The white spot on Ceres in a series of new photos taken on Jan. 13 by NASA’s Dawn spacecraft, which is rapidly approaching the round dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. But when the initial photo release on Monday (Jan. 19), the Dawn scientists gave no indication of what the white dot might be.
“Yes, we can confirm that it is something on Ceres that reflects more sunlight, but what that is remains a mystery,” Marc Rayman, mission director and chief engineer for the Dawn mission, told Space.com in an email.
The new images show areas of light and dark on the face of Ceres, which indicate surface features like craters. But at the moment, none of the specific features can be resolved, including the white spot.
“We do not know what the white spot is, but it’s certainly intriguing,” Rayman said. “In fact, it makes you want to send a spacecraft there to find out, and of course that is exactly what we are doing! So as Dawn brings Ceres into sharper focus, we will be able to see with exquisite detail what [the white spot] is.”
Ceres is a unique object in our solar system. It is the largest object in the asteroid belt and is classified as an asteroid. It is simultaneously classified as a dwarf planet, and at 590 miles across (950 kilometers, or about the size of Texas), Ceres is the smallest known dwarf planet in the solar system.
The $466 million Dawn spacecraft is set to enter into orbit around Ceres on March 6. Dawn left Earth in 2007 and in the summer of 2011, it made a year-long pit stop at the asteroid Vesta, the second largest object in the asteroid belt.
While Vesta shared many properties with our solar system’s inner planets, scientists with the Dawn mission suspect that Ceres has more in common with the outer most planets. 25 percent of Ceres’ mass is thought to be composed of water, which would mean the space rock contains even more fresh water than Earth. Scientists have observed water vapor plumes erupting off the surface of Ceres, which may erupt from volcano-like ice geysers.
The mysterious white spot captured by the Dawn probe is one more curious feature of this already intriguing object.
Asteroids have long been regarded as planetary building blocks. But they may actually be byproducts of planet formation, born when violent collisions smashed an earlier generation of objects apart, a new study suggests.
Asteroid fragments that fall to Earth as meteorites often contain tiny, round pellets called chondrules that formed when molten droplets quickly cooled in space in the solar system’s early years. Chondrules are found in 92 percent of all meteorites, and are often thought to be the building blocks of planets.
Chondrules were part of the protoplanetary disc of gas and dust surrounding the newborn sun that gave birth to Earth and the other planets. A recent study found that chondrules formed about 1 million years after planetesimals — the building blocks of protoplanets — came together.
Prior research had suggested that chondrules in some meteorites were probably born when rocks in space collided at speeds of more than 22,370 mph (36,000 km/h). However, it was uncertain how the majority of chondrules formed.
Now, scientists have found that cosmic impacts could have generated enough chondrules during the first 5 million years or so of planet formation to explain the large quantity of these pellets.
“The most surprising implication of our work is that the meteorites we find on Earth are not actually the building blocks of planets, as has been thought for a long time,” lead study author Brandon Johnson, a planetary scientist at MIT, told Space.com. “Instead, they may be a byproduct of planetary formation.”
Chondrule-bearing meteorites — known as chondrites — may thus not be representative of the objects that built the solar system’s planets, study team members said.
The researchers simulated impacts of varying speeds between protoplanetary objects about 60 to 650 miles (100 to 1,000 kilometers) wide. They found that when collision speeds exceeded 5,590 mph (9,000 km/h), plumes of molten rock that blasted out from these impacts could form millimeter-size droplets that could have cooled into chondrules.
The scientists calculated that cosmic impacts within a typical protoplanetary disc could have generated more than 44 billion trillion lbs. (20 billion trillion kilograms) of chondrules. For comparison, the present asteroid belt currently has a mass of about 6.6 billion trillion lbs. (3 billion trillion kg).
This finding suggests that cosmic impacts could have generated many of the chondrules in the asteroid belt from which nearly all meteorites originate.
