vendredi 22 janvier 2016
NASA - Hubble Space Telescope patch.
Jan. 22, 2016
Most galaxies possess a majestic spiral or elliptical structure. About a quarter of galaxies, though, defy such conventional, rounded aesthetics, instead sporting a messy, indefinable shape. Known as irregular galaxies, this group includes NGC 5408, the galaxy that has been snapped here by the NASA/ESA Hubble Space Telescope.
John Herschel recorded the existence of NGC 5408 in June 1834. Astronomers had long mistaken NGC 5408 for a planetary nebula, an expelled cloud of material from an aging star. Instead, bucking labels, NGC 5408 turned out to be an entire galaxy, located about 16 million light-years from Earth in the constellation of Centaurus (The Centaur).
In yet another sign of NGC 5408 breaking convention, the galaxy is associated with an object known as an ultraluminous X-ray source, dubbed NGC 5408 X-1, one of the best studied of its class. These rare objects beam out prodigious amounts of energetic X-rays. Astrophysicists believe these sources to be strong candidates for intermediate-mass black holes. This hypothetical type of black hole has significantly less mass than the supermassive black holes found in galactic centers, which can have billions of times the mass of the sun, but have a good deal more mass than the black holes formed when giant stars collapse.
Hubble Space Telescope websites:
Text credit: European Space Agency/Image credits: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt/Ashley Morrow.
Publié par Orbiter.ch à 19:02
Jan. 22, 2016
Image above: Early risers have an opportunity to see five naked-eye planets in pre-dawn skies during late January and continuing through late February. Image Credits: NASA/JPL-Caltech.
Well, it's not quite like the song about the dawning of the Age of Aquarius, but our solar system is experiencing an uncommon lineup that should be quite a treat for sky-watchers. The solar system itself hasn't changed -- it's just that the timing of the planets orbiting the sun puts them into a lineup that makes for good viewing by Earthlings.
From now until about Feb. 20, early risers will stand a good chance of seeing five planets simultaneously in the pre-dawn sky: Mercury, Venus, Saturn, Mars and Jupiter (technically six, if you count the Earth you're standing on). Those planets should be visible to the naked eye. Of course, if you happen to have binoculars or a telescope, you'll get an even better view.
The last appearance by the quintet on one nighttime stage was in December 2004 and January 2005. If you miss this month's viewing opportunity, the five will be back in the evening sky in late July through mid-August, but Mercury and Venus won't be easily visible from northern latitudes.
If you go outside during the five-planet display, and if weather conditions are favorable, here's what you should be able to see: Jupiter will rise in the evening, then Mars will pop up after midnight, followed by Saturn, brilliant Venus, and finally, Mercury. All five will be visible from southeast to southwest between 6 and 6:30 a.m. local time, over the span. Earth’s moon will also join the cosmic display from Jan. 23 to Feb. 7. During that time, the moon will shift from the west-northwest to east-southeast and will be visible near the five planets and some stars.
During the day and night between Jan. 27 and 28, the morning view of the moon will switch from right of Jupiter to left of Jupiter. Then, on Feb. 1, the moon will be visible near Mars, followed by an appearance near Saturn on Feb. 3. On Feb. 6, the moon, Mercury and dazzling Venus will appear in a triangular formation before sunrise.
For Jim Green, director of NASA's Planetary Science Division, the rare planetary lineup reminds him how far we have come in exploring our solar system.
"NASA spacecraft have visited each one of the five planets that we will be able to see over the next few weeks, as well as Uranus, Neptune and Pluto," Green said. "We can be proud that American curiosity, technology and determination are helping us unlock many mysteries about our solar system."
Solar System: http://www.nasa.gov/topics/solarsystem/index.html
Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Jane Platt.
Publié par Orbiter.ch à 18:51
NASA - Voyager 2 patch.
January 22, 2016
Image above: Arriving at Uranus in 1986, Voyager 2 observed a bluish orb with extremely subtle features. A haze layer hid most of the planet's cloud features from view. Image Credits: NASA/JPL-Caltech.
Humanity has visited Uranus only once, and that was 30 years ago. NASA's Voyager 2 spacecraft got its closest look at the mysterious, distant, gaseous planet on Jan. 24, 1986.
Voyager 2 sent back stunning images of the planet and its moons during the flyby, which allowed for about 5.5 hours of close study. The spacecraft got within 50,600 miles (81,500 kilometers) of Uranus during that time.
Image above: Uranus' icy moon Miranda wowed scientists during the Voyager encounter with its dramatically fractured landscapes. Image Credits: NASA/JPL-Caltech.
"We knew Uranus would be different because it's tipped on its side, and we expected surprises," said Ed Stone, project scientist for the Voyager mission, based at the California Institute of Technology, Pasadena. Stone has served as project scientist since 1972, continuing in that role today.
Uranus revealed itself to be the coldest planet known in our solar system, even though it's not the farthest from the sun. This is because it has no internal heat source.
Image above: Voyager 2 captured this moody parting shot of Uranus as the spacecraft sped off toward its next adventure at Neptune. Image Credits: NASA/JPL-Caltech.
Scientists determined that the atmosphere of Uranus is 85 percent hydrogen and 15 percent helium. There was also evidence of a boiling ocean about 500 miles (800 kilometers) below the cloud tops.
Scientists found that Uranus has a magnetic field different from any they had ever encountered previously. At Mercury, Earth, Jupiter and Saturn, the magnetic field is aligned approximately with the rotational axis.
"Then we got to Uranus and saw that the poles were closer to the equator," Stone said. "Neptune turned out to be similar. The magnetic field was not quite centered with the center of the planet."
Image above: The false-color and contrast-enhanced image of Uranus at right reveals subtle bands of concentric clouds surrounding the planet's south pole. Image Credits: NASA/JPL-Caltech.
This surface magnetic field of Uranus was also stronger than that of Saturn. Data from Voyager 2 helped scientists determine that the magnetic tail of Uranus twists into a helix stretching 6 million miles (10 million kilometers) in the direction pointed away from the sun. Understanding how planetary magnetic fields interact with the sun is a key part of NASA's goal to understand the very nature of space. Not only does studying the sun-planet connection provide information useful for space travel, but it helps shed light on the origins of planets and their potential for harboring life.
Image above: Voyager 2 discovered 10 new moons during its encounter with Uranus, including the three pictured here: Portia (1986 U1), Cressida (1986 U3) and Rosalind (1986 U4). Image Credits: NASA/JPL-Caltech.
