Posted on by Nancy Atkinson

Crater Ahoy! Mars Rover Gets First Glimpse of Faraway Destination

The raised rim of Endeavour Crater as seen by Opportunity. Credit: NASA/JPL

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The journey seems almost impossible and endless for the Opportunity rover, heading through the dunes of Meridiani Planum on its way to a distant crater. But now the rover’s Panoramic Camera has caught the first glimpse on the horizon of the uplifted rim of Endeavour Crater, providing optimism for the MER team and rover fans alike, that Opportunity can perhaps complete the journey. “We can now see our landfall on the horizon,” said Steve Squyres, principal investigator for the rovers’ science instruments.”It’s far away, but we can anticipate seeing it gradually look larger and larger as we get closer to Endeavour. We had a similar experience during the early months of the mission watching the Columbia Hills get bigger in the images from Spirit as Spirit drove toward them.”

Opportunity has been ‘on the road’ for six months, heading toward the huge crater, which is 22 kilometers (14 miles) in diameter. Endeavour Crater is still 12 kilometers (7 miles) away from Opportunity as the crow flies, and at least 30 percent farther away on routes mapped for evading dune hazards on the plain. Opportunity has already driven about 3.2 kilometers (2 miles) since it climbed out of Victoria Crater last August after two years of studying Victoria, which is less than one-twentieth the size of Endeavour.

“It’s exciting to see our destination, even if we can’t be certain whether we’ll ever get all the way there,” said John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., project manager for the twin Mars rovers, Opportunity and Spirit. “At the pace we’ve made since leaving Victoria, the rest of the trek will take more than a Martian year.” A Martian year lasts about 23 months.

Image from Opportunity's navigation camera on sol 1825. Credit: NASA/JPL
Image from Opportunity's navigation camera on sol 1825. Credit: NASA/JPL

Opportunity will take a brief breather the next several days. The rover team plans to have Opportunity use the tools on its robotic arm to examine soil and rock at an outcrop along the route the rover is taking toward Endeavour.

“We’re stopping to taste the terrain at intervals along our route so that we can watch for trends in the composition of the soil and bedrock,” Squyres said. “It’s part of systematic exploration.”

The pause for using the tools on the arm also provides two other benefits. Opportunity’s right-front wheel has been drawing more electric current than usual, an indication of friction within the wheel. Resting the wheel for a few days is one strategy that has in the past helped reduce the amount of current drawn by the motor.

Also, on March 7, the rover did not complete the backwards-driving portion of its commanded drive due to unanticipated interaction between the day’s driving commands and onboard testing of capabilities for a future drive. The team is analyzing that interaction before it will resume use of Opportunity’s autonomous-driving capabilities.

Spirit navigation camera panorama from Sol 1849. Credit: NASA/JPL
Spirit navigation camera panorama from Sol 1849. Credit: NASA/JPL

Opportunity’s twin, Spirit, also has a challenging destination, and last week switched to a different route for making progress.On March 10, the rover team decided to end efforts to drive Spirit around the northeastern corner of a low plateau called “Home Plate” in the inner basin of the Columbia Hills, on the other side of Mars from Opportunity. Spirit’s right front wheel stopped working in 2006, and consequently, it usually drives backwards, dragging that wheel. So climbing steep slopes is no longer an option.

Callas said, “After several attempts to drive up-slope in loose material to get around the northeast corner of Home Plate, the team judged that route to be impassable.”

The new route to get toward science targets south of Home Plate is to go around the west side of the plateau.

Squyres said, “The western route is by no means a slam dunk. It is unexplored territory. There are no rover tracks on that side of Home Plate like there are on the eastern side. But that also makes it an appealing place to explore. Every time we’ve gone someplace new with Spirit since we got into the hills, we’ve found surprises.”

Source: JPL

Posted on by Nancy Atkinson

Where In The Universe #47



Are you ready for another Where In The Universe Challenge? Take a look at the image above and see if you can name where in the Universe this image is from. Give yourself extra points if you can name the spacecraft responsible for the image. We’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Check back tomorrow on this same post to see how you did. Good luck!

UPDATE: The answer has now been posted below. Don’t peek before you make your guess!

