Tag Archives: cosmos

Earth like exoplanet story telling

As more and more exoplanets (at first) and earth-like exoplanets (eventually) have been discovered, the way thy are described to us has become increasingly sophisticated. Below are embeds of diverse video descriptions that have been very quickly developed and distributed given the freshness of this latest scientific discovery. Note that the practice of very clearly stating that a particular depiction of something that no human has ever seen, or will ever see, as being an artist’s reconstruction has largely fallen by the wayside. Exoplanets are no longer physical features of the universe occassionally glimpsed by astronomers with very fancy Big Science Gear. They are now stories, where almost all the details and even implications are made up.

From the Telegraph:

From the Guardian:

From NASA via CNN:

Additional small exoplanet discovered in alleyway:

Oh, no, wait, that’s a plastic bag, never mind.

Pluto Has Tail, X-Rays

Did you ever notice that Pluto doesn’t have much of a tail? No, not that Pluto! This Pluto:

03_bagenal_02

This has been known for a while. NASA noted this last year:

New Horizons has discovered a region of cold, dense ionized gas tens of thousands of miles beyond Pluto — the planet’s atmosphere being stripped away by the solar wind and lost to space. Beginning an hour and half after closest approach, the Solar Wind Around Pluto (SWAP) instrument observed a cavity in the solar wind — the outflow of electrically charged particles from the Sun — between 48,000 miles (77,000 km) and 68,000 miles (109,000 km) downstream of Pluto. SWAP data revealed this cavity to be populated with nitrogen ions forming a “plasma tail” of undetermined structure and length extending behind the planet.

Not long ago it was not known that Pluto had an atmosphere. But it does, and it is probably made from solid ice that makes up a good portion of the planet. When Pluto is nearer the Sun, this atmosphere burns off and forms an unimpressive tail. (Existentially impressive, but not fireworks impressive.) If Pluto were to come really close to the sun, like a typical comet, it would … well, it would essentially be a a comet. A pretty big one, at first. But then after several passes…

Anyway, more recently, it has been discovered that Pluto also puts out X-rays, and if confirmed, this is interesting. The total number of X-rays that have been detected is very small. The existence of these X-rays is likely linked to the atmosphere. From NASA:

Scientists using NASA’s Chandra X-ray Observatory have made the first detections of X-rays from Pluto. These observations offer new insight into the space environment surrounding the largest and best-known object in the solar system’s outermost regions.

While NASA’s New Horizons spacecraft was speeding toward and beyond Pluto, Chandra was aimed several times on the dwarf planet and its moons, gathering data on Pluto that the missions could compare after the flyby. Each time Chandra pointed at Pluto – four times in all, from February 2014 through August 2015 – it detected low-energy X-rays from the small planet.

Pluto is the largest object in the Kuiper Belt, a ring or belt containing a vast population of small bodies orbiting the Sun beyond Neptune. The Kuiper belt extends from the orbit of Neptune, at 30 times the distance of Earth from the Sun, to about 50 times the Earth-Sun distance. Pluto’s orbit ranges over the same span as the overall Kupier Belt.

“We’ve just detected, for the first time, X-rays coming from an object in our Kuiper Belt, and learned that Pluto is interacting with the solar wind in an unexpected and energetic fashion,” said Carey Lisse, an astrophysicist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, who led the Chandra observation team with APL colleague and New Horizons Co-Investigator Ralph McNutt. “We can expect other large Kuiper Belt objects to be doing the same.”

The team recently published its findings online in the journal Icarus. The report details what Lisse says was a somewhat surprising detection given that Pluto – being cold, rocky and without a magnetic field – has no natural mechanism for emitting X-rays. But Lisse, having also led the team that made the first X-ray detections from a comet two decades ago, knew the interaction between the gases surrounding such planetary bodies and the solar wind – the constant streams of charged particles from the sun that speed throughout the solar system ­– can create X-rays.

