A 25-acre sinkhole near Bayou Corne, Louisiana that formed in Aug. 2012. In 2014, a new analysis of NASA radar data found that the sinkhole was evident in that information before its collapse. Credit: On Wings of Care, New Orleans, La.
A Louisiana sinkhole the size of 19 American football fields shifted sideways in radar measurements before its collapse and resulting evacuations in 2012, a study reveals.
The implication is that if certain types of radar measurements are collected regularly from above, it is possible to see some sinkholes before they collapse. The researchers added, however, that their discovery was “serendipitous” and there are no plans to immediately use a NASA robotic Gulfstream plane used for the study to fly over spots that could be vulnerable to sinkholes.
Data showed the ground near Bayou Corne moving horizontally up to 10.2 inches (26 centimeters) toward where the sinkhole appeared suddenly in August 2012. The hole started out at about 2 acres of size (1 hectare) — an area smaller than the initial ground movements — and now measures about 25 acres (10 hectares).
The research was published in the journal Geology in February, and was first made available online in December. NASA highlighted the information in a press release published in early March.
“While horizontal surface deformations had not previously been considered a signature of sinkholes, the new study shows they can precede sinkhole formation well in advance,” stated Cathleen Jones, leader of the research and a part of NASA’s Jet Propulsion Laboratory in California.
Regions and rock types of the United States that could be vulnerable to sinkholes. Credit: U.S. Geological Survey
“This kind of movement may be more common than previously thought, particularly in areas with loose soil near the surface.”
Jones and her NASA JPL colleague, Blom, found the information in NASA’s interferometric synthetic aperture radar (inSAR), which flew over the region in June 2011 and July 2012 on the agency’s Uninhabitated Aerial Vehicle Synthetic Aperture Radar. The radar can see shifts in the Earth’s surface.
The sinkhole — which is full of water and ground-up solids and is still getting bigger — collapsed after several small earthquakes and after the community became aware of “bubbling natural gas” in the area, NASA stated.
A sinkhole threatens the nearby community of Bayou Corne, Louisiana in this image released on NASA’s website in March 2014. Credit: NASA/JPL-Caltech
“It was caused by the collapse of a sidewall of an underground storage cavity connected to a nearby well operated by Texas Brine Company and owned by Occidental Petroleum,” the agency added.
“On-site investigation revealed the storage cavity, located more than 3,000 feet (914 meters) underground, had been mined closer to the edge of the subterranean Napoleonville salt dome than thought.” (A salt dome is a location in sedimentary rocks where salt is pushed up beneath the surface.)
Measurements of the area were taken as recently as October 2013, as the growing sinkhole is threatening the nearby community as well as a highway in the region.
Like anyone else who’s ever looked up at the night sky in any but the smallest cities, I’ve seen light pollution first-hand. Like anyone else even marginally involved in amateur astronomy, I know about the fight against light pollution. And I know that, what with new LED lights and everything, it’s not going to be easy.
When, the other day, I was looking around for images demonstrating the effects of light pollution, it didn’t take me long to find some scary examples – the satellite images tracing human presence on Earth by its light pollution are rather unequivocal, and on Wikimedia Commons, there was an impressive image showing the same region of the night sky when viewed from a dark and from a lighter location:
The images were taken by Jeremy Stanley and are available via Wikimedia Commons under the CC BY 2.0 license. According to the author’s comment, he tried to match the two images’ sky brightness to his memory of how bright the sky appeared to his eyes.
What I didn’t find was an image showing a comparison of two images with the same specs (same camera and lens, same ISO, aperture and exposure time) under different viewing conditions. In the end, I found that I could produce such an example myself, using images I had taken during a trip to South Africa last spring.
During the first leg of our trip, we had visited South Africa’s national science festival, SciFest Africa, which is held annually in Grahamstown in the Eastern Cape Province. Grahamstown has a population of 70.000, and there is some visible light pollution. I took an image of the Milky Way, including the Southern Cross, from the reasonably well-lit courtyard of our hotel:
Some days later, we visited the Sutherland site of South Africa’s National Observatory SAAO, home, among other things, to the 10 m South African Large Telescope (SALT). In the small city of Sutherland, with a population of only about 3000, the observatory a mere 7 miles away and a spirit of cooperation with the astronomers’ needs, light pollution levels are low.
