Asteroids Archives

December 30, 2009December 24, 2015 by Nancy Atkinson

Russia May Head Mission to Deflect Asteroid Apophis

Orbital path of Apophis. Credit: NASA NEO Program

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Russia is considering sending a spacecraft to deflect a large asteroid and prevent a possible collision with Earth, according to a radio interview by the head of the country’s space agency. Anatoly Perminov said the space agency will hold a meeting soon to assess a mission to asteroid Apophis, and said NASA, ESA, the Chinese space agency and others would be invited to join the project. Apophis is a 270-meter (885-foot) asteroid that was spotted in 2004. It is projected to come within 29,450 kilometers (18,300 miles) of Earth in 2029, and currently has an estimated 1-in-250,000 chance of hitting Earth in 2036.

A panel at the recent American Geophysical Union conference stressed that asteroid deflection is a international issue.

“There is a geopolitical misconception that NASA is taking care of it,” said former Apollo astronaut Rusty Schweickart, who is part of the B612 Foundation, which hopes to prove the technology to significantly alter the orbit of an asteroid by 2015. “They aren’t and this is an international issue. The decisions have to be world decisions.”

Perminov seemed unaware that NASA’s Near Earth Object program recently downgraded the possibility of a 2036 asteroid impact and also for a subsequent pass in 2068.

Perminov said that he heard from a scientist that Apophis asteroid is getting closer and may hit the planet. “I don’t remember exactly, but it seems to me it could hit the Earth by 2032,” Perminov said. “People’s lives are at stake. We should pay several hundred million dollars and build a system that would allow to prevent a collision, rather than sit and wait for it to happen and kill hundreds of thousands of people.”

Perminov wouldn’t disclose any details of the project, saying they still need to be worked out. But he said the mission wouldn’t require any nuclear explosions.

“Calculations show that it’s possible to create a special purpose spacecraft within the time we have, which would help avoid the collision without destroying it (the asteroid) and without detonating any nuclear charges,” Perminov said. “The threat of collision can be averted.”

Boris Shustov, the director of the Institute of Astronomy under the Russian Academy of Sciences, hailed Perminov’s statement as a signal that officials had come to recognize the danger posed by asteroids like 2036 Apophis.

“Apophis is just a symbolic example, there are many other dangerous objects we know little about,” he said, according to RIA Novosti news agency.

Sources: Associated Press/Yahoo News, AGU panel discussion

Here’s some more information on the 2036 meteor.

December 29, 2009December 24, 2015 by Nancy Atkinson

Where To Next for NASA’s Solar System Exploration?

From top to bottom, pictured are the moon, Venus, and an asteroid.From top to bottom, pictured (not to scale) are the moon, Venus, and an asteroid. These three celestial bodies from our solar system are possible candidates for NASA's next space venture.

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Where is NASA going next to probe our solar system? The space agency announced today they have selected three proposals as candidates for the agency’s next space venture to another celestial body in our solar system. The proposed missions would probe the atmosphere composition and crust of Venus; return a piece of a near-Earth asteroid for analysis; or drop a robotic lander into a basin at the moon’s south pole to return lunar rocks back to Earth for study. All three sound exciting!

Here are the finalists:

Surface and Atmosphere Geochemical Explorer, or SAGE, mission to Venus would release a probe to descend through the planet’s atmosphere. During descent, instruments would conduct extensive measurements of the atmosphere’s composition and obtain meteorological data. The probe then would land on the surface of Venus, where its abrading tool would expose both a weathered and a pristine surface area to measure its composition and mineralogy. Scientists hope to understand the origin of Venus and why it is so different from Earth. Larry Esposito of the University of Colorado in Boulder, is the principal investigator.

Origins Spectral Interpretation Resource Identification Security Regolith Explorer spacecraft, called Osiris-Rex, would rendezvous and orbit a primitive asteroid. After extensive measurements, instruments would collect more than two ounces of material from the asteriod’s surface for return to Earth. The returned samples would help scientists better undertand and answer long-held questions about the formation of our solar system and the origin of complex molecules necessary for life. Michael Drake, of the University of Arizona in Tucson, is the principal investigator.