This is an image of the Pleiades star cluster, also known as the Seven Sisters, taken by the Spitzer Space Telescope. The Pleiades, located more than 400 light-years away in the Taurus constellation, are the subject of many legends and writings. Greek mythology holds that the flock of stars was transformed into celestial doves by Zeus to save them from a pursuant Orion. The 19th-century poet Alfred Lord Tennyson described them as “glittering like a swarm of fireflies tangled in a silver braid.”

This image from Spitzer highlights the “tangled silver braid.” The spider-web-like network of filaments, colored yellow, green and red in this view, is made up of dust associated with the cloud through which the cluster is traveling. The densest portion of the cloud appears in yellow and red, and the more diffuse outskirts are shown in green hues. One of the parent stars, Atlas, can be seen at the bottom, while six of the sisters are visible at top. Additional stars in the cluster are sprinkled throughout the picture in blue.

How did you do? Come back again next week for another WITU Challenge.

Posted on by Anne Minard

New Particle Throws Monkeywrench in Particle Physics

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The hits just keep on coming from Department of Energy’s Fermi National Accelerator Laboratory. So far this month, the lab has announced the discovery of a rare single top quark, and then narrowed the gap — twice, actually — for the mass of the elusive Higgs Boson particle, or “God particle,” thought to give all other particles their mass. 

Now, scientists have detected a new, completely untheorized particle that challenges what physicists thought they knew about how quarks combine to form matter. They’re calling it Y(4140), reflecting its measured mass of 4140 Mega-electron volts. 

“It must be trying to tell us something,” said Jacobo Konigsberg of the University of Florida, a spokesman for Fermilab’s collider detector team. “So far, we’re not sure what that is, but rest assured we’ll keep on listening.”

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The Standard Model of elementary particles and forces includes six quarks, which bind together to form composite particles. Credit: Fermilab

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Matter as we know it comprises building blocks called quarks. Quarks fit together in various well-established ways to build other particles: mesons, made of a quark-antiquark pair, and baryons, made of three quarks. 

But recently, electron-positron colliders at Stanford’s SLAC National Accelerator Laboratory and the Japanese laboratory KEK have revealed examples of composite quark structures — named X and Y particles — that are not the usual mesons and baryons. And now, the Collider Detector at Fermilab (CDF) collaboration has found evidence for the Y(4140) particle.

The Y(4140) particle decays into a pair of other particles, the J/psi and the phi, suggesting to physicists that it might be a composition of charm and anticharm quarks. However, the characteristics of this decay do not fit the conventional expectations for such a make-up. Other possible interpretations beyond a simple quark-antiquark structure are hybrid particles that also contain gluons, or even four-quark combinations.

The Fermilab scientists observed Y(4140) particles in the decay of a much more commonly produced particle containing a bottom quark, called the B+ meson. Sifting through trillions of proton-antiproton collisions from Fermilab’s Tevatron, they identified a small sampling of B+ mesons that decayed in an unexpected pattern. Further analysis showed that the B+ mesons were decaying into Y(4140).

The Y(4140) particle is the newest member of a family of particles of similar unusual characteristics observed in the last several years by experimenters at Fermilab’s Tevatron as well as at KEK and the SLAC lab, which operates at Stanford through a partnership with the U.S. Department of Energy.

“We congratulate CDF on the first evidence for a new unexpected Y state that decays to J/psi and phi,” said Japanese physicist Masanori Yamauchi, a KEK spokesperson. “This state may be related to the Y(3940) state discovered by Belle and might be another example of an exotic hadron containing charm quarks. We will try to confirm this state in our own Belle data.”

Theoretical physicists are trying to decode the true nature of these exotic combinations of quarks that fall outside our current understanding of mesons and baryons. Meanwhile, experimentalists happily continue to search for more such particles.

“We’re building upon our knowledge piece by piece,” said Fermilab spokesperson Rob Roser, “and with enough pieces, we’ll understand how this puzzle fits together.”

The Y(4140) observation is the subject of an article submitted by CDF to Physical Review Letters this week. Besides announcing Y(4140), the CDF experiment collaboration is presenting more than 40 new results at the Moriond Conference on Quantum Chromodynamics in Europe this week, including the discovery of electroweak top-quark production and a new limit on the Higgs boson, in concert with experimenters from Fermilab’s DZero collaboration. 

