- Balloon Carries Two Student Experiments to the Edge of Space
- Implications for Mars Research: Scientists Identify Mineral That Destroys Organic Compounds
- Boeing, ULA Break Ground on New Crew Access Tower
- NASA Announces Winning Ideas for Mars Balance Mass Challenge
- A Disintegrating Rocky Exoplanet Could Unlock Secrets to How Our Solar System Was Formed
- Hubble Gets Best View of a Circumstellar Debris Disk Distorted by a Planet
- Orion Flight Test Yields Critical Data as Engineers Improve Spacecraft for Next Mission
- Solar Storm Found to Produce 'Ultrarelativistic, Killer Electrons' in 60 Seconds
- MAVEN Spacecraft Completes First Deep Dip Campaign
- Classical Nova Explosions are Major Lithium Factories in the Universe
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Posted: 21 Feb 2015 06:45 AM PST
A balloon that traveled to the edge of space this week carried two Montana State University (MSU) experiments. One experiment -- launched Feb. 19 and retrieved Feb. 20 after reaching 102,200 feet -- tested a tracking and high-definition link that MSU hopes to use during a total solar eclipse on Aug. 21, 2017. The Montana Space Grant Consortium is organizing a national effort where college students across the United States will monitor the eclipse with high-altitude balloons. The second experiment tested a computer system that’s designed to resist radiation in space. MSU recently received word that the tiny satellite it designed to carry the system was one of 14 CubeSats selected to fly on an upcoming NASA mission. “It was just awesome,” Angela Des Jardins, director of the Montana Space Grant Consortium, said about the 7 a.m. balloon launch. “Our students were thrilled to be there and be part of it.”
MSU was one of two universities invited to send experiments on the balloon, an opportunity that arose from connections between MSU’s Dave Klumpar and World View, Des Jardins said. World View is the commercial balloon spaceflight company that launched the research flight from the Tucson, Ariz., area. Klumpar is director of MSU’s Space Science and Engineering Laboratory.
The other university that flew an experiment on the balloon was the University of North Florida. That experiment was designed to measure the ozone gas profile in the stratosphere.
The research and education payloads are part of World View’s commitment to opening routine access to high-altitude balloon flights, as well as its dedication to advancing science, technology, engineering and math (STEM) programs in schools, according to a Feb. 20 press release from World View. All three experiments involved multiple students over multiple years.
Randy Larimer, deputy director of the Montana Space Grant Consortium, said more than 40 graduate students and undergraduate students over eight years were involved in designing the computer system. They are led by MSU faculty member Brock LaMeres. Besides flying on an upcoming satellite mission in 2016, the technology is scheduled to be tested on the International Space Station later this year.
More than 15 students at MSU and Iowa State University contributed to the design of the video link that flew on the World View balloon, Larimer added. The video link test verified that the technology setup works well.
Larimer and four MSU students went to Arizona for the balloon launch. The students were Sam Harkness, a graduate student in electrical engineering; Scott Miller, a senior in computer engineering; Tim Basta, a senior in mechanical engineering; and Trevor Clark, a senior in electrical engineering.
Credit: montana.edu
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Posted: 21 Feb 2015 06:08 AM PST
Scientists have discovered that the mineral jarosite breaks down organic compounds when it is flash-heated, with implications for Mars research. Jarosite is an iron sulphate and it is one of several minerals that NASA’s Curiosity Mission is searching for, as its presence could indicate ancient habitable environments, which may have once hosted life on the red planet. In a new study published in the journal Astrobiology, researchers from Imperial College London and the Natural History Museum replicated a technique that one of the Curiosity Rover’s on-board instruments is using to analyse soil samples, in its quest to find organic compounds. They tested a combination of jarosite and organic compounds. They discovered that the instrument’s technique -which uses intense bursts of heat called flash-heating – broke down jarosite into sulphur dioxide and oxygen, with the oxygen then destroying the organic compounds, leaving no trace of it behind.
The concern is that if jarosite is present in soil samples that Curiosity analyses, researchers may not be able to detect it because both the jarosite and any organic compounds could be destroyed by the flash-heating process.
In 2014, Professor Mark Sephton, co-author of today’s study, investigated the mineral perchlorate. This mineral also causes problems for flash-heating experiments as it breaks down to give off oxygen and chlorine gas, which in turn react with any organic compounds, breaking them down into carbon dioxide and water. Professor Sephton showed that though perchlorate was problematic, scientists could potentially use the carbon dioxide resulting from the experiment to detect the presence of organic compounds in the sample being analysed.
Professor Sephton, from the Department of Earth Science and Engineering at Imperial College London, said: “The destructive properties of some iron sulphates and perchlorate to organic matter may explain why current and previous missions have so far offered no conclusive evidence of organic matter preserved on Mars’ surface. This is despite the fact that scientists have known from previous studies that organic compounds have been delivered to Mars via comets, meteorites and interplanetary dust throughout its history.”
