vendredi 18 décembre 2015
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.
- 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.
Publié par Orbiter.ch à 15:45
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.
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.
Publié par Orbiter.ch à 13:38
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.
Wide Field Planetary Camera 2: https://www.spacetelescope.org/about/general/instruments/wfpc2/
Hubble Space Telescope websites:
Image, Video, Credits: NASA & ESA, Acknowledgement: Judy Schmidt/Text Credits: European Space Agency/NASA/Ashley Morrow.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 13:27
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:
For more information about Lunar Reconnaissance Orbiter (LRO). visit:
Images, Text, Credits: NASA/Goddard/Arizona State University/Bill Steigerwald.
Publié par Orbiter.ch à 09:45
jeudi 17 décembre 2015
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:
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.
LHC experiments back in business at record energy ( LHC Run 2):
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
Publié par Orbiter.ch à 18:08
New Findings from NASA’s New Horizons Shape Understanding of Pluto and its Moons
NASA - New Horizons Mission logo.
Dec. 17, 2015
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
Publié par Orbiter.ch à 13:54
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.
Publié par Orbiter.ch à 13:42
NASA’s LADEE Mission Shows the Force of Meteoroid Strikes on Lunar Exosphere
NASA - LADEE Mission patch.
Dec. 17, 2015
NASA scientists have released new findings about the moon’s tenuous exosphere – the thin layer of gas surrounding the moon that’s one 25-trillionth the density of Earth’s atmosphere. The data reveal, for the first time, that meteoroid strikes cause a predictable increase in the abundance of two key elements within the lunar exosphere.
Image above: Artist’s concept of NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in orbit above the moon. Image Credits: NASA Ames/Dana Berry.
Physical processes such as meteoroid stream impacts, the bombardment of helium and hydrogen particles from the sun, thermal absorption, and space weathering constantly modify the moon’s surface as they work within the lunar exosphere. NASA’s Lunar Atmosphere and Dust Environment Explorer, or LADEE, spacecraft observed an increase in exospheric gases when the rain of meteoroid impacts increases during a stream. These interplanetary grains can hit the lunar surface at speeds exceeding 21 miles (34 kilometers) per second, releasing immense heat, and vaporizing part of the soil and meteoroids themselves.
Within this vapor are sodium and potassium gases. LADEE’s Ultraviolet Visible Spectrometer (UVS) instrument measured levels of sodium and potassium around the moon every 12 hours for more than five months. These frequent readings revealed a dynamic rise of gas levels in the exosphere as meteor streams bombarded the moon, with the concentrations of both elements returning to normal background levels after the stream passed. Interestingly, the time it took to return to “normal” was dramatically different for the two gases, with potassium returning to its pre-shower state within days, while sodium took several months.
The findings are being presented at this week’s meeting of the American Geophysical Union in San Francisco and appear in the journal Science. Researchers will incorporate these observations into exosphere models of the moon and similar bodies to help NASA unravel the mysteries of how our solar system originated and is changing over time.
“To understand the moon’s exosphere requires insight into the processes controlling it, including the interaction of meteoroid showers as well as solar wind bombardment and ultraviolet radiation of the surface,” said Anthony Colaprete, researcher at NASA’s Ames Research Center in Moffett Field, California, and principal investigator of the UVS instrument. “Understanding how these processes modify the exosphere allows researchers to infer its original state. Since these processes are ubiquitous across the solar system, knowledge gained by examining the moon’s exosphere can be applied to a range of other bodies, granting us greater insight into their evolution through time.”
A majority of bodies in the solar system are small and are considered “airless,” with exospheres in place of dense atmospheres. Our moon, icy moons within our solar system, the planet Mercury, asteroids and even Pluto are examples of small bodies with known exospheres that start from their surface – surface-boundary exospheres. Larger bodies, such as Earth, also have tenuous exospheres as the outermost layer of their atmospheres.
Our moon can act as a nearby laboratory for learning more about both the soil composition and the processes active in the atmospheres across our solar system and beyond.
