Posted on by Nancy Atkinson

Video of California Daytime Fireball Surfaces

Dr. Peter Jenniskens take a closer look at the image from the AVS Cineflex HiDEF camera mounted on the nose of the Eureka Airship. Mike Coop, can be seen in the background checking the map, further back other flight members continue to look for potential impact sites. Image credit: NASA / Eric James

Video footage has finally surfaced of the daytime fireball that illuminated the sky over the Sierra Nevada Mountains in California back in April. NASA and the SETI Institute had asked the public to submit any amateur photos or video footage of the event, and previously a just few photos were taken of the event, even though it happened in broad daylight and created sonic booms that were heard over a wide area, back on Sunday, April 22, 2012 at 7:51 a.m. PDT. A few weeks later, Shon Bollock, who was making a time-lapse kayaking video just outside Kernville, California realized he had captured the bolide streaking through the air. This video shows the event several times, successively zooming in for a closer look. According to NASA it is the only footage of the meteor thus far.


Meteorite hunters have been successful in locating fragments of the meteor, now called the Sutter’s Mill meteor since the event occurred near the area famous for where gold was discovered back in 1848, creating the California gold rush.

NASA estimated fragments could be dispersed over a 16-km (10-mile) area.

Phil Plait says the video is being studied by astronomers and meteoriticists to try to calculate the trajectory, speed, and possible orbit of the object, which is difficult with just one video, so if anyone finds they have ‘accidently’ taken footage of the event, contact the NASA Lunar Science Institute at the NASA Ames Research Center.

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NASA used an airship to search for meteorites from this event. Noted meteorite expert Peter Jenniskens said the meteorites found so far from the fall are Carbonaceous Chondrites from the CM group of meteorites, “a rare type of primitive meteorite rich in organic compounds,”and scientists have precious few samples of this kind of material. The meteorites are very interesting to scientists from an astrobiology perspective, as they contain molecules related to how the building blocks for life on Earth may have been delivered from outer space. Scientist believe that this meteor could hold the answers to the origin of life on Earth and the universe. By studying the meteor, scientists also will learn more about the early solar system and the formation of our planets.

“This is among the most chemically primitive meteorites,” said NLSI Deputy Director Greg Schmidt. “It’s like asking ‘how did life on Earth begin?’ and then having a fossil fall right in your back yard. This is exciting stuff — who knows what’s inside? The Sutter’s Mill Meteorite could be the most profound sample collected in over 40 years.”

Via the Bad Astronomer

Posted on by Nancy Atkinson

Meteorites Could Provide New Explanation for Mars Methane

A Murchison meteorite specimen at the National Museum of Natural History in Washington DC.

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Where does the methane on Mars come from? That has been one of the biggest unanswered questions in planetary science since the discovery of large plumes of methane gas in the Martian atmosphere. Scientists have been trying to figure out how the planet’s environment or geology can keep replenishing this short-lived gas, and of course, in the back of everyone’s mind is whether the methane has any connection to possible life on Mars.

A new potential explanation squelches both the life and environment prospect and offers a unique answer. A group of researchers found that meteorites, which continually bombard the surface of Mars, may contain enough carbon compounds to generate methane when they are exposed to strong UV sunlight.

“Whether or not Mars is able to sustain life is not yet known, but future studies should take into account the role of sunlight and debris from meteorites in shaping the planet’s atmosphere,” said Dr. Andrew McLeod, of the University of Edinburgh, co-author of a new study published in Nature this week.

The group of European researchers looked at the famous Murchison meteorite, a carbonaceous chondrite meteorites that fell in Australia more than 40 years ago. Carbonaceous chondrites are very common meteorites, so they likely will be falling on Mars. The team exposed particles of the Murchison meteorite to levels of ultraviolet radiation equivalent to sunlight on Mars.

When the meteorite pieces were exposed to ample amounts of UV light the meteor fragments rapidly released methane. After the UV exposure was reduced, the amount of methane produced would lessen, but if there were other activities, such as heating, shaking or lowering the pressure on the meteorite, the amount of methane released would rise again.