To make Curiosity’s search for signs of life more effective, the team are now exploring how Curiosity might be able to compensate for the impact of these minerals on the search for organic compounds. Their work could have important implications for both the Curiosity mission and also the upcoming European-led ExoMars 2018 Rover mission, which will be drilling for subsurface samples of the red planet and using the same flash-heating method to look for evidence of past or present alien life.
James Lewis, co-author of the study from the Department of Earth Science and Engineering at Imperial College London, added: “Our study is helping us to see that if jarosite is detected then it is clear that flash-heating experiments looking for organic compounds may not be completely successful. However, the problem is that jarosite is evidence of systems that might have supported life, so it is not a mineral that scientists can completely avoid in their analysis of soils on Mars. We hope our study will help scientists with interpreting Mars data and assist them to sift through the huge amount of excellent data that Curiosity is currently generating to find signs that Mars was once able to sustain life.”
On Earth, iron sulphate minerals like jarosite form in the harsh acidic waters flowing out of sulphur rich rocks. Despite the adverse conditions, these waters are a habitat for bacteria that use these dissolved sulphate ions. This makes these minerals of great interest to scientists studying Mars, as their presence on the red planet provide evidence that acidic liquid water was present at the same time the minerals formed, which could have provided an environment favourable for harbouring ancient microbial Martian life.
On board Curiosity, the Sample Analysis at Mars (SAM) instrument analyses soil samples for evidence of organic compounds by progressively heating samples up to around 1000 C, which releases gases. These gases can then be analysed by techniques called gas chromatography and mass spectrometry, which can identify molecules in the gas and see if any organic compounds are present. It is these SAM instrument experiments that the researchers behind today’s study replicated with jarosite and organic compounds.
The researchers stress that not all sulphates break down to react with organic compounds. For example, those containing calcium and magnesium would not break down until extremely high temperatures were reached during the analysis, and therefore would not affect any organic compounds present.
The team suggest that if jarosite is found in samples on Mars, then it may be possible for Curiosity’s SAM instrument to distinguish a spike in carbon dioxide level, which, as Professor Sephton has shown previously with perchlorate, would act as an indicator that organic material is present and being broken down by the heating process.
The next step will see the researchers using synthetic jarosite in their experiments, which will enable a cleaner decomposition process to occur when the mineral is flash-heated. This will allow for more precise quantitative measurements to be taken when the oxygen is being released. Ultimately, they hope this will enable more precise calculations to be carried out on Mars mineral samples to find ways in which Curiosity can identify the presence of these mineral to mitigate their impact on organic matter.
The jarosite samples used in the experiments in the study were collected from Brownsea Island in Dorset, with the permission and assistance from the National Trust.
Credit: imperial.ac.uk
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Posted: 21 Feb 2015 03:58 AM PST
Boeing and United Launch Alliance teams held a ceremonial groundbreaking Feb. 20 to begin construction on the first new crew access structure at Cape Canaveral Air Force Station in decades. The preparations will enable Space Launch Complex 41 to host astronauts and their support personnel for flight tests and missions to the International Space Station. The tower will be used for launches of Boeing's CST-100 spacecraft atop an Atlas V rocket. Boeing was selected to finalize the design of its integrated crew transportation system and work with NASA’s Commercial Crew Program to certify it for crew launches to the station by 2017. "Fifty-three years ago today, John Glenn became the first American to orbit the Earth, launching on an Atlas just a few miles from here,” said Jim Sponnick, vice president of ULA’s Atlas and Delta programs. “The ULA team is very proud to be collaborating with Boeing and NASA on the Commercial Crew Program to continue that legacy and to return America to launching astronauts to the station.”
Boeing and ULA finished the design for the 200-foot-tall, metal latticework crew access structure in the summer of 2013. The design was made modular so crews could build large sections of the structure away from the pad then truck them in and stack them up to complete the work in between Atlas V launches. It will take about 18 months to build the tower.
“This is truly an integrated effort by a lot of partners and that’s really represented here today by the guests celebrating this groundbreaking with us,” said John Mulholland, Boeing Vice President of Commercial Programs. “This is the first construction of its type on the Cape since the 1960s, so building this crew tower, returning of the human launch capability to the United States, is very significant.”
Construction crews will face all the usual challenges of building a 20-story-high tower beside the ocean, plus the fact that one of the busiest launchers in the American catalog is not going to take time off during the construction phase.
The crew access structure will visually stand out at SLC-41, largely because the launch complex is a "clean pad" design with only the reinforced concrete hard stand and four lightning towers in place. About 1,800 feet to the south is a building called the Vertical Integration Facility, which houses the cranes and work platforms to assemble an Atlas V.