Voyager 2 also discovered 10 new moons (there are 27 total) and two new rings at the planet, which also proved fascinating. An icy moon called Miranda revealed a peculiar, varied landscape and evidence of active geologic activity in the past. While only about 300 miles (500 kilometers) in diameter, this small object boasts giant canyons that could be up to 12 times as deep as the Grand Canyon in Arizona. Miranda also has three unique features called "coronae," which are lightly cratered collections of ridges and valleys. Scientists think this moon could have been shattered and then reassembled.
Mission planners designed Voyager 2's Uranus encounter so that the spacecraft would receive a gravity assist to help it reach Neptune. In 1989, Voyager 2 added Neptune to its resume of first-ever looks.
Image above: Voyager observed the expansive rings of Uranus, discovering two previously unknown rings. Image Credits: NASA/JPL-Caltech.
"The Uranus encounter was very exciting for me," said Suzanne Dodd, project manager for Voyager, based at NASA's Jet Propulsion Laboratory, Pasadena, California, who began her career with the mission while Voyager 2 was en route to Uranus." It was my first planetary encounter and it was of a planet humanity had never seen up close before. Every new image showed more details of Uranus, and it had lots of surprises for the scientists. I hope another spacecraft will be sent to explore Uranus, to explore the planet in more detail, in my lifetime."
Voyager 2 was launched on Aug. 20, 1977, 16 days before its twin, Voyager 1. In August 2012, Voyager 1 made history as the first spacecraft to enter interstellar space, crossing the boundary encompassing our solar system's planets, sun and solar wind. Voyager 2 is also expected to reach interstellar space within the next several years.
The Voyagers were built by JPL, which continues to operate both spacecraft. JPL is a division of Caltech. For more information about the Voyager spacecraft, visit:
Images (mentioned), Text, Credits: NASA's Jet Propulsion Laboratory/Elizabeth Landau.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 18:37
jeudi 21 janvier 2016
NASA - New Horizons Mission logo.
Jan. 21, 2016
After its close approach to Pluto, the New Horizons spacecraft snapped this hauntingly beautiful image of the night side of Pluto’s largest moon, Charon.
Only an imager on the far side of Pluto could catch such a view, with a bright, thin sliver of Charon near the lower left illuminated by the sun. Night has fallen over the rest of this side of Charon, yet despite the lack of sunlight over most of the surface, Charon’s nighttime landscapes are still faintly visible by light softly reflected off Pluto, just as “Earthshine” lights up a new moon each month. Charon is 750 miles (1,214 kilometers) in diameter, approximately as wide as Texas.
Scientists on the New Horizons team are using this and similar images to map portions of Charon otherwise not visible during the flyby. This includes Charon’s south pole – toward the top of this image – which entered polar night in 1989 and will not see sunlight again until 2107. Charon’s polar temperatures drop to near absolute zero during this long winter.
This combination of 16 one-second exposures was taken by New Horizons’ Long Range Reconnaissance Imager (LORRI) at 2:30 UT on July 17, 2015, nearly three days after closest approach to Pluto and Charon, from a range of 1.9 million miles (3.1 million kilometers).
For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html
Image, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.
Publié par Orbiter.ch à 16:07
NASA - Mars Science Laboratory (MSL) logo.
Jan. 21, 2016
At its current location for inspecting an active sand dune, NASA's Curiosity Mars rover is adding some sample-processing moves not previously used on Mars.
Image above: This view captures Curiosity's current work area where the rover continues its campaign to study an active sand dune on Mars. This site is part of the Bagnold Dunes, a band of dark sand dunes along the northwestern flank of Mars’ Mount Sharp. This image was taken on Jan. 20, 2016, during the 1,229th Martian day, or sol, by Curiosity’s front hazardous avoidance camera. Image Credits: NASA/JPL-Caltech.
Sand from the second and third samples the rover is scooping from "Namib Dune" will be sorted by grain size with two sieves. The coarser sieve is making its debut, and using it also changes the way the treated sample is dropped into an inlet port for laboratory analysis inside the rover.
Positioning of the rover to grab a bite of the dune posed a challenge, too. Curiosity reached this sampling site, called "Gobabeb," on Jan. 12.
"It was pretty challenging to drive into the sloping sand and then turn on the sand into the position that was the best to study the dunes," said Michael McHenry of NASA's Jet Propulsion Laboratory, Pasadena, California. He is the Curiosity mission's campaign rover planner for collecting these samples.
Curiosity has scooped up sample material at only one other site since it landed on Mars in August 2012. It sampled dust and sand at a windblown drift site called "Rocknest" in October and November 2012. Between there and Gobabeb, the rover collected sample material for analysis at nine rock targets, by drilling rather than scooping.
The mission's current work is the first close-up study of active sand dunes anywhere other than Earth. Namib and nearby mounds of dark sand are part of the "Bagnold Dune Field," which lines the northwestern flank of a layered mountain where Curiosity is examining rock records of ancient environmental conditions on Mars. Investigation of the dunes is providing information about how wind moves and sorts sand particles in conditions with much less atmosphere and less gravity than on Earth.
Image above: This false-color engineering drawing shows the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device, attached to the turret at the end of the robotic arm on NASA's Curiosity Mars rover. This device processes samples acquired from the built-in scoop (red) and the drill, which is not shown but is also part of the turret. CHIMRA also delivers samples to the analytical lab instruments inside the rover. Two paths to get material into CHIMRA are shown (the scoop delivers material to the location marked at the bottom, and the drill deposits material to the sample transfer tube shown at top). Also marked are the location of the vibration mechanism used to shake the turret and cause the sample to move inside CHIMRA, and the portion box (yellow) from which the material processed through a sieve is delivered to the analytical lab instruments. Image Credits: NASA/JPL-Caltech.
Sand in dunes has a range of grain sizes and compositions. Sorting by wind will concentrate certain grain sizes and compositions, because composition is related to density, based on where and when the wind has been active. The Gobabeb site was chosen to include recently formed ripples. Information about these aspects of Mars' modern environment may also aid the mission's interpretation of composition variations and ripple patterns in ancient sandstones that formed from wind or flowing water.
Curiosity scooped its first dune sample on Jan. 14, but the rover probed the dune first by scuffing it with a wheel. "The scuff helped give us confidence we have enough sand where we're scooping that the path of the scoop won't hit the ground under the sand," McHenry said.
