Posted on by Jason Major

A Salad Bar for the Space Station

Romaine lettuce grows inside a prototype "Veggie" pillow (NASA/Gioia Massa)

Freeze-dried bags of dehydrated “astronaut food” may seem like a fun novelty for school kids on Earth, but despite all the hard work that goes into providing the residents of the Space Station with nutritious and varied meal options there’s one thing that remains a rare and elusive commodity on astronauts’ menus: fresh produce.

Although fruit and vegetables do occasionally find their way aboard the ISS via resupply missions (to the delight of the crew) researchers are moving one step closer to actually having a vegetable garden in orbit. On Monday, April 14 Friday, April 18, NASA’s Veg-01 experiment will launch to the ISS aboard a SpaceX Dragon capsule to test the in-flight viability of an expandable plant growth chamber named “Veggie.”

In development for several years, Veggie is now getting its chance to be space-tested with the launch of the SpaceX-3 resupply mission. Veggie uses clear collapsible bellows as miniature greenhouses, inside which plant “pillows” can be cultivated with the aid of root-mats and a bank of LED lights.

Crops successfully grown in Veggie include lettuce, Swiss chard, radishes, Chinese cabbage and peas. (NASA)
Crops successfully grown in Veggie include lettuce, Swiss chard, radishes, Chinese cabbage and peas. (NASA)

Astronauts will see how well “Outredgeous” romaine lettuce fares in microgravity inside the Veg-01 experiment, and can also use the LED bank as a light source for other experiments.

“Veggie will provide a new resource for U.S. astronauts and researchers as we begin to develop the capabilities of growing fresh produce and other large plants on the space station,” said Gioia Massa, the NASA payload scientist for Veggie. “Determining food safety is one of our primary goals for this validation test.”

While other plant-growth experiments are currently aboard ISS, Veggie boasts the simplest design and largest growing area of any of them to date.

The Veggie "pillow" is expandable to 11.5 inched wide by 14 inches deep. Credit: NASA/Bryan Onate
Veggie’s Teflon bellows is expandable to 11.5 inched wide by 14 inches deep. Credit: NASA/Bryan Onate

“Our hope is that even though VEGGIE is not a highly complex plant growth apparatus, it will allow the crew to rapidly grow vegetables using a fairly simple nutrient and water delivery approach.”
– Howard Levine, Ph.D. and chief scientist at  Kennedy Space Center (2012)

In addition to providing fresh food, maintaining a miniature garden in orbit would be therapeutic for astronauts on long-duration missions.

“Based upon anecdotal evidence, crews report that having plants around was very comforting and helped them feel less out of touch with Earth,” Massa said. “You could also think of plants as pets. The crew just likes to nurture them.” 

The Veggie system was developed for NASA by Orbital Technologies Corporation (ORBITEC) in Madison, Wisconsin, via a Small Business Innovative Research Program. Its innovations may eventually lead to better food production not only in space but also in limited-resource regions on Earth.

With the ultimate success of Veggie, ISS astronauts may soon find themselves floating in line at the in-house salad bar. (Watch out for those rogue croutons!)

Read more in the NASA news article by Linda Herridge here, and learn more about the Veggie project here.

Posted on by Nancy Atkinson

Follow-Up on Skydiving Meteorite: Crowdsourcing Concludes it Was Just a Rock

A multiple frame picture of the rock falling, taken from a video taken during a skydive in 2012. Credit and copyright: Anders Helstrup, used by permission.

For all those involved with the initial investigation of the skydiver and the possible meteorite, they now feel they have resolution to their puzzle, thanks to the beauty of crowdsourcing. The rock that showed up in a video taken during a skydive in Norway in 2012 was likely just a rock — accidentally packed in the parachute — and not a meteoroid.

Steinar Midtskogen, from the Norwegian Meteor Network who was involved in the initial investigation of the video, suggested an adaptation of Linus’s Law to explain what has happened in the past week: “Given enough eyeballs, all mysteries are shallow.”

With all the comments, opinions and analysis following the release of the video last week, the team of scientists and video experts from Norway have conceded that the likelihood of the rock being a meteoroid is extremely low. After nearly two years of analyzing the video, the Norwegian team was unable to fully resolve the puzzle, and so they went public, hoping to get input from others.

