Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.
Artist's conception of the alien planet system orbiting Gliese 581. Credit: ESO/L. Calçada
One big challenge in astronomy is everything is so darn far away. This makes it hard to see the signs of life in planets, which are usually but tiny dots of light using the telescope technology we have today.
There are signs in Earth’s atmosphere that life is on the surface — methane from microbes, for example — and already scientists have years of research concerning ideas to find “biomarkers” on other planets. A new model focuses on a theoretical Earth-sized planet orbiting a red dwarf star, where it is believed biomarkers would be easier to find because these stars are smaller and fainter than that of the sun.
“We developed computer models of exoplanets which simulate the abundances of different biomarkers and the way they affect the light shining through a planet’s atmosphere,” stated Lee Grenfell, who is with the German Aerospace Center (DLR) institute of planetary science.
Preliminary work has already been done to find chemicals in the planet’s atmosphere (by looking at how they affect light that pass through the chemicals) particularly on large exoplanets that are close to their star (sometimes called “hot Jupiters“). Signs of life would be found through a similar process, but would be much fainter.
Artist’s impression of a red dwarf (courtesy NASA)
The research team constructed a model of a planet similar to Earth, at different orbits and distances from a red dwarf stars. Their work shows a sort of “Goldilocks” effect (or, a condition that is “just right”) to find ozone when the ultraviolet radiation falls into the medium of a given range. If it is too high, the UV heats the middle atmosphere and obliterates the biomarker signal. Too low UV makes the signal very hard to find.
“We find that variations in the UV emissions of red-dwarf stars have a potentially large impact on atmospheric biosignatures in simulations of Earth-like exoplanets. Our work emphasizes the need for future missions to characterise the UV emissions of this type of star,” said Grenfell.
The research has plenty of limitations, he added. We don’t know what alien life would look like, we don’t know if planets near red dwarfs are a good place to search, and even if we found a signal that looked like life, it could have come from another process. Still, Grenfell’s team expects the model is a good basis on which to continue asking the question: is life really out there?
The research has been submitted to the journal Planetary and Space Science.
A very zoomed-in image of Phaethon from NASA's STEREO spacecraft, showing a comet-like extension. Credit: Jewitt, Li, Agarwal /NASA/STEREO
Sometimes, putting things into categories difficult. Witness how many members of the general public are still unhappy that Pluto was reclassified as a dwarf planet, a decision made by the International Astronomical Union more than seven years ago.
And now we have 3200 Phaethon, an asteroid that is actually behaving like a comet. Scientists found dust that is streaming from this space rock as it gets close to the sun — similarly to how ices melt and form a tail as comets zoom by our closest stellar neighbor.
Phaethon’s orbit puts it in the same originating region as other asteroids (between Mars and Jupiter), but its dust stream is much closer to actions performed by a comet — an object that typically comes from an icy region way beyond Neptune. So far, therefore, the research team is calling Phaethon a “rock comet.” And after first proposing a theory a few years ago, they now have observations as to what may be going on.
Phaethon is not only an asteroid, but also a source of a prominent meteor shower called the Geminids. This shower happens every year around December when the Earth plows into the cloud of debris that Phaethon leaves in its wake. Astronomers have known about the Geminids’ source for a generation, but for decades could not catch the asteroid in the act of shedding its stuff.
That finally came with images of NASA’s twin sun-gazing Solar TErrestrial RElations Observatory (STEREO) spacecraft that were taken between 2009 and 2012. The researchers saw a “comet-like tail” extending from the 3.1-mile (five kilometer) asteroid. “The tail gives incontrovertible evidence that Phaethon ejects dust,” stated David Jewitt, an astronomer at the University of California, Los Angeles who led the research. “That still leaves the question: why?”
Time lapse-photo showing geminids over Pendleton, OR. Credit: Thomas W. Earle
The answer lies in just how close Phaethon whizzes past the sun. At perihelion, its closest approach to the sun, it only appears eight degrees (16 solar diameters) away from the sun in Earth’s sky. This close distance makes it all but impossible to study the asteroid without special equipment, which is why STEREO came in so handy.