MoonRise: Lunar South Pole-Aitken Basin Sample Return Mission would place a lander in a broad basin near the moon’s south pole and return approximately two pounds of lunar materials for study. This region of the lunar surface is believed to harbor rocks excavated from the moon’s mantle. The samples would provide new insight into the early history of the Earth-moon system. Bradley Jolliff, of Washington University in St. Louis, is the principal investigator.

The final project will be selected in mid-2011, and for now, the three finalists will receive approximately $3.3 million in 2010 to conduct a 12-month mission concept study that focuses on implementation feasibility, cost, management and technical plans. Studies also will include plans for educational outreach and small business opportunities.

The selected mission must be ready for launch no later than Dec. 30, 2018. Mission cost, excluding the launch vehicle, is limited to $650 million.

“These are projects that inspire and excite young scientists, engineers and the public,” said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “These three proposals provide the best science value among eight submitted to NASA this year.”

The final selection will become the third mission in the program. New Horizons, launched in 2006, will fly by the Pluto-Charon system in 2015 then target another Kuiper Belt object for study. The second mission, called Juno, is designed to orbit Jupiter from pole to pole for the first time, conducting an in-depth study of the giant planet’s atmosphere and interior. It is slated for launch in August 2011.

Visit the New Frontiers program site for more information.

November 26, 2009December 24, 2015 by Jon Voisey

Comets Posing as Asteroids (or is the the other way around?)

Images of known MBCs from UH 2.2-meter telescope data. Credit: Henry Hsieh

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Asteroids are rocky bodies which belong between Mars and Jupiter. Comets are icy bodies that belong way out beyond Pluto. So what are comet-like objects doing in the asteroid belt?

On the night of August 7, 1996, astronomers Eric Elst and Guido Pizarro were observing what was previously thought to be an ordinary asteroid. To their surprise, the object revealed a faint but distinct tail similar to that of a comet. Initially, this was written off as a minor impact kicking up a debris cloud, but when the tail returned in 2002, when the supposed asteroid again returned to perihelion (the closest approach to the Sun), it once again displayed a tenuous tail. The “asteroid” was then given the designation of 133P/Elst-Pizarro. In 2005, two new asteroids were discovered to sport tails: P/2005 U1 and 118401. In 2008, yet another one of these odd objects was found (P/2008 R1). This new class of objects has been dubbed “Main Belt Comets (MBCs)”.

So where are these objects coming from?

A previous article here on Universe Today explored the possibility that these objects formed like other asteroids in the main belt. After all, each of the objects has an orbit consistent with other apparently normal asteroids. They have a similar distance at with they orbit the Sun, as well as similar eccentricities and inclinations of their orbit. So trying to explain these objects as having origins in the outer solar system that migrated just right into the asteroid belt seemed like little more than special pleading.

Furthermore, a 2008 study by Schorghofer at the University of Hawaii predicted that, if such an icy body were to form, it would be able to avoid sublimation for several billion years if only it were covered with a few meters of dust and dirt thus negating the problems of these objects suffering an early death. (Keep in mind that, much like a melting snowball, the water will evaporate but the dirt won’t, so the dirt will pile up quickly on the surface making this entirely plausible!) However, if the ice were covered by such an amount of dust, it would take a collision to remove the dust and trigger the cometary appearance.

In a recent paper, Nader Haghighipour also at the University of Hawaii explores the viability of collisions to trigger this activation as well as the stability of the orbits of these objects to assess the expectation that they were formed at the same time as other asteroids in the main belt.

For the orbital range in which three of the MBCs lie, it was predicted that “on average, one m[eter]-sized object collides … every 40,000 years.” They stress this is an upper limit since their simulation did not include other, nearby asteroids which would likely deplete the number of available impactors.