“We were left with scenarios that we were unable to find possible solutions for against something that fits but is extremely improbable, though possible,” Midtskogen wrote on the NMN website. “We seemed to get no further, and we decided to go public with what we had and at the same time invite anyone to have a go at the puzzle. … We expressed our hope that it would go viral and scrutinized for something that we might have missed, and the result was beyond our expectations.”

The group welcomed all the input (and criticism) but were especially swayed by the ballistics analysis provided by NASA planetary scientist Dr. Phil Metzger, who posted his investigation on Facebook:

Here is my conclusion: the ballistics are consistent with it being a small piece of gravel that came out of his parachute pack and flew past at close distance. The ballistics are also consistent with it being a large meteorite that flew past at about 12 to 18 meters distance. It could be either one, but IMO not anything in between. Based on the odds of parachute packing debris (common) versus meteorite personal flybys (extremely rare), and based on the timing (right after he opened his parachute), I vote for the parachute debris as the more likely.

His three plots are below:

Ballistics analysis from Dr. Phil Metzger: The first one shows how the measured and predicted velocity agree only at the two different distances mentioned above. The second assumes it was parachute debris, and shows the velocity of the debris as a function of time after being released from his pack. the third shows the separation between the skydiver and the debris as a function of time. Note that the debris passes the skydiver at 12 seconds after the debris was released, which is the same amount of time in the video from when the drogue chute was opened until the debris passed the skydiver.
Ballistics analysis from Dr. Phil Metzger: The first one shows how the measured and predicted velocity agree only at the two different distances mentioned above. The second assumes it was parachute debris, and shows the velocity of the debris as a function of time after being released from his pack. the third shows the separation between the skydiver and the debris as a function of time. Note that the debris passes the skydiver at 12 seconds after the debris was released, which is the same amount of time in the video from when the drogue chute was opened until the debris passed the skydiver.

Metzger concluded the likely outcome is that a small piece of gravel about 3.3 cm in diameter flew by the camera by at about 30 meters per second, or 10 meters per second relative to the skydiver.

But while Metzter feels Occam’s razor favors parachute debris, he said his model only shows feasibility.

“I don’t consider it to be a smoking gun,” he told Universe Today. “There could be other, better scenarios.”

And so, Midtskogen told Universe Today, while the rock being a meteoroid isn’t completely ruled out, they feel the best answer is that it was a small rock embedded in the chute, and no further analysis is needed.

“I can confirm that the group will no longer do coordinated work on this,” Midtskogen said via email. “I think all of us feel confident about the conclusion and won’t work more on this individually either – although here I can only speak for myself. It was shown how a pebble packed in the chute could reappear well above the chute, and there is no strong evidence against a small size, so this has been easy to accept.”

While this rock ended up not likely to be a meteoroid, Midtskogen added, the crowdsourcing and interest in the video was overwhelming and encouraging.

“So, no meteorite, but a good story,” he said good-naturedly in his email to Universe Today. “Our mood is still good, and we talk about putting up a plaque at ground zero: “On 17th June 2012 a pebble fell here, witnessed by 6 million people on YouTube”.

Additionally, the skydiver, Anders Helstrup, seemed relieved more than anything.

“After all we seem to have found a more natural explanation to the video,” he told Universe Today. “And that is a good thing. I see that this had to have been MY mistake – packing a pebble into my parachute (I always pack myself). Our intention was to find out more and this way let the story out in the public, for people to make up their own minds. This became way bigger than I had imagined.”

In the end, while this story was not as fantastic as it might have been, it shows the beauty of crowdsourcing and using science to analyze a puzzle. And I readily admit to being overly enthusiastic in my initial article about this being a meteoroid, but I have to agree with Phil Plait who may have said it best in his update today: I would have loved to have this to have been a real meteoroid, but I’m glad this worked the way it did:

The video-makers were honest, did their level best to figure this out, and when they got as far as they could, they put it out to the public. And when it was shown to not be what they had hoped, they admitted it openly and clearly.
— Phil Plait

Posted on by Elizabeth Howell

Twin Peeks: Astronaut Brothers To Go Under Microscope During One-Year Mission

NASA astronaut Scott Kelly plays with fresh fruit in the Unity node of the International Space Station. This 2010 picture was taken during Expedition 25. Credit: NASA

Identical twin astronauts, one headed to space for a year and the other happily at home. Imagine just how excited health researchers are by the prospect of this situation which yes, is happening for real. Scott Kelly is preparing to blast off on a lengthy mission to the International Space Station in 2015 while his retired twin, Mark, will serve as a control.