“We’ve put together a coherent model for chondrule formation,” Johnson said. “Once we have a proper context for how chondrules formed, we can really understand what was happening in the nascent solar system.”
Johnson noted that the team’s work only investigated vertical impacts. “More realistic impacts may be at an angle,” Johnson said. Still, such oblique impacts “produce more jetted materials, more chondrules,” he added.
A NASA probe is about to get the first up-close look at a potentially habitable alien world.
In March 2015, NASA’s Dawn spacecraft will arrive in orbit around the dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. Ceres is a relatively warm and wet body that deserves to be mentioned in the same breath as the Jovian moon Europa and the Saturn satellite Enceladus, both of which may be capable of supporting life as we know it, some researchers say.
“I don’t think Ceres is less interesting in terms of astrobiology than other potentially habitable worlds,” Jian-Yang Li, of the Planetary Science Institute in Tucson, Arizona, said Thursday (Dec. 18) during a talk here at the annual fall meeting of the American Geophysical Union.
Life as we know it requires three main ingredients, Li said: liquid water, an energy source and certain chemical building blocks (namely, carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur).
The dwarf planet Ceres — which is about 590 miles (950 kilometers) wide — is thought to have a lot of water, based on its low overall density (2.09 grams per cubic centimeter; compared to 5.5 g/cubic cm for Earth). Ceres is likely a differentiated body with a rocky core and a mantle comprised of water ice, researchers say, and water-bearing minerals have been detected on its surface.
Indeed, water appears to make up about 40 percent of Ceres’ volume, Li said.
“Ceres is actually the largest water reservoir in the inner solar system other than the Earth,” he said. However, it’s unclear at the moment how much, if any, of this water is liquid, he added.
As far as energy goes, Ceres has access to a decent amount via solar heating, since the dwarf planet lies just 2.8 astronomical units (AU) from the sun, Li said. (One AU is the distance between Earth and the sun — about 93 million miles, or 150 million km). Europa and Enceladus are much farther away from our star — 5.2 and 9 AU, respectively.
Both Europa and Enceladus possess stores of internal heat, which is generated by tidal forces. This heat keeps the ice-covered moons’ subsurface oceans of liquid water from freezing up, and also drives the eruption of water-vapor plumes on Enceladus (and probably Europa as well; researchers announced last year that NASA’s Hubble Space Telescope spotted water vapor erupting from the Jupiter moon in December 2012).
Intriguingly, scientists announced the discovery of water-vapor emission from Ceres — which may also possess a subsurface ocean — earlier this year.
Ceres’ plumes may or may not be evidence of internal heat, Li said. For example, they may result when water ice near Ceres’ surface is heated by sunlight and warms enough to sublimate into space.
“Right now, we just don’t know much about the outgassing on Ceres,” Li said.
Dawn should help bring Ceres into much clearer focus when it reaches the dwarf planet this spring. The spacecraft, which orbited the huge asteroid Vesta from July 2011 through September 2012, will map Ceres’ surface in detail and beam home a great deal of information about the body’s geology and thermal conditions before the scheduled end of its prime mission in July 2015.
Ground-based instruments should also play a role in unveiling Ceres. For example, the Atacama Large Millimeter/submillimeter Array, or ALMA — a huge system of radio dishes in Chile — has the ability to probe deeper than Dawn, going into Ceres’ subsurface and shedding more light on the dwarf planet’s composition and thermal properties, Li said.
“This is highly complementary to the Dawn mission,” he said.
Ceres’ relative proximity to Earth also makes it an attractive target for future space missions, Li added.
The molecule in question — iso-propyl cyanide (i-C3H7CN) — was spotted in Sagittarius B2, a huge star-making cloud of gas and dust near the center of the Milky Way, about 27,000 light-years from the sun. The discovery suggests that some of the key ingredients for life on Earth could have originated in interstellar space.