When they explored the orbital stability of these objects, the discovered at least two of them were dynamically unstable and would eventually be ejected from their orbits on a timescale of 20 million years. As such, it would be unreasonable to expect such objects to have lasted for the nearly 5 billion year history of the solar system. Thus, an in-situ formation was ruled out. However, due to a similarity in orbital characteristics to a family of asteroids known as the Themis family, suggesting they may have resulted from the same break up of a larger body that created this group. This begs the question of whether or not more of these asteroids are secretly hiding water ice reservoirs and are just waiting for an impact to expose them.

Distinctly separate from this orbital family was P/2008 R1 which exists in an especially unstable orbit near one of the resonances from Jupiter. This suggests that this MBC was likely scattered to its present location, but from where remains to be determined.

So while such Main Belt Comets may not have formed simply as they are now, they are likely to be in orbits not far removed from their original formation. Also, this work supported the earlier notion that minor impacts could reliably expected to expose ice allowing for the cometary tails. Whether or not more asteroids have tails tucked between their legs will be the target of future exploration.

Haghighipour’s Paper

November 25, 2009December 24, 2015 by Jon Voisey

Jupiter – Our Silent Guardian?

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We live in a cosmic shooting gallery. In Phil Plait’s Death From the Skies, he lays out the dangers of a massive impact: destructive shockwaves, tsunamis, flash fires, atmospheric darkening…. The scenario isn’t pretty should a big one come our way. Fortunately, we may have a silent guardian: Jupiter.

Although many astronomers have assumed that Jupiter would likely sweep out dangerous interlopers (an important feat if we want life to gain a toehold), little work has been done to actually test the idea. To explore the hypothesis, a recent series of papers by J. Horner and B. W. Jones explores the effects of Jupiter’s gravitational pull on three different types of objects: main belt asteroids (which orbit between Mars and Jupiter), short period comets, and in their newest publication, submitted to the International Journal of Astrobiology, the Oort cloud comets (long period comets with the most distant part of their orbits far out in the solar system). In each paper, they simulated the primitive solar systems with the bodies in question with an Earth like planet, and gas giants of varying masses to determine the effect on the impact rate.

Somewhat surprisingly, for main belt asteroids, they determined, “that the notion that any ‘Jupiter’ would provide more shielding than no ‘Jupiter’ at all is incorrect.” Even without the simulation, the astronomers say that this should be expected and explain it by noting that, although Jupiter may shepherd some asteroids, it is also the main gravitational force perturbing their orbits and causing them to move into the inner solar system, where they may collide with Earth.

Contrary to the popular wisdom (which expected that the more massive the planet, the better it would shield us), there were notably fewer asteroids pushed into our line of sight for lower masses of the test Jupiter. Also surprisingly, they found that the most dangerous scenario was an instance in which the test Jupiter had 20% in which the planet “is massive enough to efficiently inject objects to Earth-crossing orbits.” However, they note that this 20% mass is dependent on how they chose to model the primordial asteroid belt and would likely change had they chosen a different model.

When the simulation was redone for for short period comets, they again found that, although Jupiter (and the other gas giants) may be effective at removing these dangerous objects, quite often they did so by sending them our way. As such, they again concluded that, as with asteroids, Jupiter’s gravitational jiggling was more dangerous than it was helpful.

Their most recent treatise explored Oort cloud objects. These objects are generally considered the largest potential threat since they normally reside so far out in the solar system’s gravitational well and thus, will have a greater distance to fall in and pick up momentum. From this situation, the researchers determined that the more massive the planet in Jupiter’s orbit, the better it does protect us from Oort cloud comets. The attribute this to the fact that these objects are initially so far from the Sun, that they are scarcely bound to the solar system. Even a little bit of extra momentum gained if they swing by Jupiter will likely be sufficient to eject them from the solar system all together, preventing them from settling into a closed orbit that would endanger the Earth every time it passed.

So whether or not Jupiter truly defends us or surreptitiously nudges danger our way depends on the type of object. For asteroids and short period comets, Jupiter’s gravitational agitation shoves more our direction, but for the ones that would potentially hurt is the most, the long period comets, Jupiter does provide some relief.