The 50-year-old men will do a suite of experiments before, during and after the mission to see how much (if at all) Scott’s body changes from his brother in the long term. This ranges from examining their DNA, to their vision, and even changes in the gut.

“These will not be 10 individual studies,” stated Craig Kundrot of NASA’s human research program at the Johnson Space Center. “The real power comes in combining them to form an integrated picture of all levels from biomolecular to psychological.  We’ll be studying the entire astronaut.”

One experiment will examine telomeres, which NASA says are “molecular caps” that sit on the ends of human DNA. As the theory goes, these telomeres are affected in space by cosmic rays (high-energy particles originating from outside the solar system) — which could speed up the aging process. If Scott’s telomeres change after the mission, this could help determine if space is linked to rapid aging.

Another experiment asks how the immune system alters. “We already know that the human immune system changes in space.  It’s not as strong as it is on the ground,” said Kundrot. “In one of the experiments, Mark and Scott will be given identical flu vaccines, and we will study how their immune systems react.”

Then there are experiments looking at gut bacteria that help digestion, seeking out how human vision changes, and even a phenomenon known as “space fog” — how some astronauts find themselves losing alertness in orbit.

Although the twins have inherent fascination for researchers and sociologists, the Kellys themselves have emphasized that to them, having an identical counterpart is something that always was.

NASA astronaut Mark Kelly peers out a window during the penultimate shuttle mission, STS-134, in 2011. Around his neck is the ring of his wife, Gabrielle Giffords, who was recovering from a gunshot head wound during the mission. Credit: NASA
NASA astronaut Mark Kelly peers out a window during the penultimate shuttle mission, STS-134, in 2011. Around his neck is the ring of his wife, Gabrielle Giffords, who was recovering from a gunshot head wound during the mission. Credit: NASA

“We didn’t know anything differently and, you know, he’s not my clone,” Scott said in a joint 2010 NASA interview with Mark.

“You know, a lot of times people would ask, ‘So what’s it like to be a twin?’ and … the response I would usually give is, ‘Well, what’s it like not to be a twin?’ I mean, it’s just, it is,” Mark added, to which Scott responded, “It’s more like … he’s my brother but we just happen to have the same birthday, to me.”

Scott will leave Earth with Russian cosmonaut Mikhail Kornienko in 2015 for the first one-year mission in space since a handful of lengthy stays on the former Russian space station, Mir, in the 1990s. Scott will serve as Expedition 43/44 flight engineer and have the distinction of commanding two space station missions, Expedition 45 and 46. (He also commanded Expedition 26 in 2010.)

Source: NASA

Posted on by Elizabeth Howell

After The Flood: Ancient Waters Carved These Martian Channels

A December 2013 image of Osuga Valles taken by the European Space Agency's Mars Express spacecraft, highlighted by the agency in April 2014. Credit: ESA/DLR/FU Berlin

This picture is an example of why Martian scientists like to get their groove on. This late 2013 snapshot of Osuga Valles — a part of the vast Valles Marineris gorge that cuts across the Red Planet — shows the leftovers of an ancient flood. The European Space Agency highlighted the area in a release this week.

“Catastrophic flooding is thought to have created the heavily eroded Osuga Valles and the features within it. Streamlines around the islands in the valley indicate that the direction of flow was towards the northeast … and sets of parallel, narrow grooves on the floor of the channel suggest that the water was fast flowing,” the European Space Agency stated.

“Differences in elevation within the feature, along with the presence and cross-cutting relationships of channels carved onto the islands, suggest that Osuga Valles experienced several episodes of flooding.”

Things get even more interesting when you look a bit closer up, as you can see below.

A close-up view of Osuga Valles created from data acquired with the Mars Express' High Resolution Stereo Camera. Water flowed towards the top of this image. Credit: ESA/DLR/FU Berlin
A close-up view of Osuga Valles created from data acquired with the Mars Express’ High Resolution Stereo Camera. Water flowed towards the top of this image. Credit: ESA/DLR/FU Berlin

“The grooved nature of the valley floor suggests the water was fast flowing, carving out the features as it flooded the region,” ESA added. “The elevated ‘island’ blocks are also carved with small channels, recording the history of previous flood episodes.”

