spikes in calcium. This suggests a periodic source of additional dust, for example, a cometary debris field. Examination of the handful of comets in orbits that would permit their debris to cross Mercury’s orbit indicated that the likely source of the planet’s event is Encke.

MESSENGER spacecraft orbiting Mercury. Image Credit: NASA

“If our scenario is correct, Mercury is a giant dust collector,” said Joseph Hahn, a planetary dynamist in the Austin, Texas, office of the Space Science Institute and coauthor of the study. “The planet is under steady siege from interplanetary dust and then regularly passes through this other dust storm, which we think is from comet Encke.”

The researchers created detailed computer simulations to test the comet Encke hypothesis. However, the calcium spikes found in the MESSENGER data were offset a bit from the expected results. This shift is probably due to changes in the comet’s orbit over time, due to the gravitational pull of Jupiter and other planets.

“The variation of Mercury’s calcium exosphere with the planet’s position in its orbit has been known for several years from MESSENGER observations, but the proposal that the source of this variation is a meteor shower associated with a specific comet is novel,” added MESSENGER Principal Investigator Sean Solomon, of the Lamont-Doherty Earth Observatory at Columbia University in New York. “This study should provide a basis for searches for further evidence of the influence of meteor showers on the interaction of Mercury with its solar-system environment.”

The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.

Related Link:

NASA's MESSENGER website: http://www.nasa.gov/messenger

Images, Text, Credits: NASA's Goddard Space Flight Center/Nancy Neal-Jones.

Greetings, Orbiter.ch

vendredi 12 décembre 2014

Signs of Ancient Mars Lakes and Quakes Seen in New Map












NASA - Mars Reconnaissance Orbiter (MRO) logo.

December 12, 2014

video
Simulated Flyover of Mars Canyon Map

Video above: This animation simulates a flyover of a portion of a Martian canyon detailed in a geological map produced by the U.S. Geological Survey and based on observations by the HiRISE camera on NASA's Mars Reconnaissance Orbiter. The landforms include a series of hills called Candor Colles.

Long ago, in the largest canyon system in our solar system, vibrations from "marsquakes" shook soft sediments that had accumulated in Martian lakes.

The shaken sediments formed features that now appear as a series of low hills apparent in a geological map based on NASA images. The map was released today by the U.S. Geological Survey (USGS).

This map of the western Candor Chasma canyon within Mars' Valles Marineris is the highest-resolution Martian geological map ever relased by USGS. It is derived from images taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, which reveal details smaller than a desk. The map is available for download at:

http://pubs.usgs.gov/sim/3309/

Additional information about the map is available at:

http://www.usgs.gov/blogs/features/usgs_top_story/new-usgs-map-of-mars-is-most-detailed-one-yet/

"This new map shows that at the time these sediments were deposited, a part of west Candor Chasma, specifically Condor Colles, contained numerous shallow, spring-fed lakes," said map author Chris Okubo of the USGS Astrogeology Science Center, Flagstaff, Arizona. "These lakes helped to trap wind-blown sand and dust, which accumulated over time and formed the extensive sedimentary deposits we see today."


Image above: Details of hilly terrain within a large Martian canyon are shown on a geological map based on observations from NASA's Mars Reconnaissance Orbiter and produced by the U.S. Geological Survey. Image Credit: NASA/JPL-Caltech/Univ. of Arizona/USGS.

The wet sediments experienced seismic shaking in "marsquakes" related to movement along several large geological faults in the area. A series of low hills resulted.

Valles Marineris is more than 2,500 miles (4,000 kilometers) long. The conditions under which sedimentary deposits in it formed have been an open issue for decades. Possibilities proposed have included accumulation in lakebeds, volcanic eruptions under glaciers within the canyons, and acculation of wind-blown sand and dust.

HiRISE is operated by the University of Arizona, Tucson. The instrument was built by Ball Aerospace & Technologies Corp. of Boulder, Colorado. The Mars Reconnaissance Orbiter Project is managed for NASA's Science Mission Directorate in Washington, by NASA's Jet Propulsion Laboratory, Pasadena, California, a division of the California Institute of Technology, also in Pasadena.

For more information about HiRISE, visit: http://hirise.lpl.arizona.edu

Additional information about MRO is online at: http://www.nasa.gov/mro

Image (mentioned), Video, Text, Credits: NASA/Dwayne Brown/JPL/Guy Webster/U.S. Geological Survey/Jennifer LaVista.

Greetings, Orbiter.ch

ESA and Omega: a watch for astronauts










ESA - European Astronauts patch.

12 December 2014

Swiss watchmaker Omega has announced a new version of its historic space watch, tested and qualified with ESA’s help and drawing on an invention of ESA astronaut Jean-François Clervoy.

Jean-François flew in space three times in the 1990s and began thinking how to improve the wristwatches he wore on his missions. ESA filed a patent based on his ideas for a timepiece that helps astronauts to track their mission events.

Speedmaster Skywalker X-33

One of the new functions allows the wearer to set a date in the past or future down to the second and have the watch calculate how much time has elapsed or is left.

Other features useful for astronauts include flexible programming of multiple alarms with different ring tones.

The Omega company, with its strong links to spaceflight since the first Moon landings in the 1960s, was interested in improving its line of Speedmaster Professional watches, and called on ESA’s patent for the new Speedmaster Skywalker X-33.

Jean François Clervoy

Testing the new watch

The Skywalker has passed rigorous testing at ESA’s technical heart, ESTEC, in Noordwijk, the Netherlands, where many ESA satellites are put through their paces before launch.

The timepiece proved itself capable of surviving anything an astronaut might experience – and more. First, it displayed ruggedness by surviving ESTEC’s shaker simulating the intense vibrations of a launch. Then it was spun in a centrifuge to reach seven times the gravity we feel on Earth, just like an astronaut might endure when returning to our planet.

Speedmaster Skywalker X-33 - back

The next step was to analyse its performance after sitting in a vacuum chamber with temperatures ranging from –45°C to +75°C, a far greater range than an astronaut would ever have to endure.