November 9, 2009December 24, 2015 by Nancy Atkinson

Surprise! Unknown Asteroid Buzzed Earth

Trajectory of Asteroid 2009 VA Past Earth on November 6, 2009. Credit: NASA/JPL

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A previously undiscovered asteroid came within 14,000 km (8,700 miles) of Earth last week, and astronomers noticed it only 15 hours before closest approach. On Nov. 6 at around 16:30 EST a 7 meter asteroid, now called 2009 VA, came only about 2 Earth radii from impacting our home planet. This is the third-closest known non-impacting Earth approach on record for a cataloged asteroid.

Early on Nov. 6 the asteroid was discovered by the Catalina Sky Survey and was quickly identified by the Minor Planet Center in Cambridge MA as an object that would soon pass very close to the Earth. JPL’s Near-Earth Object Program Office also computed an orbit solution for this object, and determined that it was not headed for an impact.

The two closer approaches include the 1-meter sized asteroid 2008 TS26, which passed within 6,150 km (3,800 miles) of the Earth’s surface on October 9, 2008, and the 7-meter sized asteroid 2004 FU162 that passed within 6,535 km (4,060 miles) on March 31, 2004. On average, objects the size of 2009 VA pass this close about twice per year and impact Earth about once every 5 years.

Only thirteen months ago, another asteroid, 2008 TC3 was discovered under similar circumstances, but that one was found to be on a trajectory headed for the Earth, with impact only about 11 hours away. It impacted in a remote area of Africa; no one was injured and fragments have since been recovered for study.

Source: JPL NEO office

November 9, 2009December 24, 2015 by Nicholos Wethington

Camera Network Spies Anomalous Meteorite

A network of time-lapse cameras set up in the Nullarbor Plain desert of Western Australia has allowed researchers to track a fallen meteorite to the ground, and enabled them to determine its original orbit and parent body. The meteorite has a composition different than that of other meteors, leading researchers to believe that it originates from a different parent body than most meteorites that impact Earth. The Desert Fireball Network, a project coordinated by the Imperial College of London, was able to track the meteor when it entered the atmosphere, giving researchers an impact location and information on where it originated.

The Bunburra Rockhole meteorite – so named for the location where it was discovered – fell to the Earth on July 20th, 2007. The Desert Fireball Network cameras recorded the fireball produced when the meteor passed through the Earth’s atmosphere, and by studying the entry angle of the meteor, researchers from the Imperial College were able to locate it on the ground. It was found within 100 meters (300 feet) of where they had predicted it to be.

This meteorite weighs 324 grams (12 oz), and is composed of a rare type of basalt igneous rock. More specific information on the meteorite itself can be found on the Meteorological Society’s index. Most meteorites of this composition come from one parent body, the asteroid 4 Vesta. However, the Bunburra Rockhole meteorite likely came from a different asteroid with a different orbit, which means that the formation process for the asteroid happened in a different place in the Solar System than for 4 Vesta.

The researchers determined that the Bunburra Rockhole originated from an asteroid located in the innermost main asteroid belt between Mars and Jupiter. Because the Desert Fireball Network captured images on multiple cameras of how it entered the Earth’s atmosphere, the researchers were able to triangulate the position of the rock, and model its orbit backwards in time to determine its origins.

Dr Gretchen Benedix of the Natural History Museum – where the largest fragment of the meteorite is located – analyzed the mineral content of the meteorite. She said in a press release:

“It’s vital to have a meteorite with information about where it comes from in the solar system…. We’ve known for a long time that most meteorites are from the asteroid belt, but we don’t know exactly where. This kind of information helps us fit one more piece in the puzzle of how the solar system formed and evolved. The fact that this meteorite is compositionally unusual increases it’s value even more. It helps us to uncover more information about the conditions of the early solar system.”

The Desert Fireball Network monitors the Nullarbor desert in Western Australia, and has tracked a total of 7 meteorites, three of which have been recovered. The desert is an excellent location for this type of project, as observing conditions are clear many nights out of the year, and the sparse vegetation and monotone landscape make finding the meteorites easier than in other locations.