When we took some images of the sky from the backyard of our hotel, the biggest light pollution problem was the moon. Here’s an image that shows, among other objects, the Southern Cross, Alpha Centauri and Carina:
It was only much later that I realized that these images could be used for the light pollution comparison I was looking for. They were both taken with the same camera (Canon EOS 450D = EOS Rebel XSi), the same lens (Tokina 11-16 mm at 11 mm) with the same settings (ISO 1600, aperture 2.8, exposure time 10 seconds). Whatever difference you see is really due to the viewing conditions. To show what you can do with a dark, high-contrast sky, I added a third image. Its only difference to the second image is the exposure time (20 seconds to 10 seconds), which brings out the Milky Way much more strongly.
I combined the images, used GIMP to increase the contrast and saturation on the combined image (to make sure I treated all three images the same), and separated the images again. Here is the result:
The difference between the first two images is fairly drastic. And keep in mind that, as far as light pollution goes, Grahamstown is likely to be fairly harmless, compared with a big, brightly-lit city. (And yes, if I should get the chance, I’ll try to take an image with the same set-up in a larger city!)
This is just one of all too many examples. Through careless lighting, many of us are missing out on one of humanity’s most fundamental experiences: an unobstructed view of the enormity of what’s out there, far beyond space-ship Earth.
Researchers at NASA’s Goddard Spaceflight Center and the Massachusetts Institute of Technology have identified a fascinating natural process by which the magnetosphere of our fair planet can — to use a sports analogy — “shot block,” or at least partially buffer an incoming solar event.
The study, released today in Science Express and titled “Feedback of the Magnetosphere” describes new process discovered in which our planet protects the near-Earth environment from the fluctuating effects of inbound space weather.
Our planet’s magnetic field, or magnetosphere, spans our world from the Earth’s core out into space. This sheath typically acts as a shield. We can be thankful that we inhabit a world with a robust magnetic field, unlike the other rocky planets in the inner solar system.
But when a magnetic reconnection event occurs, our magnetosphere merges with the magnetic field of the Sun, letting in powerful electric currents that wreak havoc.
Now, researchers from NASA and MIT have used ground and space-based assets to identify a process that buffers the magnetosphere, often keeping incoming solar energy at bay.
The results came from NASA’s Time History Events and Macroscale Interactions during Substorms (THEMIS) constellation of spacecraft and was backed up by data gathered over the past decade for MIT’s Haystack Observatory.
Observations confirm the existence of low-energy plasma plumes that travel along magnetic field lines, rising tens of thousands of kilometres above the Earth’s surface to meet incoming solar energy at a “merging point.”
“The Earth’s magnetic field protects life on the surface from the full impact of these solar outbursts,” said associate director of MIT’s Haystack Observatory John Foster in the recent press release. “Reconnection strips away some of our magnetic shield and lets energy leak in, giving us large, violent storms. These plasmas get pulled into space and slow down the reconnection process, so the impact of the Sun on the Earth is less violent.”
The study also utilized an interesting technique known as GPS Total Electron Content or GPS-TEC. This ground-based technique analyzes satellite transmitted GPS transmissions to thousands of ground based receivers, looking for tell-tale distortions that that signify clumps of moving plasma particles. This paints a two dimensional picture of atmospheric plasma activity, which can be extended into three dimensions using space based information gathered by THEMIS.
And scientists got their chance to put this network to the test during the moderate solar outburst of January 2013. Researchers realized that three of the THEMIS spacecraft were positioned at points in the magnetosphere that plasma plumes had been tracked along during ground-based observations. The spacecraft all observed the same cold dense plumes of rising plasma interacting with the incoming solar stream, matching predictions and verifying the technique.
Launched in 2007, THEMIS consists of five spacecraft used to study substorms in the Earth’s magnetosphere. The Haystack Observatory is an astronomical radio observatory founded in 1960 located just 45 kilometres northwest of Boston, Massachusetts.
How will this study influence future predictions of the impact that solar storms have on the Earth space weather environment?
“This study opens new doors for future predictions,” NASA Goddard researcher Brian Walsh told Universe Today. “The work validates that the signatures of the plume far away from the Earth measured by spacecraft match signatures in the Earth’s upper atmosphere made from the surface of the Earth. Although we might not always have spacecraft in exactly the correct position to measure one of these plumes, we have almost continuous coverage from ground-based monitors probing the upper atmosphere. Future studies can now use these signatures as a proxy for when the plume has reached the edge of our magnetic shield (known as the magnetopause) which will help us predict how large a geomagnetic storm will occur from a given explosion from the Sun when it reaches the Earth.”