Source: Fermilab

Posted on by Tammy Plotner

Turning the Tides – NGC 3109 by Ken Crawford

NGC 3109 by Ken Crawford

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Somewhere off in the far reaches of Hydra about 4.3 million light years away is a local subgroup of galaxies and a small, barred spiral that just seems to be quietly minding its own business. Or is it? NGC 3109 might not look like much at first, but this little island universe is really turning the tides…

First discovered by John Herschel on March 24, 1835 while in South Africa, NGC 3109 was first classed as an irregular galaxy – the dominating member of a small group of dwarf galaxies believed to be Local Group Member candidates – a determination which isn’t easy to make. “The Local Group dwarf galaxies offer a unique window to the detailed properties of the most common type of galaxy in the Universe.” says Mario L. Mateo, “Our understanding of these galaxies has grown impressively in the past decade, but fundamental puzzles remain that will keep the Local Group at the forefront of galaxy evolution studies for some time.”

What makes NGC 3109 and its little band of followers so interesting? Well, chances are it may not be a member of our Local Group at all, but the nearest of the outsiders. “The small Antlia-Sextans clustering of galaxies is located at a distance of only 1.36 Mpc from the Sun and 1.72 Mpc from the adopted barycenter of the Local Group. The latter value is significantly greater than the radius of the zero-velocity surface of the Local Group that, for an assumed age of 14 Gyr, has R_0=1.18+/-0.15 Mpc.” says Sidney Van den Bergh, “This, together with the observation that the members of the Ant-Sex group have a mean redshift of 114+/-12 km s^-1 relative to the centroid of the Local Group, suggests that the Antlia-Sextans group is not bound to our Local Group and that it is expanding with the Hubble flow. If this conclusion is correct, then Antlia-Sextans may be the nearest external clustering of galaxies.”

So, if NGC 3109 can hold those kind of secrets… What other kinds of secrets can it keep to itself? Try a tiny tidally interacting elliptical galaxy discovered in 1999 by Alan Whiting, George Hau and Mike Irwin. It’s called the Antlia dwarf and it was found to be just beyond the zero-velocity surface of the Local Group. “These data increase the number of certain (or probable) Local Group members to 36. The spatial distribution of these galaxies supports Hubble’s claim that the Local Group “is isolated in the general field.” Currently available evidence suggests that star formation continued much longer in many dwarf spheroidals than it did in the main body of the Galactic halo.” says Sidney Van den Bergh, “It is suggested that “young” globular clusters, such as Ruprecht 106, might have formed in now defunct dwarf spheroidals. Assuming SagDIG, which is the most remote Local Group galaxy, to lie on, or just inside, the zero-velocity surface of the Local Group yields a dynamical age >~17.9+/-2.7 Gyr. However, this value is meaningful only if the outer regions of the local Group are in virial equilibrium.”

Take a look at the full-size image done by Ken Crawford and check out all the red and blue super giant stars and scattered HII regions where new stars are forming – along with all the background galaxies. According to the work of D.G. Barnes; “A substantial warp in the disk of NGC 3109 is detected in the H I emission image in the form of an extended low surface brightness feature. We report a positive detection in H I of the nearby Antlia dwarf galaxy and measure its total neutral gas mass to be 6.8+/-1.4×105 M solar. We show the warp in NGC 3109 to lie at exactly the same radial velocity as the gas in the Antlia dwarf galaxy and speculate that Antlia disturbed the disk of NGC 3109 during a mild encounter ~1 Gyr in the past. H I data for a further eight galaxies detected in the background are presented.”

In the meantime, NGC 3109 continues to be an on-going object of study. Its many compact HII regions could be an indicator of planetary nebulae formations that are totally unlike anything we’ve seen before. “The excitation patterns of the PNe in NGC 3109 are very different from the excitation patterns of PNe in other galaxies.” says Miriam Pena, “This would imply that the evolution of PNe depends upon the properties of their progenitor stellar populations, which vary from galaxy to galaxy. This should affect the PN luminosity function and its use as a distance indicator.” And NGC 3109’s unique structure has equally fascinated Sebastian Hidalgo; “Its edge-on orientation (which simplifies the study of a possible halo) and the possibility that it could, in fact, be a small spiral (the smallest in the Local Group) makes its deep analysis of major relevance to understand the properties of dwarf galaxies and the transition from dwarf irregulars to spirals.”