With Mars thin atmosphere, UV light easily gets to the surface of the planet. The thin atmosphere also allows more meteorites to hit Mars than on Earth (estimates range from just a few thousands of metric tons to as much as 60,000 metric tons.) The team said that temperature changes on Mars, especially during the summertime when it gets warm, could account for a boost of methane release from meteorites, and seasonal dust storms could shake or move the meteorites.

However, while only small amounts of methane are present in the Martian atmosphere, it seems to be coming from very specific, localized sources. Meteorites would likely be falling across the planet.

Top: Map of methane concentrations in Autumn (first martian year observed). Peak emissions fall over Tharsis (home to the Solar System's largest volcano, Olympus Mons), the Arabia Terrae plains and the Elysium region, also the site of volcanos. Bottom: True colour map of Mars. Credit: NASA/Università del Salento

Additionally, levels of methane vary in the seasons, and are highest in autumn in the northern hemisphere, with localized peaks of 70 parts per billion. There is a sharp decrease in winter, with only a faint band of methane appearing in the atmosphere between 40-50 degrees north.

Methane was first detected in the Martian atmosphere by ground based telescopes in 2003 and confirmed a year later by ESA’s Mars Express spacecraft. In 2009, observations using ground based telescopes showed the first evidence of a seasonal cycle.

Other research has said that the methane in the Martian atmosphere lasts less than a year, making it a flitting – and difficult – feature to study.

Another issue is that the estimates for the amount of meteorites hitting Mars’ surface would likely not bring enough carbon to explain the amount of methane seen in the atmosphere.

The researchers said, however, that their findings give valuable insights into the planet’s atmosphere and these findings would be helpful for future robotic missions to Mars so scientists could fine-tune their experiments, potentially making their trips more valuable.

Read the team’s paper in Nature.

Posted on by Jason Major

A New Look at Apollo Samples Supports Ancient Impact Theory

Apollo 16 astronaut Charlie Duke collects lunar samples during EVA on April 23, 1972 (NASA)

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New investigations of lunar samples collected during the Apollo missions have revealed origins from beyond the Earth-Moon system, supporting a hypothesis of ancient cataclysmic bombardment for both worlds.

Samples of Apollo 16 breccia that contain chondritic material (JSC)

Using scanning electron microscopes, researchers at the Lunar-Planetary Institute and Johnson Space Center have re-examined breccia regolith samples returned from the Moon, chemically mapping the lunar rocks to discern more compositional detail than ever before.

What they discovered was that many of the rocks contain bits of material that is chondritic in origin — that is, it came from asteroids, and not from elsewhere on the Moon or Earth.

Chondrites are meteorites that originate from the oldest asteroids, formed during the development of the Solar System. They are composed of the initial material that made up the stellar disk, compressed into spherical chondrules. Chondrites are some of the rarest types of meteorites found on Earth today but it’s thought that at one time they rained down onto our planet… as well as our moon.

The Lunar Cataclysm Hypothesis suggests that there was a period of extremely active bombardment of the Moon’s surface by meteorite impacts around 3.9 billion years ago. Because very few large impact events — based on melt rock samples — seem to have taken place more than 3.85 billion years ago, scientists suspect such an event heated the Moon’s surface enough prior to that period to eradicate any older impact features — a literal resurfacing of the young Moon.

There’s also evidence that there was a common source for the impactors, based on composition of the chondrites. What event took place in the Solar System that sent so much material hurtling our way? Was there a massive collision between asteroids? Did a slew of comets come streaking into the inner solar system? Were we paid a brief, gravitationally-disruptive visit by some other rogue interstellar object? Whatever it was that occurred, it changed the face of our Moon forever.

Curiously enough, it was at just about that time that we find the first fossil evidence of life on Earth. If there’s indeed a correlation, then whatever happened to wipe out the Moon’s oldest craters may also have cleared the slate for life here — either by removing any initial biological development that may have occurred or by delivering organic materials necessary for life in large amounts… or perhaps a combination of both.