LADEE Mission Animation: Meteorite Impact on the Moon
Video above: In this LADEE mission animation, a meteorite impacts the lunar surface. Video Credits: NASA/Ames.
“These observations enable us to constrain the physical processes that contribute to the lunar exosphere,” said Menelaos Sarantos of NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, and the University of Maryland, Baltimore County, and co-author of the paper. “We’re using these findings to build new exosphere models of how the space environment interacts with the surfaces of airless bodies, which we can use to better predict the processes and behaviors around similar bodies.”
LADEE was launched in September 2013 and orbited the moon for about six months. The robotic mission orbited the moon to gather detailed information about the lunar atmosphere, conditions near the surface, and environmental influences on lunar dust. Ames was responsible for the LADEE spacecraft design, development, testing and mission operations, in addition to managing the overall mission.
For more information about Lunar Atmosphere Dust Environment Explorer (LADEE), visit: http://www.nasa.gov/mission_pages/ladee/main/index.html
Image (mentioned), Video (mentioned), Text, Credits: NASA/Ames Research Center/Darryl E. Waller.
Publié par Orbiter.ch à 13:20
NuSTAR Finds Cosmic Clumpy Doughnut Around Black Hole
NASA - NuSTAR Mission patch.
Dec. 17, 2015
Image above: Galaxy 1068 can be seen in close-up in this view from NASA's Hubble Space Telescope. NuSTAR's high-energy X-rays eyes were able to obtain the best view yet into the hidden lair of the galaxy's central, supermassive black hole. This active black hole -- shown as an illustration in the zoomed-in inset -- is one of the most obscured known, meaning that it is surrounded by extremely thick clouds of gas and dust. t this is true for even the thickest of donuts. Image Credits: NASA/JPL-Caltech.
The most massive black holes in the universe are often encircled by thick, doughnut-shaped disks of gas and dust. This deep-space doughnut material ultimately feeds and nourishes the growing black holes tucked inside.
Until recently, telescopes weren't able to penetrate some of these doughnuts, also known as tori.
"Originally, we thought that some black holes were hidden behind walls or screens of material that could not be seen through," said Andrea Marinucci of the Roma Tre University in Italy, lead author of a new Monthly Notices of the Royal Astronomical Society study describing results from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency's XMM-Newton space observatory.
With its X-ray vision, NuSTAR recently peered inside one of the densest of these doughnuts known to surround a supermassive black hole. This black hole lies at the center of a well-studied spiral galaxy called NGC 1068, located 47 million light-years away in the Cetus constellation.
The observations revealed a clumpy, cosmic doughnut.
"The rotating material is not a simple, rounded doughnut as originally thought, but clumpy," said Marinucci.
Doughnut-shaped disks of gas and dust around supermassive black holes were first proposed in the mid-1980s to explain why some black holes are hidden behind gas and dust, while others are not. The idea is that the orientation of the doughnut relative to Earth affects the way we perceive a black hole and its intense radiation. If the doughnut is viewed edge-on, the black hole is blocked. If the doughnut is viewed face-on, the black hole and its surrounding, blazing materials can be detected. This idea is referred to as the unified model because it neatly joins together the different black hole types, based solely upon orientation.
Image above: Galaxy 1068 is shown in visible light and X-rays in this composite image. High-energy X-rays (magenta) captured by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, are overlaid on visible-light images from both NASA's Hubble Space Telescope and the Sloan Digital Sky Survey. The X-ray light is coming from an active supermassive black hole, also known as a quasar, in the center of the galaxy. This supermassive black hole has been extensively studied due to its relatively close proximity to our galaxy. Image Credits: NASA/JPL-Caltech/Roma Tre Univ.
In the past decade, astronomers have been finding hints that these doughnuts aren't as smoothly shaped as once thought. They are more like defective, lumpy doughnuts that a doughnut shop might throw away.