Many thanks to Ken Crawford for this inspiring image!

Posted on by Ian O'Neill

The Discovery Bat’s Fate is Confirmed

The injured long-tailed bat clings onto Discovery's external fuel tank (NASA)

[/caption]On Sunday, Space Shuttle Discovery lit up the Florida evening skies, cutting through a magnificent sunset. The STS-119 mission is set to assemble the final stages of the International Space Station’s solar array, making the outpost the second brightest object in the night sky (after the Moon). Today, Discovery successfully docked with the space station and all is set for the upcoming spacewalks.

However, space launch successes to one side, there has been an undercurrent of concern captivating the world. On Sunday, the shuttle had a stowaway attached to the external fuel tank, and although NASA was sure the little animal wouldn’t be a debris risk, the bat remained attached to the shuttle, apparently stuck in place. New details have now emerged about why the bat didn’t fly away before Discovery launched…

Brian the Bat was clearly not frozen in this IR image shortly before launch (NASA)
Brian the Bat was clearly not frozen in this IR image shortly before launch (NASA)
On Sunday, there was some chat about the a bat roosting on the orange external fuel tank of the space shuttle. This isn’t such a strange occurrence, this is Florida after all, there is plenty of wildlife around Cape Canaveral, animals are bound to feature in shuttle launches every now and again. A bat has even roosted on the Shuttle before (STS-72 in 1996), only to fly away shortly before launch. Therefore, the bat discovered on Sunday morning was met with some mild curiosity and NASA was certain it would fly away before countdown.

However, during coverage of the shuttle launch, it became clear the bat was still roosting and some theories pointed at the possibility that the creature had become frozen to the tank as the cryogenic hydrogen and oxygen fuel was pumped into the external tank. However, the area where Brian was located (yes, I felt compelled to name him when chatting on Twitter about the situation), was not expected to drop below freezing. On watching Discovery blast off, the assumption was that Brian (then thought to be a fruit bat, he was in fact a Free-tailed bat) had long gone. How wrong we were.

This morning, images of Discovery’s launch surfaced and it would appear the bat remained attached to the fuel tank even when the shuttle passed the height of the launch tower. The bat was in it for the duration, he seemed determined to be the first bat in space!

The shuttle climbs, bat still holding on (NASA)
The shuttle climbs, bat still holding on (NASA)
So what happened? If the bat wasn’t frozen to the shuttle, why would he remain stuck on the external fuel tank? Surely he should have flown away when the shuttle powered up and vibrated before lift off? According to a NASA press release, the bat may have had little choice but to cling onto the shuttle. When the images were examined by a wildlife specialist, the conclusion was the bat may have had a broken wing, forcing him to hold on tight. Unfortunately, holding onto the fuel tank spelled certain doom; it is doubtful he would have been able to remain attached as the violent shaking and g-forces took hold. Although he made it as high as the launch tower, it is likely the bat dropped off and died in the searing 1400°C exhaust of the throttling boosters.

A sad reminder that small animals can be hurt and killed on the ground as we push into space. However, NASA goes through great effort to ensure there is minimal impact on birds and other animals during launches, and NASA can’t be blamed for the death of this one bat. At the end of the day, previous experience suggested the bat would simply fly away, unfortunately in this case, a broken wing was the bat’s downfall.

Sources: Space.com, NASA, Astroengine.com

Posted on by Ian O'Neill

Newly Discovered Asteroid 2009 FH to Buzz Past the Earth Tonight

2009 FH fly past, only 85,000 km away from Earth (NASA)

[/caption]Another asteroid is set to make a close approach of 79,000 km according to NASA, a distance twice that of geosynchronous orbit around the Earth. Although the 15-20 metre-wide rock is not expected to cause any problems to Earth or satellites, some observers may be lucky to spot the faint light from 2009 FH as it passes.