Timeline for the Lunar Cataclysm Hypothesis (LPI)

The new findings from the Apollo samples provide unambiguous evidence that a large-scale impact event was taking place during this period  on the Moon — and most likely on Earth too. Since the Moon lacks atmospheric weathering or water erosion processes it serves as a sort of “time capsule”, recording the evidence of cosmic events that take place around the Earth-Moon neighborhood. While evidence for any such impacts would have long been erased from Earth’s surface, on the Moon it’s just a matter of locating it.

In fact, due to the difference in surface area, Earth may have received up to ten times more impacts than the Moon during such a cosmic cataclysm. With over 1,700 craters over 20 km identified on the Moon dating to a period around 3.9 billion years ago, Earth should have  17,000 craters over 20 km… with some ranging over 1,000 km! Of course, that’s if the craters could had survived 3.9 billion years of erosion and tectonic activity, which they didn’t. Still, it would have been a major event for our planet and anything that may have managed to start eking out an existence on it. We might never know if life had gained a foothold on Earth prior to such a cataclysmic bombardment, but thanks to the Moon (and the Apollo missions!) we do have some evidence of the events that took place.

Sample of lunar impact melt breccia, showing exterior and chondrule-filled interior. (Click for sample report.) Source: JSC

The LPI-JSC team’s paper was submitted to the journal Science and accepted for publication on May 2. See the abstract here, and read more on the Lunar Science Institute’s website here.

And if you want to browse through the Apollo lunar samples you can do so in depth on the JSC Lunar Sample Compendum site.

Posted on by Jason Major

Fragments of Meteorite Worth Their Weight in Gold

Fragments collected from the April 22 fireball over central California. (Franck Marchis)

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Actually it’s more like 3.5 times their weight in gold, according to today’s market value… and meteorite experts from SETI and NASA’s Marshall Space Flight Center.

During the daylight hours of April 22, 2012, reports came in from all over the north central California area of an extremely bright fireball — described as a “glittering sparkler” — and accompanying loud explosion. It was soon determined that this was the result of a meteoroid about the size of a minivan entering the atmosphere and disintegrating. It was later estimated that the object weighed about 70 metric tons and detonated with a 5-kiloton force.

Read more about the California fireball event here.

Over a thousand meteorite hunters scrambled to the area, searching for any traces of the cosmic visitor’s remains. After a few days, several pieces of the meteorite were found and reported by five individuals, adding up to 46 grams in total.

Those pieces could be worth over $9,000 USD, according to Bill Cooke of NASA’s Meteoroid Environment Office at Marshall Space Flight Center.

Based on today’s market, that’s about 3.6 times the value of gold (about $1,660 per troy ounce — 31.1 grams).

The high value is due to the extreme rarity of the meteorite fragments. The California fireball is now known to have been created by a CM chondrite, a type of carbonaceous meteorite with material characteristics similar to comets.

SETI Institute's Franck Marchis and the chondrite fragments (F. Marchis)

According to Franck Marchis, Planetary Astronomer at the Carl Sagan Center of the SETI Institute and one of the coordinators of the meteorite reporting teams, CM chondrites appear to have been altered by water, and have deuterium-to-hydrogen ratios in line with what’s been measured in the tails of comets Halley and Hyakutake.

They also have been found to contain organic compounds and amino acids, lending to the hypothesis that such meteorites may have helped supply early Earth with the building blocks for life.

But due to their fragile composition, they are also incredibly rare. Only 1% of known meteorites are CM chondrites, making even the small handful of fragments found in California very valuable.

“This will be only the third observed CM fall in the US, after Crescent, OK, in 1936, (78 g) and Murray, KY, in 1950 (13 kg),” Marchis told Universe Today.

As far as what the finders will do with the fragments, that’s entirely up to them.

“They can sell them on eBay or they can lend them to the scientists… or make a donation.” Marchis said.

Just goes to show that all that glitters really isn’t gold — it could be even better.

Read more in an article by Sara Reardon on New Scientist, and read more on the comet/chondrite connection here. And the ongoing search for pieces of what’s now being referred to as the “Sutter’s Mill Meteorite” can be followed here and here.