You can read more about Mars Express’ 10 years of exploration at this ESA website. We’ve also highlighted the top 10 discoveries in this past Universe Today story.

Source: European Space Agency

Posted on by Elizabeth Howell

Supernova Sweeps Away Rubbish In New Composite Image

The supernova remnant G352.7-0.1 in a composite image with X-rays from the Chandra X-Ray Telescope (blue), radio waves from the Very Large Array (pink), infrared information from the Spitzer Space Telescope (orange) and optical data from the Digital Sky Survey (white). Credit: X-ray: NASA/CXC/Morehead State Univ/T.Pannuti et al.; Optical: DSS; Infrared: NASA/JPL-Caltech; Radio: NRAO/VLA/Argentinian Institute of Radioastronomy/G.Dubner

Shining 24,000 light-years from Earth is an expanding leftover of a supernova that is doing a great cleanup job in its neighborhood. As this new composite image from NASA reveals, G352.7-0.1 (G352 for short) is more efficient than expected, picking up debris equivalent to about 45 times the mass of the Sun.

“A recent study suggests that, surprisingly, the X-ray emission in G352 is dominated by the hotter (about 30 million degrees Celsius) debris from the explosion, rather than cooler (about 2 million degrees) emission from surrounding material that has been swept up by the expanding shock wave,” the Chandra X-Ray Observatory’s website stated.

“This is curious because astronomers estimate that G352 exploded about 2,200 years ago, and supernova remnants of this age usually produce X-rays that are dominated by swept-up material. Scientists are still trying to come up with an explanation for this behavior.”

More information about G352 is available in the Astrophysical Journal and also in preprint version on Arxiv.

Source: Chandra X-Ray Telescope

Posted on by Ken Kremer

Super Secret Spy Satellite Soars Spectacularly to Space aboard Atlas V booster from Cape Canaveral – Launch Gallery

Blastoff of the Atlas V rocket with the super secret NROL-67 intelligence gathering payload on April 10, 2014 from Cape Canaveral Air Force Station, Fla. Credit: Alan Walters/AmericaSpace

Blastoff of the Atlas V rocket with the super secret NROL-67 intelligence gathering payload on April 10, 2014 from Cape Canaveral Air Force Station, Fla. Credit: Alan Walters/AmericaSpace
Launch gallery expanded and updated – with timelapse ![/caption]

A super secret US spy satellite soared spectacularly to space this afternoon from Cape Canaveral atop a very powerful version of the Atlas V rocket on a classified flight for the National Reconnaissance Office.

The United Launch Alliance (ULA) Atlas V carrying the NROL-67 intelligence gathering satellite on a US national security mission for the NRO lifted off from Space Launch Complex-41 ignited its engines precisely on the targeted time on April 10 at 1:45 p.m. EDT into brilliant blue Florida skies on Cape Canaveral Air Force Station.

This mighty version of the 191 ft (58 m) tall Atlas V whose thrust was augmented with four strap on solid rocket motors has only been used once before – to loft NASA’s Curiosity rover to the Red Planet back in November 2011.

Atlas V NROL-67 launch photographed by iPhone from Cocoa Beach on April 10, 2014 while swimming. Credit: Nicole Solomon
Atlas V NROL-67 launch photographed by iPhone from Cocoa Beach on April 10, 2014 while swimming with the Florida fish. Credit: Nicole Solomon

Today’s Atlas V launch, as well as another for SpaceX/NASA, was postponed over two weeks ago from March 25 & 30 amidst final launch preparations when an electrical short completely knocked out use of the US Air Force’s crucial tracking radar that is mandatory to insure public safety for all launches on the Eastern Range.

Atlas V/NROL-67 spy satellite soars off Launch Complex 41 at Cape Canaveral on April 10, 2014. Credit: Jeff Seibert/WiredforSpace
Atlas V/NROL-67 spy satellite soars off Launch Complex 41 at Cape Canaveral on April 10, 2014. Credit: Jeff Seibert/Wired4space.com

Nothing is publicly known about the NROL surveillance satellite, its capabilities, orbit or mission or goals.

Due to the covert nature of this mission, the flight entered the now standard total news blackout and the TV transmission ceased barely five minutes after liftoff.