Interestingly, this new object comes only two weeks after a larger (50 metre wide) asteroid was spotted passing the Earth at a similar distance. So it begs the question, why are we seeing so many asteroids lately?

“This asteroid flyby will be a good viewing opportunity for both professional and amateur astronomers,” said Don Yeomans from the Near-Earth Object Office at NASA’s Jet Propulsion Laboratory in Pasadena, California. “The asteroid poses no risk of impact to Earth now or for the foreseeable future.”

NASA is always very quick to point out these objects are harmless, passing the Earth at a very safe distance, often beyond the Moon’s orbit. However, 2009 FH will pass at a similar distance to the 50 metre-wide 2009 DD45 on March 2nd.

The orbit of 2009 FH (NASA JPL Small-Body Database Browser)
The orbit of 2009 FH (NASA JPL Small-Body Database Browser)
In this case, 2009 FH will pass through the constellation of Gemini, as bright as a 14th magnitude star. Unfortunately there appears to be some fuzziness as to the time of observing opportunity. SpaceWeather.com reports that the best time to observe the asteroid has already passed (after sunset on March 17th, over North America), however, the NASA JPL news release states that close approach occurs at 5:17 am PST Wednesday morning. There is little more information available. However, check the 2009 FH ephemerides for more information.

This discovery was made by NASA’s Near Earth Object Observation Program, known as Spaceguard, to detect and track potentially hazardous asteroids that stray close to the Earth. It appears the Spaceguard team are getting better and better at spotting these chunks of rock. Although it might seem there are a lot more asteroids than before, this isn’t the case, we’re just getting better at finding them.

Sources: NASA, Spaceweather.com

Posted on by Fraser Cain

Cinder Cone Volcanoes

Cinder cone Paricutin. Image credit: USGS

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Picture a volcano in your mind. You’re probably thinking of a cinder cone volcano, the simplest type of volcano. Cinder cone volcanos have steep sides with a bowl-shaped crater at the top.

Cinder cone volcanoes grow from a single vent in the Earth’s crust. Gas-charged lava is blown violently out of the volcano’s central vent, and the ash and rocks rain down around the vent. After multiple eruptions, the volcano takes on the familiar cone shape, with the erupted rubble forming the steep slopes. Cinder cones rarely grow much taller than 300 meters above their surroundings, and they’re common in western North America, and wherever there’s volcanic activity.

Although they can be solitary structures, cinder cones are often associated with other kinds of volcanoes, like shield volcanoes and stratovolcanoes (or a composite volcano). For example, geologists have discovered more than 100 cinder cones on the sides of Hawaii’s Mauna Kea, one of the biggest volcano in the world. Each cinder cone comes from a vent that opened up on the sides of the volcano.

One of the most famous cinder cone volcanoes erupted out of a Mexican corn field in 1943. The volcano erupted for 9 years, and quickly built up the cinder cone to 424 meters, and covered 25 km2 of fields in lava flows and rubble. Nearby towns were eventually buried in ash by the eruptions.

We have written many articles about volcanoes for Universe Today. Here’s an article about the biggest volcano on Earth, and here’s one about the largest volcano in the Solar System.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Posted on by Nancy Atkinson

Rocket Scientists Use ‘Star Wars’ Technology to Fight Mosquitoes

Artist impression of the Stategic Defense Initiative.

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Mosquitoes are a hardy, resilient sort; these insect have been around for thousands of years and recently, one mosquito even survived a stint in space. Mosquitoes aren’t just an annoyance, but they also carry deadly diseases. Now, humans may have a new defense against mosquitoes and the diseases they carry, like malaria. Laser technology developed for the Cold War missile defense system called the Strategic Defense Initiative (also known as Star Wars) is now being retooled to for the fight against mosquitoes. The laser system is intelligent enough that humans and butterflies aren’t affected by the beams, but it zaps mosquitoes flat. It can even tell the difference between female mosquitoes, the blood-drinkers, and males. “We like to think back then we made some contribution to the ending of the Cold War” with the Star Wars program, said Dr. Jordin Kare. “Now we’re just trying to make a dent in a war that’s actually gone on a lot longer and claimed a lot more lives.”