When Phaethon reaches its closest approach of 0.14 Earth-sun distances, surface temperatures rise above an estimated 1,300 degrees Fahrenheit (700 degrees Celsius). It’ s way too hot for ice, as what happens with a comet. In fact, it’s probably hot enough to make the rocks crack and break apart. The researchers publicly hypothesized this was happening at least as far back as 2010, but this finding provided more evidence to support that theory.
“The team believes that thermal fracture and desiccation fracture (formed like mud cracks in a dry lake bed) may be launching small dust particles that are then picked up by sunlight and pushed into the tail,” a statement from the research team read.
“While this is the first time that thermal disintegration has been found to play an important role in the solar system,” they added, “astronomers have already detected unexpected amounts of hot dust around some nearby stars that might have been similarly produced.”
The results were presented at the European Planetary Science Congress on Tuesday. By the way, STEREO also caught Mercury behaving somewhat like a comet in results released in 2010, although that find was related to the planet’s escaping sodium atmosphere.
Read more about the research in the June 26 issue of Astrophysical Letters. A preprint version is also available on Arxiv.
An artist's conception of the European Space Agency's ExoMars rover, scheduled to launch in 2018. Credit: ESA
Signs of life on the Martian surface would still be visible even after bacteria were zapped with a potentially fatal dose of radiation, according to new research — if life ever existed there, of course.
Using “model” bacteria expected to resemble what microbes could look like on the Red Planet, the research team used a Raman spectrometer — an instrument type that the ExoMars rover will carry in 2018 — to see how the signal from the bacteria change as they get exposed to more and more radiation.
The bottom line is the study authors believe the European Space Agency rover’s instrument would be capable of seeing bacteria on Mars — from the past or the present — if the bacteria were there in the first place.
Readings from the NASA Mars Curiosity rover recently found that humans on the surface of Mars would have a higher risk of cancer due to the increased radiation level on the surface. Mars does not have a global magnetic field to deflect radiation from solar flares, nor a thick atmosphere to shelter the surface.
The new study still found the signature of life in these model microbes at 15,000 Gray of radiation, which is thousands of times higher than the radiation dose that would kill a human. At 10 times more, or 150,000 Gray, the signature is erased.
ExoMars 2016 Mission to the Red Planet. It consists of two spacecraft – the Trace Gas Orbiter (TGO) and the Entry, Descent and Landing Demonstrator Module (EDM) which will land. Credit: ESA
“What we’ve been able to show is how the tell-tale signature of life is erased as the energetic radiation smashes up the cells’ molecules,” stated Lewis Dartnell, an astrobiology researcher at the University of Leicester who led the study.
Specifically, the spectrometer detected carotenoid molecules, which can be used to protect a microorganism against difficult conditions in the environment. The research teams stated that these cartenoids have been proposed as “good biosignatures of life” on Mars.
This image shows a river that sprang from a past glacier from an unnamed crater in Mars’ middle latitudes. Credit: NASA/JPL/MSSS
“In this study we’ve used a bacterium with unrivaled resistance to radiation as a model for the type of bacteria we might find signs of on Mars. What we want to explore now is how other signs of life might be distorted or degraded by irradiation,” Dartnell added. “This is crucial work for understanding what signs to look for to detect remnants of ancient life on Mars that has been exposed to the bombardment of cosmic radiation for very long periods of time.”
Many scientists believe flowing water existed on the planet, though, based on rock findings from three NASA rovers and the appearance of channels, streams and perhaps even oceans as spotted by orbiting satellites. Some scientists say the atmosphere of Mars was much thicker in the past, but it then dissipated for reasons that are still being investigated. Water, however, does not necessarily point to life.
The dark material in Becquerel crater on Mars might have come from a volcanic eruption. Credit: ESA/DLR/FU Berlin (G. Neukum)
At first glance, it looks like somebody dropped a huge paint can on Mars, spilling black stuff all over Becquerel crater. That dark material, however, is likely blown from another location on the Red Planet. It could even be volcanic eruption remnants, the European Space Agency says.