The results of the meteorite mineral and orbital study are published in Science, and two previous papers about the Bunburra Rockhole are available on the Desert Fireball Network site.

Source: Natural History Museum, Imperial College of London

October 30, 2009April 26, 2016 by Nicholos Wethington

Asteroid Explosion over Indonesia

This has taken awhile to filter into the Western press, but an asteroid exploded over the town of Bone,Indonesia on October 8th at around 11am local time. Initially, locals called the police to report that a plane had crashed, or that an earthquake shook the ground, as reported in the Jakarta Globe. The Jakarta Post quoted Thomas Djamaluddin, head of the Lapan Center for Climate and Atmosphere Science Implementation as saying that the explosion was due to a meteorite or bit of space junk that had entered the Earth’s atmosphere. As it turns out after further analysis, the explosion was due to an asteroid about 5-10 meters (15-30 feet) in diameter exploding in the air between 15 and 20 km (nine to 12 miles) above sea level. Nobody was injured as a result of the explosion, but it evidently caused quite a scare with the local population!

In a press release from the Near Earth Object (NEO) program, the explosion was detected by many International Monitoring System (IMS) infrasound stations, five of them 10,000 km (6200 miles) away, and one 18,000 km (11,100 miles) from the blast. These stations monitor seismic waves, infrasound (low frequency soundwaves), hydroacoustic, and radionuclide emissions as part of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). They are well equipped to monitor explosions of nuclear weapons, but also detect other events such as meteorite impacts and asteroid explosions, tsunamis and earthquakes.

When analyzed, the amount and intensity of low frequency sound waves created by the explosion allowed researchers Elizabeth Silber and Peter Brown of the Meteor Infrasound Group at the Univ. of Western Ontario to determine that the explosion caused by the asteroid was on the scale of 30 – 50 kilotons of TNT. To give you an idea of how powerful of an explosion this is, the bombs dropped over Hiroshima and Nagasaki in World War II exploded with the force of 20 kilotons of TNT.

The fireball – also called a bolide – created a dusty tail upon entering the atmosphere of the Earth. It is estimated that the asteroid was traveling around 72,000 km/hour (45,000 miles/hour) when it hit the atmosphere. As an asteroid enters the thick Earth atmosphere, it slows down abruptly and heats up due to the process of ablation. If this asteroid were made of metal instead of rock, it would likely have impacted the ground causing a lot of damage. Fortunately for the residents of Bone and the surrounding area, the rock broke up in a large fireball instead. There haven’t been any reports of pieces that have touched down as of yet.

Asteroids of this size are predicted to impact the Earth about every 2-12 years, and the last one of this magnitude was a bolide over the Marshall Islands on February 1, 1994. That impactor was estimated to be between 4.4 and 13.5 meters. A full analysis of that event is available on the SAO/NASA Astrophysics Data System.

Of course, events like this always raise the question of why the object wasn’t detected before it even entered the atmosphere. The NEO program has cataloged over 600 objects in the size of 10 meters, but there are many, many more out there. The cost of a monitoring and cataloging all of the Near Earth Objects would be in the hundreds of millions of dollars, but more events like this may spur the political will and capital to further efforts at protecting human lives from the potential damage of meteorite impacts.

Source: Night Sky, Spaceweather.com, JPL Press Release

October 19, 2009December 24, 2015 by Nancy Atkinson

Giant Impact Near India — Not Mexico — May Have Killed Dinosaurs

Three-dimensional reconstruction of the submerged Shiva crater (~500 km diameter) at the Mumbai Offshore Basin, western shelf of India from different cross-sectional and geophysical data. The overlying 4.3-mile-tick Cenozoic strata and water column were removed to show the morphology of the crater.