The successful blastoff follows closely on the heels of another Atlas V launch just seven days ago.

On April 3, ULA launched a less powerful version of the Atlas V carrying an Air Force weather satellite from Vandenberg Air Force Base, Calif.

Blastoff of the Atlas V rocket with the super secret NROL-67 intelligence gathering payload on April 10, 2014 from Cape Canaveral Air Force Station, Fla. Credit: Alan Walters/AmericaSpace
Blastoff of the Atlas V rocket with the super secret NROL-67 intelligence gathering payload on April 10, 2014 from Cape Canaveral Air Force Station, Fla. Credit: Alan Walters/AmericaSpace
Clear of the catenary lightning wires the Atlas 5-541 booster with its NROL-67 payload roar to orbit on April 10, 2014 from Cape Canaveral, FL. Credit: nasatech.net
Clear of the catenary lightning wires the Atlas 5-541 booster with its NROL-67 payload roar to orbit on April 10, 2014 from Cape Canaveral, FL. Credit: nasatech.net

“We are honored to deliver this national security asset to orbit together with our customers the NRO Office of Space Launch and the Air Force,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs.

“Successfully launching two missions from two different coasts in just seven days is a testament to the team’s one-launch-at-a-time focus and ULA’s commitment to mission success and schedule reliability.”

Today’s liftoff involved use of the Atlas V in the 541 configuration. The NROL-67 payload was housed inside a 5-meter diameter payload fairing. And a total of four US built Aerojet Rocketdyne solid rocket motors were mounted on the first stage of the booster.

Atlas V/NROL-67 spy satellite soars off Launch Complex 41 at Cape Canaveral on April 10, 2014. Credit: Jeff Seibert/WiredforSpace
Atlas V/NROL-67 spy satellite soars off Launch Complex 41 at Cape Canaveral on April 10, 2014. Credit: Jeff Seibert/Wired4space.com

The Centaur upper stage which boosted NROL-67 to Earth orbit was powered by a single Aerojet Rocketdyne RL10A engine.

The Atlas V first stage was also powered by the dual nozzle RD AMROSS RD-180 engine manufactured in Russia.

Use of the Russian designed and built RD AMROSS RD-180 engine potentially puts Atlas V launches and US National Security launches at risk, if the crisis in Ukraine and Crimea spins out of control as I have reported previously.

“ULA maintains a two year stockpile of the RD-180 engines at all times,” ULA Jessica Rye spokesperson told me recently at Cape Canaveral Air Force Station.

The next ULA launch from the Cape is scheduled for May 15 when a Delta IV rocket will loft the GPS IIF-6 mission for the United States Air Force from Space Launch Complex-37.

Rising quickly from Pad 41 on its RD-180 and 4 SRBs, the Atlas 5-541 vehicle begins its mission to geosync orbit. Credit: nasatech.net
Rising quickly from Pad 41 on its RD-180 and 4 SRBs, the Atlas 5-541 vehicle begins its mission to geosync orbit. Credit: nasatech.net

A SpaceX Falcon 9 is slated to launch on Monday, April 14 at 4:58 p.m. EDT.

The Falcon 9 is lofting a SpaceX Dragon cargo ship and delivering some 5000 pounds of science experiments and supplies for the six man space station crew – under a resupply contract with NASA.

Also packed aboard the Dragon are a pair of legs for NASA’s experimental Robonaut 2 crew member.

Stay tuned here for Ken’s continuing Atlas V NROL 67, SpaceX, Orbital Sciences, commercial space, Orion, Chang’e-3, LADEE, Mars rover, MAVEN, MOM and more planetary and human spaceflight news.

Learn more at Ken’s upcoming presentations at the NEAF astro/space convention, NY on April 12/13.