That first scoop was processed much as Rocknest samples were: A set of complex moves of a multi-chambered device on the rover's arm passed the material through a sieve that screened out particles bigger than 150 microns (0.006 inch); some of the material that passed the sieve was dropped into laboratory inlet ports from a "portioner" on the device; material blocked by the sieve was dumped onto the ground.
The portioner is positioned directly over an opened inlet port on the deck of the rover to drop a portion into it when the processing device is vibrating and a release door is opened. Besides analyzing samples delivered to its internal laboratory instruments, Curiosity can use other instruments to examine sample material dumped onto the ground.
Curiosity collected its second scoop of Gobabeb on Jan. 19. This is when the coarser sieve came into play. It allows particles up to 1 millimeter (1,000 microns or 0.04 inch) to pass through.
Sand from the second scoop was initially fed to the 150-micron sieve. Material that did not pass through that sieve was then fed to the 1-millimeter sieve. The fraction routed for laboratory analysis is sand grains that did not pass through the finer sieve, but did pass through the coarser one.
"What you have left is predominantly grains that are smaller than 1 millimeter and larger than 150 microns," said JPL's John Michael Morookian, rover planning team lead for Curiosity.
This fraction is dropped into a laboratory inlet by the scoop, rather than the portioner. Morookian decribed this step: "We start the vibration and gradually tilt the scoop. The material flows off the end of the scoop, in more of a stream than all at once."
Curiosity reached the base of Mount Sharp in 2014 after fruitfully investigating outcrops closer to its landing site and then trekking to the layered mountain. On the lower portion of the mountain, the mission is studying how Mars' ancient environment changed from wet conditions favorable for microbial life to harsher, drier conditions. For more information about Curiosity, visit:
Images (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/Tony Greicius/JPL/Guy Webster.
Publié par Orbiter.ch à 15:59
ESA - LISA Pathfinder Mission patch.
Jan. 21, 2016
Image above: The LISA Pathfinder spacecraft will help pave the way for a mission to detect gravitational waves. NASA/JPL developed a thruster system onboard. Image Credit: ESA.
While some technologies were created to make spacecraft move billions of miles, the Disturbance Reduction System has the opposite goal: To keep a spacecraft as still as possible.
The thruster system, managed by NASA's Jet Propulsion Laboratory, Pasadena, California, is part of the European Space Agency's LISA Pathfinder spacecraft, which launched from Kourou, French Guiana on Dec. 3, 2015 GMT (Dec. 2 PST). LISA Pathfinder will test technologies that could one day allow detection of gravitational waves, whose effects are so miniscule that a spacecraft would need to remain extremely steady to detect them. Observing gravitational waves would be a huge step forward in our understanding of the evolution of the universe.
Now, LISA Pathfinder is on its way to Lagrange Point L1, about 930,000 miles (1.5 million kilometers) from Earth in the direction of the sun. L1 is a special point that a spacecraft can orbit while maintaining a nearly constant distance to Earth. This month, scientists and engineers have been switching on LISA Pathfinder's instruments to test them in space. This has included the Disturbance Reduction System instrument computer and thrusters.
Image above: A portion of Earth, its atmosphere and a starry sky are seen by ESA's LISA Pathfinder's star trackers on Dec. 3, 2015, the day it launched. Image Credits: ESA/LPF/Airbus-DS; Acknowledgement to J. Grzymisch & M. Watt.
The system uses colloid micronewton thrusters, which operate by applying an electric charge to small droplets of liquid and accelerating them through an electric field, to precisely control the position of the spacecraft. Thrusters that work this way had never been successfully operated in space before LISA Pathfinder launched.
As of Jan. 10, all eight identical thrusters, developed by Busek Co., Natick, Massachusetts, with technical support from JPL, passed their functional tests. The thrusters achieved their maximum thrust of 30 micronewtons, equivalent to the weight of a mosquito. This level of precision is necessary to counteract small forces on the spacecraft such as the pressure of sunlight, with the result that the spacecraft and the instruments inside are in near-perfect free-fall. A mission to detect gravitational waves would need that level of stability.
"We reached a major milestone with this technology development," said Phil Barela, Disturbance Reduction System project manager at JPL. "The DRS is helping point the way to a system that could be used to detect gravitational waves in the future."
Gravitational waves are one of the last unverified predictions from the theory of General Relativity, which Albert Einstein published about a century ago. Einstein wrote that as massive bodies accelerate, such as black holes, they produce distortions in space-time. Scientists are interested in observing and characterizing these ripples in space-time so that they can learn more about the astrophysical systems that produce them, and about gravity itself. Proposed experiments to detect them from space, such as a future LISA mission, would need to measure how two freely-falling objects move ever so slightly, relative to each other, as a result of gravitational waves. In order to rule out any disturbances that could mask these waves, there must be a system to compensate for solar pressure and other factors. The Disturbance Reduction System on LISA Pathfinder will demonstrate this technology.
Image above: This cluster of four colloid thrusters is part of the Disturbance Reduction System, developed by NASA/JPL, which will help keep the LISA Pathfinder spacecraft extremely stable. Image Credits: ESA/NASA/JPL-Caltech.
The Disturbance Reduction System could also lead to advanced thruster systems for other space applications. Space telescopes need to be very stable to detect distant planets in other solar systems, for example, and could use a similar system. A set of thrusters like the Disturbance Reduction System's could also be used in small satellites to help synchronize flying patterns.
LISA Pathfinder will reach its final orbit on Jan. 22, and begin science operations on March 1. For the first phase of the mission's science operations, a thruster technology system designed by the European Space Agency will be used. JPL's Disturbance Reduction System will then take over in June or July, operating for 90 days.
LISA Pathfinder is managed by the European Space Agency. The spacecraft was built by Airbus Defence and Space, Ltd., United Kingdom. Airbus Defence and Space, GmbH, Germany, is the payload architect for the LISA Technology Package. The DRS is managed by JPL. The California Institute of Technology manages JPL for NASA.
Lagrange Point L1: http://map.gsfc.nasa.gov/mission/observatory_l2.html
LISA Pathfinder: http://sci.esa.int/lisa-pathfinder/
Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau.
Publié par Orbiter.ch à 15:48
CERN - European Organization for Nuclear Research logo.
Jan. 21, 2016
In a paper published in the journal Nature (link is external), researchers at CERN’s ALPHA experiment have shown – to the most accurate degree yet – that particles of antihydrogen have a neutral electrical charge.
Image above: In a new paper published in the journal Nature, the ALPHA experiment at CERN's Antiproton Decelerator (AD) reported the most accurate measurement yet of the electric charge of antihydrogen atoms. (Image: Maximilien Brice/CERN).