The new discovery is the first time this clumpiness has been observed in an ultra-thick doughnut, and supports the idea that this phenomenon may be common. The research is important for understanding the growth and evolution of massive black holes and their host galaxies.
"We don't fully understand why some supermassive black holes are so heavily obscured, or why the surrounding material is clumpy," said co-author Poshak Gandhi of the University of Southampton in the United Kingdom. "This is a subject of hot research."
Both NuSTAR and XMM-Newton observed the supermassive black hole in NGC 1068 simultaneously on two occasions between 2014 to 2015. On one of those occasions, in August 2014, NuSTAR observed a spike in brightness. NuSTAR observes X-rays in a higher-energy range than XMM-Newton, and those high-energy X-rays can uniquely pierce thick clouds around the black hole. The scientists say the spike in high-energy X-rays was due to a clearing in the thickness of the material entombing the supermassive black hole.
"It's like a cloudy day, when the clouds partially move away from the sun to let more light shine through," said Marinucci.
NGC 1068 is well known to astronomers as the first black hole to give birth to the unification idea. “But it is only with NuSTAR that we now have a direct glimpse of its black hole through such clouds, albeit fleeting, allowing a better test of the unification concept," said Marinucci.
The team says that future research will address the question of what causes the unevenness in doughnuts. The answer could come in many flavors. It's possible that a black hole generates turbulence as it chomps on nearby material. Or, the energy given off by young stars could stir up turbulence, which would then percolate outward through the doughnut. Another possibility is that the clumps may come from material falling onto the doughnut. As galaxies form, material migrates toward the center, where the density and gravity is greatest. The material tends to fall in clumps, almost like a falling stream of water condensing into droplets as it hits the ground.
"We'd like to figure out if the unevenness of the material is being generated from outside the doughnut, or within it," said Gandhi.
"These coordinated observations with NuSTAR and XMM-Newton show yet again the exciting science possible when these satellites work together," said Daniel Stern, NuSTAR project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.
For more information on NuSTAR, visit:
Images (mentioned), Text, Credits: NASA/JPL/Whitney Clavin/Tony Greicius.
Publié par Orbiter.ch à 10:18
Hubble Sees the Force Awakening in a Newborn Star
NASA - Hubble Space Telescope patch.
Dec. 17, 2015
Just in time for the release of the movie “Star Wars Episode VII: The Force Awakens,” NASA’s Hubble Space Telescope has photographed what looks like a cosmic, double-bladed lightsaber.
In the center of the image, partially obscured by a dark, Jedi-like cloak of dust, a newborn star shoots twin jets out into space as a sort of birth announcement to the universe.
Celestial Lightsabers: The Stellar Jets of HH 24
Video above: This sequence combines a two-dimensional zoom and a three-dimensional flight to explore the Hubble Space Telescope's striking image of the Herbig-Haro object known as HH 24. Video Credits: NASA, ESA, and F. Summers, G. Bacon, Z. Levay, and L. Frattare (Viz 3D Team, STScI).
“Science fiction has been an inspiration to generations of scientists and engineers, and the film series Star Wars is no exception,” said John Grunsfeld, astronaut and associate administrator for the NASA Science Mission directorate. “There is no stronger case for the motivational power of real science than the discoveries that come from the Hubble Space Telescope as it unravels the mysteries of the universe."
This celestial lightsaber does not lie in a galaxy far, far away, but rather inside our home galaxy, the Milky Way. It’s inside a turbulent birthing ground for new stars known as the Orion B molecular cloud complex, located 1,350 light-years away.
Image above: This celestial lightsaber does not lie in a galaxy far, far away, but rather inside our home galaxy, the Milky Way. It's inside a turbulent birthing ground for new stars known as the Orion B molecular cloud complex, located 1,350 light-years away. Image Credits: NASA/ESA.
When stars form within giant clouds of cool molecular hydrogen, some of the surrounding material collapses under gravity to form a rotating, flattened disk encircling the newborn star.