Finally, the watch was blasted with radiation in Sweden under supervision by France’s ONERA/DESP aerospace centre to simulate space radiation. Each watch was inspected visually and its functions were reviewed before and after each test. 

Ready for spaceflight

The Skywalker model is upgraded with new software loaded in an advanced quartz-based timekeeping unit with a more robust, redesigned case. A dual analogue and digital display provides quick access to multiple time references such as time zones or elapsed time for precise time logging.

President of Omega, Stephen Urquhart, said: “We are delighted that our friends at the European Space Agency have tested and qualified the Speedmaster Skywalker X-33 for all its piloted missions, which is a natural extension of our long relationship with NASA and its space programme.

Speedmaster Skywalker X-33 - dark

“ESA’s abilities and ambitions are extraordinary, as demonstrated by their recent high-profile successes with Rosetta and Philae, and we are proud that their name and endorsement grace the back of this iconic chronograph.”

Jean-François Clervoy concludes: “I am excited and proud to see my invention implemented in a high-precision wristwatch.

“Having Omega in this partnership with ESA, based on our patent, will allow all ESA astronauts to benefit from its innovative functions.”

This invention, owned and protected by ESA, is one of 135 available for commercialisation by non-space industry.

Note: ESA is an intergovernmental organisation and is not involved in the manufacturing or commercialisation of the Omega Skywalker X-33.

Related links:

Omega Speedmaster Skywalker X-33: http://www.omegawatches.com/press/press-release-detail/2847

Jean-François Clervoy: http://www.esa.int/esaKIDSen/SEM0H0DR5GG_LifeinSpace_0.html

ESTEC: http://www.esa.int/About_Us/ESTEC

Images, Text, Credits: ESA/NASA/Omega.

Best regards, Orbiter.ch

jeudi 11 décembre 2014

Galactic Get-Together Has Impressive Light Display












NASA - Chandra X-ray Observatory patch.

December 11, 2014

At this time of year, there are lots of gatherings often decorated with festive lights. When galaxies get together, there is the chance of a spectacular light show as is the case with NGC 2207 and IC 2163

Located about 130 million light years from Earth, in the constellation of Canis Major, this pair of spiral galaxies has been caught in a grazing encounter. NGC 2207 and IC 2163 have hosted three supernova explosions in the past 15 years and have produced one of the most bountiful collections of super bright X-ray lights known. These special objects – known as “ultraluminous X-ray sources” (ULXs) – have been found using data from NASA’s Chandra X-ray Observatory.


Image above: Chandra image of “ultraluminous X-ray sources” (ULXs) found using data from NASA’s Chandra X-ray Observatory. Image Credit: X-ray: NASA/CXC/SAO/S.Mineo et al, Optical: NASA/STScI, Infr.

As in our Milky Way galaxy, NGC 2207 and IC 2163 are sprinkled with many star systems known as X-ray binaries, which consist of a star in a tight orbit around either a neutron star or a “stellar-mass” black hole. The strong gravity of the neutron star or black hole pulls matter from the companion star.  As this matter falls toward the neutron star or black hole, it is heated to millions of degrees and generates X-rays.

ULXs have far brighter X-rays than most “normal” X-ray binaries. The true nature of ULXs is still debated, but they are likely a peculiar type of X-ray binary. The black holes in some ULXs may be heavier than stellar mass black holes and could represent a hypothesized, but as yet unconfirmed, intermediate-mass category of black holes.

This composite image of NGC 2207 and IC 2163 contains Chandra data in pink, optical light data from the Hubble Space Telescope in red, green, and blue (appearing as blue, white, orange, and brown), and infrared data from the Spitzer Space Telescope in red.

The new Chandra image contains about five times more observing time than previous efforts to study ULXs in this galaxy pair. Scientists now tally a total of 28 ULXs between NGC 2207 and IC 2163. Twelve of these vary over a span of several years, including seven that were not detected before because they were in a “quiet” phase during earlier observations.

The scientists involved in studying this system note that there is a strong correlation between the number of X-ray sources in different regions of the galaxies and the rate at which stars are forming in these regions. The composite image shows this correlation through X-ray sources concentrated in the spiral arms of the galaxies, where large amounts of stars are known to be forming. This correlation also suggests that the companion star in the binary systems is young and massive.

Artist's view of Chandra X-ray Observatory. Image Credits: NASA/CXC

Colliding galaxies like this pair are well known to contain intense star formation. Shock waves – like the sonic booms from supersonic aircraft – form during the collision, leading to the collapse of clouds of gas and the formation of star clusters. In fact, researchers estimate that the stars associated with the ULXs are very young and may only be about 10 million years old. In contrast, our Sun is about halfway through its 10-billion-year lifetime. Moreover, analysis shows that stars of various masses are forming in this galaxy pair at a rate equivalent to form 24 stars the mass of our sun per year. In comparison, a galaxy like our Milky Way is expected to spawn new stars at a rate equivalent to only about one to three new suns every year.

A paper describing these results has been accepted for publication in The Astrophysical Journal and is available online. The authors of the paper are Stefano Mineo of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA; Saul Rappaport from the Massachusetts Institute of Technology (MIT) in Cambridge, MA; Alan Levine from MIT; David Pooley from Sam Houston State University in Huntsville, TX; Benjamin Steinhorn from Harvard Medical School in Boston, MA, and Jeroen Homan from MIT.

Related link:

The Astrophysical Journal: http://arxiv.org/abs/1410.2472

For an additional interactive image, podcast, and video on the finding, visit: http://chandra.si.edu

For Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

Images (mentioned), Text, Credits: NASA/Marshall Space Flight Center/Janet Anderson/Chandra X-ray Center/Megan Watzke.

Greetings, Orbiter.ch

Building a Worldwide Genetic Library BRIC-by-BRIC














ISS - International Space Station patch / NASA - STS-131 BRIC Mission logo.

December 11, 2014

A house is only as good as its foundation. Built solid and strong, the resulting structure should last for decades. NASA is laying a strong foundation of life science research with results from a recent investigation on the International Space Station called BRIC-19.