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A huge, mysterious basin off the coast of India could be the largest, multi-ringed impact crater ever found on Earth. And if a new study is right, this impact may supercede the one that created the Chicxulub crater off Mexico’s Yucatán Peninsula as what may have been responsible for killing the dinosaurs 65 million years ago. Sankar Chatterjee of Texas Tech University and a team of researchers have been studying a 500-kilometer-wide (300-mile-wide) depression on the Indian Ocean seafloor which was likely created by a bolide perhaps 40 kilometers (25 miles) in diameter. Such an event would have triggered worldwide climate changes, including intensified volcanism, that led to mass extinction.

Since the 1990’s the leading candidate for what killed the dinosaurs was a ten-kilometer-wide (six-mile-wide) asteroid thought to have carved out the Chicxulub crater. This impact may have done the job, but if not, 300,000 later the impact that created the Shiva basin surely would have finished off large life on Earth.

The massive Shiva basin, a submerged depression west of India that is intensely mined for its oil and gas resources. Some complex craters are among the most productive hydrocarbon sites on the planet.

“If we are right, this is the largest crater known on our planet,” Chatterjee said. “A bolide of this size, creates its own tectonics.”

However, some geologists have disputed whether the Shiva depression was created by an impact, or if it is just a hole in Earth’s crust, possibly created by volcanism. Christian Koeberl, a geochemist at the University of Vienna in Austria, has been adamant in the past that Shiva is not an impact crater. He said not only is there no evidence of impact in the case of Shiva, there is no crater structure. He calls Shiva, “a figment of imagination.”

“There’s not even ambiguous evidence, or inconclusive evidence,” says Koeberl. “There are a couple of people that keep pushing for some crater in the Indian Ocean, but this is inconsistent not only with the regional geology and geophysics, but also with anything we know about impact cratering.”

But Chatterjee feels sure that Shiva is an impact crater and said the geological evidence is dramatic. Shiva’s outer rim forms a rough, faulted ring some 500 kilometers in diameter, encircling the central peak, known as the Bombay High, which would be 3 miles tall from the ocean floor (about the height of Mount McKinley). Most of the crater lies submerged on India’s continental shelf, but where it does come ashore it is marked by tall cliffs, active faults and hot springs. The impact appears to have sheared or destroyed much of the 30-mile-thick granite layer in the western coast of India.

If the huge depression was created by an impact, Earth’s crust at the point of collision would have been vaporized, leaving nothing but ultra-hot mantle material to well up in its place. It is likely that the impact enhanced the nearby Deccan Traps volcanic eruptions that covered much of western India. What’s more, the impact broke the Seychelles islands off of the Indian tectonic plate, and sent them drifting toward Africa.

The team hopes to go India later this year to examine rocks drill from the center of the putative crater for clues that would prove the strange basin was formed by a gigantic impact.

“Rocks from the bottom of the crater will tell us the telltale sign of the impact event from shattered and melted target rocks. And we want to see if there are breccias, shocked quartz, and an iridium anomaly,” Chatterjee said. Asteroids are rich in iridium, and such anomalies are thought of as the fingerprint of an impact.

Read the Abstract

Source: Geological Society of America

October 13, 2009December 24, 2015 by Nancy Atkinson

Asteroid Pallas is Also a Protoplanet

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Some objects in the solar system are in a “gray area,” and can be classified under more than one heading. Add the asteroid Pallas to that group. New close-up images of Pallas from the Hubble Space Telescope reveal that the second largest asteroid in the solar system appears to be a protoplanet, as well.

Britney E. Schmidt, a UCLA doctoral student, led a team of researchers to create a 3D model of the 600km-wide rock which lies within the main asteroid belt between the orbits of Jupiter and Mars.

With the Hubble images, Schmidt and her colleagues were able to take new measurements of Pallas’ size and shape. What they found showed that Pallas wasn’t just a big rock made of hydrated silicate and ice.

An artist’s conception of an impact event on Pallas. This artwork was created using the three-dimensional shape model published by Britney Schmidt, et al. in Science. Credit: Image courtesy of B. E. Schmidt and S. C. Radcliffe

“It was incredibly exciting to have this new perspective on an object that is really interesting and hadn’t been observed by Hubble at high resolution,” Schmidt said of the first high-resolution images of Pallas, which is believed to have been intact since its formation, most likely within a few million years of the birth of our solar system.