According to the Standard Model, which explains how the basic building blocks of matter interact, all antimatter – such as antihydrogen – should have the exact opposite charge to its matter counterpart. For example, in a hydrogen atom a negatively charged electron combines with a positively charged proton to give a net charge of zero. In contrast, an antihydrogen atom should have a positively charged positron combining with a negatively charged antiproton to give a net charge of zero. The Standard Model also says that during the Big Bang equal amounts of antimatter and matter were created. But today this isn’t the case, there is much less antimatter in the universe than matter.
Since physicists know that hydrogen has a neutral charge, by studying the charge of antihydrogen, they hoped to see something different or surprising, which could help scientists to understand why nature has a preference for matter over antimatter. “It’s a very important question: is the universe neutral? Do all the positive charges and negative charges have exactly the opposite sign and to what level can you determine that?” explains Jeffrey Hangst, the spokesperson for the ALPHA experiment at CERN's Antiproton Decelerator (AD) and the lead scientist on the study. “For normal matter that’s known very precisely: to about one part in 1021, that’s one and 21 zeros, that’s an enormous number, we really know that well. Now we have the first opportunity to study this with antiatoms, with antihydrogen, and that’s what we’re publishing now. We made the best possible study that we can make with trapped antihydrogen.”
Image above: Spokesperson Jeffrey Hangst at the ALPHA experiment, one of the experiments at CERN’s Antiproton Decelerator.(Image: Maximilien Brice/CERN).
At ALPHA, physicists study the antihydrogen particles by first combining an antiproton and a positron (the antimatter equivalent of an electron) to make antihydrogen, which they trap in a magnetic field. They then kick the trapped particles with an electric field to see if they react. If an antihydrogen reacts and escapes from the trap then it means it has a charge, if it doesn’t then it’s neutral. “ALPHA is designed to trap antihydrogen, and CERN the only place in the world that does this kind of physics,” Hangst says.
Alternatively, the new result can be interpreted to put a new limit on the charge of a positron. “The antiproton charge has been accurately measured before, so if we assume that antihydrogen is in fact neutral, we can put a new limit on how much the positron charge could differ from the charge of its matter counterpart – the electron. Our results makes that charge better known by a factor of 25,” says Hangst.
ALPHA experiment: an improved limit on the charge of antihydrogen
Video above: ALPHA spokesperson, Jeffrey Hangst, explains how the experiment works and the significance of this new result. (Video/CERN).
While ALPHA is able to study the charge of antihydrogen, the experiment’s main goal is to study the spectroscopy of the trapped antihydrogen. Researchers will shine a laser onto antihydrogen to discover if it will absorb the same frequencies of light compared to hydrogen. “Spectroscopy would give us the most accurate comparison you can get between antihydrogen and hydrogen,” Hangst explains. “It’s the main reason ALPHA was built and has always been the long term goal.” Physicists hope that they will get the first spectroscopy results from ALPHA this year.
Paper published in the journal Nature: http://www.nature.com/nature/journal/v529/n7586/full/nature16491.html
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.
ALPHA experiment: http://home.cern/about/experiments/alpha
CERN's Antiproton Decelerator: http://home.cern/about/accelerators/antiproton-decelerator
The Standard Model: http://home.cern/about/physics/standard-model
The Big Bang: http://home.cern/about/physics/early-universe
For more information about European Organization for Nuclear Research (CERN), visit: http://home.cern/
Images (mentioned), Video (mentioned), Text, Credits: CERN/Harriet Jarlett/Corinne Pralavorio.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 14:45
ESA - Hubble Space Telescope logo.
21 January 2016
Dazzling diamonds of Trumpler 14
Single stars are often overlooked in favour of their larger cosmic cousins — but when they join forces, they create truly breathtaking scenes to rival even the most glowing of nebulae or swirling of galaxies. This NASA/ESA Hubble Space Telescope image features the star cluster Trumpler 14. One of the largest gatherings of hot, massive and bright stars in the Milky Way, this cluster houses some of the most luminous stars in our entire galaxy.
Around 1100 open clusters have so far been discovered within the Milky Way, although many more are thought to exist. Trumpler 14 is one of these, located some 8000 light-years away towards the centre of the well-known Carina Nebula.
Trumpler 14 embedded in the Carina Nebula
At a mere 500 000 years old — a small fraction of the Pleiades open cluster’s age of 115 million years — Trumpler 14 is not only one of the most populous clusters within the Carina Nebula, but also the youngest. However, it is fast making up for lost time, forming stars at an incredible rate and putting on a stunning visual display.
This region of space houses one of the highest concentrations of massive, luminous stars in the entire Milky Way — a spectacular family of young, bright, white-blue stars. These stars are rapidly working their way through their vast supplies of hydrogen, and have only a few million years of life left before they meet a dramatic demise and explode as supernovae. In the meantime, despite their youth, these stars are making a huge impact on their environment. They are literally making waves!
Zoom in onto Trumpler 14
As the stars fling out high-speed particles from their surfaces, strong winds surge out into space. These winds collide with the surrounding material, causing shock waves that heat the gas to millions of degrees and trigger intense bursts of X-rays. These strong stellar winds also carve out cavities in nearby clouds of gas and dust, and kickstart the formation of new stars.
The peculiar arc-shaped cloud visible at the very bottom of this image is suspected to be the result of such a wind. This feature is thought to be a bow shock created by the wind flowing from the nearby star Trumpler 14 MJ 218. Astronomers have observed this star to be moving through space at some 350 000 kilometres per hour, sculpting the surrounding clumps of gas and dust as it does so.
Astronomers estimate that around 2000 stars reside within Trumpler 14, ranging in size from less than one tenth to up to several tens of times the mass of the Sun. The most prominent star in Trumpler 14, and the brightest star in this image, is the supergiant HD 93129Aa . It is one of the most brilliant and hottest stars in our entire galaxy.
 HD 93129Aa is part of the binary star system HD 93129AaAb consisting of HD 93129Aa and HD 93129Ab. HD 93129Aa is an O-type star that is approximately two and a half million times brighter than the Sun, and has a mass 80 times greater. It forms a close binary with another massive star within the open cluster, meaning that the two orbit around a shared centre of mass. With a surface temperature of over 50 000 degrees, HD 93129Aa is one of the hottest O-type stars in the entire Milky Way.