Though planets will later congeal in the disk, at this early stage the protostar is feeding on the disk with a Jabba-like appetite. Gas from the disk rains down onto the protostar and engorges it. Superheated material spills away and is shot outward from the star in opposite directions along an uncluttered escape route — the star’s rotation axis.
Shock fronts develop along the jets and heat the surrounding gas to thousands of degrees Fahrenheit. The jets collide with the surrounding gas and dust and clear vast spaces, like a stream of water plowing into a hill of sand. The shock fronts form tangled, knotted clumps of nebulosity and are collectively known as Herbig-Haro (HH) objects. The prominent HH object shown in this image is HH 24.
Just to the right of the cloaked star, a couple of bright points are young stars peeking through and showing off their own faint lightsabers — including one that has bored a tunnel through the cloud towards the upper-right side of the picture.
Image above: This is an artist's concept of the fireworks that accompany the birth of a star. The young stellar object is encircled by a pancake-shaped disk of dust and gas left over from the collapse of the nebula that formed the star. Gas falls onto the newly forming star and is heated to the point that some of it escapes along the star's spin axis. Intertwined by magnetic fields, the bipolar jets blast into space at over 100,000 miles per hour. As seen from far away, they resemble a double-bladed lightsaber from the Star Wars film series. Image Credits: NASA, ESA, and A. Feild (STScI).
Overall, just a handful of HH jets have been spotted in this region in visible light, and about the same number in the infrared. Hubble’s observations for this image were performed in infrared light, which enabled the telescope to peer through the gas and dust cocooning the newly forming stars and capture a clear view of the HH objects.
These young stellar jets are ideal targets for NASA’s upcoming James Webb Space Telescope, which will have even greater infrared wavelength vision to see deeper into the dust surrounding newly forming stars.
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.
For images and more information, visit:
Images (mentioned), Video (mentioned), Text, Credits: NASA/ESA/D. Padgett (GSFC)/T. Megeath (U. Toledo)/B. Reipurth (U. Hawaii)/Space Telescope Science Institute/Ray Villard/Ashley Morrow.
Publié par Orbiter.ch à 09:58
Soyuz Lifts Off From French Guiana With Two Galileo FOC Spacecrafts
ESA / ARIANESPACE - Flight VS13 Mission poster / ESA - Galileo Programme logo.
Dec 17, 2015
Image above: Flight VS13 was the 13th Soyuz liftoff performed from French Guiana since this vehicle’s 2011 introduction at the Spaceport.
Ascending from the Spaceport at precisely 8:51 a.m. local time in French Guiana (12:51 GMT / UT), the medium-lift vehicle performed a mission of nearly 3 hours and 48 minutes to deploy its two Galileo FOC (Full Operational Capability) satellite passengers – which are the constellation’s 11th and 12th spacecraft to be orbited to date.
Soyuz Lifts Off From French Guiana With Two Galileo FOC Spacecrafts
After an initial powered phase of Soyuz’ three lower stages, the flight – designated VS13 in Arianespace’s numbering system – included two burns of the Fregat upper stage, separated by a three-plus-hour ballistic phase, to place the two satellites at their targeted deployment point.
Galileo FOC configuration
The record number of Arianespace launcher family missions performed during the year were composed of six heavy-lift Ariane 5 flights, three with the medium-lift Soyuz and three using the lightweight Vega – evenly divided between institutional and commercial customers.
Galileo 11 & 12 satellites separation
Additional records set by Arianespace include the largest total payload mass injected into geostationary transfer orbit in a year (greater than 53 metric tons) and the highest order intake in one year since the company’s creation (representing a value of nearly 2.4 billion euros).
Galileo: a success for Europe
At full capability, the Galileo program – supported by Arianespace launches – will provide a European-operated navigation system to deliver highly accurate global positioning services through a satellite constellation in medium-Earth orbit and its associated ground infrastructure.