A set of stunning new images of the spot in the Arabia Terra region — which straddles the so-called “transition zone” between the north and south regions of the planet — reveal a combination of probable effects from wind, water and perhaps even the tilt of the axis of Mars. These pictures came courtesy of ESA’s Mars Express, which is orbiting the planet.
The crater — named after French physicist Antoine Henri Becquerel, a co-discoverer of radioactivity — is 103 miles (167 kilometers) in diameter and sinks 2.2 miles (3.5 km) below the rest of the area. This depression might have held water at some point.
“The mound rises about 1 km [0.62 miles] above the crater floor and comprises hundreds of layers of light-toned sediments, each just a few metres thick, made of sulphate-bearing rocks,” ESA stated. “On Earth, sulphates are most often formed via the evaporation of water, so the presence of these minerals in Becquerel crater suggests that water may once have pooled here in a vast crater lake, before evaporating away.”
This view of Becquerel Crater on Mars shows the effects of wind on the Red Planet. Credit: ESA/DLR/FU Berlin (G. Neukum)
The mystery of Mars’ missing water is one that is still puzzling scientists — NASA’s Spirit, Curiosity and Opportunity rovers all found rocks that likely formed in the presence of water, and several spacecraft have spotted features that appear to be similar to riverbeds or perhaps even oceans.
“One popular theory is that large changes in the tilt of the rotational axis of Mars leads to significant changes in its climate, reflected in the thickness and repeating patterns found in the layers of sediment,” ESA added. “A change in the environmental conditions would affect the way in which the sediments were initially deposited, as well as their subsequent resistance to erosion.”
Speaking of sediments, the image above shows the dark material extending far beyond the crater walls, a sign of powerful winds on the Red Planet. Now who’s tempted to go down there with a shovel to see what’s underneath?
As a point of trivia, another spot in Arabia Terra (Vernal Crater) was once considered a possible landing site for Mars Curiosity because scientists found evidence of ancient hot springs on the Red Planet. On Earth, these locations are usually filled with bacterial life.
The topography of Becquerel crater on Mars. Credit: ESA/DLR/FU Berlin (G. Neukum)
Virgin Galactic's SpaceShipTwo soars in a powered flight test on Sept. 5, 2013. Credit: MarsScientific.com and Clay Center Observatory
Is that the smell of rocket fuel in the air, or customer excitement?
The reported 600+ customers waiting in line for a trip to space aboard SpaceShipTwo (nickname: Enterprise) surely must have been excited when the suborbital spaceship successfully sailed through another powered flight test today (Thursday).
“SS2 has successfully completed another supersonic rocket-powered test flight! Hit our planned duration, altitude, and speed,” Virgin Galactic wrote on Twitter.
Watch the video of the flight below:
SpaceShipTwo also tested a “feathering” system that it has on board to assist with controlled re-entry. It allows the entire tail of the spaceship to rotate up to about 65 degrees, which Virgin says allows fine control of the attitude as the spacecraft comes back to Earth. “The feather configuration is also highly stable, effectively giving the pilot a hands-free re-entry capability, something that has not been possible on spacecraft before,” Virgin said of the system on its website.
Virgin Galactic’s SpaceShipTwo, aboard WhiteKnightTwo, takes off during a flight test Sept. 5, 2013. Credit: Virgin Galactic (Twitter)
The test, which started at about 8 a.m. Mojave time, saw the WhiteKnightTwo carrier aircraft take off from the Mojave Air and Space Port carrying SpaceShipTwo underneath. At 46,000 feet, pilots Mark Stucky and Clint Nichols released their spacecraft from the carrier and turned on the rocket motor for a 20-second burn. They climbed as high as 69,000 feet at a maximum speed of Mach 1.43, or 1.43 times the speed of sound.
“The main progress with this test is that we deployed the full expansion (up and down) of the feather mechanism at a high altitude, alongside testing the rocket motor performance,” wrote Virgin founder Richard Branson on his blog. “This feather mechanism was the key innovation that enabled us to get into the space program in the first place. It acts like a giant shuttlecock and slows the spaceship up as it comes back into the earth’s atmosphere.”