The structure of Earth’s magnetosphere. Credit-NASA graphic in the Public Domain.
Understanding how these plasma plumes essentially hinder or throttle incoming energy during magnetic reconnection events, as well as the triggering or source mechanism for these plumes is vital.
“The source of these plumes is an extension of the upper atmosphere, a region that space physicists call the plasmasphere,” Mr. Walsh told Universe Today. “The particles that make the plume are actually with us almost all of the time, but they normally reside relatively close to the Earth. During a solar storm, a large electric field forms and causes the upper layers of the plasmasphere to be stripped away and are sent streaming sunward towards the boundary of our magnetic field. This stream of particles is the ‘plume’ or ‘tail’”
Recognizing the impacts that these plumes have on space weather will lead to better predictions and forecasts for on- and off- the planet as well, including potential impacts on astronauts aboard the International Space Station. Flights over the poles are also periodically rerouted towards lower latitudes during geomagnetic storms.
“This study defines new tools for the toolbox we use to predict how large or how dangerous a given solar eruption will be for astronauts and satellites,” Walsh said. “This work offers valuable new insights and we hope these tools will improve prediction capabilities in the near future.”
And speaking of which, there’s a common misconception out there that we see reported every time auroral activity makes the news… remember that aurorae aren’t actually caused by solar wind particles colliding with our atmosphere, but the acceleration of particles trapped in our magnetic field fueled by the solar wind.
And speaking of solar activity, there’s also an ongoing controversy in the world of solar heliophysics as to the lackluster solar maximum for this cycle, and what it means for concurrent cycles #25 and #26.
It’s exciting times indeed in the science of space weather forecasting…
and hey, we got to drop in sports analogy, a rarity in science writing!
On March 3, 2014 the The Ground-to-Rocket Electrodynamics – Electron Correlative Experiment (GREECE) sounding rocket launched straight into an aurora from the Poker Flat Research Range in Poker Flat, Alaska. Credit: NASA
If you’ve ever wondered what makes the aurora take on the amazing forms it does you’ve got company. Marilia Samara and the crew of aurora researchers at Alaska’s Poker Flat Range head up the NASA-funded Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment, or GREECE. Their mission is to understand what causes the swirls seen in very active auroras.
Robert Michell, who built some of the instruments on the sounding rocket, and Marilia Samara, the principal investigator for the GREECE project. Credit: NASA
“Our overarching goal is to study the transfer of energy from the sun to Earth,” said Samara, a space scientist at the Southwest Research Institute, or SwRI, in San Antonio, Texas. “We target a particular manifestation of that connection – the aurora.”
Here’s what we know. Electrons and protons from the sun come charging into Earth’s magnetic domain called the magnetosphere and strike and energize molecules of oxygen and nitrogen in the atmosphere between 60 and 200 miles overhead. The molecules release that extra energy as the greens, reds and purples of the northern lights.
Earth has a magnetic field much like an ordinary refrigerator magnet but shaped by charged particles flowing from the sun called the solar wind. When those particles travel down the planet’s magnetic field lines and excite atmospheric gases, they create the familiar parallel rays seen in auroras. Credit: Greg Shirah and Tom Bridgman, NASA/Goddard Space Flight Center Scientific Visualization Studio (left); Bob King (right)
And those picket-fence, parallel rays that can suddenly spring from a quiet arc are created by billions of electrons spiraling down individual magnetic field lines, crashing into atoms and molecules as they go. Because the lines of magnetic force are closely bunched, as shown in the illustration above, we see side-by-side, tightly spaced rays.
What we less about is how the twists, swirls and eddies form.
Wave clouds forming over Mount Duval, Australia from a Kelvin-Helmholtz Instability. Credit: GRAHAMUK / English language Wikipedia
Scientists suspect the swirls may take shape as a result of Kelvin-Helmholtz instabilities or Alfven waves. The first occurs when two fluids or gases moving at different rates of speed flow by one another. In a familiar example, wind blowing over water creates ripples that are amplified into curling, white-topped waves.
Alfven waves are created when flows of electrified particles from the sun (plasma) interact with Earth’s magnetic field. To study the structures, sounding or research rockets are launched directly into an active display of northern lights to gather electrical and magnetic measurements. At the same time, cameras on the ground record the dance of rays and arcs above. Samilla and her team at GREECE then compare the aurora’s shifting shapes with real-time data gathered during the rocket’s 600 seconds of flight.