New Horizons scientists were particularly interested in learning more about the interaction between the gases in Pluto’s atmosphere and the solar wind. The spacecraft itself carries an instrument designed to measure that activity up-close – the aptly named Solar Wind Around Pluto (SWAP) – and scientists are using that data to craft a picture of Pluto that contains a very mild, close-in bowshock, where the solar wind first “meets” Pluto (similar to a shock wave that forms ahead of a supersonic aircraft) and a small wake or tail behind the planet.

The immediate mystery is that Chandra’s readings on the brightness of the X-rays are much higher than expected from the solar wind interacting with Pluto’s atmosphere.

“Before our observations, scientists thought it was highly unlikely that we’d detect X-rays from Pluto, causing a strong debate as to whether Chandra should observe it at all,” said co-author Scott Wolk, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “Prior to Pluto, the most distant solar system body with detected X-ray emission was Saturn’s rings and disk.”

The Chandra detection is especially surprising since New Horizons discovered Pluto’s atmosphere was much more stable than the rapidly escaping, “comet-like” atmosphere that many scientists expected before the spacecraft flew past in July 2015. In fact, New Horizons found that Pluto’s interaction with the solar wind is much more like the interaction of the solar wind with Mars, than with a comet. However, although Pluto is releasing enough gas from its atmosphere to make the observed X-rays, in simple models for the intensity of the solar wind at the distance of Pluto, there isn’t enough solar wind flowing directly at Pluto to make them.

Lisse and his colleagues – who also include SWAP co-investigators David McComas from Princeton University and Heather Elliott from Southwest Research Institute – suggest several possibilities for the enhanced X-ray emission from Pluto. These include a much wider and longer tail of gases trailing Pluto than New Horizons detected using its SWAP instrument. Other possibilities are that interplanetary magnetic fields are focusing more particles than expected from the solar wind into the region around Pluto, or the low density of the solar wind in the outer solar system at the distance of Pluto could allow for the formation of a doughnut, or torus, of neutral gas centered around Pluto’s orbit.

That the Chandra measurements don’t quite match up with New Horizons up-close observations is the benefit – and beauty – of an opportunity like the New Horizons flyby. “When you have a chance at a once in a lifetime flyby like New Horizons at Pluto, you want to point every piece of glass – every telescope on and around Earth – at the target,” McNutt says. “The measurements come together and give you a much more complete picture you couldn’t get at any other time, from anywhere else.”

New Horizons has an opportunity to test these findings and shed even more light on this distant region – billions of miles from Earth – as part of its recently approved extended mission to survey the Kuiper Belt and encounter another smaller Kuiper Belt object, 2014 MU69, on Jan. 1, 2019. It is unlikely to be feasible to detect X-rays from MU69, but Chandra might detect X-rays from other larger and closer objects that New Horizons will observe as it flies through the Kuiper Belt towards MU69.

The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Pluto

Captain. We’ve found an M-Class Planet

The star that is nearest our own has a planet that could be habitable by Earthlings.

This is very important news.

The news comes to us from this research paper in Nature: A terrestrial planet candidate in a temperate orbit around Proxima Centauri by Guillem Anglada-Escudé, Pedro J. Amado, John Barnes, Zaira M. Berdiñas, R. Paul Butler, Gavin A. L. Coleman, Ignacio de la Cueva, Stefan Dreizler, Michael Endl, Benjamin Giesers, Sandra V. Jeffers, James S. Jenkins, Hugh R. A. Jones, Marcin Kiraga, Martin Kürster, Mar?a J. López-González, Christopher J. Marvin, Nicolás Morales, Julien Morin, Richard P. Nelson, José L. Ortiz, Aviv Ofir, Sijme-Jan Paardekooper, Ansgar Reiners, Eloy Rodríguez, Cristina Rodr?guez-López, Luis F. Sarmiento, John P. Strachan, Yiannis Tsapras, Mikko Tuomi & Mathias Zechmeister.

Abstract:

At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (? Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.

Here’s why this is important. We knew that some stars that are like ours had Earth-like planets. How did we know that? Because we live on one. But how many Sun-like stars have Earth-like planets?