Branson also described Thursday’s test — the second powered flight for SpaceShipTwo, which did its first in April — as “the highest commercial winged vehicle [flight] in history.”
Artist's conception of GJ 1214 b passing across its host star, as viewed in blue light. Credit: NAOJ
Playing with the filters on a telescope can show us amazing things. In a recent case, Japanese astronomers looked at the star Gilese 1214 in blue light and watched its “super-Earth” planet (Gliese 1214 b, or GJ 1214 b) passing across the surface from the viewpoint of Earth. The result — a probable detection of water in the planet’s atmosphere.
Observations with the Subaru Telescope using a blue filter revealed the atmosphere does not preferentially scatter any light. If the Rayleigh scattering had been observed, this would have shown hydrogen in the atmosphere, researchers said. (On Earth, Rayleigh scattering of the atmosphere makes the sky blue.)
“When combined with the findings of previous observations in other colors, this new observational result implies that GJ 1214 b is likely to have a water-rich atmosphere,” stated the National Astronomical Observatory of Japan.
The planet is an ideal candidate for exoplanet observations because it is relatively close to Earth (40 light years away) and is about 2.7 times the size of our planet, allowing for possible comparisons between the worlds.
Three images showing the relationship between the atmosphere’s composition and the transmitted colors of light. Top: Hydrogen-dominated atmospheres see much of the blue light scattered, meaning that transits become more visible in blue light than red light. Middle: Atmospheres with less hydrogen scatter blue wavelengths more weakly. Bottom: Cloud-covered planets make it more difficult for light to make its way up through the atmosphere, even if the atmosphere is dominated by hydrogen. Credit: NAOJ
There’s still some debate over whether “super-Earths” are closer in nature to Earth or to Uranus or Neptune (each about four times Earth’s diameter), requiring scientists to scrutinize that class of exoplanets to learn more about their properties.
One area under investigation is where the super-Earths form. It is believed that planets arise out of a protoplanetary disk, or cloud of gas, ice and debris that surrounds a young star at the beginning of its life. Hydrogen is a big part of this disk, as well as water ice beyond the “snow line“, or the region in a planetary system where waning heat makes it possible for ice to form.
“Findings about where super-Earths have formed and how they have migrated to their current orbits point to the prediction that hydrogen or water vapor is a major atmospheric component of a super-Earth,” NAOJ stated. “If scientists can determine the major atmospheric component of a super-Earth, they can then infer the planet’s birthplace and formation history.”
The team acknowledges it’s still possible there is hydrogen in GJ 1214 b’s atmosphere, but add their findings do corroborate with past ones suggesting water.
An ultracold vacuum chamber ran a simulation of the early universe and came up with some interesting findings about how the environment looked shortly after the Big Bang occurred.
Specifically, the atoms clustered in patterns similar to the cosmic microwave background — believed to be the echo of the intense burst that formed the beginning of the universe. Scientists have mapped the CMB at progressively higher resolution using several telescopes, but this experiment is the first of its kind to show how structure evolved at the beginning of time as we understand it.
The Big Bang theory (not to be confused with the popular television show) is intended to describe the universe’s evolution. While many pundits say it shows how the universe came “from nothing”, the concordance cosmological model that describes the theory says nothing about where the universe came from. Instead, it focuses on applying two big physics models (general relativity and the standard model of particle physics). Read more about the Big Bang here.
CMB is, more simply stated, electromagnetic radiation that fills the Universe. Scientists believe it shows an echo of a time when the Universe was much smaller, hotter and denser, and filled to the brim with hydrogen plasma. The plasma and radiation surrounding it gradually cooled as the Universe grew bigger. (More information on the CMB is here.) At one time, the glow from the plasma was so dense that the Universe was opaque, but transparency increased as stable atoms formed. But the leftovers are still visible in the microwave range.