Galileo’s FOC satellite in orbit
The European Commission is funding and executing Galileo’s FOC phase, with the European Space Agency (ESA) designated as the system’s development and sourcing agent. Prime contractor OHB System in Bremen, Germany produced the satellites, and their onboard payloads are supplied by UK-based Surrey Satellite Technology Limited (SSTL).
Flight VS13’s success continues the key role of Arianespace – as well as Soyuz – in Galileo’s development. The medium-lift workhorse lofted a total of four satellites in the program’s IOV (In-Orbit Validation) phase in 2011 and 2012; plus the first eight FOC spacecraft on four separate missions – including today’s – performed over the past two years.
30-satellite Galileo constellation
The Galileo system will be further expanded next year on an Ariane 5 mission that will carry four more satellites – with half of the constellation to be deployed at this point – followed in 2017-2018 with two additional flights using Ariane 5s, plus one with Soyuz.
For more information about ARIANESPACE, visit: http://www.arianespace.com/
For more information about Galileo navigation system, visit: http://www.esa.int/Our_Activities/Navigation
Learn more about ESA at http://www.esa.int
Images, Video, Text, Credits: ARIANESPACE/ESA/P. Carril/Orbiter.ch Aerospace.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 08:56
mercredi 16 décembre 2015
Cassini Closes in on Enceladus, One Last Time
NASA - Cassini Mission to Saturn patch.
Dec. 16, 2015
Image above: Cassini will complete its final close flyby of Saturn's active moon Enceladus on Dec. 19. Image Credits: NASA/JPL-Caltech.
A thrilling chapter in the exploration of the solar system will soon conclude, as NASA's Saturn-orbiting Cassini spacecraft makes its final close flyby of the ocean-bearing moon Enceladus. Cassini is scheduled to fly past Enceladus at a distance of 3,106 miles (4,999 kilometers) on Saturday, Dec. 19, at 9:49 a.m. PST (12:49 p.m. EST).
Although the spacecraft will continue to observe Enceladus during the remainder of its mission (through September 2017), it will be from much greater distances -- at closest, more than four times farther away than the Dec. 19 encounter.
The upcoming flyby will focus on measuring how much heat is coming through the ice from the moon's interior -- an important consideration for understanding what is driving the plume of gas and icy particles that sprays continuously from an ocean below the surface.
"Understanding how much warmth Enceladus has in its heart provides insight into its remarkable geologic activity, and that makes this last close flyby a fantastic scientific opportunity," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.
By design, the encounter will not be Cassini's closest. The flyby was designed to allow Cassini's Composite Infrared Spectrometer (CIRS) instrument to observe heat flow across Enceladus' south polar terrain.
Cassini Final "E22" Enceladus Flyby
Video above: Animation of Cassini's Dec. 19 Enceladus encounter.
"The distance of this flyby is in the sweet spot for us to map the heat coming from within Enceladus -- not too close, and not too far away. It allows us to map a good portion of the intriguing south polar region at good resolution," said Mike Flasar, CIRS team lead at NASA's Goddard Space Flight Center, Greenbelt, Maryland.
The south polar region of Enceladus, while well lit for observing observations by Cassini's visible light cameras when the spacecraft arrived at Saturn in mid-2004, is presently in the darkness of the years-long Saturnian winter. The absence of heat from the sun makes it easier for Cassini to observe the warmth from Enceladus itself. By the time the mission concludes, Cassini will have obtained observations over six years of winter darkness in the moon's southern hemisphere.
Cassini completed a daring dive through the moon's erupting plume on Oct. 28, passing just 30 miles (49 kilometers) above the surface. Scientists are still analyzing data collected during that encounter to better understand the nature of the plume, its particles and whether hydrogen gas is present -- the latter would be an independent line of evidence for active hydrothermal systems in the seafloor.
This moderately close flyby will be the 22nd of Cassini's long mission. The spacecraft's surprising discovery of geologic activity on Enceladus, not long after arriving at Saturn, prompted changes to the mission's flight plan in order to maximize the number and quality of encounters with the icy moon. Cassini made its closest Enceladus flyby on Oct. 9, 2008, at an altitude of 16 miles (25 kilometers).