Ken Kremer

Startled Florida space coast sunbathers see sudden blastoff of Atlas V/NROl-67 from Cocoa Beach on April 10, 2014. Credit: Nicolle Solomon by iPhone
Startled Florida space coast sunbathers see sudden blastoff of Atlas V/NROl-67 from Cocoa Beach on April 10, 2014. Credit: Nicole Solomon by iPhone
Timelapse of Atlas V/NROL-67 blastoff on April 10, 2014. Credit: Chuck Higgins
Timelapse of Atlas V/NROL-67 blastoff on April 10, 2014. Credit: Chuck Higgins
April 10, 2014 blastoff of Atlas V rocket with super secret NROL-67 intelligence gathering payload from Cape Canaveral Air Force Station, Fla. Credit: Ken Kremer/kenkremer.com
April 10, 2014 blastoff of Atlas V rocket with super secret NROL-67 intelligence gathering payload from Cape Canaveral Air Force Station, Fla. Credit: Ken Kremer/kenkremer.com
Atlas V rocket and Super Secret NROL-67 intelligence gathering payload following rollout to Space Launch Complex 41 at Cape Canaveral Air Force Station, FL, on March 24, 2014. Credit: Ken Kremer - kenkremer.com
Atlas V rocket and Super Secret NROL-67 intelligence gathering payload following rollout to Space Launch Complex 41 at Cape Canaveral Air Force Station, FL. The Atlas V launched on April 10, 2014. Credit: Ken Kremer – kenkremer.com
Posted on by Jason Major

JPL Tests Big with a Supersonic Parachute for Mars

No rocket sleds were harmed in the making of this video. (NASA/JPL)

“You wanna go to Mars, you wanna go big? Then you gotta test big here,” says mechanical engineer Michael Meacham, and testing big is exactly what he and other engineers at NASA’s Jet Propulsion Laboratory have done to develop a new supersonic parachute for future Mars landings.

The process of putting things onto Mars has traditionally used the same couple of tried-and-true methods: inflatable, shock-absorbing bouncers and large parachutes combined with retro-rockets (most recently seen in the famous “Seven Minutes of Terror” Curiosity landing in August 2012.) But both methods are limited in how large and massive of an object can safely be placed on the Martian surface. For even larger-scale future missions, new technology will have to be developed to make successful landings possible.

Enter the LDSD, or Low-Density Supersonic Decelerator, an enormous parachute — similar to the one used by Curiosity except bigger — that can slow the descent of even more massive payloads through the thin Martian atmosphere.

Of course, part of the development process is testing. And in order to run such a large chute through the same sorts of rigors it would experience during an actual Mars landing, JPL engineers had to step outside of the wind tunnel and devise another method.

The one they came up with involves a rocket sled, a Night Hawk helicopter, a 100-lb steel bullet, a kilometer-long cable (and lots and lots of math.) It’s an experiment worthy of “Mythbusters”… watch the video above to see how it turned out.

“When we land spacecraft on Mars, we’re going extremely fast… we have got to slow down. So we use a parachute. And we use a really BIG parachute.”
– Michael Meacham, Mechanical Engineer at JPL

Read more about the LDSD program here.

Source/credit: NASA/JPL

Posted on by Brian Koberlein

How CERN’s Discovery of Exotic Particles May Affect Astrophysics

The difference between a neutron star and a quark star (Chandra)

You may have heard that CERN announced the discovery (confirmation, actually. See addendum below.) of a strange particle known as Z(4430).  A paper summarizing the results has been published on the physics arxiv, which is a repository for preprint (not yet peer reviewed) physics papers.  The new particle is about 4 times more massive than a proton, has a negative charge, and appears to be a theoretical particle known as a tetraquark.  The results are still young, but if this discovery holds up it could have implications for our understanding of neutron stars.

A periodic table of elementary particles. Credit: Wikipedia
A periodic table of elementary particles.
Credit: Wikipedia

The building blocks of matter are made of leptons (such as the electron and neutrinos) and quarks (which make up protons, neutrons, and other particles).  Quarks are very different from other particles in that they have an electric charge that is 1/3 or 2/3 that of the electron and proton.  They also possess a different kind of “charge” known as color.  Just as electric charges interact through an electromagnetic force, color charges interact through the strong nuclear force.  It is the color charge of quarks that works to hold the nuclei of atoms together. Color charge is much more complex than electric charge.  With electric charge there is simply positive (+) and its opposite, negative (-).  With color, there are three types (red, green, and blue) and their opposites (anti-red, anti-green, and anti-blue).

Because of the way the strong force works, we can never observe a free quark.  The strong force requires that quarks always group together to form a particle that is color neutral. For example, a proton consists of three quarks (two up and one down), where each quark is a different color.  With visible light, adding red, green and blue light gives you white light, which is colorless. In the same way, combining a red, green and blue quark gives you a particle which is color neutral.  This similarity to the color properties of light is why quark charge is named after colors.