WMAP data of the Cosmic Microwave Background. Credit: NASA
The new research used ultracold cesium atoms in a vacuum chamber at the University of Chicago. When the team cooled these atoms to a billionth of a degree above absolute zero (which is -459.67 degrees Fahrenheit, or -273.15 degrees Celsius), the structures they saw appeared very similar to the CMB.
By quenching the 10,000 atoms in the experiment to control how strongly the atoms interact with each other, they were able to generate a phenomenon that is, very roughly speaking, similar to how sound waves move in air.
“At this ultracold temperature, atoms get excited collectively,” stated Cheng Chin, a physics researcher at the University of Chicago who participated in the research. This phenomenon was first described by Russian physicist Andrei Sakharov, and is known as Sakharov acoustic oscillations.
So why is the experiment important? It allows us to more closely track what happened after the Big Bang.
Atom density is greater at left (the beginning of the experiment) than 80 milliseconds after the simulated Big Bang. Credit: Chen-Lung Hung
The CMB is simply a frozen moment of time and is not evolving, requiring researchers to delve into the lab to figure out what is happening.
“In our simulation we can actually monitor the entire evolution of the Sakharov oscillations,” said Chen-Lung Hung, who led the research, earned his Ph.D. in 2011 at the University of Chicago, and is now at the California Institute of Technology.
Both Hung and Chin plan to do more work with the ultracold atoms. Future research directions could include things such as how black holes work, or how galaxies were formed.
Astronaut Drew Feustel reenters the space station after completing an 8-hour, 7-minute spacewalk at on Sunday, May 22, 2011. He and fellow spacewalker Mike Fincke conducted the second of the four EVAs during the STS-134 mission. Credit: NASA
It’s easy to take the International Space Station for granted. It’s been planned, under construction and/or operated for decades. Humans have occupied it continuously for 4,684 days (close to 13 years) as of today. According to two space policy experts, however, NASA should already be thinking of what it’s going to do next after the station’s current agreement expires in 2020.
Ignoring the deadline, they said, could lead to consequences such as (in one scenario) the end of U.S. government spaceflight altogether.
Below are edited excerpts from two officials from George Washington University’s Elliott School of International Affairs. Scott Pace is its director, and John M. Logsdon is a professor emeritus. They spoke with reporters Thursday (Aug. 29) about the coming NASA budget decision and their views on the agency’s future.
We’d also like to get your feedback on their ideas, so please leave your thoughts in the comments.
Pace: In my view, the House numbers are complying with the Budget Control Act in terms of sequestration numbers. In the Senate, the numbers were not in line with the Budget Control Act, but reflected what the priorities of the authorization committee were … I would argue, and we’ll see if others agree, that the Senate has marginalized themselves in this discussion. The appropriations staff will have the larger say in that, but on the House side, the authorizors and the appropriators will be together because they have discussed what their priorities were.”
Where NASA’s direction comes from:
Logsdon: It’s a residual of 40 years of failure to reach consensus of what the U.S. should be doing in space and particularly, human spaceflight. In the first year and a half of the Nixon administration, he was faced with what to do after Apollo and basically punted. He said, “Let’s develop means, rather than set goals.” The means was the shuttle … The lack of leadership of this administration, which is not much different than most presidents since Nixon and including Nixon, have put us in a situation that is unfortunate, and, as Scott [Pace] says, leads to a lot of drift and lack of sense of purpose.
Pace: [One goal for NASA often is to implement] priorities of decadal surveys from the National Academy of Sciences. Things like the asteroid redirect mission, which will burden portions of the human and science programs, have no decadal survey mention or no larger contribution to the science. It’s another capability-driven-evolution sort of project, with some very basic flaws to it in terms of not providing that long-term sense of strategic purpose.
Concept of NASA spacecraft with Asteroid capture mechanism deployed to redirect a small space rock to a stable lunar orbit for later study by astronauts aboard Orion crew capsule. Credit: NASA.