"Besides the VIF and the lightning towers, the crew access tower will be the tallest structure at the launch site," said Howard Biegler, Launch Operations lead of Human Launch Services for ULA.
The Atlas V launch pad has been used only for non-crewed spacecraft to this point, hosting Titan rockets beginning in 1965 and then the Atlas V since 2002. NASA missions launched from SLC-41 include the Viking robots that landed on Mars, the Voyager spacecraft that toured the outer planets, the New Horizons probe now headed to Pluto, and the Curiosity rover currently traversing Mars.
Although the pad has proved adept at servicing those extremely complex spacecraft and probes, the demands for handling a capsule that will carry humans are far greater. For instance, the rocket cannot be rolled to the pad and fueled while astronauts are aboard. Safety considerations also require a way to get away from the rocket quickly in case of an emergency before the rocket lifts off.
"I can’t wait to see this tower erected and an Atlas V up there with a CST-100 headed off to the International Space Station," said Bob Cabana, director of NASA’s Kennedy Space Center. "This historic pad has launched a number of NASA scientific missions and will now launch an even more valuable, precious piece of cargo, and that’s NASA astronauts to the station."
Missions flown on commercial crew spacecraft are vital to the national goal of restoring to America the ability to launch astronauts to the station so the unique orbiting laboratory can continue to fulfill its promise of achieving cutting-edge research for the benefit of all on Earth. With the new spacecraft, the station's crew can expand by one, which will enable research time on the station to double from its current 40 hours a week to 80 hours a week.
“This is a shining example of the progress we’ll see along the Space Coast as industry works toward safely flying our astronauts to and from the station,” said Kathy Lueders, manager of NASA’s Commercial Crew Program. “Once this crew access tower is complete, this historical launch complex will be an integral part of a new era in human spaceflight.”
Credit: NASA
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Posted: 21 Feb 2015 03:34 AM PST
A member of the public with an idea to study the Martian atmosphere and a team with a way to study Martian weather are the winners of NASA’s Mars Balance Mass Challenge. Ted Ground of Rising Star, Texas, was awarded $20,000 for his idea to study the Martian atmosphere by releasing material that could be seen and studied by other Martian spacecraft in orbit and on the ground. A team of engineers, Brian Kujawski, Louis Olds, and Leslie Hall, from Grand Rapids, Michigan, received an honorable mention and $5,000 for their idea to study Martian weather by looking at wind patterns near the planet’s surface. “The 219 submissions from 43 countries to the Mars Balance Mass Challenge show the interest the public has in directly engaging with NASA,” said NASA Chief Technologist David Miller. “And the two winning ideas highlight how effective these activities can be at helping NASA bring innovative ideas into our missions.”
The Mars Balance Mass Challenge, announced in September 2014 at the World Maker Faire in New York City, sought design ideas for small science and technology payloads that could potentially provide dual purpose as ejectable balance masses on spacecraft entering the Martian atmosphere. The payloads would serve two roles: perform scientific or technology functions that help us learn more about the Red Planet, and provide the necessary weight to balance planetary landers.
“We want citizens to join us on the Journey to Mars,” said George Tahu, program executive for Mars Exploration at NASA Headquarters in Washington. “Challenges such as this invite innovative design ideas and creative solutions that will support our science and technology planning processes as well as encourage science, technology, engineering and math (STEM) education.”
Submissions to the challenge ranged from analyzing Martian weather or the Martian surface, to demonstrating new technologies such as 3D printing or parachutes, to pre-positioning supplies for future human missions on the planet’s surface.
Ground’s concept would release trace elements such as barium or strontium during the main spacecraft’s entry and decent into the Martian atmosphere, while other spacecraft in orbit and on the surface of the planet observed the patterns made by the tracer elements in the atmosphere. A similar process is used to study Earth’s atmosphere by sending sounding rockets along a parabolic path anywhere from 30 to 800 miles above the Earth.
The challenge selection team also evaluated a number of concepts using balloon-carried payloads. The best of these was chosen as an honorable mention for its realistic approach to delivering the payloads and for its possible benefit to future human missions to Mars.
All four selectees are new to the world of NASA prizes and challenges, but are now eager to work on upcoming NASA challenges.
Kujawski said, “I now tell everyone that these sorts of challenges are worth giving a shot – you get an opportunity to learn more about something that you’re passionate about, and the satisfaction of coming up with a solution to a tough problem.”
Ground, who was inspired to pursue other NASA challenges, agrees, “I think there are lots of skilled, creative, and educated citizens that could contribute, to help ‘shape’ the contents or overall goals of NASA missions, perhaps more closely than they have in the past.”