Still and video cameras on the ground simultaneously image the aurora as the instrument-laded rocket flies into the aurora to gather data. Credit: Marilia Samara / Robert Michell / SwRI
“Auroral curls are visible from the ground with high-resolution imaging,” said Samara. “And we can infer from those observations what’s happening farther out. But to truly understand the physics we need to take measurements in the aurora itself.”
Poker Flat rocket launch – Jason Ahrns
And that’s exactly what the team did this past Monday morning March 3. Conditions looked good from Poker Flat the previous evening with a flurry of red and green arcs after sunset. At about 2:10 a.m. Alaska time, after careful monitoring of activity, the order was given to launch.
“It was a wonderful auroral event,” said Kathe Rich, Poker Flat Range manager. “We got good data throughout the flight, and all the instruments worked.”
Time exposure showing the trail of the rocket after it was launched into the aurora over Poker Flat early Monday morning March 3, 2014. Credit: Jason Ahrns
The rocket soared to an altitude of 220 miles (354 km) and recorded data as the video and still cameras whirred on the ground during the 10 minute 15 second long flight.
There must be a bunch of happy scientists at the Range this week. They have their work cut out for them; those few minutes of data collecting will mean years of work to track down the cause of the beautiful curlicues that make our hearts leap at the sight.
Happy researchers at the Poker Flat Research Range. Credit: Lex Wingfield / NASA
Poker Flat Research Range, the world’s only scientific rocket launching facility owned by a university, is located about 30 miles north of Fairbanks, Alaska and is operated by the University of Alaska’s Geophysical Institute under contract with NASA. Most of the research there involves the aurora with sounding rocket launches done about once a year. While waiting for the right moment to launch, members of the team exercise their poetic side by writing and sharing haikus about their beloved aurora. Here’s a sampling, and there are more HERE.
Dim, wide green madness Electromagnetic ghost Surrender your soul – EM
Hey elusive arc Zenith is over there, dude It’s about damn time -EM
Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh So ready to launch! -JC
While the cause of auroras is understood, what causes the swirl shapes is an open question. University of Alaska researchers at Poker Flat hope to find an answer. Aurora photographed on Dec. 15, 2012 from Tromso, Norway. Credit: Ole Salomonsen
You might be surprised to know that you’re living in a very special time in the Universe. And in the far future, our descendant astronomers will wish they could live in such an exciting time Let’s find out why.
You might be interested to know that you are living in a unique important and special time in the age of the Universe. Our view of the night sky won’t be around forever, in fact, as we think about the vast time that lies ahead, our time in the Universe will sound very special.
Astronomers figure the Universe has been around for 13.8 billion years. Everything in the entire Universe was once collected together into a singularity of space and time. And then, in a flash, Big Bang. Within a fraction of a second, the fundamental forces of the Universe came into existence, followed by the earliest types of matter and energy. For a few minutes, the entire Universe was like a core of a star, fusing hydrogen into helium. Approximately 377,000 years after the Big Bang, the entire Universe had cooled to the point that it became transparent. We see this flash of released light as the Cosmic Microwave Background Radiation.
Over the next few billion years, the first stars and galaxies formed, leading to the large scale structures of the Universe. These new galaxies with their furious star formation would have been an amazing sight. It would have been a very special time in the Universe, but it’s not our time.
Over the next few billion years, the Universe continued to expand. And it was during this time that the mysterious force called dark energy crept in, further driving the expansion of the Universe. We don’t know what dark energy is, but we know it’s a constant pressure that’s accelerating the expansion of the Universe.
As the volume of the Universe increases, the rate of its expansion increases. And over vast periods of time, it’ll make the Universe unrecognizable from what we see today. The further we look out into space, the faster galaxies are moving away from us. There are galaxies moving away from us faster than the speed of light. In other words, the light from those galaxies will never reach us.
The Universe 1.9 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
As dark energy increases, more and more galaxies will cross this cosmic horizon, invisible to us forever. And so, we can imagine a time in the far future, where the Cosmic Microwave Background Radiation has been stretched away until it’s undetectable. And eventually there will be a time when there will be no other galaxies visible in the night sky. Future astronomers will see a Universe without a cosmological history. There will be no way to know that there was ever a Big Bang, that there was ever a large scale structure to the Universe.