The unfolding story of Enceladus has been one of the great triumphs of Cassini's historic mission at Saturn. Scientists first detected signs of the moon's icy plume in early 2005, followed by a series of discoveries about the material gushing from warm fractures near its south pole. They announced strong evidence for a regional subsurface sea in 2014, revising their understanding in 2015 to confirm that the moon hosts a global ocean beneath its icy crust.
"Cassini’s legacy of discoveries in the Saturn system is profound," said Spilker. "We won't get this close to Enceladus again with Cassini, but our travels have opened a path to the exploration of this and other ocean worlds."
An online toolkit for all three final Enceladus flybys is available at: http://solarsystem.nasa.gov/finalflybys
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington.
For more information about Cassini, visit:
Image (mentioned), Video (mentioned), Text, Credits: NASA/JPL/Preston Dyches/Tony Greicius.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 13:40
NASA to Launch FORTIS to Study Extra-Galactic Dust
Dec. 16, 2015
This month, the NASA-funded FORTIS sounding rocket—short for Far-ultraviolet Off Rowland-circle Telescope for Imaging and Spectroscopy—will launch from the White Sands Missile Range in New Mexico to investigate the properties of galaxy NGC 1365, also known as the Great Barred Spiral Galaxy.
FORTIS will use an instrument called a spectrograph to split the light from the target galaxy into its composite wavelengths, creating a kind of image called a spectrum. How much of each wavelength is present can hold clues to the atoms present in the space through which the light is traveling. In this case, scientists will study the wavelengths of light emitted and absorbed by different types of hydrogen to quantify how much material is flowing in and out of the galaxy.
Image above: The FORTIS team prepares for a test on Dec. 8, 2015. FORTIS will study far-ultraviolet light from star-forming galaxy NGC 1365 to understand how material is flowing in and out of the galaxy. Image Credits: NASA/Johns Hopkins University/Stephan McCandliss.
“Star-forming galaxies like NGC 1365 are swallowing mass from the intergalactic medium, and that material becomes stars,” said Stephan McCandliss, principal investigator for FORTIS from Johns Hopkins University in Baltimore, Maryland. “When these new stars ignite, they heat the surrounding gas and dust, making it emit light in these particular wavelengths.”
FORTIS will fly on a Black Brant IX suborbital sounding rocket to an altitude of about 173 miles, taking data for six minutes. In the first 30 seconds, FORTIS will use its auto-targeting system to pick out the 40 brightest regions of NGC 1365 to study. It will then focus in on these promising regions—using a micro-shutter array originally developed for NASA’s James Webb Space Telescope—and take spectra of these regions focusing on far ultraviolet wavelengths of light.
Image above: FORTIS will focus on galaxy NGC 1365, otherwise known as the Great Barred Spiral Galaxy. By examining specific wavelengths of absorption and emission, scientists will use FORTIS’ data to quantify the amounts of materials flowing in and out of the galaxy. Image Credits: ESO/IDA/Danish 1.5 m/ R. Gendler, J-E. Ovaldsen, C. Thöne, and C. Feron.
These types of observations can only be taken from space, because Earth’s atmosphere absorbs far ultraviolet light. Sounding rockets provide a low-cost way to access space, collecting valuable data from outside Earth’s atmosphere for a fraction of the cost of a full-fledged satellite mission.
The FORTIS launch is supported through NASA’s Sounding Rocket Program at the Goddard Space Flight Center’s Wallops Flight Facility in Virginia. NASA’s Heliophysics Division manages the sounding rocket program.
NASA’s Goddard Space Flight Center: http://www.nasa.gov/centers/goddard/home/index.html
Sounding Rockets: http://www.nasa.gov/mission_pages/sounding-rockets/index.html
Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Sarah Frazier/Rob Garner.