Trivially, we knew that all the known Sun-like stars had Earth-like planets. But that was with a sample size of one. We needed a larger sample size to estimate the actual percentage of Sun-like stars that had Earth-like planets.

Given that, consider the following question. We have a second Sun-like star. If it has no Earth-like planets, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 50-50, but the sample size is too small. Safer to simply guess, “maybe not many, because the first time we got to increment our sample size, we got nada.” Now, if it does have an Earth-like planet, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 100%, but again, the sample size is too small. But, you would safely say something like, “Well, hell, maybe a lot of them, because of the two where we have enough information to say … both have them!”

There really is no reasonable statistical way to treat this problem, but this sort of seat of the pants conjecture isn’t bad for now. But, if we were to have, say, five or six Sun-like stars to look at, we could start making real guesses.

There is a second reason. Now that we have an Earth like planet in our sights, perhaps there will be impetus for both funding and effort to squint really really hard at it and see if any life is there. Using fancy science, not actual squinting, of course.

Let us be clear. This planet is not Earth-like in that it has an atmosphere, water, or any sign of life. The planet might be locked in its orbit around its star in such a way that one side always faces that star. That would be bad for an atmosphere and for life. We don’t know if it has an atmosphere, or water. What we do know is that if water is on the surface, it might be liquid, and if an atmosphere ever formed there, maybe (though this is highly debatable) it did not necessarily get blown away into space or otherwise destroyed.

Nature made a video about the discovery:

For more information, check out these posts:

Phil Plait: Astronomers Discover a New Planet Orbiting the Closest Star to the Sun!

Mike Wall: Found! Potentially Earth-Like Planet at Proxima Centauri Is Closest Ever

Nature Podcast, an interview with the chief author:

Happy Anniversary Exoplanets

This month is the twentieth anniversary of the discovery of exoplanets, which are really just planets that are not in our solar system. (Frankly, I dislike the term exoplanet. It is so solarcentric.)

When you think about it, the discovery of planets outside our solar system (we need a word for that) is a special thing. On a graph of how expected and mundane a scientific discovery is vs. how exciting a scientific discovery is, these planets are distant outliers.

Screen Shot 2015-11-19 at 11.55.55 AM

For years astronomers and cosmologists and others assumed that stars would generally have planets around them, or at least, this would often be the case. This is all part of the famous Drake Equation, best stated by Carl Sagan using the word “Billions” (with two b’s) over and over again. Like this.

OK, he didn’t really use “Billions” a bunch of times. But he might have.

Anyway, Nature.com has a nice set of infographics on the topic, one of which I’ve posted above. The rest are here.

That Orion Thing Is Great!

Watch the Orion test flight:

Splashdown:

Why is it great? Well, speaking as a Gemini (not my horoscope sign, but the space program going when I first gained sentience) …

<li>First, it is big, fast, cool looking.  It actually looks like a rocket that might have been designed a decade before they ever actually made any rockets.  It is almost Deco.</li>


<li>Second, they got a guy from the 1960s -- with that slightly, nasal, black and white voice people spoke in back then -- to call the <del datetime="2014-12-06T02:10:27+00:00">race</del> <em>launch</em>. </li>


<li>Third, Orion is really good at taking selfies. </li>


<li>Fourth, it didn't take long. The whole thing was like literally tl;dr.</li>

Oh, and fifth: It worked! Didn’t blow up or anything!

Apparently, the rocket that shot this unit into space is small compared to the one they’ll be using in the future. (More info on the project here.)

Onward to Mars! Finally!

#Cosmos with @neiltyson – The first episode is a win.

If you missed the first (or later any) episode of Cosmos 2014, you can get it on Amazon Prime streaming (for a fee). It’s worth it. Here are a few comments I jotted down (then lightly edited) while watching the first episode.

Neil does have his own spaceship, like Carl did. That’s important because it lets him fly to interesting places. It is one of those spaceships of the imagination. Everybody should have one.