Notes for editors:
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/
Trumpler 14 observed in 1994 by ESO’s Very Large Telescope: http://www.eso.org/public/news/eso0947/
Link to hubblesite release: http://hubblesite.org/newscenter/archive/releases/2016/03/
Images, Text, Credits: NASA & ESA, Jesús Maíz Apellániz (Instituto de Astrofisica de Andalucia)/ESO/Video: ESO, DSS, ESA/Hubble, Risinger (skysurvey.org). Music: Johan B. Monell.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 10:26
California Institute of Technology (Caltech) logo.
Jan. 21, 2016
Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.
Image above: This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Image Credits: Caltech/R. Hurt (IPAC).
The researchers, Konstantin Batygin and Mike Brown, discovered the planet's existence through mathematical modeling and computer simulations but have not yet observed the object directly.
"This would be a real ninth planet," says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. "There have only been two true planets discovered since ancient times, and this would be a third. It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting."
Brown notes that the putative ninth planet—at 5,000 times the mass of Pluto—is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets—a fact that Brown says makes it "the most planet-y of the planets in the whole solar system."
Batygin and Brown describe their work in the current issue of the Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt.
"Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there," says Batygin, an assistant professor of planetary science. "For the first time in over 150 years, there is solid evidence that the solar system's planetary census is incomplete."
The road to the theoretical discovery was not straightforward. In 2014, a former postdoc of Brown's, Chad Trujillo, and his colleague Scott Sheppard published a paper noting that 13 of the most distant objects in the Kuiper Belt are similar with respect to an obscure orbital feature. To explain that similarity, they suggested the possible presence of a small planet. Brown thought the planet solution was unlikely, but his interest was piqued.
He took the problem down the hall to Batygin, and the two started what became a year-and-a-half-long collaboration to investigate the distant objects. As an observer and a theorist, respectively, the researchers approached the work from very different perspectives—Brown as someone who looks at the sky and tries to anchor everything in the context of what can be seen, and Batygin as someone who puts himself within the context of dynamics, considering how things might work from a physics standpoint. Those differences allowed the researchers to challenge each other's ideas and to consider new possibilities. "I would bring in some of these observational aspects; he would come back with arguments from theory, and we would push each other. I don't think the discovery would have happened without that back and forth," says Brown. " It was perhaps the most fun year of working on a problem in the solar system that I've ever had."
Fairly quickly Batygin and Brown realized that the six most distant objects from Trujillo and Sheppard's original collection all follow elliptical orbits that point in the same direction in physical space. That is particularly surprising because the outermost points of their orbits move around the solar system, and they travel at different rates.
"It's almost like having six hands on a clock all moving at different rates, and when you happen to look up, they're all in exactly the same place," says Brown. The odds of having that happen are something like 1 in 100, he says. But on top of that, the orbits of the six objects are also all tilted in the same way—pointing about 30 degrees downward in the same direction relative to the plane of the eight known planets. The probability of that happening is about 0.007 percent. "Basically it shouldn't happen randomly," Brown says. "So we thought something else must be shaping these orbits."
Evidence of a Ninth Planet
Video above: Caltech's Konstantin Batygin, an assistant professor of planetary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, discuss new research that provides evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. Video Credit: Caltech AMT.
The first possibility they investigated was that perhaps there are enough distant Kuiper Belt objects—some of which have not yet been discovered—to exert the gravity needed to keep that subpopulation clustered together. The researchers quickly ruled this out when it turned out that such a scenario would require the Kuiper Belt to have about 100 times the mass it has today.
That left them with the idea of a planet. Their first instinct was to run simulations involving a planet in a distant orbit that encircled the orbits of the six Kuiper Belt objects, acting like a giant lasso to wrangle them into their alignment. Batygin says that almost works but does not provide the observed eccentricities precisely. "Close, but no cigar," he says.
Then, effectively by accident, Batygin and Brown noticed that if they ran their simulations with a massive planet in an anti-aligned orbit—an orbit in which the planet's closest approach to the sun, or perihelion, is 180 degrees across from the perihelion of all the other objects and known planets—the distant Kuiper Belt objects in the simulation assumed the alignment that is actually observed.
"Your natural response is 'This orbital geometry can't be right. This can't be stable over the long term because, after all, this would cause the planet and these objects to meet and eventually collide,'" says Batygin. But through a mechanism known as mean-motion resonance, the anti-aligned orbit of the ninth planet actually prevents the Kuiper Belt objects from colliding with it and keeps them aligned. As orbiting objects approach each other they exchange energy. So, for example, for every four orbits Planet Nine makes, a distant Kuiper Belt object might complete nine orbits. They never collide. Instead, like a parent maintaining the arc of a child on a swing with periodic pushes, Planet Nine nudges the orbits of distant Kuiper Belt objects such that their configuration with relation to the planet is preserved.
"Still, I was very skeptical," says Batygin. "I had never seen anything like this in celestial mechanics."
But little by little, as the researchers investigated additional features and consequences of the model, they became persuaded. "A good theory should not only explain things that you set out to explain. It should hopefully explain things that you didn't set out to explain and make predictions that are testable," says Batygin.
And indeed Planet Nine's existence helps explain more than just the alignment of the distant Kuiper Belt objects. It also provides an explanation for the mysterious orbits that two of them trace. The first of those objects, dubbed Sedna, was discovered by Brown in 2003. Unlike standard-variety Kuiper Belt objects, which get gravitationally "kicked out" by Neptune and then return back to it, Sedna never gets very close to Neptune. A second object like Sedna, known as 2012 VP113, was announced by Trujillo and Sheppard in 2014. Batygin and Brown found that the presence of Planet Nine in its proposed orbit naturally produces Sedna-like objects by taking a standard Kuiper Belt object and slowly pulling it away into an orbit less connected to Neptune.
Image above: A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely. Image Credits: Caltech/R. Hurt (IPAC) [Diagram was created using WorldWide Telescope.]
But the real kicker for the researchers was the fact that their simulations also predicted that there would be objects in the Kuiper Belt on orbits inclined perpendicularly to the plane of the planets. Batygin kept finding evidence for these in his simulations and took them to Brown. "Suddenly I realized there are objects like that," recalls Brown. In the last three years, observers have identified four objects tracing orbits roughly along one perpendicular line from Neptune and one object along another. "We plotted up the positions of those objects and their orbits, and they matched the simulations exactly," says Brown. "When we found that, my jaw sort of hit the floor."
"When the simulation aligned the distant Kuiper Belt objects and created objects like Sedna, we thought this is kind of awesome—you kill two birds with one stone," says Batygin. "But with the existence of the planet also explaining these perpendicular orbits, not only do you kill two birds, you also take down a bird that you didn't realize was sitting in a nearby tree."