So how long will this be? According to Dr. Lawrence Krauss and Robert J. Scherrer, in as soon as 100 billion years, there will be no way to see other galaxies and calculate their velocity away from us. That sounds like a long time, but there are red dwarf stars that could live for more than a trillion years. We will have lost our history forever.
Cherish and make the most of these next hundred billion years. Keep our history alive and remember to tell our great great grandchildren and their robotic companions the tales of a time when we knew about the Big Bang.
What about you? What would you go see if you could witness any astronomical event in the history of the universe?
One of my favorite pet peeves is the inability of conventional models to accurately convey the gigantic scale of the Solar System. Most of us grew up with models of the planets made of wood or plastic or spray painted styrofoam balls impaled on bent wire hangers (don’t tell Mommy), or, more commonly, illustrations on posters and in textbooks. While these can be fun to look at and even show the correct relative sizes of the planets (although usually not as compared to the Sun) there’s one thing that they simply cannot relate to the viewer: space is really, really, really big.
Now there are some more human-scale models out there that do show how far the planets are from each other, but many of them require some walking, driving, or even flying to traverse their full distances. Alternatively, thanks to the magic of web pages which can be any size you like limited only by the imagination of the creator (and the patience of the viewer), accurate models can be easily presented showing the average (read: mind-blowingly enormous) distances between the planets… and no traveling or wire hangers required.
Despite their similar apparent sizes in our sky, the Moon and Sun are (obviously) quite different in actual size. Which is a good thing for us. (Credit: Josh Worth)
Created by designer Josh Worth, “If the Moon Were Only 1 Pixel: A Tediously Accurate Scale Model of the Solar System” uses a horizontally-sliding HTML page to show how far it is from one planet to another, as well as their relative sizes, based on our Moon being just a single pixel in diameter (and everything lined up neatly in a row, which it never is.) You can use the scroll bar at the bottom of the page or arrow keys to travel the distances or, if you want to feel like you’re at least getting some exercise, scroll with your mouse or computer’s swipe pad (where applicable.) You can also use the astronomical symbols at the top of the page to “warp” to each planet.
Just try not to miss anything — it’s a surprisingly big place out there.
“You may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”
A still from Space Racers, a half-hour preschool series premiering in 2014. Credit: SpaceRacers.org
Blastoff! A new space show aimed at preschoolers aims to showcase the joy of space, while making sure that the youngsters learn as much as they can about the science. Space Racers (which is being distributed by Maryland Public Television) is coming to television screens across several countries this year, including the United States.
Universe Today was lucky enough to see one of the episodes of the series, which is made up of two short animated segments (and a live-action section in between) featuring the spaceship characters Eagle, Hawk, Robyn, Starling and Raven. There were some fun action segments showing them zooming towards the Sun and also doing a race on Mars. And in between this, preschoolers get to learn about things such as how a solar eclipse works (and how to look at it safely).
“It’s entertaining, but there’s also a very strong sense of making sure there is a curriculum part of the show that is based on science,” said Richard Schweiger, the creator of Space Racers and its executive producer. “NASA helped us develop that curriculum.”
Schweiger is the parent of two young boys, 10 and 8, and told Universe Todaythe idea for Space Racers germinated when they were around 3, 4 and 5. At the time, vehicle shows were very popular for them, such as Thomas the Tank Engine, the Cars movie and Jay Jay The Jet Plane. He also brought them on visits to the Smithsonian National Air and Space Museum, which he called the “coolest place in the world to bring a four-year-old.”
As an entrepreneur, Schweiger saw an opportunity. “That’s when I said, ‘Oh my gosh, what if we did a vehicle show where the characters were spaceships?’ ”
Working with a friend from college who has a masters in creative writing, Schweiger developed a screenplay and received an award in 2009. “That gave us some confidence and credibility,” he said.
He formed a company in January 2010 and raised some money from friends, family and a few other interested people. Schweiger’s group determined that instead of a film, the much better platform would be television. And they knew exactly who they wanted for subject matter experts.
A still from Space Racers, a half-hour preschool series premiering in 2014. Credit: SpaceRacers.org
“It was a simple phone call from Richard Schweiger. He explained the effort, the Space Racers team, what they were doing, and that they were looking for subject matter experts to review and clarify the information,” Ruth Netting, NASA’s communications and public engagement director, told Universe Today.