The Mars Balance Mass challenge was managed by NASA's Center of Excellence for Collaborative Innovation (CoECI). CoECI was established in coordination with White House Office of Science and Technology Policy to advance NASA open innovation efforts and extend that expertise to other federal agencies. The challenges are being released on the NASA Innovation Pavilion, one of the CoECI platforms available to NASA team members, through its contract with InnoCentive, Inc.
Credit: NASA
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Posted: 20 Feb 2015 01:48 PM PST
Exciting new research by astronomers at The Open University (OU) and the Universities of Warwick and Sheffield has opened up the chance to find out what distant planets are made of. The team of astronomers have made observations which can help reveal the chemical makeup of a small rocky world orbiting a distant star about 1500 light years away from Earth, increasing our understanding of how planets, including ours, were formed. Using a state-of-the-art, ultra-fast camera, ULTRACAM, on Science and Technology Facilities Council’s (STFC) William Herschel Telescope (WHT) the researchers have observed an extraordinary exoplanet named ‘KIC 1255 b’.
"A single year on KIC 1255b lasts only 16 hours on Earth and the whole planet seems to be slowly boiling away under intense heat of its sun" said Jakub Bochinski, research student at the OU, and lead author of the study. The planet’s surface is heated to over 2100K (over 1800°C), hot enough to vapourise rock. As a result, the planet’s outer layers are continuously destroyed, with the evaporating rock creating a comet-like dust tail following the planet in its orbit.
Once every orbit, the planet and the dusty tail pass across the host star, blocking some of its light from our view. The planet itself is tiny, similar in size to Mercury - far too small to be seen on its own. The dust cloud, however, is much bigger and blocks up to 1% of the star’s light each orbit. For comparison, the largest planet in our Solar System, Jupiter, would block 1% of the Sun’s light in a similar arrangement. The dust cloud grows and shrinks in size seemingly at random, some of the time disappearing from our view completely. Five nights of the WHT observations show this variation clearly, offering a unique chance to pin down the mechanism responsible for this unusual behaviour.
The ULTRACAM measurements were the most sensitive yet made, and revealed that the dust cloud, when visible, blocks a slightly larger fraction of the star’s blue light than red light. A similar effect is seen at sunset on Earth when the Sun’s light is scattered by dust in the Earth’s atmosphere, making the remaining light appear reddened. The exact colour-dependence of the scattering by dust (measured by carrying out simultaneous, multi-colour measurements with ULTRACAM) can reveal the size and composition of the dust grains. Ultimately, a series of measurements of KIC 1255b’s dust cloud could reveal the chemical composition of the dust.
Since the dust is made from the rocky surface of the disintegrating planet, the same technique will allow the chemical makeup of the planet’s surface to be measured. The team will attempt to make these first exogeological measurements with further observations in summer 2015. Jakub Bochinski added: “This is an incredibly exciting breakthrough as it opens up the possibility of determining the chemical composition of this rocky planet. By doing that we can find out how typical our solar system is, helping us learn more about how Earth and other planets were formed.”
The paper Direct evidence for an evolving dust cloud from the exoplanet KIC12557548 b is published in the journal The Astrophysical Journal Letters and the work was originated and supervised by Dr Carole Haswell, Senior Lecturer in Astrophysics at The Open University.
Credit: open.ac.uk
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Posted: 20 Feb 2015 01:26 PM PST
Astronomers have used NASA's Hubble Space Telescope to take the most detailed picture to date of a large, edge-on, gas-and-dust disk encircling the 20-million-year-old star Beta Pictoris. Beta Pictoris remains the only directly imaged debris disk that has a giant planet (discovered in 2009). Because the orbital period is comparatively short (estimated to be between 18 and 22 years), astronomers can see large motion in just a few years. This allows scientists to study how the Beta Pictoris disk is distorted by the presence of a massive planet embedded within the disk. The new visible-light Hubble image traces the disk in closer to the star to within about 650 million miles of the star (which is inside the radius of Saturn's orbit about the Sun).
"Some computer simulations predicted a complicated structure for the inner disk due to the gravitational pull by the short-period giant planet. The new images reveal the inner disk and confirm the predicted structures. This finding validates models, which will help us to deduce the presence of other exoplanets in other disks," said Daniel Apai of the University of Arizona. The gas-giant planet in the Beta Pictoris system was directly imaged in infrared light by the European Southern Observatory's Very Large Telescope six years ago.
When comparing the latest Hubble images to Hubble images taken in 1997, astronomers find that the disk's dust distribution has barely changed over 15 years despite the fact that the entire structure is orbiting the star like a carousel. This means the disk's structure is smoothly continuous in the direction of its rotation on the timescale, roughly, of the accompanying planet's orbital period.