“We were trying to understand not only the object, but how the solar system formed,” Schmidt said. “We think of these large asteroids not only as the building blocks of planets but as a chance to look at planet formation frozen in time.”

Visible in the Hubble images were areas of dark and light on Pallus’ surface, indicating that the water-rich body might have undergone an internal change in the same way planets do.

“That’s what makes it more like a planet — the color variation and the round shape are very important as far as understanding, is this a dynamic object or has it been exactly the same since it’s been formed?” Schmidt said. “We think it’s probably a dynamic object.”

For the first time, a large depression was also seen on Pallas. They were unable to determine if it was a crater, but the depression did suggest something else important: that it could have led to Pallas’ small family of asteroids orbiting in space.

“It’s interesting, because there are very few large, intact asteroids left,” Schmidt said. “There were probably many more. Most have been broken up completely. It’s an interesting chance to almost look into the object, at the layer underneath. It’s helping to unravel one of the big questions that we have about Pallas, why does it have this family?”

The massive body is unique, she said, partly because “its orbit is so much different from other asteroids. It’s highly inclined.”

“It was incredibly exciting to have this new perspective on an object that is really interesting and hadn’t been observed by Hubble at high resolution,” said Schmidt.

“When people think of asteroids, they think of ‘Star Wars’ or of tiny little rocks floating through space,” Schmidt said. “But some of these have been really physically dynamic. Around 5 million years after the formation of the solar system, Pallas was probably doing something kind of interesting.”

Source: PhysOrg

October 8, 2009December 24, 2015 by Nancy Atkinson

More Water ‘Out There:’ Ice Found on Asteroid

Artist concept of the asteroid belt. Credit: NASA

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For the first time, astronomers have confirmed that an asteroid contains frozen water on its surface. Analysis of asteroid 24 Themis shows evidence of water ice along with organic compounds widespread across the surface. The scientists say these new findings support the theory that asteroids brought both water and organic compounds to the early Earth, helping lay the foundation for life on the planet.

Humberto Campins of the University of Central Florida in Orlando and colleagues recorded spectra of 24 Themis over a seven-hour period, and were able to study 84 percent of the rotational period of the spinning rock, Rob Cowen reported in Science News. Using NASA’s Infrared Telescope Facility on Hawaii’s Mauna Kea, the spectra revealed the consistent presence of frozen water as different parts of the asteroid’s surface came into view.

Analyses of the sunlight reflected off the asteroid also show that organic compounds are widespread on the surface, he added, including polycyclic aromatic hydrocarbons, CH2 and CH3.

The new finding corroborates earlier observations of the same asteroid by astronomers Andrew S. Rivkin and Joshua Emery who also used the Infrared Telescope Facility. Over several years, Rivkin and Emery had found evidence of frozen water in single spots on 24 Themis but had not studied the asteroid as it made one entire rotation. Together, the two teams’ findings reveal that the asteroid’s entire surface is coated with frozen water, Campins says.

The 160-kilometer wide asteroid averages a distance from the sun of about 3.2 times that of Earth’s. At that range, frozen water on the surface would readily vaporize, Campins said. That means the ice must be continually replenished, possibly by a reservoir of frozen water within the rock.

One possibility is that ice lies buried several meters below the surface of 24 Themis, and when hit by space debris, the ice makes its way to the surface. If this is the case, it could confirm that some asteroids resemble comets, becoming active suddenly and venting material into space when pockets of ice vaporize, Campins said.

Another option is that an action similar to the recent findings of water on the Moon, where solar wind interacts with a rocky body without an atmosphere to create H2O and OH molecules. Without an atmosphere, the body is exposed to solar wind, which includes hydrogen ions. The hydrogen is able to interact with oxygen in surface of the asteroid to create water molecules.

Campins shared his findings at the annual meeting of the American Astronomical Society’s Division for Planetary Sciences.

Source: Science News