A preschool audience was a first for NASA, but the agency relished the challenge. Officials determined it would be best to “show and tell” certain concepts rather than use technical terms. There also were subtle adjustments for scientific accuracy, such as when the characters talk to each other in space. Because sound doesn’t carry there, NASA suggested the characters’ voices sound like they’re talking over a radio.
Science not only means teaching the concepts, but showing that you don’t always get things right the first time, added Tom Wagner, a NASA cryospheric scientist. “It includes learning from their elders and making mistakes. I don’t know if kids always get this today. They see stories about an app created and somebody making $19 million off of one little thing.” A “discovery aspect” is also included, meaning that kids see characters forming hypotheses and then changing their minds as more evidence comes in.
A still from Space Racers, a half-hour preschool series premiering in 2014. Credit: SpaceRacers.org
The U.S. national premiere will occur on May 2, but the show is already showing in New Zealand (where it premiered Feb. 15). Space Racers‘ international distributor (CAKE) also has commitments signed with the following locations: France, Russia, Norway, Sweden, Finland, New Zealand, Israel, Taiwan and parts of Africa, with dubbing taking place for those countries who have another language besides English as a first language.
Season 1 has 26 episodes in it. There are no immediate plans to produce a Season 2, but depending on how Season 1 is received, that is something Schweiger says he is willing to consider, along with merchandising for the $5 million production. Check out the Space Racers website for more information, and preschool activities.
This series of images shows the asteroid P/2013 R3 breaking apart, as viewed by the NASA/ESA Hubble Space Telescope in 2013. This is the first time that such a body has been seen to undergo this kind of break-up. Credit: NASA, ESA, D. Jewitt (UCLA).
Asteroid P/2013 R3 appears to be crumbling apart in space, and astronomers using the Hubble Space Telescope recently saw the asteroid breaking into as many as 10 smaller pieces. The best explanation for the break-up is the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, a subtle effect from sunlight that can change the asteroid’s rotation rate and basically cause a rubbly-type asteroid to spin apart.
“This is a really bizarre thing to observe — we’ve never seen anything like it before,” said co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany. “The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible.”
Astronomers first noticed this asteroid on September 15, 2013 and it appeared as a weird, fuzzy-looking object, as seen by the Catalina and Pan-STARRS sky-survey telescopes. A follow-up observation on Oct. 1 with the W.M. Keck telescope on Hawaii’s Mauna Kea revealed three co-moving bodies embedded in a dusty envelope that is nearly the diameter of Earth.
Then on October 29, 2013, astronomers used the Hubble Space Telescope to observe the object and saw there were actually 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 200 meters/yards in radius, about twice the length of a football field.
The Hubble data showed that the fragments are drifting away from each other at a leisurely pace of 1.6 km/hr (one mile per hour), which would be slower than a strolling human.
“Seeing this rock fall apart before our eyes is pretty amazing,” said David Jewitt, from UCLA’s Department of Physics and Astronomy, who led the investigation.
The slowness of the speed at which the pieces are coming apart makes it unlikely that the asteroid is disintegrating because of a collision. That would be instantaneous and violent, with the pieces traveling away from each other at much higher speeds.
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Jewitt also said the asteroid is not coming unglued due to the pressure of interior ices warming and vaporizing, like comets do as they approach the Sun. The asteroid is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480 million-km (300 million–mile) distance from the Sun for much of its life.
Jewitt described the YORP torque effect as like grapes on a stem being gently pulled apart due to centrifugal force of an unusually shaped asteroid as it speeds up in its spin. This effect occurs when light from the Sun is absorbed by a body and then re-emitted as heat. When the shape of the emitting body is not perfectly regular, more heat is emitted from some regions than others. This creates a small imbalance that causes a small but constant torque on the body, which changes its spin rate. This effect has been discussed by scientists for several years but, so far, never reliably observed.
For the break-up to happen, P/2013 R3 must have a weak, fractured interior, probably as the result of previous but ancient collisions with other asteroids. Most small asteroids, in fact, are thought to have been severely damaged in this way, giving them a “rubble pile” internal structure. P/2013 R3 itself is probably the product of collisional shattering of a bigger body some time in the last billion years.
With Hubble’s recent discovery of an a different active asteroid spouting six tails (P/2013 P5), astronomers are seeing more circumstantial evidence that the pressure of sunlight may be the primary force that disintegrates small asteroids (less than a mile across) in the Solar System.
