News Article | April 14, 2017
City skylines are always beautiful at night. The beauty of planet Earth at night can be enjoyed from crisp images captured by NASA, called night light maps, and recently released by the space agency. The latest NASA Earth night images of 2016 showcase concrete patterns of human settlement. Compiled from satellite views, NASA's global maps for 2016 stand out for clarity and accuracy compared with similar images that have been around for 25 years. Previously, these images were compiled once in 10 years. In early April, NASA released a global map of night lights in 2016 based on satellite observations. It also released an updated version of the 2012 night light map. The NASA images of cities at night will be serving a scientific purpose besides the conventional use as a tool for studying cities. The night images are being used in research projects of economics, social science, and the environment. In the words of the space agency, the night maps have been offering a "gee-whiz curiosity for the public and a tool for fundamental research for nearly 25 years." The images of 2016 express better clarity and accuracy compared with the relatively vague images of 2012. It is an advancement of the globe being lit up and a bigger contribution of humans in shaping up the earth. In the time to come, the satellite images of night Earth referred to as "night lights" will see greater frequency as NASA will be launching more images. This will also help in shoring up weather forecasting, improving responses to natural disasters, and studying the effects of war on the planet. Determined to optimize the potential of NASA night lights, the space agency is planning rapid updates, breaking the 10-year interval. Already, a team led by Miguel Román, an earth scientist at Goddard Space Flight Center of NASA, is at work to develop new software to attain more clarity and accuracy for the night lights. The plan is to produce high-definition views of Earth at night. Since the 2011 launch of NASA's NOAA Suomi National Polar-orbiting Partnership or NPP satellite, Román and team have been analyzing night lights data and developing new software and algorithms to make images brighter, clearer, and more accurate. NASA coped with many challenges in preparing the night images as the quantum of light shining on Earth varies constantly and predictably. NASA examined how light is radiated, reflected and scattered by land, atmospheric, and ocean surfaces. Normally, it is hard to make an image at night as constantly shifting light is a problem. Then the changing phases of the moon also affects light patterns. There are also factors affecting the path of light and their visibility in various parts of the world such as vegetation, clouds, aerosols, ice cover, and feeble emissions like auroras. However, things have changed now with the advent of new technology. NASA has an able tool in the Visible Infrared Imaging Radiometer Suite or VIIRS from the Suomi NPP weather satellite. VIIRS boasts of the capability to detect light reflected from Earth's surface and atmosphere in 22 wavelengths. It also excels as the first satellite instrument that takes quantitative measurements of emitted and reflected light. The measurements can determine the intensity and source of light over a number of years. In September 2016, VIIRS mapped the power outages in southeast America and the Caribbean after Hurricane Matthew hit the continent. "Thanks to VIIRS, we can now monitor short-term changes caused by disturbances in power delivery, such as conflict, storms, earthquakes and brownouts," said NASA scientist Román. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
News Article | May 2, 2017
Gobbling gas from a neighbour should make neutron stars spin faster, but sometimes the exact opposite happens. Now there might be an explanation: the gas arrives “backwards”. Neutron stars are dense, fast-spinning stellar corpses that can pull material from a smaller orbiting star, spooling it into a disc before gobbling it up. This material carries momentum, which is why the neutron star should end up spinning faster. But when Demos Kazanas at the NASA Goddard Space Flight Center in Maryland and his colleagues looked at 18 years’ worth of X-ray observations of neutron stars in binary systems in the Small Magellanic Cloud, they found that half were slowing down. “That’s harder to understand, because you’d think that they’d be tending to spin up if our current understanding of their evolution is correct,” says Tim Kallman, also at NASA Goddard, who wasn’t involved in the work. Even stranger, the rate of their slowdowns seemed to be the same as the rate at which the others were accelerating. “The two distributions are really very similar, which means that the process by which the spin up and spin down [happen] could be the same,” says Kazanas. The team have put forward an explanation for the slowdowns: they happen when the swallowed gas is spooling around the neutron star in the opposite direction to the star’s spin. If borne out by future observations, this idea could alter the commonly accepted view of the evolution of neutron stars in such binary systems, which is that they will keep spinning faster and faster until the end of their companion stars’ lives. Kazanas and his colleagues speculate instead that neutron stars can repeatedly speed up, slow down and switch direction. It could also have surprising implications for the neutron stars’ less exotic partners as their gas is stripped away. “We understand those normal stars somewhat,” Kallman says. “It’s surprising that it would change [their] character so dramatically.” It’s not yet clear whether backwards-spinning gas is the right explanation – or how that would even work. “Their explanation is charmingly simple, that it’s the same phenomenon in the opposite direction,” says Anne Archibald at the University of Amsterdam in the Netherlands. “But there are other ways [to account for the slowdown].”