The visuals are amazing and informative and seem to be scientifically accurate to the extent possible. There is quite a bit of attention to scale, and how perspective shifts with changing scales, throughout the episode.

The predominant metaphor is that of a journey, starting with Earth which Neil takes little time to leave, where he quickly covers the details of the solar system. He spends a lot of time on Jupiter but barely touches on Uranus. Uranus and Neptune are the outermost planets. Then “beyond the outermost planet there is a swarm of tens of thousands of frozen worlds. And Pluto is one of them.” (Made me laugh.)

Then Voyager One, which reminds me of a story. Neil notes that this spacecraft, the one that has gone farthest of any we’ve launched, bears a message to distant and future possible recipients that includes “the music we made.”

One day in the Ituri Forest, living in a camp with the Efe Pygmies, we had a tape player and a few cassettes (a pre-iTunes device using plastic ribbons on which sounds could be stored). The music was playing, and Happiness Is A Warm Gun by the Beatles came on. About the time Mother Superior jumped the gun, the Efe guy who was one of our main informants, who also turned out to be something of a shaman, came running over.

“Turn that off, turn that off,” he said. He was perturbed.

“Why?” I replied, switching off the machine, thinking that he had heard something out in the forest, perhaps a herd of elephants heading our way, which had been a concern lately since they were in the neighborhood.

“That music is evil. It will make it rain, really bad.”

“Oh, OK.”

“Thunder and ligtning and floods!”

“OK, Ok.”

“Don’t play that again!”

I never played that tape again while in the Ituri.

But it occurs to me now that something similar could happen a billion years from now when Voyager One is finally discovered by intelligent beings from some other planet. How do we know that what we think of as music, with all it’s meaning and lack thereof, a thing that expresses cultural depth but usually enjoyed with no reference to meaning at all, will be seen in the same way by the Blorgons, or whoever it is that discovers it? Maybe they will think it is powerful magic and they will want more. Maybe they fight with music and will see it as a challenge. Maybe to them it will be a mating call. Either way, we could be screwed.

OK, back to Cosmos.

I’ve noticed that so far Neil has used the terms “countless” and “numberless” and “trillion” but not yet Billions. Just sayin’

Wait wait there it is! Approximately countdown 34:33 from the end. Billions of something. Orts.

Now on to other stars’ planets, and the new post-original-Cosmos scientific fact: Planets outnumber the stars. Carl may have guessed that but he didn’t know. Now we know. Also, that there are rogue planets, that are not in orbit around any sun. There are billions of them in our galaxy. Another post-Sagan fact. Possible places for life.

Life: What is it? We only know about Earth Life.

And now on to the spectrographic analysis of the universe. This is a theme Neil has written about and that we chatted about in our interview in 2011 (here). How astronomers see. Very interesting stuff. I’ll bet he’ll do a lot of that in the series.

Eventually, we’re outside the Milky Way Galaxy, and looking at other galaxies. Helpful text overlays give us the key terminology. And more with scale; the tiny dots are stars, then the tiny dots are galaxies. Then all this wiggly wobbly stuff that is the stuff of the universe. Super mind blowing cosmic fact: There are parts of the universe that are too far away to see because there hasn’t been time for the light from those regions to reach us. So how do we see cosmic background radiation which comes from the entire universe? Aha. That will probably be covered later.

Then the Multiverse. Looks a bit like Niagara Falls.

Now back to a brief history of human thinking about the cosmos. All that wrong stuff that we eventually climbed out of. Giordano Bruno, back to earth, Neil is on the streets of Italy.

Here we see animated cartoon graphics. I love the fact that the basic style of the cartoons is a serious version of the Scooby Doo style.

Copernicus, Giodna Brno, Galileo, the search for a better understanding of the universe. Reference to Lucretius, “On the nature of things” which includes the metaphor of shooting an arrow out beyond the edge of the universe. That reminds me of a story.