Where did Planet Nine come from and how did it end up in the outer solar system? Scientists have long believed that the early solar system began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets—Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations. "But there is no reason that there could not have been five cores, rather than four," says Brown. Planet Nine could represent that fifth core, and if it got too close to Jupiter or Saturn, it could have been ejected into its distant, eccentric orbit.
Batygin and Brown continue to refine their simulations and learn more about the planet's orbit and its influence on the distant solar system. Meanwhile, Brown and other colleagues have begun searching the skies for Planet Nine. Only the planet's rough orbit is known, not the precise location of the planet on that elliptical path. If the planet happens to be close to its perihelion, Brown says, astronomers should be able to spot it in images captured by previous surveys. If it is in the most distant part of its orbit, the world's largest telescopes—such as the twin 10-meter telescopes at the W. M. Keck Observatory and the Subaru Telescope, all on Mauna Kea in Hawaii—will be needed to see it. If, however, Planet Nine is now located anywhere in between, many telescopes have a shot at finding it.
"I would love to find it," says Brown. "But I'd also be perfectly happy if someone else found it. That is why we're publishing this paper. We hope that other people are going to get inspired and start searching."
Image above: Caltech professor Mike Brown and assistant professor Konstanin Batygin have been working together to investigate distant objects in our solar system for more than a year and a half. The two bring very different perspectives to the work: Brown is an observer, used to looking at the sky to try and anchor everything in the reality of what can be seen; Batygin is a theorist who considers how things might work from a physics standpoint. Image Credits: Credit: Lance Hayashida/Caltech.
In terms of understanding more about the solar system's context in the rest of the universe, Batygin says that in a couple of ways, this ninth planet that seems like such an oddball to us would actually make our solar system more similar to the other planetary systems that astronomers are finding around other stars. First, most of the planets around other sunlike stars have no single orbital range—that is, some orbit extremely close to their host stars while others follow exceptionally distant orbits. Second, the most common planets around other stars range between 1 and 10 Earth-masses.
"One of the most startling discoveries about other planetary systems has been that the most common type of planet out there has a mass between that of Earth and that of Neptune," says Batygin. "Until now, we've thought that the solar system was lacking in this most common type of planet. Maybe we're more normal after all."
Brown, well known for the significant role he played in the demotion of Pluto from a planet to a dwarf planet adds, "All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found," he says. "Now we can go and find this planet and make the solar system have nine planets once again."
The paper is titled "Evidence for a Distant Giant Planet in the Solar System."
Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt. - See more at: http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22
Images (mentioned), Video (mentioned), Text Written by Kimm Fesenmaier, California Institute of Technology (Caltech).
Best regards, Orbiter.ch
Publié par Orbiter.ch à 06:58
mercredi 20 janvier 2016
NASA - Cassini Mission to Saturn patch
Jan. 19, 2016
Janus and Tethys demonstrate the main difference between small moons and large ones. It's all about the moon's shape.
Moons like Tethys (660 miles or 1,062 kilometers across) are large enough that their own gravity is sufficient to overcome the material strength of the substances they are made of (mostly ice in the case of Tethys) and mold them into spherical shapes. But small moons like Janus (111 miles or 179 kilometers across) are not massive enough for their gravity to form them into a sphere. Janus and its like are left as irregularly shaped bodies.
Saturn's narrow F ring and the outer edge of its A ring slice across the scene.
This view looks toward the unilluminated side of the rings from about 0.23 degrees below the ring plane. The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Oct. 27, 2015.
The view was obtained at a distance of approximately 593,000 miles (955,000 kilometers) from Janus. Image scale at Janus is 3.7 miles (6 kilometers) per pixel. Tethys was at a distance of 810,000 miles (1.3 million kilometers) for an image scale of 5 miles (8 kilometers) per pixel.
The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens
Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Tony Greicius.
Publié par Orbiter.ch à 20:38
NASA logo / NOAA logo.
Jan. 20, 2016
Image above: 2015 was the warmest year since modern record-keeping began in 1880, according to a new analysis by NASA’s Goddard Institute for Space Studies. The record-breaking year continues a long-term warming trend — 15 of the 16 warmest years on record have now occurred since 2001. Image Credits: Scientific Visualization Studio/Goddard Space Flight Center.
Earth’s 2015 surface temperatures were the warmest since modern record keeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA).
Globally-averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius). Only once before, in 1998, has the new record been greater than the old record by this much.
The 2015 temperatures continue a long-term warming trend, according to analyses by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York (GISTEMP). NOAA scientists concur with the finding that 2015 was the warmest year on record based on separate, independent analyses of the data. Because weather station locations and measurements change over time, there is some uncertainty in the individual values in the GISTEMP index. Taking this into account, NASA analysis estimates 2015 was the warmest year with 94 percent certainty.
“Climate change is the challenge of our generation, and NASA’s vital work on this important issue affects every person on Earth,” said NASA Administrator Charles Bolden. “Today’s announcement not only underscores how critical NASA’s Earth observation program is, it is a key data point that should make policy makers stand up and take notice - now is the time to act on climate.”
The planet’s average surface temperature has risen about 1.8 degrees Fahrenheit (1.0 degree Celsius) since the late-19th century, a change largely driven by increased carbon dioxide and other human-made emissions into the atmosphere.
Most of the warming occurred in the past 35 years, with 15 of the 16 warmest years on record occurring since 2001. Last year was the first time the global average temperatures were 1 degree Celsius or more above the 1880-1899 average.
Phenomena such as El Niño or La Niña, which warm or cool the tropical Pacific Ocean, can contribute to short-term variations in global average temperature. A warming El Niño was in effect for most of 2015.
“2015 was remarkable even in the context of the ongoing El Niño,” said GISS Director Gavin Schmidt. “Last year’s temperatures had an assist from El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”
Weather dynamics often affect regional temperatures, so not every region on Earth experienced record average temperatures last year. For example, NASA and NOAA found that the 2015 annual mean temperature for the contiguous 48 United States was the second warmest on record.
NASA’s analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations. These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heating effects that could skew the conclusions if left unaccounted for. The result of these calculations is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.
NOAA scientists used much of the same raw temperature data, but a different baseline period, and different methods to analyze Earth’s polar regions and global temperatures.
GISS is a NASA laboratory managed by the Earth Sciences Division of the agency’s Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is affiliated with Columbia University’s Earth Institute and School of Engineering and Applied Science in New York.