News Article | April 24, 2017
(NASA/Goddard Space Flight Center) New data from three NASA missions show that the heliosphere -- the bubble of the sun's magnetic influence that surrounds the inner solar system -- may be much more compact and rounded than previously thought.
News Article | April 24, 2017
(NASA/Goddard Space Flight Center) An animation created by NASA using imagery from NOAA's GOES-East satellite shows the North Atlantic Ocean's first tropical storm of the season being "eaten" by a large frontal system.
News Article | April 17, 2017
Millions of pieces of human-made trash are now orbiting the Earth. Some are tiny, others are large enough to be seen with a telescope, but all pose a risk to space craft and satellites. And according to experts the threat is growing as space becomes more and more crowded. Some 23,000 pieces of space junk are large enough to be tracked by the US Space Surveillance Network. But most objects are under 10cm (4in) in diameter and can't be monitored. Even something the size of a paper clip can cause catastrophic damage. "At the moment we're not tracking stuff that small," says Brian Weeden of the Secure World Foundation, a Washington based organisation dedicated to the sustainable use of space. "And that's important because something as small as a centimetre can cause problems if it runs into a satellite." Collisions are rare, but half of all near-misses today are caused by debris from just two incidents. In 2007, China destroyed one of its own satellites with a ballistic missile. In 2009 an American commercial communications satellite collided with a defunct Russian weather satellite. As recently as 2015, the debris from that collision forced the crew of the International Space Station to evacuate to the Soyuz capsule. No-one was harmed, but the debris will likely remain in the Earth's orbit for hundreds, if not thousands of years. Scientists are experimenting with ways to clean up space. So far, there is no space vacuum cleaner. And debris have a nasty habit of creating more debris that get exponentially smaller and harder to spot. More than 7,000 satellites have been put into space but only 1,500 are currently functioning. And within the next decade the number could increase to 18,000 with the planned launch of mega-constellations - large groups of satellites aimed at improving global internet coverage. "That's going to amplify the problems we have with tracking objects, predicting close approaches and preventing collisions," says Weeden. "The problem is going to become much, much harder in the next several years." Everything travels at the same speed relative to its altitude in space. That's not a problem if everything moves in the same direction, says Weeden, but objects often follow different orbits and can cross paths - a situation known as a conjunction. "Think of it like all the cars on a highway are doing a hundred miles an hour. If the car next to you is doing that speed you don't really notice it. But if the car coming at you is doing that speed - you'll collide at 200 miles an hour." Lauri Newman is NASA's traffic cop at Goddard Space Flight Center, Maryland. She is responsible for using military data to decide whether the space agency's unmanned craft such as satellites need to be moved to prevent a collision with debris. "Satellites can protect themselves from things that are smaller than a centimetre by putting up extra shielding," she says. "But the things between one and 10cm - if you can't track it there's nothing you can do." Satellite technology is essential to almost every modern convenience - from communications to GPS navigation and downloading movies on demand. It's also vital to national security. "It affects everything," says Lt Col Jeremy Raley a program manager at Darpa, the Defense Advanced Research Projects Agency. "So I need to be able to see everything (in space) all the time and know what it is when I see it." That's why Darpa is leading military efforts to find better ways of tracking space debris. In October last year it delivered a massive 90-ton telescope to the US Air Force at White Sands, New Mexico. The Space Surveillance Telescope is designed to penetrate Geosynchronous orbit (GEO) which is becoming increasingly important. Communications and television satellites in GEO can remain in a fixed position above the Earth, offering uninterrupted service. "The telescope is a big deal because it can see more objects and smaller objects. And rather than having to take time to look at an object and then look at something else, it can keep track of things on a more persistent basis," says Lt Col Raley. But that level of scrutiny costs money and also raises the question of whether the US should share its data to improve space safety overall. That was one of the issues discussed at a recent symposium in Washington organised by the Universities Space Research Association and the Space Policy Institute at George Washington University. Experts discussed who should manage space, who should be responsible for debris and whether there should be an agreed set of international guidelines for the sustainable use of space. "There's a classic public policy, economic question here," says Weeden. "It's like pollution. It might not be worth it for you to pick up your garbage and avoid polluting the river, but there are costs to society if you don't. How do you get people to be responsible when the costs may not be borne by them?" No single nation or entity is responsible for space although in 1959 the UN set up a Committee on the Peaceful Uses of Outer Space (COPUOS). "There are currently 85 countries that are members of this committee and they range from space powers such as the US, Russia and China to countries like Costa Rica that don't even have a satellite in orbit but are an end user of satellite functions," says Weeden. "Getting all of those countries to agree on this stuff is a really difficult challenge." But with more nations and commercial organisations operating in Earth's orbit and many looking beyond, such issues are becoming increasingly urgent. Do nothing is no longer an option.