Again, back to the Ituri Forest. My friend Steve Winn told me this story, while we were both in the Ituri. Most of the researchers who went there had a similar experience in that we were expected to tell the story of our journey from home to the forest. One of the elements of that journey is, for most, crossing the ocean in a plane. But in the Ituri, there are only tiny planes that are rarely seen and the largest bodies of water are medium size rivers and large swamps. It is almost impossible to convey the vastness of even a mid-sized ocean like the North Atlantic.

So one day Steve tried this, when talking about the journey across the sea.

“Imagine standing on the edge of the Uele river,” pointing down to the nearby, rather small, river. “And shooting across an arrow. That would be easy.”

Nods of assent from the Efe men listening to the story.

“Now imagine a larger river that most people couldn’t shoot across.”

Hmmmm.

“Now imagine the strongest archer with the strongest bow shooting the straightest arrow across the water and it can never reach the other side.”

Eyes widening.

“The ocean is much much bigger than that.”

Personally, I don’t think that conveys the size of the ocean, but it does serve to begin to break the barrier at the edge of knowable experience. Did the Efe men really understand the size of the ocean from that story? Do the watchers of Cosmos really understand the vastness of the Universe by Neil’s reference to some of it being so far away that the light from it has not reached us yet?

Anyway, Brno had a hallucinogenic dream that the sun was only one of many stars. Got in all sorts of trouble. I guess he didn’t expect the Italian Inquisition. Good version of the story of the first realizations of the nature of the universe.

And now, finally, the Cosmic Calendar, Neil deGrasse Tyson style. Here comes the Big Bang. Better put on sunglasses.

It would be interesting to do a day by day comparison between Sagan’s Cosmic Calendar and Neil’s to compare what we now know vs. then, what is emphasized, and the styles. Any volunteers?

Anyway, “We are made of starstuff.” Scrape that moment out and put it in Memeland.

Tides. Turns out you can explain them. Life. And sex is invented. It must be getting December.

The KT extinction event totally made me laugh. Contingently.

Sagan did not have the Laetoli footprints but Neil does.

And the introductory episode, which is bookended by appropriate references to Sagan, ends with a very quick summary of human history, the invention of astronomy, writing, and science. And finally the Sagan-Tyson link is made, which you would know if you read Neil’s autobiography but if you don’t you’ll enjoy hearing about it here. You’ll get all choked up.

Cosmic Bombardment of the Earth ca 2.2 Million Years Ago?

There are bacteria that use Iron (and other elements) to make tiny magnets that they carry around so they don’t get lost. (I anthropomorphize slightly.) There are isotopes of Iron that are not of the Earth, but are found only elsewhere in the universe.

Suppose an event happened elsewhere and spewed some of that cosmic Iron isotope, say Fe-60, onto the earth, and the bacteria who were busy making their tiny compasses at that time used some of it. Then the bacteria died and were trapped inlayers in seafloor sediment and later examined by scientists looking for … well, looking for evidence of cosmic events trapped in bacterial compasses!

Well, that happened.

A bit of sea floor was found to have Iron-60 in it a few years back. Iron-60 is radioactive and decays into Cobalt-60, with a known (but only recently known as it turns out) decay rate. That bit of rock was taken as possible evidence of an ancient supernova. The event was tied, conjecturally, to human evolution as all things must be whenever even remotely possible:

Cosmic fallout from an exploding star dusted the Earth about 2.8 million years ago, and may have triggered a change in climate that affected the course of human evolution. The evidence comes from an unusual form of iron that was blasted through space by a supernova before eventually settling into the rocky crust beneath the Pacific Ocean.

The team has now analysed a … piece of ocean crust, where the supernova detritus is concentrated into a clear band of rock that can be accurately dated. The researchers found small but significant amounts of an isotope called iron-60 in the rock, which could only have come from a supernova.

“We’ve looked at all the possibilities and we can’t find anything else that could produce such quantities,” Korschinek says.