The Biological Research in Canisters (BRIC) series of investigations encapsulates samples inside rectangular containers about the size of shoeboxes. BRIC-19 launched on the fourth SpaceX cargo resupply services mission in September 2014, carrying Arabidopsis thaliana seedlings. The plant -- more commonly known as thale cress -- germinated and spent weeks growing in petri dishes in BRIC-19 before returning to Earth in a Dragon capsule Oct. 25 for examination by scientists.

Thale cress is a model organism. These are plants, microbes or animals that are studied and have a genetic makeup scientists understand. Researchers compare structure and development of organisms exposed to microgravity with what is already known about them.


Image above: NASA astronaut Reid Wiseman chemically "freezes" a set of samples in one of the Biological Research in Canisters for the BRIC-19 investigation on the International Space Station before the sample is returned to Earth. Image Credit: NASA.

Besides the potential benefits to future astronauts, BRIC-19 may also provide insight into basic plant growth. On Earth, gravity affects the way plants and animals grow. Removing that variable can teach us about how living things develop.

"We have been trying to address how plants respond to the stresses and strains of their own growth" said Simon Gilroy, Ph.D., principal investigator for BRIC-19. "How they sense their own weight and lay down strengthening tissues to combat these forces. We needed to remove gravity and watch how the plants develop, making the weightless environment of the space station the only laboratory where we can do this work."

In microgravity, growth and development alter, revealing fundamental processes. Scientists will investigate the differences in development in space and on Earth and how this might be used to tailor plant growth to thrive in space. Understanding how plants grow at a genetic level could improve biomass production on Earth.


Image above: A. View of a PDFU on its side (launch position). B. Five PDFUs plus one temperature logger within a BRIC-PDFU canister prior to closure. C. BRIC-PDFU canister with two pin guards attached. D. Eight BRIC-PDFU canisters stowed within a half middeck locker (as flown on STS-131). Image Credit: NASA.

"From our previous work on gravity and touch sensing, we think we pinpointed a gene that is a master regulator of this process, and engineered mutants where it is either always activated or always off," Gilroy said. "These are the plants we put into space and we are really excited to see whether the plant that has its mechanical response system engineered to be 'always on' grows more like a plant on Earth."

BRIC-19 is one of the first to be part of GeneLab, an open, innovative approach to doing science. GeneLab is a collection of life science investigations designed to produce results that will benefit people living and working in space as well as those on Earth and improve the health of the environment. Through GeneLab, NASA is creating a database where scientists around the world can contribute information and retrieve data from other investigations that could assist in their own studies.

"GeneLab is a collaborative tool, a new research model enabling a variety of scientific developments," said Marshall Porterfield, director of Space Life and Physical Sciences at NASA Headquarters in Washington. "The database will take advantage of research technologies to create a comprehensive and open source of scientific data comparing life in space to life on Earth."

International Space Station (ISS). Image Credit: NASA

Studies on the orbiting laboratory, such as BRIC-19, will generate enormous amounts of raw data. All possible biological molecules -- DNA, RNA, protein and metabolites -- will be extracted from microbes, tissues and organisms at several points during space missions. The raw data will come from mapping the complete genes of the tissues flown in space. The data will be uploaded into a universally available life sciences database that will contain the integrated gene and biomolecular "maps" for the tissues and organisms that have flown aboard the station.

As with constructing any kind of strong, complex facility -- mortaring each carefully laid brick -- building this database will take time. With the help of investigations such as BRIC-19, the end result will be a monument to science to assist in pioneering breakthroughs for years to come.

Related links:

BRIC-19: http://www.nasa.gov/mission_pages/station/research/experiments/1082.html

GeneLab: http://genelab.nasa.gov/

Fourth SpaceX cargo resupply services mission: http://www.nasa.gov/mission_pages/station/research/news/new_investigations_to_station/

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

Images (mentioned), Text, Credits: NASA's Marshall Space Flight Center/International Space Station Program Science Office/Bill Hubscher.

Best regards, Orbiter.ch

mercredi 10 décembre 2014

NASA Study Shows 13-year Record of Drying Amazon Caused Vegetation Declines











NASA logo.

December 10, 2014

A 13-year decline in vegetation in the eastern and southeastern Amazon has been linked to a decade-long rainfall decline in the region, a new NASA-funded study finds.


Image above: Change in Amazon greenness from 2000 to 2012, measured as Normalized Difference Vegetation Index (NDVI). Greener colors represent increased greenness, gray is no change, and yellow represents decreased greenness over the 13-year record. Image Credit: Hilker et al.

With global climate models projecting further drying over the Amazon in the future, the potential loss of vegetation and the associated loss of carbon storage may speed up global climate change.

The study was based on a new way to measure the “greenness” of plants and trees using satellites. While one NASA satellite measured up to 25 percent decline in rainfall across two thirds of the Amazon from 2000 to 2012, a set of different satellite instruments observed a 0.8 percent decline in greenness over the Amazon. The study was published on Nov. 11 in Proceedings of the National Academy of Sciences.

While the decline of green vegetation was small, the area affected was not: 2.1 million square miles (5.4 million square kilometers), equivalent to over half the area of the continental United States. The Amazon's tropical forests are one of the largest sinks for atmospheric carbon dioxide on the planet.

"In other words, if greenness declines, this is an indication that less carbon will be removed from the atmosphere. The carbon storage of the Amazon basin is huge, and losing the ability to take up as much carbon could have global implications for climate change," said lead author Thomas Hilker, remote sensing specialist at Oregon State University in Corvallis, Oregon.

Plants absorb carbon dioxide as part of photosynthesis, the process by which green plants harvest sunlight. The healthier the plants, the greener the forest.

The Amazon basin stores an estimated 120 billion tons of Earth's carbon – that's about 3 times more carbon than humans release into the atmosphere each year. If vegetation becomes less green, it would absorb less of that carbon dioxide. As a result, more of human emissions would remain in the atmosphere, increasing the greenhouse effect that contributes to global warming and alters Earth's climate.

Can't See the Forest for the Clouds

Teasing out changes in vegetation greenness over the Amazon is one of the most challenging problems for satellite remote sensors because there's no tougher place on Earth to observe the surface.