The asteroid’s remnant debris, estimated at weighing in at 200,000 tons, in the future will provide a rich source of meteoroids, Jewitt said. Most will eventually plunge into the sun, but a small fraction of the debris may one day enter the Earth’s atmosphere to blaze across the sky as meteors, he said.
The discovery is published online March 6 in Astrophysical Journal Letters. A preprint of the paper can be found here.
Artistic representations of the only known planets around other stars (exoplanets) with any possibility to support life as we know it. The authors of this study wanted to know how people react to the discovery of alien life and potentially habitable planets. Credit: Planetary Habitability Laboratory, University of Puerto Rico, Arecibo.
Measuring the atmospheric pressure of a distant exoplanet may seem like a daunting task but astronomers at the University of Washington have now developed a new technique to do just that.
When exoplanet discoveries first started rolling in, astronomers laid emphasis in finding planets within the habitable zone — the band around a star where water neither freezes nor boils. But characterizing the environment and habitability of an exoplanet doesn’t depend on the planet’s surface temperature alone.
Atmospheric pressure is just as important in gauging whether or not the surface of an exoplanet may likely hold liquid water. Anyone familiar with camping at high-altitude should have a good understanding of how pressure affects water’s boiling point.
The method developed by Amit Misra, a PhD candidate, involves isolating “dimers” — bonded pairs of molecules that tend to form at high pressures and densities in a planet’s atmosphere — not to be confused with “monomers,” which are simply free-floating molecules. While there are many types of dimers, the research team focused exclusively on oxygen molecules, which are temporarily bound to each other through hydrogen bonding.
We may indirectly detect dimers in an exoplanet’s atmosphere when the exoplanet transits in front of its host star. As the star’s light passes through a thin layer of the planet’s atmosphere the dimers absorb certain wavelengths of it. Once the starlight reaches Earth it’s imprinted with the chemical fingerprints of the dimers.
Dimers absorb light in a distinctive pattern, which typically has four peaks due to the rotational motion of the molecules. But the amount of absorption may change depending on the atmospheric pressure and density. This difference is much more pronounced in dimers than in monomers, allowing astronomers to gain additional information about the atmospheric pressure based on the ratio of these two signatures.
While water dimers were detected in the Earth’s atmosphere as early as last year, powerful telescopes soon to come online may enable astronomers to use this method in observing distant exoplanets. The team analyzed the likelihood of using the James Webb Space Telescope to make such a detection and found it challenging but possible.
Detecting dimers in an exoplanet’s atmosphere would not only help us evaluate the atmospheric pressure, and therefore the state of water on the surface, but other biosignature markers as well. Oxygen is directly tied to photosynthesis, and will most likely not be abundant in an exoplanet’s atmosphere unless it is regularly produced by algae or other plants.
“So if we find a good target planet, and you could detect these dimer molecules — which might be possible within the next 10 to 15 years — that would not only tell you something about pressure, but actually tell you that there’s life on that planet,” said Misra in a press release.
The paper has been published in the February issue of Astrobiology and is available for download here.
NASA's Morpheus Project -- a prototype for vertical landing and takeoff for other planets -- during a free flight test Dec. 10, 2013. Credit: NASA (@MorpheusLander Twitter feed)
And we have a big foom and a big flight! The Morpheus prototype lander, which is intended to see how well automated technologies would work to fly spacecraft and land them on other planets, finished up its latest free-flight test yesterday. You can see the results in the latest video above, and we have a link to past videos below the jump.
The robot soared 467 feet high (142 meters) at the Kennedy Space Center in Florida before doing a planned sideways move that brought it 637 feet (194 m) in 36 seconds. It also did a mid-course correction to avoid a planned obstacle before touching down about 10 inches from its target. The flight lasted 79 seconds in all.
“Initial data indicates a nominal flight meeting all test objectives,” the team stated on its YouTube video. “The Morpheus Team again demonstrated engineering and operational excellence, relying upon training, discipline and experience to ensure today’s success.”
After overcoming an early setback that saw a lander crash and burn, Morpheus has been regularly doing free flights and in some cases, getting quite high off the ground (such as this flight last month that went as high as the Great Pyramid). And by the way, if that’s not enough rocket power for you today, there’s a lot more historical video where that flight came from. Check out this link on the Morpheus webpage to scroll back through its past free flights and tethered tests.