Publié par Orbiter.ch à 13:25
PSLV Successfully Launches Six Satellites from Singapore
ISRO - Indian Space Research Organisation logo.
Dec 16, 2015
In its thirty second flight conducted from Satish Dhawan Space Centre (SDSC), SHAR, Sriharikota today evening (December 16, 2015) at 12:30 GMT (7:30 a.m. EST), ISRO's Polar Satellite Launch Vehicle PSLV-C29 (PSLV-CA configuration) successfully launched six satellites from Singapore, including the 400 kg TeLEOS-1, the primary satellite.
The other five satellites were co. passenger payloads. PSLV-C29 launched all the six payloads into an orbit of 549 km height inclined at an angle of 15 deg to the equator. The six satellites carried by PSLV-C29 today together weighed about 624 kg at lift-off.
These six satellites were launched as part of the agreement entered into between ST Electronics (Satcom & Sensor Systems), Singapore and Antrix Corporation Limited, the commercial arm of the Indian Space Research Organisation (ISRO), a government of India Company under the Department of Space (DOS).
Launch of Indian PSLV Rocket with TeLEOS-1 Onboard (C-29)
This is the eleventh flight of PSLV in ‘core-alone’ configuration (without the use of solid strap-on motors). PSLV has successfully launched 57 satellites for customers from abroad including the six Singapore satellites launched today. After a 59 hour smooth count down, the 227.6 ton PSLV-C29 lifted off from the First Launch Pad (FLP) at SDSC SHAR at 1800 hrs (6:00 pm) IST with the ignition of its first stage.
The important flight events included the separation of the first stage, ignition of the second stage, separation of the payload fairing at about 117 km altitude, second stage separation, third stage ignition and separation, fourth stage ignition and cut-off. Once the intended orbit was achieved, TeLEOS-1 was deployed at about 18 min 12 seconds after lift-off. This was followed by the deployment of other five satellites, viz., Kent Ridge-1, VELOX-C1, VELOX-II, Galassia and Athenoxat-1 in quick succession in the subsequent three minutes.
TeLEOS 1 satellite
The largest of the satellites, TeLEOS 1, is an Earth observation satellite designed to operate in an equatorial orbit for AgilSpace. Four other satellites aboard the launch were developed by university students in Singapore will test new technologies, observe Earth and study the climate.
For more information about Indian Space Research Organisation (ISRO), visit: http://www.isro.gov.in/
Images, Video, Text, Credits: ISRO/Günter Space Page/Orbiter.ch Aerospace.
Publié par Orbiter.ch à 12:44
Hubble captures first-ever predicted exploding star
ESA - Hubble Space Telescope logo.
16 December 2015
Caught in the act
Third appearance of the Refsdal supernova
The NASA/ESA Hubble Space Telescope has captured the image of the first-ever predicted supernova explosion. The reappearance of the Refsdal supernova was calculated from different models of the galaxy cluster whose immense gravity is warping the supernova’s light.
Many stars end their lives with a with a bang, but only a few of these stellar explosions have been caught in the act. When they are, spotting them successfully has been down to pure luck — until now. On 11 December 2015 astronomers not only imaged a supernova in action, but saw it when and where they had predicted it would be.
The supernova, nicknamed Refsdal , has been spotted in the galaxy cluster MACS J1149.5+2223. While the light from the cluster has taken about five billion years to reach us, the supernova itself exploded much earlier, nearly 10 billion years ago .
Appearance of the the Refsdal supernova
Refsdal’s story began in November 2014 when scientists spotted four separate images of the supernova in a rare arrangement known as an Einstein Cross around a galaxy within MACS J1149.5+2223 (heic1505) . The cosmic optical illusion was due to the mass of a single galaxy within the cluster warping and magnifying the light from the distant stellar explosion in a process known as gravitational lensing .
"While studying the supernova, we realised that the galaxy in which it exploded is already known to be a galaxy that is being lensed by the cluster,” explains Steve Rodney, co-author, from the University of South Carolina. “The supernova's host galaxy appears to us in at least three distinct images caused by the warping mass of the galaxy cluster.”