The original use of the lasers would shield the US against the Soviet nuclear arms. Its rebirth as a bug killer came from Nathan Myhrvold, a former Microsoft Corp. executive who now runs Intellectual Ventures LLC., a company that collects patents and funds inventions. His old boss, Bill Gates, had asked him to explore new ways of combating malaria. At a brainstorming session in 2007, Dr. Lowell Wood, an astrophysicist who helped develop the Star Wars technology, suggested using lasers on mosquitoes.

The scientists envision their technology might one day be used to draw a laser barrier around a house or village that could kill or blind the bugs. Or, laser-equipped drone aircraft could track bugs by radar, sweeping the sky with death-dealing photons.
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They now face one big challenge: deciding how strong to make the weapon. The laser has to be weak enough to not harm humans and smart enough to avoid hitting useful bugs. “You could kill billions of mosquitoes a night, and you could do so without harming butterflies,” says Myhrvold.

During a recent demonstration, the researchers were able to locate mosquitoes in an old 10-gallon fish tank using a camera with a zoom lens which fed the visual data into a computer which controls the laser and aims the beam at the bugs. When hit, the mosquitoes burst into flame. Each time a beam strikes a bug, the computer makes a gunshot sound to signal a direct hit.

Not only can the laser target a mosquito, it can also tell a male from a female based on wing-beat. That’s a crucial distinction, since only females feed on blood and thus transmit disease.
“If you really were a purist, you could only kill the females, not the males,” Myhrvold sad. But since they’re mosquitoes, he says, he’ll probably “just slay them all.”

Other scientists have worked on ways to eradicate mosquitoes with microwaves, or genetically altering the insects to build a version that is malaria free. Another researcher is looking for a way to make mosquitoes as a force for good, by transforming them into “flying syringes” that deliver vaccines each time they bite.

Source: Wall Street Journal

Posted on by Fraser Cain

What are the Different Types of Volcanoes?

Several volcanoes in Russia, as seen by astronauts on the ISS. Credit: NASA

A volcano is an opening in the Earth’s surface where molten rock can escape from underneath. The Earth’s surface is made up of tectonic plates, which are spreading apart, crunching into each other, or sliding beside one another. Volcanoes are typically found at the fault lines between these plates. There can be active volcanos, which are currently, or have recently erupted. There are also dormant volcanoes, which haven’t erupted recently, and extinct volcanoes, which will never erupt again.

There are 4 major types of volcanoes:

Cinder Cone Volcanoes:

These are the simplest type of volcano. They occur when particles and blobs of lava are ejected from a volcanic vent. The lava is blown violently into the air, and the pieces rain down around the vent. Over time, this builds up a circular or oval-shaped cone, with a bowl-shaped crater at the top. Cinder cone volcanoes rarely grow larger than about 1,000 feet above their surroundings.

Composite Volcanoes:

Composite volcanoes, or stratovolcanoes make up some of the world’s most memorable mountains: Mount Rainier, Mount Fuji, and Mount Cotopaxi, for example. These volcanoes have a conduit system inside them that channels magma from deep within the Earth to the surface. They can have clusters of vents, with lava breaking through walls, or issuing from fissures on the sides of the mountain. With all this material coming out, they can grow thousands of meters tall. As we’ve seen with the famous Mount Saint Helens, composite volcanoes can explode violently.

Shield Volcanoes:

These are large, broad volcanoes that look like shields from above – hence the name. The lava that pours out of shield volcanoes is thin, so it can travel for great distances down the shallow slopes of the volcano. These volcanos build up slowly over time, with hundreds of eruptions, creating many layers. They’re not likely to explode catastrophically. Perhaps the best known shield volcanoes are the ones that make up the Hawaiian Islands, especially Mauna Loa and Mauna Kea.

Lava Domes:

Volcanic or lava domes are created by small masses of lava which are too viscous (thick) to flow very far. Unlike shield volcanoes, with low-viscosity lava, the magma from volcanic domes just pile up over and around the vent. The dome grows by expansion of the lava within, and the mountain forms from material spilling off the sides of the growing dome. Lava domes can explode violently, releasing a huge amount of hot rock and ash.

We have written many articles about volcanoes for Universe Today. Here’s an article about how a volcano sparked lightning storms.