The largest CM chondrite ever recovered was from a fall in Murchison, Australia on September 28, 1969. The total mass of its collected fragments weighed in at over 100 kg (220 lbs).

Posted on by Nancy Atkinson

Meteorite Hunters Find Fragments from the Recent ‘Daytime Fireball’ in California

Meteorite expert and researcher Peter Jenniskens with a fragment of the bolide seen over California on April 22, 2012. Image via Franck Marchis' Cosmic Diary blog.

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Meteorite hunters have been successful in locating fragments from the huge meteor visible in the daytime skies over California last weekend. One of the successful hunters was Peter Jenniskens, an expert in meteors and meteorites, perhaps best known for retrieving the fragments of asteroid 2008 TC3 which fell in Sudan in 2008. Astronomer Franck Marchis wrote in his Cosmic Diary blog that Jenniskens realized the size of the California meteor was very similar to 2008 TC3, and so fragments should have reached the surface, just like they did in 2008.

Jenniskens went out searching and found a four-gram fragment of the meteor in a parking lot in Lotus, California.

Update: NASA and the SETI Institute are asking the public to submit any amateur photos or video footage of the meteor that illuminated the sky over the Sierra Nevada mountains and created sonic booms that were heard over a wide area at 7:51 a.m. PDT Sunday, April 22, 2012.


Marchis wrote that several scientists from the Bay Area met at NASA Ames Research Center on April 24 to discuss a strategy for a search campaign, examining a radar data map which showed that dozens of fragments from the 100g to 1 kg range may have reached the ground.

Jenniskens said the fragment he found was a Carbonaceous Chondrites from the CM group of meteorites, “a rare type of primitive meteorite rich in organic compounds,” he said.

“We are very interested in this rare find,” said Greg Schmidt, deputy director of the NASA Lunar Science Institute. “With the public’s help, this could lead to a better understanding of these fascinating objects.”

Several other fragments were found, the first one by noted meteorite hunter Robert Ward.

“Getting fresh fragments of meteoroids, called meteorites, is key for astronomers to understand the composition of those remnants of the formation of the solar system,” Marchis wrote. “Fresh fragments are unaltered by the Earth’s weather and erosion processes, so they are pristine samples which can be used to detect organic materials for instance.”

Photos and video footage would help the scientists to better analyze the trajectory of the meteor and learn about its orbit in space. This information will also help scientists to locate the places along the meteor path where fragments may have fallen to the ground.

People who have photos or video of the meteorite are asked to contact Jenniskens at [email protected].

Marchis noted that a storm is heading towards the region and rain could alter the remaining fragments. So if you live nearby, consider heading out to take a look. Here is the radar map:

Radar map by Marc Fries showing the possible location of fragments (green area) of the meteor between Auburn and Placerville.

Marchis also said that if anyone has access to security camera footage taken on April 22, 2012 in the area of the fireball sighting, it may be useful to check them to see if the fireball was visible. “Astronomers could use them to pin down the site of the fall, maximizing the hunt for fragments,” he said.

Read more at the Cosmic Diary.

Posted on by Nancy Atkinson

Fireball Over California Exploded with Force of 5 Kilotons

Location of daylight (8 AM) fireball over California on April 22, 2012. Credit: NASA's Meteor Watch

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A daytime fireball over the skies of central/northern California on Sunday morning, April 22, 2012 caused a loud explosion and the event was also detected on several seismographs stations in the area. According to Bill Cooke, head of NASA’s Meteoroid Environments Office, the source of the blast was a meteoroid about the size of a minivan, weighing in at around 70 metric tons (154,300 pounds) and at the time of disintegration released energy equivalent to a 5-kiloton explosion.

For comparison, conventional bombs yield energy from less than 1 ton to 44 tons, and the approximate energy released when the Chicxulub impact caused the mass extinction 65 million years ago was estimated to be equal to 96 million megatons of TNT.

“This was a BIG event,” said Elizabeth Silber of the Meteor Group at the Western University in Ontario, Canada.