News Article | May 3, 2017
Big planets come with big surprises. Last week, delegates at the annual European Geosciences Union meeting got the first glimpse of data from the Juno spacecraft now in orbit around Jupiter, and the findings are already challenging assumptions about everything from the planet’s atmosphere to its interior. “The whole inside of Jupiter is just working differently than our models expected,” said mission principal investigator Scott Bolton of the Southwest Research Institute in Texas. Launched on 5 August 2011, Juno reached Jupiter and began its first orbit on 4 July last year. Since then, it has performed four more circuits. There are 33 planned pole-to-pole circuits in all, encircling the entire planet bit by bit. The findings presented in Vienna come from these first few circuits, which each last 53 Earth days and include a 6-hour scan of the planet from north to south. Although the information is preliminary, the researchers involved are thrilled. Much of the excitement centres on the discovery of a dense zone of ammonia gas around Jupiter’s equator, plus other regions where ammonia is depleted, which together suggest an ammonia-based weather system. We have long known that Jupiter is completely shrouded in ammonia clouds, but the existence of such a deep “belt” is surprising. “We’ve known there’s a spike at the equator, but the new microwave data is showing that the spike goes way, way down into the abyss, 300 kilometres below the cloud,” says Leigh Fletcher of the University of Leicester, UK, who was not involved in the work. “It suggests ammonia is being distributed by a weather system that penetrates much deeper than anyone expected.” The findings are also challenging models of what’s inside the planet. We had assumed Jupiter has a uniform interior, with a shallow “crust” of liquid hydrogen overlying a thin layer where helium rains down. Under that is a much deeper layer of metallic hydrogen, with a smaller solid core around 70,000 kilometres down. Those assumptions were based on mapping the planet’s gravity. But initial gravity measurements from Juno challenge the idea that the internal layers inside are completely regular in their make-up. “Jupiter’s molecular envelope is not uniform,” said Tristan Guillot of the University of the Cote d’Azur in France. “We assumed we could treat the envelope as global, but now, with the finer data, it appears less regular.” Fletcher says it points to a core that is not solid like Earth’s, but “fuzzy” and dilutely mingled with the overlying metallic hydrogen layer. Another shock is that Jupiter’s huge magnetic field is even stronger and much more irregular than expected. The irregularity of the field so far is a sign that the dynamo driving it may originate higher up in Jupiter’s interior, perhaps from a layer of metallic hydrogen. “I didn’t expect all the theories to be wrong, but there’s motion going on in the planet we did not anticipate,” Bolton said. Jupiter’s magnetic field also dwarfs the 0.25 to 0.65 gauss at Earth’s surface by an even bigger margin than we expected. Juno readings on its closest approaches so far, presented by Jack Connerney of the NASA Goddard Space Flight Center in Maryland, suggest it could be 8 to 9 gauss rather than the 5 gauss predicted. More tantalisingly, Juno’s magnetometers found that the field dipped in other regions, a telltale sign that the dynamo driving the field is close to the surface over the entire planet, not buried deep within it like Earth’s core. “Jupiter’s magnetic field is spatially complex, and there were deficits of up to 2 gauss elsewhere,” said Connerney. “We may need many more orbits to resolve this.” The first orbits have also produced several new insights into the planet’s atmosphere. The probe’s JunoCam camera has already sent back amazing pictures of hitherto unknown cyclones over the poles. Glenn Orton of the Jet Propulsion Laboratory in Pasadena, California, who helps manage the JunoCam website, showed stunning composite videos of the cyclones swirling. “They’re the size of Earth, or maybe half an Earth,” Orton told New Scientist. “They’re probably composed of condensed ammonia.” Strange white ovals have been spotted, too, in belts south of Jupiter’s equator. They could be clouds containing ammonia and hydrazine, a substance used as rocket fuel