"The wet season has typically 85 to over 95 percent cloudiness from late morning to early afternoon, when NASA satellites make measurements," said co-author and remote sensing specialist Alexei Lyapustin of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Even during the dry season the average cloudiness can be on the order of 50 to 70 percent." Add other atmospheric effects, soot and other particles released from fires during the dryer months, and it's very difficult for the satellite to pick up a clear signal of the surface, Lyapustin added.

Using the Moderate Resolution Imaging Spectroradiometer, or MODIS, instruments aboard NASA's Terra and Aqua satellites, Hilker, Lyapustin and their colleagues developed a new method to detect and remove clouds and other sources of error in the data. It looks at the same location on Earth's surface day after day over time and analysts pick out a pattern that is stable in contrast to the ever-changing clouds and aerosols. This knowledge of what the surface should look like from earlier observations is used later to detect and remove the atmospheric noise caused by clouds and aerosols. It's as if the signal from the ground were a song on a static-y radio station, and by listening to it over and over again for long enough, the new method detects and removes the static. By reducing those errors, they increased the accuracy of the greenness measurements over the Amazon.

"We’re much more confident that this is a gap between clouds where we can measure greenness, but standard algorithms would call it a cloud," said Lyapustin. "We can get more data about the surface, and we can start seeing more subtle changes."

One of the subtle changes visible in the new data-set is how the Amazon's greenness corresponds to one of the long-known causes of rainfall or drought to the Amazon basin: changes in sea surface temperatures in the eastern Pacific Ocean, called the El Nino Southern Oscillation. During warmer and dryer El Nino years, the Amazon appears browner. During cooler La Nina wet years, the Amazon appears greener.

In the past, with greenness data, "it's been hard to tell an El Nino year from a non-El Nino year," said Lyapustin.

The effects of large and more frequent droughts may have lasting impacts that contribute to the long-term decline in vegetation, especially in an increasingly water stressed ecosystem. Many climate models project that in the future, El Nino and La Nina events will become more intense. They also project a northward shift of the main rain belt that provides moisture to the Amazon rainforest, which could further reduce rainfall to the region.

"Our observations are too short to link drying to human causes," Hilker said. "But if, as global circulation models suggest, drying continues, our results provide evidence that this could degrade the Amazonian forest canopies, which would have cascading effects on global carbon and climate dynamics."


Image above: Popcorn clouds above the Amazon rainforest, August 19, 2009. This type of cloud forms during the dry season, likely from water vapor released by plants during transpiration. Image Credit: NASA's Earth Observatory.

Limits of Light vs. Water

The researchers found another subtlety in the Amazon's response to rainfall, which has led to new insights on a question under debate: Are seasonal changes in plant growth more limited by lack of sunlight or lack of water?

The Amazon basin, which consists of grasslands, evergreen forest, and deciduous forest where trees lose their leaves annually, has a wet season and a dry season. Past measurements from satellites have shown either no changes in greening between seasons or increased greening through the end of the dry season, attributed to fewer clouds blocking sunlight from reaching the ground. Measurements from a handful of field stations across the basin, however, indicated the vegetation greenness due to increased sunlight in the dry season would decline once the water in the soils was used up – especially in drought years.

"Our study has helped confirm field-based results across large areas from space," Hilker said. "With our work, we have shown that there is a dry season greening but that under extended drought we get a decline in vegetation greenness."

During the dry season of an average year, the evergreen plants tap into groundwater, bask in the sunlight, and become greener.

"They're deeply rooted so they have plenty of water and they have lots of leaves," said Compton Tucker, a senior research scientist at Goddard who also contributed to the paper. "However, when you come up to one of these really dry periods, [like the drought of 2005 or 2010], then there isn't enough water to take advantage of all the light during the dry season." Water becomes the limiting factor whose effects can carry over from one year into the next if trees and vegetation die off.

For the PNAS paper, please visit: http://www.pnas.org/content/111/45/16041.abstract

Images (mentioned), Text, Credits: NASA's Earth Science News Team/Ellen Gray.

Greetings, Orbiter.ch

The Science of Magnetic Reconnection












NASA - Magnetospheric Multiscale (MMS) mission logo.

December 10, 2014

Understanding vast systems in space requires understanding what's happening on widely different scales. Giant events can turn out to have tiny drivers -- take, for example, what rocked near-Earth space in October 2003. On Oct. 28, 2003, and again on Oct. 29, massive solar flares erupted on the sun, sending X-rays zooming through the solar system. Along with the flares, the sun expelled giant clouds of solar material, called coronal mass ejections, or CMEs. The CMEs slammed into Earth's magnetic field pushed material and energy in toward Earth. This created what's called a geomagnetic storm.

video
MMS Science Overview: The Many Mysteries of MMS

Video above: In March 2015, NASA will launch the Magnetospheric Multiscale mission, or MMS, to learn more about a mysterious process that drives giant explosions in space via a process called magnetic reconnection. Image Credit: NASA's Goddard Space Flight Center/Duberstein.

The Halloween Storms, as they have come to be called, triggered brilliant aurora that could be seen over much of North America -- reaching as far south as Texas. But they also interfered with GPS signals and radio communications, and caused the Federal Aviation Administration to issue their first ever warning to airlines to avoid excess radiation by flying at low altitudes.

Every step leading to these intense storms -- the flare, the CME, the transfer of energy from the CME to Earth's magnetosphere – was ultimately driven by the catalyst of magnetic reconnection. This little understood process can occur in thin layers just miles thick. Yet it can accelerate particles up to nearly the speed of light and can initiate giant eruptions from the sun many times the size of Earth. The effects of reconnection have been observed in space, but the actual reconnection process has only been observed in the laboratory.

In March 2015, NASA will launch a new mission to study magnetic reconnection. The Magnetospheric Multiscale, or MMS, mission will be the first ever mission dedicated to studying this universal process by orbiting Earth to pass directly through nearby magnetic reconnection regions and to observe the minute details of such events.