“Most meteors you see in the night’s sky are the size of tiny stones or even grains of sand and their trail lasts all of a second or two,” said Don Yeomans of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “Fireballs you can see relatively easily in the daytime and are many times that size – anywhere from a baseball-sized object to something as big as a minivan.”

Silber estimates the location of its explosion in the upper atmosphere above California’s Central Valley. It is not known yet if any pieces of the space rock survived to land as meteorites, but the entire object was likely vaporized before hitting the ground. However, you can bet there are people out looking. (Silber said on the Meteorobs newsgroup that based on infrasonic data the approximate source coordinates are 37.6N, 120.5W).

Descriptions of the fireball range from a “silver flash” to like a “green glittering sparkler,” and one person said their sighting of the object was followed 4-5 minutes later by a loud sonic boom.

Unfortunately, since the huge fireball occurred during the day, all of NASA’s meteor-seeking cameras were turned off, so images of the event are sparse. You can see some at news station KTVN’s website.

This type of fireball is quite rare, and visual observations of them are even more rare. “An event of this size might happen about once a year,” said Yeomans. “But most of them occur over the ocean or an uninhabited area, so getting to see one is something special.”

That the fireball occurred during the Lyrid meteor shower is probably a coincidence, most experts are saying, as meteor shower meteors are generally small bits space dust that don’t produce large fireballs. However, another large fireball also occurred on April 20 in Brazil. See more information about that bolide here.

Posted on by Jason Major

Shaking Up Theories Of Earth’s Formation

Earth may not have formed quite like once thought (Image: NASA/Suomi NPP)

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Researchers from The Australian National University are suggesting that Earth didn’t form as previously thought, shaking up some long-standing hypotheses of our planet’s origins right down to the core — literally.

Ian Campbell and Hugh O’Neill, both professors at ANU’s Research School for Earth Sciences, have challenged the concept that Earth formed from the same material as the Sun — and thus has a “chondritic” composition — an idea that has been assumed accurate by planetary scientists for quite some time.

 

Chondrite meteorites are composed of spherical chondrules, which formed in the solar nebula before the asteroids. (NASA)

Chondrites are meteorites that were formed from the solar nebula that surrounded the Sun over 4.6 billion years ago. They are valuable to scientists because of their direct relationship with the early Solar System and the primordial material they contain.

“For decades it has been assumed that the Earth had the same composition as the Sun, as long the most volatile elements like hydrogen are excluded,” O’Neill said. “This theory is based on the idea that everything in the solar system in general has the same composition. Since the Sun comprises 99 per cent of the solar system, this composition is essentially that of the Sun.”

Instead, they propose that our planet was formed through the collision of larger planet-sized bodies, bodies that had already grown massive enough themselves to develop an outer shell.

This scenario is supported by over 20 years of research by Campbell on columns of hot rock that rise from Earth’s core, called mantle plumes. Campbell discovered no evidence for “hidden reservoirs” of heat-producing elements such as uranium and thorium that had been assumed to exist, had Earth actually formed from chondritic material.

“Mantle plumes simply don’t release enough heat for these reservoirs to exist. As a consequence the Earth simply does not have the same composition as chondrites or the Sun,” Campbell said.

The outer shell of early Earth, containing heat-producing elements obtained from the impacting smaller planets, would have been eroded away by all the collisions.

“This produced an Earth that has fewer heat producing elements than chondritic meteorites, which explains why the Earth doesn’t have the same chemical composition,” O’Neill said.

The team’s paper has been published in the journal Nature. Read the press release from The Australian National University here.

Posted on by Jason Major

Valuable Space Rock Crashes Into Oslo Cabin

This meteorite struck the Thomassen family's cabin in Oslo. (Photo: Rune Thomassen)

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A family in Oslo got a surprise when they visited their allotment garden cabin for the first time this season and found that a 585-gram (20 oz.) meteorite had ripped a hole through the roof. The space rock was discovered “lying five or six metres away,” the cabin’s owner, Rune Thomassen, told the local newspaper VG.

Such an event is rare in Norway; since 1848 the country has noted only 14 meteorite discoveries.