In 1984 Beta Pictoris was the very first star discovered to host a bright disk of light-scattering circumstellar dust and debris. Ever since then Beta Pictoris has been an object of intensive scrutiny with Hubble and with ground-based telescopes. Hubble spectroscopic observations in 1991 found evidence for extrasolar comets frequently falling into the star.
The disk is easily seen because it is tilted edge-on and is especially bright due to a very large amount of starlight-scattering dust. What's more, Beta Pictoris is closer to Earth (63 light-years) than most of the other known disk systems.
Though nearly all of the approximately two-dozen known light-scattering circumstellar disks have been viewed by Hubble to date, Beta Pictoris is the first and best example of what a young planetary system looks like, say researchers.
One thing astronomers have recently learned about circumstellar debris disks is that their structure, and amount of dust, is incredibly diverse and may be related to the locations and masses of planets in those systems. "The Beta Pictoris disk is the prototype for circumstellar debris systems, but it may not be a good archetype," said co-author Glenn Schneider of the University of Arizona.
For one thing the Beta Pictoris disk is exceptionally dusty. This may be due to recent major collisions among unseen planetary-sized and asteroid-sized bodies embedded within it. In particular, a bright lobe of dust and gas on the southwestern side of the disk may be the result of the pulverization of a Mars-sized body in a giant collision.
Both the 1997 and 2012 images were taken in visible light with Hubble's Space Telescope Imaging Spectrograph in its coronagraphic imaging mode. A coronagraph blocks out the glare of the central star so that the disk can be seen.
Credit: hubblesite.org
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Posted: 20 Feb 2015 01:05 PM PST
NASA’s Orion spacecraft continues on the agency’s journey to Mars as engineers analyze data from the spacecraft’s December flight test and make progress developing and building the spacecraft for its first mission atop NASA Space Launch System (SLS) heavy-lift rocket. On future missions, Orion will send astronauts to an asteroid and onward toward the Red Planet. At machine houses across the country, elements of the primary structure for the next Orion to fly in space are coming together. Avionics components are being built and simulators for the ESA (European Space Agency)-built service module that will house the spacecraft’s propulsion and solar arrays are being delivered. By the end of the year, engineers hope to have the primary structure for Orion’s next mission to NASA’s Kennedy Space Center in Florida for processing. Meanwhile, every piece of data and each element of the spacecraft flown in the December test is being analyzed and compared to pre-flight models to improve Orion’s design.
“Orion’s flight test was a big success and what we learned is informing how we design, develop and build future Orions that will help us pioneer deep space destinations,” said Mark Geyer, NASA’s Orion Program manager. “Taking a look at all the flight test data is a huge part of the development process and a key part off in why we flew a test flight. We have critical work happening this year, both on the data analysis and development side, to keep us moving toward our first mission with SLS.”
Engineers and technicians at Kennedy, where Orion was assembled and returned after its flight test, recently took off the back shell and heat shield that protected Orion during its reentry to Earth’s atmosphere, to unload unused propellants and allow for a close-up analysis of the spacecraft’s systems.
One of the main objectives of Orion’s flight, which sent the vehicle 3,600 miles into space during a two-orbit, 4.5-hour test, was to test how the spacecraft would fare returning to Earth at high speeds and temperatures.
“The heat shield looks in great shape,” said Michael Hawes, Orion Program manager for Lockheed Martin, NASA’s prime contractor for the spacecraft. “The char on the shield is consistent. If you look at it now, you’d see a few big holes because we’ve taken core samples. We’ve also done a total laser scan of the surface of the heat shield. That’ll give us a very detailed engineering base of knowledge of what the heat shield did.”
In March, the heat shield will be shipped to NASA’s Marshall Space Flight Center in Huntsville, Alabama, where the ablative material on the heat shield will be taken off. From there, the heat shield structure will be shipped to the agency’s Langley Research Center in Hampton, Virginia, where it will be reused on a test capsule for water impact testing. NASA and Lockheed Martin also are taking a look at potential modifications to the heat shield’s design to make it even stronger.
Evaluating how the thermal protection system fared during Orion’s reentry wasn’t the only critical objective of the flight. The test also provided important insight into key separation events, including whether the Launch Abort System and protective fairings came off at the right times, how the parachutes assisting Orion during its descent fared and how the operations to recovery Orion from the Pacific Ocean progressed.
According to Hawes, all of the spacecraft separation events happened within fractions of a second of when predictive models said they would occur; Orion’s 11 parachutes worked to allow the spacecraft to touchdown in the Ocean relatively gently; and the recovery team of NASA, U.S. Navy and Lockheed Martin personnel recovered it within about six hours.
The flight also examined the performance of a 3-D printed vent. It performed well, so teams will be looking at other hardware that could be made using the additive manufacturing process.