Reconnection occurs wherever charged gases, called plasma, are present. It's rare on Earth, but plasma makes up 99% of the visible universe. Plasma fuels stars and fills the near vacuum of space. Plasmas behave unlike what we regularly experience on Earth because they travel with their own set of magnetic fields entrapped in the material. Changing magnetic fields affect the way charged particles move and vice versa, so the net effect is a complex, constantly-adjusting system that is sensitive to minute variations.

Under normal conditions, the magnetic field lines inside plasmas don't break or merge with other field lines. But sometimes, as field lines get close to each other, the entire pattern changes and everything realign into a new configuration. The amount of energy released can be formidable. Magnetic reconnection taps into the stored energy of the magnetic field, converting it into heat and kinetic energy that sends particles streaming out along the field lines.

Magnetospheric Multiscale mission, or MMS spacecrafts constellation. Image Credits: NASA

Scientists want to know exactly what conditions, what tipping points, trigger magnetic reconnection events. Much of what we currently know about the small-scale physics of magnetic reconnection comes from theoretical studies, computer models, and laboratory experiments. True understanding, however, requires observing magnetic reconnection up close – so MMS will take its measurements in Earth's own magnetosphere, an ideal natural laboratory in which reconnection can be observed under a wide range of conditions.

Orbiting Earth, MMS will pass through known areas of magnetic reconnection. During its first phase it will travel through reconnection sites on the sun side of Earth. Here the interplanetary magnetic field connects with Earth's magnetic field, transferring particles, momentum and energy to the magnetosphere via magnetic reconnection. During the second phase of its mission, MMS will observe reconnection on the night side of Earth, where that connected field flows around both sides of Earth to a second reconnection point in what's known as the magnetotail, where they then disconnect.

These reconnection sites are so thin, that MMS will fly through them in under a second -- but the MMS sensors have been built to be fast, operating at unprecedented speed. As the spacecraft fly through such a site, they will measure the magnetic and electric fields present as well as the movement of particles.

Armed with this data, scientists will have their first chance to watch magnetic reconnection from the inside, right as it's occurring. By focusing on the small-scale process, scientists open the door to understanding what happens on larger scales throughout the universe.  Determining how reconnection occurs nearby will improve our understanding of how this fundamental process works on the sun, on other stars, throughout space -- and, of course, it will teach us more about giant geomagnetic storms like the Halloween storms, thus helping us safeguard our home planet Earth.

For more on MMS: http://www.nasa.gov/mms

Image (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Karen C. Fox.

Cheers, Orbiter.ch

Rosetta fuels debate on origin of Earth’s oceans












ESA - Rosetta Mission patch.

10 December 2014

ESA’s Rosetta spacecraft has found the water vapour from its target comet to be significantly different to that found on Earth. The discovery fuels the debate on the origin of our planet’s oceans.

The measurements were made in the month following the spacecraft’s arrival at Comet 67P/Churyumov–Gerasimenko on 6 August. It is one of the most anticipated early results of the mission, because the origin of Earth’s water is still an open question.

 First measurements of comet’s water ratio

Image above Credits: Spacecraft: ESA/ATG medialab; Comet: ESA/Rosetta/NavCam; Data: Altwegg et al. 2014 and references therein.

One of the leading hypotheses on Earth’s formation is that it was so hot when it formed 4.6 billion years ago that any original water content should have boiled off. But, today, two thirds of the surface is covered in water, so where did it come from?

In this scenario, it should have been delivered after our planet had cooled down, most likely from collisions with comets and asteroids. The relative contribution of each class of object to our planet’s water supply is, however, still debated.

Comet on 20 November – NavCam

Image above Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

The key to determining where the water originated is in its ‘flavour’, in this case the proportion of deuterium – a form of hydrogen with an additional neutron – to normal hydrogen.

This proportion is an important indicator of the formation and early evolution of the Solar System, with theoretical simulations showing that it should change with distance from the Sun and with time in the first few million years.

One key goal is to compare the value for different kinds of object with that measured for Earth’s oceans, in order to determine how much each type of object may have contributed to Earth’s water.

Comets in particular are unique tools for probing the early Solar System: they harbour material left over from the protoplanetary disc out of which the planets formed, and therefore should reflect the primordial composition of their places of origin.

Kuiper Belt and Oort Cloud in context. Image Credit: NASA

But thanks to the dynamics of the early Solar System, this is not a straightforward process. Long-period comets that hail from the distant Oort cloud originally formed in Uranus–Neptune region, far enough from the Sun that water ice could survive.

They were later scattered to the Solar System’s far outer reaches as a result of gravitational interactions with the gas giant planets as they settled in their orbits.

Conversely, Jupiter-family comets like Rosetta’s comet were thought to have formed further out, in the Kuiper Belt beyond Neptune. Occasionally these bodies are disrupted from this location and sent towards the inner Solar System, where their orbits become controlled by the gravitational influence of Jupiter.

Indeed, Rosetta’s comet now travels around the Sun between the orbits of Earth and Mars at its closest and just beyond Jupiter at its furthest, with a period of about 6.5 years.

Previous measurements of the deuterium/hydrogen (D/H) ratio in other comets have shown a wide range of values. Of the 11 comets for which measurements have been made, it is only the Jupiter-family Comet 103P/Hartley 2 that was found to match the composition of Earth’s water, in observations made by ESA’s Herschel mission in 2011.

Deuterium-to-hydrogen in the Solar System

Graphic above Credits: Data from Altwegg et al. 2014 and references therein.

By contrast, meteorites originally hailing from asteroids in the Asteroid Belt also match the composition of Earth’s water. Thus, despite the fact that asteroids have a much lower overall water content, impacts by a large number of them could still have resulted in Earth’s oceans.

It is against this backdrop that Rosetta’s investigations are important. Interestingly, the D/H ratio measured by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, or ROSINA, is more than three times greater than for Earth’s oceans and for its Jupiter-family companion, Comet Hartley 2. Indeed, it is even higher than measured for any Oort cloud comet as well.