on Earth, according to an analysis of Juno infrared radiation readings presented by Alberto Adriani of the Institute for Space Astrophysics and Planetology in Rome. Adriani also presented stunning infrared images of the auroras which occur daily at the poles. His analyses revealed that the areas where they glow are composed mainly of methane and an ion containing three hydrogen atoms (H +), at temperatures ranging from 500 to 950 kelvin. Adriani’s composite movies of the auroras – not released to the public yet – were equalled by others showing similar features imaged with ultraviolet spectrometers, presented by Bertrand Bonfond of the University of Liège in Belgium. The camera is proving tougher than expected, too. Fears that it would last just a dozen circuits because of the battering from Jupiter’s intense radiation have turned out to be misplaced. “The good news is radiation damage so far is almost negligible, so it will operate for many years,” Orton said. And more data will arrive after the next closest approach on 19 May. Eventually, Juno will fly over Jupiter’s famous Great Red Spot, and Fletcher is excited about the data that will generate. “It means that for the first time, we can go down deep and find out what’s going on underneath,” he says.
News Article | April 17, 2017
Mars’s atmosphere harbours a layer of electrically charged metal atoms, and they’re not behaving as expected. NASA’s MAVEN (Mars Atmosphere and Volatile Emission) spacecraft found layers of atmospheric metal ions that defy models based loosely on Earth’s atmosphere. “Mars is giving us observations both like and unlike Earth, and that’s very exciting,” says Joseph Grebowsky at the NASA Goddard Space Flight Center in Greenbelt, Maryland, head of the team that found these Martian metals. The space between planets is full of metallic dust and rocks. As they are drawn into a planet’s atmosphere, they burn up, leaving behind metal particles like iron and magnesium. On Earth, the behaviour of those particles is mostly controlled by the planet’s strong magnetic field. They use magnetic fields as a sort of highway, and stream along the magnetic field lines to form thin layers throughout the atmosphere. But Mars has no such field. The planet does have small regions with weak magnetic fields in its southern hemisphere, but without a global field like Earth’s, it should not be able to form the layers that MAVEN sees. “Something is causing these layers – something is pushing them around – but we don’t know what,” says Grebowsky. Mars’s nubs of magnetic field certainly play a part, and winds through the atmosphere probably do as well, but the exact mechanism must be different from the one at work on Earth. Grebowsky says that he has expected that the Martian atmosphere would have metal ions for years, but this is the first time that a spacecraft there has confirmed their continuous presence. He and his colleagues also found an unexpected distribution of iron and magnesium ions at Mars. Iron is heavier than magnesium, so it should sink and leave less iron than magnesium higher in the atmosphere. Instead, the two are well-blended much higher in the atmosphere than expected. “The profiles are surprisingly ordered with respect to altitude,” says Grebowsky. “It’s very unlike at Earth.” These wavy clouds of metals could be related to chemistry and climate in Mars’s upper atmosphere. They may even help explain how the planet lost much of its atmosphere to space, leaving it dry and barren. “In terms of understanding the habitability of a planet, it’s very important to be sure about understanding atmospheric processes,” says Guillaume Gronoff at NASA’s Langley Research Center. “Here it’s showing that there are a couple of things that we don’t get.” These new MAVEN findings yield more questions than answers: how do the metal ions get so high up in the atmosphere? How do they form layers like Earth’s without a strong magnetic field? Why are they mixed in so well together? The models that we have now of Mars’s atmosphere can’t explain any of these phenomena. “This is neat because it shows us that the Martian atmosphere is an atmosphere all by itself,” says Dean Pesnell, who is also based at the NASA Goddard Space Flight Center but was not involved in this work. “It’s not just another Earth that’s a little different.”