Engineers are taking a closer look at the crew module uprighting system airbags on top of the crew module, which help keep Orion stable in the water after splashdown. Only two of five of the bags properly inflated during the December flight test. Initial analysis of the gas and plumbing system for the bags came up clean, and engineers suspect a possible issue with the bags themselves.
“We’re in the midst of troubleshooting that now,” Hawes said.
Orion’s flight test yielded millions of elements of data, every piece of which is providing unique insight into how to improve the spacecraft’s design so that it can safely send astronauts on their way to Mars and return them home.
Credit: NASA
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Posted: 20 Feb 2015 12:41 PM PST
.jpg "Earth’s magnetosphere is depicted with the high-energy particles of the Van Allen radiation belts (shown in red) and various processes responsible for accelerating these particles to relativistic energies indicated. The effects of an interplanetary shock penetrate deep into this system, energizing electrons to ultra-relativistic energies in a matter of seconds. Credit: NASA")
On Oct. 8, 2013, an explosion on the sun’s surface sent a supersonic blast wave of solar wind out into space. This shockwave tore past Mercury and Venus, blitzing by the moon before streaming toward Earth. The shockwave struck a massive blow to the Earth’s magnetic field, setting off a magnetized sound pulse around the planet. NASA’s Van Allen Probes, twin spacecraft orbiting within the radiation belts deep inside the Earth’s magnetic field, captured the effects of the solar shockwave just before and after it struck. Now scientists at MIT’s Haystack Observatory, the University of Colorado, and elsewhere have analyzed the probes’ data, and observed a sudden and dramatic effect in the shockwave’s aftermath: The resulting magnetosonic pulse, lasting just 60 seconds, reverberated through the Earth’s radiation belts, accelerating certain particles to ultrahigh energies.
“These are very lightweight particles, but they are ultrarelativistic, killer electrons — electrons that can go right through a satellite,” says John Foster, associate director of MIT’s Haystack Observatory. “These particles are accelerated, and their number goes up by a factor of 10, in just one minute. We were able to see this entire process taking place, and it’s exciting: We see something that, in terms of the radiation belt, is really quick.”
The findings represent the first time the effects of a solar shockwave on Earth’s radiation belts have been observed in detail from beginning to end. Foster and his colleagues have published their results in the Journal of Geophysical Research.
Since August 2012, the Van Allen Probes have been orbiting within the Van Allen radiation belts. The probes’ mission is to help characterize the extreme environment within the radiation belts, so as to design more resilient spacecraft and satellites.
One question the mission seeks to answer is how the radiation belts give rise to ultrarelativistic electrons — particles that streak around the Earth at 1,000 kilometers per second, circling the planet in just five minutes. These high-speed particles can bombard satellites and spacecraft, causing irreparable damage to onboard electronics.
The two Van Allen probes maintain the same orbit around the Earth, with one probe following an hour behind the other. On Oct. 8, 2013, the first probe was in just the right position, facing the sun, to observe the radiation belts just before the shockwave struck the Earth’s magnetic field. The second probe, catching up to the same position an hour later, recorded the shockwave’s aftermath.
Foster and his colleagues analyzed the probes’ data, and laid out the following sequence of events: As the solar shockwave made impact, according to Foster, it struck “a sledgehammer blow” to the protective barrier of the Earth’s magnetic field. But instead of breaking through this barrier, the shockwave effectively bounced away, generating a wave in the opposite direction, in the form of a magnetosonic pulse — a powerful, magnetized sound wave that propagated to the far side of the Earth within a matter of minutes.
In that time, the researchers observed that the magnetosonic pulse swept up certain lower-energy particles. The electric field within the pulse accelerated these particles to energies of 3 to 4 million electronvolts, creating 10 times the number of ultrarelativistic electrons that previously existed.
Taking a closer look at the data, the researchers were able to identify the mechanism by which certain particles in the radiation belts were accelerated. As it turns out, if particles’ velocities as they circle the Earth match that of the magnetosonic pulse, they are deemed “drift resonant,” and are more likely to gain energy from the pulse as it speeds through the radiation belts. The longer a particle interacts with the pulse, the more it is accelerated, giving rise to an extremely high-energy particle.
Foster says solar shockwaves can impact Earth’s radiation belts a couple of times each month. The event in 2013 was a relatively minor one.
“This was a relatively small shock. We know they can be much, much bigger,” Foster says. “Interactions between solar activity and Earth’s magnetosphere can create the radiation belt in a number of ways, some of which can take months, others days. The shock process takes seconds to minutes. This could be the tip of the iceberg in how we understand radiation-belt physics.”
Barry Mauk, a project scientist at Johns Hopkins University’s Applied Physics Laboratory, views the group’s findings as “the most comprehensive analysis of shock-induced acceleration within Earth’s space environment ever achieved.”