NASA monitors Earth's vital signs from land, air and space with a fleet of satellites, as well as airborne and ground-based observation campaigns. The agency develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. NASA shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.
The full 2015 surface temperature data set and the complete methodology used to make the temperature calculation are available at: http://data.giss.nasa.gov/gistemp/
The slides for the Wednesday, Jan. 20 news conference are available at:
For more information about NASA's Earth science activities, visit: http://www.nasa.gov/earth
Image (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/Goddard Institute for Space Studies/Michael Cabbage/Leslie McCarthy/Karen Northon.
Publié par Orbiter.ch à 19:13
mardi 19 janvier 2016
NASA - Van Allen Probes Mission logo.
Jan. 19, 2016
About 600 miles from Earth’s surface is the first of two donut-shaped electron swarms, known as the Van Allen Belts, or the radiation belts. Understanding the shape and size of the belts, which can shrink and swell in response to incoming radiation from the sun, is crucial for protecting our technology in space. The harsh radiation isn't good for satellites’ health, so scientists wish to know just which orbits could be jeopardized in different situations.
Since the 1950s, when scientists first began forming a picture of these rings of energetic particles, our understanding of their shape has largely remained unchanged — a small, inner belt, a largely-empty space known as the slot region, and then the outer belt, which is dominated by electrons and which is the larger and more dynamic of the two. But a new study of data from NASA’s Van Allen Probes reveals that the story may not be so simple.
Image above: (Illustration) The traditional idea of the radiation belts includes a larger, more dynamic outer belt and a smaller, more stable inner belt with an empty slot region separating the two. However, a new study based on data from NASA’s Van Allen Probes shows that all three regions — the inner belt, slot region and outer belt — can appear different depending on the energy of electrons considered and general conditions in the magnetosphere. Image Credits: NASA Goddard/Duberstein.
“The shape of the belts is actually quite different depending on what type of electron you’re looking at,” said Geoff Reeves from Los Alamos National Laboratory and the New Mexico Consortium in Los Alamos, New Mexico, lead author on the study published on Dec. 28, 2015, in the Journal of Geophysical Research. “Electrons at different energy levels are distributed differently in these regions.”
Rather than the classic picture of the radiation belts — small inner belt, empty slot region and larger outer belt — this new analysis reveals that the shape can vary from a single, continuous belt with no slot region, to a larger inner belt with a smaller outer belt, to no inner belt at all. Many of the differences are accounted for by considering electrons at different energy levels separately.
“It’s like listening to different parts of a song,” said Reeves. “The bass line sounds different from the vocals, and the vocals are different from the drums, and so on.”
Image above: (Illustration) At the highest electron energies measured — above 1 megaelectron volt (Mev) — researchers saw electrons in the outer belt only. Image Credits: NASA Goddard/Duberstein.
The researchers found that the inner belt — the smaller belt in the classic picture of the belts — is much larger than the outer belt when observing electrons with low energies, while the outer belt is larger when observing electrons at higher energies. At the very highest energies, the inner belt structure is missing completely. So, depending on what one focuses on, the radiation belts can appear to have very different structures simultaneously.
These structures are further altered by geomagnetic storms. When fast-moving magnetic material from the sun — in the form of high-speed solar wind streams or coronal mass ejections — collide with Earth’s magnetic field, they send it oscillating, creating a geomagnetic storm. Geomagnetic storms can increase or decrease the number of energetic electrons in the radiation belts temporarily, though the belts return to their normal configuration after a time.
These storm-driven electron increases and decreases are currently unpredictable, without a clear pattern showing what type or strength of storm will yield what outcomes. There’s a saying in the space physics community: if you’ve seen one geomagnetic storm, you’ve seen one geomagnetic storm. As it turns out, those observations have largely been based on electrons at only a few energy levels.
Image above: (Illustration) The radiation belts look much different at the lowest electron energy levels measured, about 0.1 MeV. Here, the inner belt is much larger than in the traditional picture, expanding into the region that has long been considered part of the empty slot region. The outer belt is diminished and doesn’t expand as far in these lower electron energies. Image Credits: NASA Goddard/Duberstein.
“When we look across a broad range of energies, we start to see some consistencies in storm dynamics,” said Reeves. “The electron response at different energy levels differs in the details, but there is some common behavior. For example, we found that electrons fade from the slot regions quickly after a geomagnetic storm, but the location of the slot region depends on the energy of the electrons.”
Often, the outer electron belt expands inwards toward the inner belt during geomagnetic storms, completely filling in the slot region with lower-energy electrons and forming one huge radiation belt. At lower energies, the slot forms further from Earth, producing an inner belt that is bigger than the outer belt. At higher energies, the slot forms closer to Earth, reversing the comparative sizes.
Image above: (Illustration) During geomagnetic storms, the empty region between the two belts can fill in completely with lower-energy electrons. Traditionally, scientists thought this slot region filled in only during the most extreme geomagnetic storms happening about once every 10 years. However, new data shows it’s not uncommon for lower-energy electrons — up to 0.8 MeV — to fill this space during almost all geomagnetic storms. Image Credits: NASA Goddard/Duberstein.
The twin Van Allen Probes satellites expand the range of energetic electron data we can capture. In addition to studying the extremely high-energy electrons — carrying millions of electron volts — that had been studied before, the Van Allen Probes can capture information on lower-energy electrons that contain only a few thousand electron volts. Additionally, the spacecraft measure radiation belt electrons at a greater number of distinct energies than was previously possible.
“Previous instruments would only measure five or ten energy levels at a time,” said Reeves. “But the Van Allen Probes measure hundreds.”
Measuring the flux of electrons at these lower energies has proved difficult in the past because of the presence of protons in the radiation belt regions closest to Earth. These protons shoot through particle detectors, creating a noisy background from which the true electron measurements needed to be picked out. But the higher-resolution Van Allen Probes data found that these lower-energy electrons circulate much closer to Earth than previously thought.
“Despite the proton noise, the Van Allen Probes can unambiguously identify the energies of the electrons it’s measuring,” said Reeves.
The twin Van Allen Probes satellites. Image Credit: NASA Goddard
Precise observations like this, from hundreds of energy levels, rather than just a few, will allow scientists to create a more precise and rigorous model of what, exactly, is going on in the radiation belts, both during geomagnetic storms and during periods of relative calm.
“You can always tweak a few parameters of your theory to get it to match observations at two or three energy levels,” said Reeves. “But having observations at hundreds of energies constrain the theories you can match to observations.”