“This surprising finding could indicate a diverse origin for the Jupiter-family comets – perhaps they formed over a wider range of distances in the young Solar System than we previously thought,” says Kathrin Altwegg, principal investigator for ROSINA and lead author of the paper reporting the results in the journal Science this week.

“Our finding also rules out the idea that Jupiter-family comets contain solely Earth ocean-like water, and adds weight to models that place more emphasis on asteroids as the main delivery mechanism for Earth’s oceans.”

“We knew that Rosetta’s in situ analysis of this comet was always going to throw up surprises for the bigger picture of Solar System science, and this outstanding observation certainly adds fuel to the debate about the origin of Earth’s water,” says Matt Taylor, ESA’s Rosetta project scientist.

“As Rosetta continues to follow the comet on its orbit around the Sun throughout next year, we’ll be keeping a close watch on how it evolves and behaves, which will give us unique insight into the mysterious world of comets and their contribution to our understanding of the evolution of the Solar System.”

Notes for Editors
“67P/Churyumov-Gerasimenko, a Jupiter Family Comet with a high D/H ratio” by K. Altwegg et al., is published in the 10 December 2014 issue of Science.

ROSINA is the Rosetta Orbiter Sensor for Ion and Neutral Analysis instrument and comprises two mass spectrometers: the double focusing mass spectrometer (DFMS) and the reflectron time of flight mass spectrometer (RTOF) – and the cometary pressure sensor (COPS). The measurements reported here were conducted with DFMS.

The analysis is based on the results of over 50 spectra collected between 8 August and 5 September 2014, and the D/H ratio was derived from measurements of HD16O/H2 16O.

The ROSINA team is led by Kathrin Altwegg of the University of Bern, Switzerland.

More about Rosetta

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together. Philae landed on the comet on 12 November 2014. Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

More about...

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

In depth:

Rosetta in depth: http://sci.esa.int/rosetta

Related links:
Rosetta at Astrium: http://www.astrium.eads.net/en/programme/rosetta-1go.html

Rosetta at DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10394/

Ground-based comet observation campaign: http://www.rosetta-campaign.net/home

Images (mentioned), Text, Credit: ESA.

Best regards, Orbiter.ch

Saturn's Moons: What a Difference a Decade Makes












NASA - Cassini Mission to Saturn patch.

December 10, 2014

Maps of Enceladus warped. Credit: JPL-Caltech

Almost immediately after NASA's twin Voyager spacecraft made their brief visits to Saturn in the early 1980s, scientists were hungry for more. The Voyagers had offered them only a brief glimpse of a family of new worlds -- Saturn's icy moons -- and the researchers were eager to spend more time among those bodies.

The successor to the Voyagers at Saturn, NASA's Cassini spacecraft, has spent the past 10 years collecting images and other data as it has toured the Ringed Planet and its family of satellites. New color maps, produced from this trove of data, show that Cassini has essentially fulfilled one of its many mission objectives: producing global maps of Saturn's six major icy moons.

These are the large Saturnian moons, excluding haze-covered Titan, known before the start of the Space Age: Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus. Aside from a gap in the north polar region of Enceladus (to be filled in next year), and some areas of Iapetus, this objective is now more or less complete.

Swipe between the Voyager and Cassini maps below to see how 10 years have changed our view of Saturn's moons.

Maps of Enceladus - 2014. Credit: JPL-Caltech

Maps of Mimas - 2014. Credit: JPL-Caltech
 
Maps of Tethys - 2014. Credit: JPL-Caltech

Maps of Dione - 2014. Credit: JPL-Caltech
 
Maps of Rhea - 2014. Credit: JPL-Caltech

Maps of Iapetus - 2014. Credit: JPL-Caltech

The new maps are the best global, color maps of these moons to date, and the first to show natural brightness variations and high-resolution color together. Colors in the maps represent a broader range than human vision, extending slightly into infrared and ultraviolet wavelengths. Differences in color across the moons' surfaces that are subtle in natural-color views become much easier to study in these enhanced colors.

Cassini's enhanced color views have yielded several important discoveries about the icy moons. The most obvious are differences in color and brightness between the two hemispheres of Tethys, Dione and Rhea. The dark reddish colors on the moons' trailing hemispheres are due to alteration by charged particles and radiation in Saturn's magnetosphere. Except for Mimas and Iapetus, the blander leading hemispheres of these moons -- that is, the sides that always face forward as the moons orbit Saturn -- are all coated with icy dust from Saturn's E-ring, formed from tiny particles erupting from the south pole of Enceladus.

Enceladus itself displays a variety of colorful features. Some of the gas and dust being vented into space from large fractures near the moon's south pole returns to the surface and paints Enceladus with a fresh coating. The yellow and magenta tones in Cassini's color map are thought to be due to differences in the thickness of these deposits. Many of the most recently formed fractures on Enceladus, those near the south pole in particular, have a stronger ultraviolet signature, which appears bluish in these maps. Their color may be due to large-grained ice exposed on the surface, not unlike blue ice seen in some places in Earth's Arctic.

The new maps were produced by Paul Schenk, a participating scientist with the Cassini imaging team based at the Lunar and Planetary Institute in Houston.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory in Pasadena, California, manages the Cassini and Voyager missions for NASA's Science Mission Directorate in Washington. The two Voyager spacecraft and the Cassini orbiter, along with its two onboard cameras, were designed, developed and assembled at JPL. The Cassini imaging team consists of scientists from the United States, England, France and Germany. The imaging team is based at the Space Science Institute in Boulder, Colorado.

More information about Cassini is available at the following sites:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images (mentioned), Text, Credits: NASA/JPL/Preston Dyches.

Greetings, Orbiter.ch

mardi 9 décembre 2014

ATV views Space Station as never seen before












ESA - ATV5 Georges Lemaître Mission logo.

9 December 2014

ESA’s fifth and last Automated Transfer Vehicle tested a new technique before docking with the International Space Station in August, at the same time revealing the orbital complex in a new light.

LIRIS on ATV

ATV Georges Lemaître demonstrated a set of European sensors that offers future improvements on the autonomous rendezvous and docking that these ferries have completed five times since 2008. ESA’s goal is to perform an automated rendezvous further from home – perhaps near Mars or with an ‘uncooperative’ target such as an inert object.