Logsdon: There’s not enough money to have a robust space exploration program and to use the space station at a $3 billion a year level in 2028. None of the current partners — with a possible exception of Canada — but certainly, Europe and Japan are not enthusiastic about spending money on space station post-2020. They really had to be dragged, their governments had to be dragged, to commit the funds for the extension to 2020. It’s not clear, if there is a decision to go beyond, whether the United States will have its early partners [committed.]
Pace: What happens with other major scientific facilities that NASA has, like the Hubble Space Telescope, is you have a senior review. After you’ve met the initial requirements [of the mission], you ask what is the facility costing me, what am I getting out of it, and make a decision whether to continue. You will see, in anticipation of 2020, you will see the beginnings of a senior review to see what will be in the NASA 2020 budget. It is dependent upon data being created now — the scientific and technical benefits — and where will the benefits flow for plans beyond space station. If there are no plans for human flight beyond space station … the default option is to do the station as long as it is technically capable, but eventually it will be deorbited. And there will be an end to U.S. government spaceflight.
A view of the International Space Station as seen by the last departing space shuttle crew, STS-135. Credit: NASA
If government-funded human spaceflight could end in the United States:
Pace: I can imagine a President presiding over the end of human spaceflight, not as a conscious decision but as an unfortunate accident. Drift is the most dangerous thing for NASA.
Logsdon: Would any President be willing to be that person to end the government-sponsored spaceflight program? I’m not sure the answer is no. It could be that a future President could say we’ve done it and there’s no future reasoning to continue at fairly high expense to continue to do it. But I would speculate the more likely answer, given the industrial and regional interests, is some sort of limping through human spaceflight. It’s more similar than different for the past four decades.
What NASA needs right now:
Logsdon: I’m taking less about the NASA leadership than I am the White House and Congressional leadership. What’s missing is a sense of strategic purpose of the organization, what should it be doing, and that is the job of a national leader. It is enunciating for NASA, as well as other government agencies, for what its long-term and even midterm strategic purpose is in terms of the natinoal interest ought to be.
Pace: [The United States must determine] what is the role of international leadership in space for the United States and to what extent are we willing to make plans for beyond the station. 2020 is not that far away. The focus on NASA right now, with ISS, is utilization. The station has been a great diplomatic success, great technical success, but it’s not clear if it will be a great scientific success.
In white suits: JAXA astronaut Koichi Wakata (left) and NASA astronaut Rick Mastracchio during spacewalk training for Expeditions 38/39. Credit: NASA
Getting into space is never a guarantee for an astronaut. Heck, getting into an astronaut program can be tough, as Koichi Wakata and Rick Mastracchio told Universe Today.
The crewmates on Expedition 38/39 are supposed to head to the International Space Station in November. But they beat incredible odds to be selected in the first place. Wakata, who is with the Japanese Aerospace Exploration Agency (JAXA), didn’t even have an astronaut program to join when he was a kid. Mastracchio (from NASA) did, but it took him nine years’ worth of applications to get in.
“When I was five years old, I saw the Apollo [11] lunar landing,” Wakata said. “This was before I was going to school, kindergarten timeframe. But there was no astronaut program in Japan, so I thought it was physically beyond my reach. It was something I longed for.”
With no Japanese astronauts to look up to, Wakata put himself in a related career: airplane engineering. Between 1989 and 1992, he worked as an aircraft structural engineer for Japan Airlines. It was while he was in this career that he saw a newspaper advertisement recruiting the first Japanese astronauts. He applied and was let in, first try.
JAXA astronaut Koichi Wakata takes photos of Earth during Expedition 19/20 in 2009. Credit: NASA
“I was lucky to get into this program,” Wakata said. And now he has a new milestone in his sights: becoming the first Japanese commander of the International Space Station during Expedition 39. Wakata’s space experience includes operating every piece of robotics hardware currently on orbit, from the Canadarm to the Japanese Kibo robotic arm.
Finally, Wakata also watched closely what his own spaceflight commanders did. He is a big admirer of Brian Duffy, who flew four times in space — including two of Wakata’s missions. “I learned a lot from him and I try to imitate what he did,” Wakata said.