Astrophysicist Knut Jørgen Røed Ødegaard from the University of Oslo investigated the report and found it to be genuine.

“You can tell immediately that it’s genuine from the burned crust, and you can also recognize it from how rough and unusual it is. It gives me goosebumps,” Ødegaard told VG.

NASA Astrobiology Institute’s Hans Amundsen noted the meteorite’s unusual composition: “This is a very rare meteorite because you can see from the cut of it that it contains fragments from many different kinds of rock that have cemented together, forming a so-called breccia.”

Such meteorites are caused by previous collisions, cementing together different types of material from impacts with asteroids or planets.This means the meteorite that landed on the Thomassens’ cabin may very well have been blown off the surface of Mars at some point in the distant past!

“This is unique. This is double-unique,” Ødegaard noted to VG.

According to Amundsen, such a meteorite is very valuable to researchers as well as private collectors, who may be willing to pay highly for it. Chunks of Mars have fetched USD $877 per gram in the past… making the Thomassens’ find potentially worth over $500,000!

Norway’s geological museum has the country’s only meteorite collection “and they’re the right ones to determine what kind of meteorite this is,” Amundsen said.

Read more on this story here, and see coverage with photos and video on the VG site here (in Norwegian).

Posted on by Amy Shira Teitel

NEOShield: a Preemptive Strike Against Asteroids

What an asteroid hitting the Earth might look like. Image credit: NASA/Don Davis.

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Scientists aren’t entirely sure when the last major asteroid hit the Earth, but it’s certain to happen again. Alan Harris, asteroid researcher at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), is hoping to head the next one off. Last month, Harris established an international collaboration of 13 researchers to investigate methods of shielding the Earth from near Earth objects (NEOs). The project is, appropriately, called NEOShield.

Asteroids approaching the planet typically travel between 5 and 30 kilometres (about 5 to 19 miles) per second. As that speed, a moderate sized body can have major consequences. The Barringer Crater in Arizona, often referred to as Meteor Crater, is a 1,200 metre crater (about 3,950 feet or 0.7 miles) that scientists hypothesize was caused by a 50 metre (164 feet) meteor.

The bad news is that there are thousands of known NEOs just like the one that made Meteor Crater, leading experts to posit that a dangerous collision could occur as often as every two hundred years.

Meteor Crater near Winslow, Arizona. Image credit: NASA.

The good news is that it’s possible to stop an asteroid hitting the Earth. You just have to be in the right place at the right time to give the object the right push in another direction.

Scientists are focusing on possible methods of redirecting threatening asteroids so they miss the Earth. “In order to modify their orbit and prevent a collision with Earth, a force must be exerted on them,” explains Alan Harris. “And at the precise time, as well.” One way to do this is to have a spacecraft impact a threatening asteroid, imparting enough force to change its orbit. “In my opinion, this is a very practical method,” said Harris. But there are still questions to answer, like how to guide the spacecraft to a moving target at the right angle for the right impact and how to minimize the effects of fuel movement on the spacecraft’s path.

Another way is to use the spacecraft’s gravitational pull to nudge the asteroid into a different orbit. If the object is far enough away, a tiny tug could have a big effect. But so far, “this method only exists on paper,” said Harris, “but it could work.”

An asteroid, docile in space but deadly to Earth. Image credit: NASA/JPL

Another third, less appealing prospect, is to use explosive power to break up an Earth-bound asteroid. But this could be disastrous, creating a shower of debris instead of one solid piece. As such, Harris considers this method a last resort. “If a very large, dangerous object with a diameter of one kilometre [0.6 miles] or more is discovered,” explains Harris, changing its orbit won’t be a option. “The greatest force we would be able to use to divert the asteroid from its path would be a nuclear explosion. This technique is regarded as a very controversial.”

Over the next three years, during which the European Union will support the project with four million Euros and international partners will contribute an additional 1.8 million Euros, the NEOShield project will research these defence methods. The scientists will focus on data from asteroid observations and lab experiments to generate computer simulations, ultimately determining how best to protect the Earth from future devastating impacts.