These multiple images of the galaxy presented a rare opportunity. As the matter in the cluster — both dark and visible — is distributed unevenly, the light creating each of these images takes a different path with a different length. Therefore the images of the host galaxy of the supernova are visible at different times.
Illustration showing gravitational lensing producing supernova images
Using other lensed galaxies within the cluster and combining them with the discovery of the Einstein Cross event in 2014, astronomers were able to make precise predictions for the reappearance of the supernova. Their calculations also indicated that the supernova appeared once before in a third image of the host galaxy in 1998 — an event not observed by any telescope. To make these predictions they had to use some very sophisticated modelling techniques.
“We used seven different models of the cluster to calculate when and where the supernova was going to appear in the future. It was a huge effort from the community to gather the necessary input data using Hubble, VLT-MUSE, and Keck and to construct the lens models,” explains Tommaso Treu, lead author of the modelling comparison paper, from the University of California at Los Angeles, USA. “And remarkably all seven models predicted approximately the same time frame for when the new image of the exploding star would appear”.
Since the end of October 2015 Hubble has been periodically peering at MACS J1149.5+2223, hoping to observe the unique rerun of the distant explosion and prove the models correct. On 11 December Refsdal finally made its predicted, but nonetheless showstopping, reappearance.
Appearances of the Refsdal supernova
“Hubble has showcased the modern scientific method at its best,” comments Patrick Kelly, lead author of the discovery and re-appearance papers and co-author of the modelling comparison paper from the University of California Berkeley, USA. “Testing predictions through observations provides powerful means of improving our understanding of the cosmos.”
The detection of Refsdal’s reappearance served as a unique opportunity for astronomers to test their models of how mass — especially that of mysterious dark matter — is distributed within this galaxy cluster. Astronomers are now eager to see what other surprises the ongoing Hubble Frontier Fields programme will bring to light.
 The supernova has been nicknamed Refsdal in honour of the Norwegian astronomer Sjur Refsdal, who, in 1964, first proposed using time-delayed images from a lensed supernova to study the expansion of the Universe.
 The W. M. Keck Observatory on Mauna Kea, in Hawaii, was used to measure the redshift of the supernova’s host galaxy (z = 1.491), which is a proxy to its distance.
 Hubble observed MACS J1149.5+2223 as part of the Grism Lens Amplified Survey from Space (GLASS) and the Frontier Fields programme. Both surveys are exploiting the lensing properties of galaxy clusters to examine the dark matter within them and some of the most distant galaxies beyond them.
 Gravitational lensing magnifies the light from fainter, background objects, allowing Hubble to spy galaxies it would otherwise not be able to detect. The process was first predicted by Albert Einstein and is now being exploited by the Frontier Fields programme in order to find some of the most distant galaxies in the Universe.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
- heic1505: http://www.spacetelescope.org/news/heic1505/
- Galaxy cluster MACS J1149.5+2223: http://frontierfields.org/2014/02/25/meet-the-frontier-fields-macs-j1149-52223/
- First observation of Refsdal supernova: http://www.spacetelescope.org/news/heic1505/
- Announcement on the search programme: https://www.spacetelescope.org/announcements/ann1526/
- Link to science paper (prediction): http://www.spacetelescope.org/static/archives/releases/science_papers/heic1525b.pdf
- Link to science paper (reappearance): http://www.spacetelescope.org/static/archives/releases/science_papers/heic1525a.pdf
- ESO announcement: https://www.eso.org/public/announcements/ann15088/
- Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/
NASA Hubble Space Telescope website: http://hubblesite.org/
Images, Video, Text, Credits: NASA/ESA/S. Rodney (John Hopkins University, USA) and the FrontierSN team; T. Treu (University of California Los Angeles, USA), P. Kelly (University of California Berkeley, USA) and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI)/Music: Johan B Monell.
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Publié par Orbiter.ch à 08:35
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