“Significant shock-induced acceleration of Earth’s radiation belts occur only occasionally, but these events are important because they have the potential of suddenly generating the most intense and energetic electrons, and therefore the most dangerous conditions for astronauts and satellites,” says Mauk, who did not contribute to the study. “Earth’s space environment serves as a wonderful laboratory for studying the nature of shock acceleration that is occurring elsewhere in the solar system and universe.”
Credit: mit.edu
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Posted: 20 Feb 2015 11:38 AM PST
NASA’S Mars Atmosphere and Volatile Evolution has completed the first of five deep-dip maneuvers designed to gather measurements closer to the lower end of the Martian upper atmosphere. “During normal science mapping, we make measurements between an altitude of about 150 km and 6,200 km (93 miles and 3,853 miles) above the surface,” said Bruce Jakosky, MAVEN principal investigator at the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder. “During the deep-dip campaigns, we lower the lowest altitude in the orbit, known as periapsis, to about 125 km (78 miles) which allows us to take measurements throughout the entire upper atmosphere.”
The 25 km (16 miles) altitude difference may not seem like much, but it allows scientists to make measurements down to the top of the lower atmosphere. At these lower altitudes, the atmospheric densities are more than ten times what they are at 150 km (93 miles).
“We are interested in the connections that run from the lower atmosphere to the upper atmosphere and then to escape to space,” said Jakosky. “We are measuring all of the relevant regions and the connections between them.”
The first deep dip campaign ran from Feb. 10 to 18. The first three days of this campaign were used to lower the periapsis. Each of the five campaigns lasts for five days allowing the spacecraft to observe for roughly 20 orbits. Since the planet rotates under the spacecraft, the 20 orbits allow sampling of different longitudes spaced around the planet, providing close to global coverage.
This month’s deep dip maneuvers began when team engineers fired the rocket motors in three separate burns to lower the periapsis. The engineers did not want to do one big burn, to ensure that they didn’t end up too deep in the atmosphere. So, they “walked” the spacecraft down gently in several smaller steps.
“Although we changed the altitude of the spacecraft, we actually aimed at a certain atmospheric density,” said Jakosky. “We wanted to go as deep as we can without putting the spacecraft or instruments at risk.”
Even though the atmosphere at these altitudes is very tenuous, it is thick enough to cause a noticeable drag on the spacecraft. Going to too high an atmospheric density could cause too much drag and heating due to friction that could damage spacecraft and instruments.
At the end of the campaign, two maneuvers were conducted to return MAVEN to normal science operation altitudes. Science data returned from the deep dip will be analyzed over the coming weeks. The science team will combine the results with what the spacecraft has seen during its regular mapping to get a better picture of the entire atmosphere and of the processes affecting it.
One of the major goals of the MAVEN mission is to understand how gas from the atmosphere escapes to space, and how this has affected the planet's climate history through time. In being lost to space, gas is removed from the top of the upper atmosphere. But it is the thicker lower atmosphere that controls the climate. MAVEN is studying the entire region from the top of the upper atmosphere all the way down to the lower atmosphere so that the connections between these regions can be understood.
MAVEN is the first mission dedicated to studying the upper atmosphere of Mars. The spacecraft launched Nov. 18, 2013, from Cape Canaveral Air Force Station in Florida. MAVEN successfully entered Mars’ orbit on Sept. 21, 2014.
MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The University of California at Berkeley's Space Sciences Laboratory also provided four science instruments for the mission. NASA's Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.
Credit: NASA
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Posted: 20 Feb 2015 09:58 AM PST
A team of astronomers from National Astronomical Observatory of Japan (NAOJ), Osaka Kyoiku University, Nagoya University, and Kyoto Sangyo University observed Nova Delphini 2013 which occurred on August 14, 2013. Using the 8.2-meter Subaru Telescope High Dispersion Spectrograph (HDS) to observe this object, they discovered that the outburst is producing a large amount of lithium (Li). Lithium is a key element in the study of the chemical evolution of the universe because it likely was and is produced in several ways: through Big Bang nucleosynthesis, in collisions between energetic cosmic rays and the interstellar medium, inside stellar interiors, and as a result of novae and supernova explosions. This new observation provides the first direct evidence for the supply of Li from stellar objects to the galactic medium. The team hopes to deepen the understandings of galactic chemical evolution, given that nova explosions must be important suppliers of Li in the current universe.
The universe consisted primarily of hydrogen (H) and helium (He) immediately after the Big Bang except for very small amounts of Li. Since there are other elements heavier than H and He in the universe now, astronomers want to understand how the heavy elements -- such as carbon (C), oxygen (O), and iron (Fe) (which are present in our bodies) -- are produced. Such heavy elements are mainly produced in stellar interiors or supernovae. Then, they are supplied to the interstellar medium as seed materials for next generation of stars.