Unlike Wakata, his crewmate Mastracchio was born in a country with a well-established astronaut program. That also meant, however, a lot of competition. Mastracchio made applications practically every year between 1987 and 1996. Every time he was turned down, he would look for a way to make himself better for the next round.
Rick Mastracchio takes a selfie during a spacewalk on STS-118. NASA’s web page says the purpose was to have a photo of his helmet visor. Credit: NASA
“I tried not to do things to become an astronaut. I tried to do things that I thought would be interesting,” Mastracchio said. At the same time, those interesting things happened to be items that astronauts would find useful.
Hired in 1987 for Rockwell Shuttle Operations Company in Houston, Mastracchio then moved to NASA in 1990 as an engineer in the flight crew operations directorate. He earned a masters degree in physical science at the nearby University of Houston-Clear Lake in 1991. Mastracchio also got a pilot’s license.
Around the same time of another unsuccessful selection in 1994, Mastracchio switched jobs and became a flight controller in the front room of Mission Control. It’s hard to say if that made the difference, he acknowledged, but for what it’s worth he was selected in 1996. “I just gained more experience, over time, in different jobs,” he said.
Mastracchio has since flown three times into space, performing six spacewalks in that time. There are no further “outside” activities planned for him during Expedition 38/39, but he has trained as a backup just in case.
The two main smoke trails left by the Russian meteorite as it passed over the city of Chelyabinsk. Credit: AP Photo/Chelyabinsk.ru
A collision or “near miss” caused melting in the Chelyabinsk meteor before it slammed into Earth’s atmosphere this February, causing damage and injuries to hundreds in the remote Russian region.
A new study, presented at the Goldschmidt Conference in Florence, Italy, says some meteorite fragments’ composition shows strong evidence of heating, which is an indication of interplanetary violence of some sort.
“The meteorite which landed near Chelyabinsk is a type known as an LL5 chondrite, and it’s fairly common for these to have undergone a melting process before they fall to Earth,” stated Victor Sharygin, a researcher from the Sobolev Institute of Geology and Mineralogy in Russia.
“This almost certainly means that there was a collision between the Chelyabinsk meteorite and another body in the solar system, or a near miss with the Sun.”
Chelyabinsk’s size of 59 feet (18 meters) was by no means a very large meteor, but it was enough to cause car alarms to go off and to shatter glass when it exploded over Russia on Feb. 15. Its arrival brought the danger of space rocks once again to public attention.
Model and satellite data show that four days after the bolide explosion, the faster, higher portion of the plume (red) had snaked its way entirely around the northern hemisphere and back to Chelyabinsk, Russia. Image Credit: NASA’s Goddard Space Flight Center Scientific Visualization
Sharygin’s team analyzed several fragments of the meteorites and put them into three groups: light, dark and intermediate. Lights ones were the most abundant. Dark fragments were most commonly found in the area where the meteorite hit the Earth.
While only three of the dark fragments show there was previous melting, the researchers say it’s quite possible that more samples might be available from the public and most notably, from the main portion that is still at the bottom of Chebarkul Lake.
“The dark fragments include a large proportion of fine-grained material, and their structure, texture and mineral composition shows they were formed by a very intensive melting process,” a press release stated.
“This material is distinct from the ‘fusion crust’ – the thin layer of material on the surface of the meteorite that melts, then solidifies, as it travels through the Earth’s atmosphere.”
A “fusion crust” or melting is visible in this fragment of the Chelyabinsk meteorite. Credit: Victor Sharygin
Researchers also spotted “bubbles” in the dark fragments that they consider either “perfect crystals” of oxides, silicates and metal or little spots that are filled up with sulfide or metal.
They also saw platinum-type elements in the crust, which was a surprise as the time it takes for a crust to fuse is too short for platinum to form.
“We think the appearance (formation) of this platinum group mineral in the fusion crust may be linked to compositional changes in metal-sulfide liquid during remelting and oxidation processes as the meteorite came into contact with atmospheric oxygen,” Sharygin stated.
The work is ongoing, and no submission date for a study for publication was disclosed.