Combining a quark of each color into groups of three is one way to create a color neutral particle, and these are known as baryons.  Protons and neutrons are the most common baryons.  Another way to combine quarks is to pair a quark of a particular color with a quark of its anti-color.  For example, a green quark and an anti-green quark could combine to form a color neutral particle.  These two-quark particles are known as mesons, and were first discovered in 1947.  For example, the positively charged pion consists of an up quark and an antiparticle down quark.

Under the rules of the strong force, there are other ways quarks could combine to form a neutral particle.  One of these, the tetraquark, combines four quarks, where two particles have a particular color and the other two have the corresponding anti-colors.  Others, such as the pentaquark (3 colors + a color anti-color pair) and the hexaquark (3 colors + 3 anti-colors) have been proposed.  But so far all of these have been hypothetical.  While such particles would be color neutral, it is also possible that they aren’t stable and would simply decay into baryons and mesons.

There has been some experimental hints of tetraquarks, but this latest result is the strongest evidence of 4 quarks forming a color neutral particle.  This means that quarks can combine in much more complex ways than we originally expected, and this has implications for the internal structure of neutron stars.

Very simply, the traditional model of a neutron star is that it is made of neutrons.  Neutrons consist of three quarks (two down and one up), but it is generally thought that particle interactions within a neutron star are interactions between neutrons.  With the existence of tetraquarks, it is possible for neutrons within the core to interact strongly enough to create tetraquarks.  This could even lead to the production of pentaquarks and hexaquarks, or even that quarks could interact individually without being bound into color neutral particles.  This would produce a hypothetical object known as a quark star.

This is all hypothetical at this point, but verified evidence of tetraquarks will force astrophysicists to reexamine some the assumptions we have about the interiors of neutron stars.

Addendum: It has been pointed out that CERN’s results are not an original discovery, but rather a confirmation of earlier results by the Belle Collaboration.  The Belle results can be found in a 2008 paper in Physical Review Letters, as well as a 2013 paper in Physical Review D.  So credit where credit is due.

Posted on by Elizabeth Howell

Asteroid That Dwarfed Dinosaur-Killer Punched Earth 3 Billion Years Ago, Study Says

A graphic comparing the asteroid that killed the dinosaurs, with an asteroid newly believed to have struck the Earth 3.26 billion years ago. Below the asteroids is a graphic showing how big the craters would have been. Credit: American Geophysical Union

Early in Earth’s history, a killer asteroid smashed a hole in our planet about 300 miles (500 kilometers) wide, which is greater than the driving distance between Washington and New York City, a new study says. The space rock set off a cycle of destruction that sounds like your worst nightmares.

That one reported collision 3.26 billion years ago made the Earth tremble, created earthquakes and set off tsunamis that were thousands of meters deep, according to a new research team. The size of this estimated destructor? About 37 kilometers (23 miles) wide, or about three times as wide as the asteroid that killed the dinosaurs 65 million years ago.

“We knew it was big, but we didn’t know how big,” stated co-author Donald Lowe, a geologist at Stanford University and a co-author of the study, of the asteroid.

Evidence of the huge impact — the first one mapped from so long ago — comes from an examination of the Barberton Greenstone Belt in South Africa, which shows rocks and “crustal fractures” that are consistent with the idea of a giant impact, the scientists said. (The asteroid struck the Earth thousands of miles away, but where isn’t known.)

An satellite view of Barberton greenstone around the town of Barberton, South Africa. Credit: NASA Earth Observatory/Landsat/U.S. Geological Survey/Jesse Allen
An satellite view of Barberton greenstone around the town of Barberton, South Africa. Credit: NASA Earth Observatory/Landsat/U.S. Geological Survey/Jesse Allen

If confirmed, the asteroid could have been one of many that smacked Earth during what is known as the Late Heavy Bombardment period, which pummeled the solar system with debris between 3 billion and 4 billion years ago.

This one event could even have changed the way the Earth formed, the scientists added. For example, it could have been broken up our planet’s crust and tectonics, creating the plate tectonics we are familiar with today.

You can read more about the research in the journal Geochemistry, Geophysics, Geosystems. It was led by Norman Sleep, a geophysicist at Stanford University.

Source: American Geophysical Union