Li is the third lightest element following H and He, and is familiar to us as the base material for the Li-ion batteries used in PCs, smart phones, eco-cars, etc. Big Bang nucleosynthesis produced a very small amount of Li. Collisions between galactic cosmic rays (energetic atomic nuclei traveling with very high speeds) and atomic nuclei in the interstellar medium are also assumed to produce Li by breaking heavy elements' nuclei (e.g., C, O). Low-mass stars like the Sun, and events such as supernova explosions are also considered as candidates of Li production sites. Furthermore, scientists have been assuming that novae should also produce this element.
Because many sites and events can produce Li as described above, Li is the best indicator to probe the complete chemical evolution of the universe. Many scientists have studied this element by measuring the amount of Li found in various stars in our galaxy. This allowed them to estimate the amount produced through each process. Today, as a result of these indirect approaches, low-mass stars or nova explosions are thought to be the most important candidates for Li production in the current galaxy epoch. However, there have been no direct observations of the processes.
On August 14th, 2013, the well-known Japanese amateur astronomer Koichi Itagaki found a bright new star in the constellation Delphinus. This star, which was named Nova Delphini 2013 (=V339 Del), was at magnitude 6.8 at discovery and peaked at 4.3 mag within two days. It was the first naked-eye nova since 2007, when V1280 Sco was found. About 40 days later, in September 2013, a team of astronomers observed the nova to investigate the materials expelled by the explosion. That is when they found that the nova produced a large amount of Li.
Nova Delphini 2013 is considered one of the "classical novae". These brighten when explosive nuclear reactions occur in materials accumulated on the surface of a white dwarf star in a close binary system. The nuclear reactions are thought to produce a different series of elements (compared to those produced in stellar interiors or supernova explosions). Li is assumed to be an element typically produced in such outbursts. Historically, no one has been able to get good observational evidence for its production in nova explosions.
When the research group observed Nova Delphini 2013 using the Subaru Telescope, they used the High Dispersion Spectrograph to discern the constituents of the expelled materials from the nova explosion at four epochs.
Absorption lines originating from many elements such as H, He, and Fe are identified in the observed spectra. Among them, there are sets of strong absorption lines in the ultraviolet (UV) range (wavelength ~313 nanometers) of the spectrum. Comparing these lines with other lines originating from H, calcium (Ca), and other elements, it turns out that they are originating from an isotope of beryllium (Be), 7Be, which is the fourth-lightest element in the universe.
In a classical nova, the isotopes of He (3He) and plentiful 4He transferring from the companion are fused together to form radioactive 7Be in a very high-temperature environment on the surface of a white dwarf. This radioactive isotope decays to form an isotope of lithium (7Li) within a short time (half-life of 53.22 days). Because 7Li is very fragile in a high-temperature environment, it is necessary to transport 7Be to a cooler region in order to enrich Li in the interstellar medium. Novae completely fill this requirement. Therefore, they are assumed to be strong candidates as suppliers of Li in the universe.
This discovery of 7Be within 50 days after the nova explosion means that this explosion is actually producing a large amount of 7Li formed from 7Be. Because 7Be is found in the gas blobs blown away from the central region of the nova at high velocities (~1000 km/s), 7Li formed from this 7Be should not be destroyed in a high-temperature environment. This 7Li spreads into interstellar space, and will be included in the next generation of stars. It is found that the 7Be abundance in the gas blobs estimated from the strengths of their absorption lines is comparable to that of Ca. This amount of 7Be (= 7Li) should be quite large, given that Li is known as a very rare element in the universe.
The amount of Li rapidly increases in the galaxy in the current epoch, where the amounts of heavy elements have increased. Therefore, it has long been speculated that low-mass stars with longer lifetimes should be among the major suppliers of Li in the universe. Because nova explosions occur in binary systems evolved from such low-mass stars (especially 3He-rich companion, which is necessary to produce 7Be), they are strong candidates as Li suppliers. The observations made using the Subaru HDS provide the first strong evidence to prove that novae produce significant amounts of Li in the universe. This discovery confirms the chemical evolution model from the Big Bang to the present universe, as predicted by scientists.
Furthermore, the observed amount of Li produced in this nova explosion is proven to be higher than predicted by theoretical estimates. Nova Delphini 2013 shows rather typical characteristics of classical novae. If other novae also produce a large amount of Li as Nova Delphini 2013 did, nova explosions must be recognized as very major Li factories in the universe. In near future, more observations of other nova explosions will provide much clearer model of Li evolution.
This research was published in Nature on February 19, 2015, titled "Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013)".
Credit: subarutelescope.org
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