Seeing through an eclipse

During Georges Lemaître’s rendezvous using its proven system, the Laser Infrared Imaging Sensors, or LIRIS, experiment was turned on some two and a half hours and 3500 m from the Space Station. All of the sensors worked as expected and a large amount of data was recorded and stored on hard disks in ATV’s cargo hold.

The disks were retrieved by ESA astronaut Alexander Gerst on 29 August and returned to Earth in Soyuz TMA-12M in September. The information is now being compared against the results from ATV’s normal navigation sensors.

With ATV-5 pointing directly at the Station, the LIRIS infrared cameras tracked the weightless research centre perfectly despite several 30-minute periods in darkness when the Sun was eclipsed by Earth and traditional cameras would have gone blind.

Infrared Space Station

The image above was taken 70 m from the Station – the first showing the complex in this configuration. Ahead of an ATV docking, the Station turns its solar wings to avoid GPS navigation signals bouncing off the structure and confusing the incoming craft.

Four days before docking, ATV flew 7 km below the Station to check the long-range capability of the infrared cameras. A first look at the readings confirms LIRIS’ ability to track targets from a distance.

Laser Radar

LIRIS includes a lidar – like a radar but using light – that pulses laser beams over a mirror to collect 3D data at high resolution. The lidar also registers the amount of reflected light, which can provide clues on the type of material it is scanning.

Station painted by laser radar

The image on the left shows how far each element of the Space Station is from ATV-5, with arbitrarily chosen colours corresponding to their distance from LIRIS.

Russia’s Zvezda module, where Georges Lemaître now sits, shows up in green from 30 m, while the Soyuz was 15 m further away (yellow). The Station’s main truss is in purple, 40 m from Zvezda.

The image on the right was created from the same data but shows how much light was reflected from each point. The Station’s retroreflector used for ATV’s normal laser docking sensors shows up brightly, just as the designers intended.

Spacecraft docking on their own

The advantage of the LIRIS approach is that it scans objects and gathers information about them without a dedicated communications link or hardware installed on the targets.

The sensors can track targets equally well during darkness and provide detailed 3D maps of an object, increasing the autonomy of a craft and allowing it to navigate around a target. LIRIS-type systems are needed for future ventures deeper into space and to help remove large pieces of debris from Earth orbit.

LIRIS was developed by Airbus Defence and Space, with German company Jena Optronik providing the lidar and France’s Sodern the infrared cameras.

Related links:

ATV’s normal navigation sensors: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV/ATV_flight_phases#rdv

ATV-5: Georges Lemaître: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV/Fifth_ATV_named_after_Georges_Lemaitre

ATV Control Centre: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV/ATV_Control_Centre

Images, Text, Credits: ESA/NASA/Roscosmos, O. Artemyev/Sodern/Jena-Optronik.

Best regards, Orbiter.ch

lundi 8 décembre 2014

Microgravity Helping Us Understand Immune System’s Tiny Warriors












ISS - International Space Station logo.

December 8, 2014

International Space Station (ISS). Image Credit: NASA

Scary threats to human health dominate the news these days. Space travel may help scientists strengthen our bodies’ ability to fight such threats. Two upcoming studies on leukocytes—human defense cells—seek to understand how these tiny warriors mount their defense.

Astronauts’ immune systems don't work as well in microgravity as on Earth. Knowing why is key to protecting astronauts' health and could lead to new treatments on Earth for those with impaired immune systems.

TripleLux-B launches to the International Space Station in December 2014 on SpaceX's fifth commercial resupply mission. In February 2015, TripleLux-A will follow aboard SpaceX's sixth mission. Both investigations examine cellular changes in the immune system and separate out the specific effects of microgravity from other spaceflight factors like radiation.

In human immune systems, large white blood cells called leukocytes are the first line of defense against infection. These cells engulf foreign bodies and produce a burst of reactive oxygen that helps destroy invaders.


Images above: The Advanced Experimental Containment (AEC) hardware for the TripleLux experiments. Image Credit: ESA.

TripleLux-A will test leukocytes in rats on the space station. TripleLux-B will explore how microgravity causes changes in cellular-level genetic mechanisms, including DNA repair. It will compare microgravity-induced changes in rat leukocytes with similar immune system cells in blue mussels.

These mussel and rat cells are considered model organisms; they have characteristics making them easy to maintain, reproduce and study in a laboratory. The mussels, for example, generate large numbers of immune system cells that are easy to collect without harming the animal.

“Our goal with TripleLux-B is to find out whether the cells of the immune system of the mussel, which is older in an evolutionary sense, are affected in the same way as those in the immune system of an astronaut—or, in this case, a rat,” says Principal Investigator Peter-Diedrich Hansen, Ph.D., professor of toxicology and senior research scientist at Germany’s Berlin Institute for Technology. “And if not, what makes it different?”

The experiments will use a safe substitute for bacteria called zymosan, which is produced from yeast cells. Researchers will use a luminescent chemical called Luminol to detect oxygen bursts occurring after the tiny warriors devour the invaders.


Image above: Immune system cells after oxygen burst reaction and stained with fluorescent dye FITC, magnified 20 times. Image Credit: ESA.

Previous studies showed gravity changes affect immune system cells. Experiments during parabolic flights and in centrifuges demonstrated rapid and reversible alterations to the immune system process. However, these studies are limited because microgravity conditions either were short-lived or artificially created. Conducting experiments on the space station provides prolonged exposure to microgravity and an opportunity to observe the leukocytes' oxygen-burst reactions.

“Gravitational conditions on Earth could have been one of the requirements for development of the machinery of the oxidative burst reaction,” says TripleLux-A Principle Investigator Oliver Ullrich, professor of anatomy and space biotechnology in Switzerland and Germany. “A major challenge is finding out if our cellular machinery is able to work without gravitational force or if our cellular architecture will keep us dependent on Earth’s gravity.” This research could help scientists develop ways to manage or prevent microgravity-induced changes in immune system function or, simply put, make these tiny warriors space-ready.