Source: DLR News Portal

Posted on by Ken Kremer

Asteroid Vesta Floats in Space in High Resolution 3-D

Vesta’s Eastern Hemisphere Floats in Space in 3-D. This anaglyph shows the varied topography of Vesta’s eastern hemisphere from craters in the north, the equatorial troughs and the huge mountain at the Souh Pole. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

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The giant Asteroid Vesta literally floats in space in a new high resolution 3-D image of the battered bodies Eastern Hemisphere taken by NASA’s Dawn Asteroid Orbiter.

Haul out your red-cyan 3-D anaglyph glasses and lets go whirling around Vesta and sledding down mountains to greet the alien Snowman! The sights are fabulous !

The Dawn imaging group based at the German Aerospace Center (DLR), in Berlin, Germany and led by team member Ralf Jaumann has released a trio of new high resolution 3-D images that are the most vivid anaglyphs yet published by the international science team.

The lead anaglyph shows the highly varied topography of the Eastern Hemisphere of Vesta and was taken during the final approach phase as Dawn was about 5,200 kilometers (3,200 miles) away and preparing to achieve orbit in July 2011.

The heavily cratered northern region is at top and is only partially illuminated because of Vesta’s tilted angle to the Sun at that time of year. Younger craters are overlain onto many older and more degraded craters. The equatorial region is dominated by the mysterious troughs which encircle most of Vesta and may have formed as a result of a gargantuan gong, eons ago.

The southern hemisphere exhibits fewer craters than in the northern hemisphere. Look closely at the bottom left and you’ll see the huge central mountain complex of the Rheasilvia impact basin visibly protruding out from Vesta’s south polar region.

This next 3-D image shows a close-up of the South Pole Mountain at the center of the Rheasilvia Impact basin otherwise known as the “Mount Everest of Vesta”.

The Mount Everest of Vesta in 3-D
This anaglyph shows the central complex and huge mountain in Vesta’s Rheasilvia impact basin at the South Pole. Does water ice lurk beneath the South Pole ?
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

The central complex is approximately 200 kilometers (120 miles) in diameter and is approximately 20 kilometers (12 miles) tall and is therefore about two and a half times taller than Earth’s Mount Everest!

Be sure to take a long look inside the deep craters and hummocky terrain surrounding “Mount Everest”.

A recent study concludes that, in theory, Vesta’s interior is cold enough for water ice to lurk beneath the North and South poles.

Finally lets gaze at the trio of craters that make up the “Snowman” in the 3-D image snapped in August 2011 as Dawn was orbiting at about 2,700 kilometers (1,700 miles) altitude. The three craters are named Minucia, Marcia and Calpurnia from top to bottom. Their diameters respectively are; 24 kilometers (15 miles), 53 kilometers (33 miles) and 63 kilometers (40 miles).

3-D image of Vesta’s “Snowman” craters
The three craters are named Minucia, Marcia and Calpurnia from top to bottom. They are 24 kilometers (15 miles), 53 kilometers (33 miles) and 63 kilometers (40 miles) in diameter, respectively. Image resolution is about 250 meters (820 feet) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

It is likely that Marcia and Calpurnia formed from the impact of a binary asteroid and that Minucia formed in a later impact. The smooth region around the craters is the ejecta blanket.

Dawn Orbiting Vesta above the “Snowman” craters
This artist's concept shows NASA's Dawn spacecraft orbiting the giant asteroid Vesta above the Snowman craters. The depiction of Vesta is based on images obtained by Dawn's framing cameras. Dawn is an international collaboration of the US, Germany and Italy. Credit: NASA/JPL-Caltech

Vesta is the second most massive asteroid in the main Asteroid Belt between Mars and Jupiter. It is 330 miles (530 km) in diameter.

Dawn is the first spacecraft from Earth to visit Vesta. It achieved orbit in July 2011 for a year long mission. Dawn will fire up its ion propulsion thrusters in July 2012 to spiral out of orbit and sail to Ceres, the biggest asteroid of them all !

Vesta and Ceres are also considered to be protoplanets.