The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, built and operates the Van Allen Probes for NASA's Science Mission Directorate. The mission is the second mission in NASA's Living With a Star program, managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland.
NASA’s Van Allen Probes website: http://www.nasa.gov/mission_pages/rbsp/main/index.html
Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Sarah Frazier/Rob Garner.
Publié par Orbiter.ch à 16:05
NASA - Veggie Experiment logo.
Jan. 19, 2016
On Jan. 16, 2016, Expedition 46 Commander Scott Kelly shared photographs of a blooming zinnia flower in the Veggie plant growth system aboard the International Space Station. Kelly wrote, "Yes, there are other life forms in space! #SpaceFlower #YearInSpace"
This flowering crop experiment began on Nov. 16, 2015, when NASA astronaut Kjell Lindgren activated the Veggie system and its rooting "pillows" containing zinnia seeds. The challenging process of growing the zinnias provided an exceptional opportunity for scientists back on Earth to better understand how plants grow in microgravity, and for astronauts to practice doing what they’ll be tasked with on a deep space mission: autonomous gardening. In late December, Kelly found that the plants "weren't looking too good," and told the ground team, “You know, I think if we’re going to Mars, and we were growing stuff, we would be responsible for deciding when the stuff needed water. Kind of like in my backyard, I look at it and say ‘Oh, maybe I should water the grass today.’ I think this is how this should be handled.”
The Veggie team on Earth created what was dubbed “The Zinnia Care Guide for the On-Orbit Gardener,” and gave basic guidelines for care while putting judgment capabilities into the hands of the astronaut who had the plants right in front of him. Rather than pages and pages of detailed procedures that most science operations follow, the care guide was a one-page, streamlined resource to support Kelly as an autonomous gardener. Soon, the flowers were on the rebound, and on Jan. 12, pictures showed the first peeks of petals beginning to sprout on a few buds.
How Mold on Space Station Flowers is Helping Get Us to Mars:
Space-Grown Flowers Will be New Year Blooms on International Space Station:
International Space Station (ISS): http://www.nasa.gov/mission_pages/station/main/index.html
Space Station Research and Technology: http://www.nasa.gov/mission_pages/station/research/index.html
One-Year Crew: http://www.nasa.gov/content/one-year-crew/index.html
Expedition 46: http://www.nasa.gov/mission_pages/station/expeditions/expedition46/index.html
Image, Text, Credits: NASA/Sarah Loff.
Publié par Orbiter.ch à 15:46
ESA - Alphasat Mission logo.
19 January 2016
Satellites are carrying increasingly diverse payloads into orbit, and resolving their often-conflicting onboard schedules requires programming wizardry and a little help from artificial intelligence.
Adding experimental payloads to already planned satellites is a smart, cost-effective way to provide critical in-orbit testing of new technologies.
Alphasat artist's impression
For example, in addition to its prime data telecommunication payload, Alphasat – operated by Inmarsat as part of a commercial fleet and the largest European telecom satellite ever flown – carries four ‘hosted’ Technology Demonstration Payloads provided by ESA and the DLR German Aerospace Center, whose operations are coordinated by ESA.
These hosted devices, however, all function quite independently of each other and have different and often conflicting requirements and limitations on when they can operate, and how they should avoid interference with the satellite’s prime telecom mission.
That’s where an ESA-developed artificial intelligence (AI) system – dubbed TECO, for “Technology Demonstration Payload – ESA Coordination Office” – is making a valuable contribution, saving time and human effort by offering a service that optimises payload activity scheduling.
Crunching numbers without the humans
The new planning and scheduling system was originally developed for ESA’s Telecommunication and Integrated Application programmes by engineers at ESOC, the Agency’s operations centre in Darmstadt, Germany, as a prototype for validating AI software. It has now evolved into a proven system that used for Alphasat.
Techniques used in TECO processing are based in part on experience gained with earlier automated planning systems developed for missions such as Mars Express and SOHO.
Under control at ESOC
For the Alphasat demonstration payloads, TECO accepts proposed activity requests from each of the four payload control centres, applies hundreds of limitations and constraints from each of the four devices, as well as from the satellite platform and its prime payload mission, and then crunches the numbers to produce a detailed weekly payload activity schedule. This typically includes over 100 separate payload actions and, in some cases, more than 500.
The process is automated, and humans need intervene only if an anomalous conflict is identified that can’t be resolved by the system’s AI engine.
Laser communication demo on Alphasat
“To date, feedback from our customers – the centres that operate the four test payloads on board Alphasat – has been extremely positive,” says Nicola Policella, the lead designer and now TECO service manager.
“It’s automated, it saves a great deal of human effort and, most importantly, it reduces the risk of human error while allowing the payload operators to focus on problems that AI and automation alone can’t solve.”
Alphasat was launched in July 2013 into geostationary orbit as a public–private partnership – the biggest of its kind – between ESA and UK operator Inmarsat.
It expands Inmarsat’s global mobile telecommunication network, delivering new capabilities in terms of performance and availability. It is also the first flight for Alphabus, the new European telecom platform.
Optimising payload scheduling
The satellite provides an ideal test bed for ESA’s four Technology Demonstration Payloads, comprising a startracker and a laser communication terminal, both developed and built in Germany (by Jena Optronik and Tesat, respectively) with funding from DLR, an extremely high-frequency transponder, provided by Italy’s ASI space agency and industrial partners Thales Alenia Space and Space Engineering, and a radiation monitor from the Efacec Group, Portugal.
The TECO scheduling system was developed at ESOC in 2011–12 and entered operation at the end of 2013.
“In recent years, ESA’s mission teams have increasingly applied automation and AI techniques to solve complex scheduling problems related to spacecraft operations in general,” says Kim Nergaard, Head of ESA’s Advanced Mission Concepts Section.
“These have covered specific scheduling activities such as ground station passes, queuing data for download from a satellite and generating commands for upload, among others.
“Automating is a smart way to enhance effectiveness and boost return on investment, generating more value from data gathered in space.”
With TECO running at ESOC as a reliable service since 2013, plans now foresee its extension to other missions and other types of scheduling problems.
Access more information on TECO via ESA's Rocket Science blog:
European Space Operations Centre (ESOC):
Centre overview: http://www.esa.int/About_Us/ESOC/Where_missions_come_alive
Images, Video, Text, Credits: ESA/ESAQ/J. Mai - CC SA-BY 3.0 IGO.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 15:33