To clarify whether microgravity, radiation or a combination is responsible for immune system changes during spaceflight, researchers will expose the cells to microgravity and simulated Earth gravity. The latter will be created in the European Space Agency’s BIOLAB centrifuge. Data from these conditions will be compared with measurements of accumulated radiation doses from a reference experiment on the ground. Researchers will assess whether microgravity and radiation work together to create a stronger effect. This investigation must be performed aboard the space station because cosmic radiation cannot be simulated on Earth.


Image above: Biolab is designed to support biological experiments. Image Credit: ESA/D. Ducros.

A measurement device developed for these experiments could potentially be adapted into a tool for monitoring astronauts' immune systems during long-duration spaceflights. The investigations also are an opportunity to test this device.

These experiments on how space affects the immune system may help us better employ its tiny warriors to keep us healthy no matter what invaders attack.

Related links:

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

TripleLux-A: http://www.nasa.gov/mission_pages/station/research/experiments/382.html

TripleLux-B: http://www.nasa.gov/mission_pages/station/research/experiments/361.html

SpaceX's fifth commercial resupply mission: http://www.nasa.gov/mission_pages/station/structure/launch/index.html

European Space Agency’s BIOLAB: http://www.esa.int/Our_Activities/Human_Spaceflight/Columbus/Biolab

Images (mentioned), Text, Credits: NASA Johnson Space Center/Melissa Gaskill.

Greetings, Orbiter.ch

NASA’s Curiosity Rover Finds Clues to How Water Helped Shape Martian Landscape












NASA - Mars Science Laboratory (MSL) patch.

December 8, 2014

Observations by NASA’s Curiosity Rover indicate Mars' Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years.


Image above: This illustration depicts a lake of water partially filling Mars' Gale Crater, receiving runoff from snow melting on the crater's northern rim. Image Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS.

This interpretation of Curiosity’s finds in Gale Crater suggests ancient Mars maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet.

"If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” said Ashwin Vasavada, Curiosity deputy project scientist at NASA's Jet Propulsion Laboratory in Pasadena. “A more radical explanation is that Mars' ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don't know how the atmosphere did that."


Image above: This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake. Image Credit: NASA/JPL-Caltech/MSSS.

Why this layered mountain sits in a crater has been a challenging question for researchers. Mount Sharp stands about 3 miles (5 kilometers) tall, its lower flanks exposing hundreds of rock layers. The rock layers – alternating between lake, river and wind deposits -- bear witness to the repeated filling and evaporation of a Martian lake much larger and longer-lasting than any previously examined close-up.

"We are making headway in solving the mystery of Mount Sharp," said Curiosity Project Scientist John Grotzinger of the California Institute of Technology in Pasadena, California. "Where there's now a mountain, there may have once been a series of lakes."


Image above: This image from Curiosity's Mastcam shows inclined beds of sandstone interpreted as the deposits of small deltas fed by rivers flowing down from the Gale Crater rim and building out into a lake where Mount Sharp is now. It was taken March 13, 2014, just north of the "Kimberley" waypoint. Image Credit: NASA/JPL-Caltech/MSSS.

Curiosity currently is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high dubbed the Murray formation. Rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle occurred over and over again.

"The great thing about a lake that occurs repeatedly, over and over, is that each time it comes back it is another experiment to tell you how the environment works," Grotzinger said. "As Curiosity climbs higher on Mount Sharp, we will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact. We may see how the chemistry changed in the lakes over time. This is a hypothesis supported by what we have observed so far, providing a framework for testing in the coming year."


Image above: This March 25, 2014, view from the Mastcam on NASA's Curiosity Mars rover looks southward at the Kimberley waypoint. In the foreground, multiple sandstone beds show systematic inclination to the south suggesting progressive build-out of delta sediments in that direction (toward Mount Sharp). Image Credit: NASA/JPL-Caltech/MSSS.

After the crater filled to a height of at least a few hundred yards and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.

On the 5-mile (8-kilometer) journey from Curiosity’s 2012 landing site to its current work site at the base of Mount Sharp, the rover uncovered clues about the changing shape of the crater floor during the era of lakes.


Image above: This image shows inclined beds characteristic of delta deposits where a stream entered a lake, but at a higher elevation and farther south than other delta deposits north of Mount Sharp. This suggests multiple episodes of delta growth building southward. It is from Curiosity's Mastcam. Image Credit: NASA/JPL-Caltech/MSSS.

"We found sedimentary rocks suggestive of small, ancient deltas stacked on top of one another," said Curiosity science team member Sanjeev Gupta of Imperial College in London. "Curiosity crossed a boundary from an environment dominated by rivers to an environment dominated by lakes."

Despite earlier evidence from several Mars missions that pointed to wet environments on ancient Mars, modeling of the ancient climate has yet to identify the conditions that could have produced long periods warm enough for stable water on the surface.


Image above: This image shows an example of a thin-laminated, evenly stratified rock type that occurs in the "Pahrump Hills" outcrop at the base of Mount Sharp on Mars. The Mastcam on NASA's Curiosity Mars rover acquired this view on Oct. 28, 2014. This type of rock can form under a lake. Image Credit: NASA/JPL-Caltech/MSSS.

NASA's Mars Science Laboratory Project uses Curiosity to assess ancient, potentially habitable environments and the significant changes the Martian environment has experienced over millions of years. This project is one element of NASA's ongoing Mars research and preparation for a human mission to the planet in the 2030s.

"Knowledge we're gaining about Mars' environmental evolution by deciphering how Mount Sharp formed will also help guide plans for future missions to seek signs of Martian life," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington.

video
 Curiosity Rover Report: The Making of Mount Sharp (Dec. 8, 2014)

Video above: Layers of intrigue: See how a Martian mountain inside of a crater came to be. Video Credit: NASA Jet Propulsion Laboratory.

JPL, managed by the California Institute of Technology, built the rover and manages the project for NASA's Science Mission Directorate in Washington.

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

Follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity

Images (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/JPL/Guy Webster.

Best regards, Orbiter.ch