News Article | April 12, 2017
NASA has confirmed that there is a permanent metal presence in the atmosphere of Mars, representing the first detection of metal ions in any planet's ionosphere aside from Earth. The discovery, which was made by the Mars Atmosphere and Volatile Evolution Mission, or simply known as MAVEN, could be key to unlocking several mysteries surrounding the Red Planet. NASA broke the news in a press release, claiming that the discovery could reveal activity in the ionosphere of Mars that was previously invisible. "MAVEN has made the first direct detection of the permanent presence of metal ions in the ionosphere of a planet other than Earth," said Joseph Grebowsky, who is from the Goddard Space Flight Center of NASA in Greenbelt, Maryland. Grebowsky added that the metallic ions have long lifetimes and travel far from their point of origin due to electric fields and neutral winds. As such, they could be used to predict motion in the ionosphere of Mars, similar to how we find out where the wind is blowing from leaves. MAVEN has been tasked with exploring the upper atmosphere of Mars to help scientists better understand how it lost most of its air, a phenomenon that transformed the Red Planet from a possibly habitable one billions of years in the past to the cold desert planet that it is today. MAVEN's discovery of metal in the ionosphere of Mars will help scientists in figuring out how the atmosphere of Mars is flowing out into space. The metal in Mars's ionosphere, however, behaves very differently compared to how it acts in Earth. While Earth has a magnetic field enveloping the planet, magnetic fields only exist in certain regions in Mars. Outside of those areas, the metal ion distributions on Mars do not resemble anything close to what can be seen in Earth. The metal in the ionosphere of Mars comes from the small meteoroids that fly into the planet's atmosphere and get vaporized. Metallic atoms in the vapor trail then have some electrons removed by charged particles in the ionosphere, changing the metal atoms into metallic ions. MAVEN has actually previously found traces of iron, magnesium, and sodium in Mars's upper atmosphere, but the latest discovery confirms that metal has a permanent presence in the planet's atmosphere. The confirmation of metal in the atmosphere of Mars as another trait shared between the planet and Earth will help in comparative studies between the two. The metallic ions on Mars gives scientists a parameter for comparing and contrasting the Red Planet with Earth for a clearer understanding of its atmosphere. In addition, scientists will need to figure out what is keeping the metal in the atmosphere of Mars. Without a magnetic field like that of Earth's, there should be no such layer on the Red Planet, but there appears to be something else that is keeping the metal ions together despite how Mars is losing its atmosphere into space. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
Seager S.,Massachusetts Institute of Technology |
Deming D.,Goddard Space Flight Center
Annual Review of Astronomy and Astrophysics | Year: 2010
At the dawn of the first discovery of exoplanets orbiting Sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features, observation of day-night temperature gradients, and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures.Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and ultimately the spaceborne direct imaging of true Earth analogs. © 2010 by Annual Reviews.
Kogut A.,Goddard Space Flight Center
Astrophysical Journal | Year: 2012
We combine surveys of the radio sky at frequencies 22MHz to 1.4GHz with data from the ARCADE-2 instrument at frequencies 3GHz to 10GHz to characterize the frequency spectrum of diffuse synchrotron emission in the Galaxy. The radio spectrum steepens with frequency from 22MHz to 10GHz. The projected spectral index at 23GHz derived from the low-frequency data agrees well with independent measurements using only data at frequencies 23GHz and above. Comparing the spectral index at 23GHz to the value from previously published analyses allows extension of the model to higher frequencies. The combined data are consistent with a power-law index β = -2.64 ± 0.03 at 0.31GHz, steepening by an amount of Δβ = 0.07 every octave in frequency. Comparison of the radio data to models including the cosmic-ray energy spectrum suggests that any break in the synchrotron spectrum must occur at frequencies above 23GHz. © 2012. The American Astronomical Society. All rights reserved..