The human evolution impact idea comes from a possible cooling effect the exploding star would have had on the earth. Back in 2004 it was estimated that the earth would have been bathed in extra cosmic rays for about 100,000 years which would have, it was said, created condensation in the atmosphere which would have cooled the earth. There was a cooling event around that time (but quite possibly well after this date, so don’t hang any hats on this) so I suppose this could be. But, I’m not going to assume that the cooling effects of cosmic rays are a thing at this point. I do know that people have gotten the effects of upper level vapor wrong a few times so I’m going to avoid making any assumptions about that here.

Anyway, last April, a paper was given at the American Physical Society conference giving preliminary findings related to some follow up research. Shawn Bishop and his team obtained a core from the Pacific dating to between 1.7 and 3. 3 million years ago. They sampled it at 100K intervals and extracted and separated out Iron in a way that would show Iron-60 if there was any. And …

“It looks like there’s something there,” Bishop told reporters at the Denver meeting. The levels of iron-60 are minuscule, but the only place they seem to appear is in layers dated to around 2.2 million years ago.

And, the iron was concentrated in the target layers by the action of compass-using bacteria.

Notice the change in date from 2.8 to 2.2. This is, I think, because the half life of Iron-60 was refigured based on some intervening research. Now, the date is probably too late for a significant cooling event. But really, there were a whole bunch of cooling events from somewhere over 5 million years ago to about 2 point something million years ago, and there is a long list of candidates for what caused them, including numerous big volcanoes, continental movements, and now, a supernova.

I don’t think anyone is claiming to know what star exploded.


Photo Credit for picture of fancy science machine: Gottfried not Bouillon via Compfight cc

It was so unexpected that we thought there was something wrong with the instrument

I love it when scientists say that! And, so said scientist Daniel Baker, speaking of a newly observed feature of the famous and well known, or at least, we thought well known, Van Allen Belts.

First discovered in 1958, the Van Allen belts have been thought to comprise two reservoirs of high-speed, electrically charged particles, corralled into separate doughnut-shaped rings by Earth’s magnetic field. The outer ring orbits at a distance of some 10,000–60,000 kilometres above Earth, and encircles an inner band of even more energetic particles, roughly 100–10,000 kilometres above Earth. … that’s … the structure that NASA’s twin Van Allen Probes recorded when they began operation on 1 September 2012.

ResearchBlogging.orgBut just two days later, telescopes on the probes revealed the emergence of an additional, narrow belt of charged particles sandwiched between the inner ring and a now highly eroded outer ring….

This was apparently caused by a burst of solar wind which messed up the outer Van Allen Belt and led to the reconfiguration of orbiting electrically charged bits and pieces. A wave of solar wind in October then removed all of the remaining outer ring and also wiped out the new middle ring. Then, a third wave of solar wind restored the Van Allen Belts to what we had been thinking was the normal configuration.

From the original paper:

Since their discovery over 50 years ago, the Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is comprised predominantly of mega-electron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days depending primarily on external forcing by the solar wind. The spatially separated inner zone is comprised of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (E > 2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for over four weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.

Here’s what it looks like:

Typical and Atypical Van Allen Belts
From Science: “Diagrams providing a cross-sectional view of the Earth’s radiation belt structure and relationship to the plasmasphere. (A) A schematic diagram showing the Earth, the outer and inner radiation belts and the normal plasmaspheric location. (B) Similar to (A) but showing a more highly distended plasmasphere and quite unexpected triple radiation belt properties during the September 2012 period. These diagrams show the highest electron fluxes as white and the lowest fluxes as blue. The radiation belts are really ‘doughnut’ or torus-shaped entities in three dimensions. The Earth is portrayed at the center. Also shown, as a translucent green overlay in each diagram, is the plasmasphere.”

Baker, D., Kanekal, S., Hoxie, V., Henderson, M., Li, X., Spence, H., Elkington, S., Friedel, R., Goldstein, J., Hudson, M., Reeves, G., Thorne, R., Kletzing, C., & Claudepierre, S. (2013). A Long-Lived Relativistic Electron Storage Ring Embedded in Earth’s Outer Van Allen Belt Science DOI: 10.1126/science.1233518