Here are more article about volcanoes:

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Posted on by Nancy Atkinson

Molecules From Space May Have Affected Life On Earth

Murchison meteorite.

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A decade ago researchers analyzed amino acids from space, brought to Earth in meteorite which landed in Australia, finding a prevalence of “left-handed” amino acids over their “right-handed” form. Now, a new study of dust from meteorites supports this finding, and offers new clues to a long-standing mystery about how life works on its most basic, molecular level. “We found more support for the idea that biological molecules, like amino acids, created in space and brought to Earth by meteorite impacts help explain why life is left-handed,” said Dr. Daniel Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Md. “By that I mean why all known life uses only left-handed versions of amino acids to build proteins.”

20 different amino acids arrange themselves in a variety of ways to build millions of different proteins. Amino acid molecules can be built in two ways that are mirror images of each other, like your hands. Although life based on right-handed amino acids would presumably work fine, “you can’t mix them,” says Dr. Jason Dworkin of NASA Goddard, co-author of the study. “If you do, life turns to something resembling scrambled eggs — it’s a mess. Since life doesn’t work with a mixture of left-handed and right-handed amino acids, the mystery is: how did life decide — what made life choose left-handed amino acids over right-handed ones?”

Over the last four years, a team lead by Glavin, carefully analyzed samples of meteorites with an abundance of carbon, called carbonaceous chondrites. The researchers looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety – as much as a record 18 percent more in the often-studied Murchison meteorite. “Finding more left-handed isovaline in a variety of meteorites supports the theory that amino acids brought to the early Earth by asteroids and comets contributed to the origin of only left-handed based protein life on Earth,” said Glavin.
The building blocks of proteins are molecules called amino acids. Most types of amino acids can exist in two different forms, one that is 'left-handed' and the other as 'right-handed.' Credit: NASA
All amino acids can switch from left-handed to right, or the reverse, by chemical reactions energized with radiation or temperature, according to the team. The scientists looked for isovaline because it has the ability to preserve its handedness for billions of years, and it is extremely rarely used by life, so its presence in meteorites is unlikely to be from contamination by terrestrial life. “The meteorites we studied are from before Earth formed, over 4.5 billion years ago,” said Glavin. “We believe the same process that created extra left-handed isovaline would have created more left-handed versions of the other amino acids found in these meteorites, but the bias toward left-handed versions has been mostly erased after all this time.”

The team’s discovery validates and extends the research first reported a decade ago by Drs. John Cronin and Sandra Pizzarello of Arizona State University, who were first to discover excess isovaline in the Murchison meteorite, believed to be a piece of an asteroid. “We used a different technique to find the excess, and discovered it for the first time in the Orgueil meteorite, which belongs to another meteorite group believed to be from an extinct comet,” said Glavin.

The team also found a pattern to the excess. Different types of meteorites had different amounts of water, as determined by the clays and water-bearing minerals found in the meteorites. The team discovered meteorites with more water also had greater amounts of left-handed isovaline. “This gives us a hint that the creation of extra left-handed amino acids had something to do with alteration by water,” said Dworkin. “Since there are many ways to make extra left-handed amino acids, this discovery considerably narrows down the search.”

If the bias toward left-handedness originated in space, it makes the search for extraterrestrial life in our solar system more difficult, while also making its origin a bit more likely, according to the team. “If we find life anywhere else in our solar system, it will probably be microscopic, since microbes can survive in extreme environments,” said Dworkin. “One of the biggest problems in determining if microscopic life is truly extra-terrestrial is making sure the sample wasn’t contaminated by microbes brought from Earth. If we find the life is based on right-handed amino acids, then we know for sure it isn’t from Earth. However, if the bias toward left-handed amino acids began in space, it likely extends across the solar system, so any life we may find on Mars, for example, will also be left-handed. On the other hand, if there is a mechanism to choose handedness before life emerges, it is one less problem prebiotic chemistry has to solve before making life. If it was solved for Earth, it probably has been solved for the other places in our solar system where the recipe for life might exist, such as beneath the surface of Mars, or in potential oceans under the icy crust of Europa and Enceladus, or on Titan.”

The team’s paper appears in the March 16 Proceedings of the National Academy of Sciences.

Source: Astrobiology Magazine