A specific molecule emits light at a particular wavelength and in a telltale pattern, or spectrum, which scientists can detect using radio telescopes. For this study, astronomers used the enormous Atacama Large Millimeter/submillimeter Array (ALMA) telescope in the Chilean desert, which went online last year and combines the power of 66 radio antennas. [5 Bold Claims of Alien Life]
Iso-propyl cyanide joins a long list of molecules detected in interstellar space. But what makes this discovery significant is the structure of iso-propyl cyanide. All other organic molecules that have been detected in space so far (including normal-propyl cyanide, the sister of i-C3H7CN) are made of a straight chain with a carbon backbone. Iso-propyl cyanide, however, has a “branched” structure. This same type of branched structure is a key characteristic of amino acids.
“Amino acids are the building blocks of proteins, which are important ingredients of life on Earth,” the study’s lead author, Arnaud Belloche, of the Max Planck Institute for Radio Astronomy, told Space.com in an email. “We are interested in the origin of amino acids in general and their distribution in our galaxy.”
Scientists have previously found amino acids in meteorites that fell to Earth, and the composition of these chemicals suggested they had an interstellar origin. The researchers in this new study did not find amino acids, but their discovery adds an “additional piece of evidence that the amino acids found in meteorites could have been formed in the interstellar medium,” Belloche wrote.
“The detection of a molecule with a branched carbon backbone in interstellar space, in a region where stars are being formed, is interesting because it shows that interstellar chemistry is indeed capable of producing molecules with such a complex, branched structure,” Belloche added.
It was first suggested in the 1980s that branched molecules could form on the surface of dust grains in interstellar space. But this is the first time such compounds have been detected. What’s more, iso-propyl cyanide seemed to be plentiful — it was almost half as abundant of its more common sister variant in Sagittarius B2, the study found. This means that branched molecules could actually be quite ordinary in interstellar space, the researchers said.
The discovery of a complex microbial ecosystem far beneath the Antarctic ice may be exciting, but it doesn’t necessarily mean that life teems on frigid worlds throughout the solar system, researcher’s caution.
Scientists announced today (Aug. 20) in the journal Nature that many different types of microbes live in subglacial Lake Whillans, a body of fresh water entombed beneath 2,600 feet (800 meters) of Antarctic ice. Many of the micro-organisms in these dark depths apparently get their energy from rocks, the researchers report.
The results could have implications for the search for life beyond Earth, notes Martyn Tranter of the University of Bristol in England, who did not participate in the study. [6 Most Likely Places for Alien Life in the Solar System]
“The team has opened a tantalizing window on microbial communities in the bed of the West Antarctic Ice Sheet, and on how they are maintained and self-organize,” Tranter wrote in an accompanying “News and Views” piece in the same issue of Nature. “The authors’ findings even beg the question of whether microbes could eat rock beneath ice sheets on extraterrestrial bodies such as Mars. This idea has more traction now.”
But just how much traction is a matter of debate. For example, astrobiologist Chris McKay of NASA’s Ames Research Center in California doesn’t see much application to Mars or any other alien world.
“First, it is clear that the water sampled is from a system that is flowing through ice and out to the ocean,” said McKay, who also was not part of the study team.
“Second, and related to this, the results are not indicative of an ecosystem that is growing in a dark, nutrient-limited system,” McKay told Space.com via email. “They are consistent with debris from the overlying ice — known to contain micro-organisms — flowing through and out to the ocean. Interesting in its own right, but not a model for an isolated ice-covered ecosystem.”
Isolated, ice-covered oceans exist on some moons of the outer solar system, such as Jupiter’s moon Europa and the Saturn satellite Enceladus — perhaps the two best bets to host life beyond Earth. McKay and other astrobiologists would love to know if these oceans do indeed host life.
It may be possible to find out without even touching down on Europa or Enceladus. Plumes of water vapor spurt into space from the south polar regions of both moons, suggesting that flyby probes could sample their subsurface seas from afar.
And Europa is on the minds of the higher-ups at both NASA and the European Space Agency (ESA). NASA is drawing up plans for a potential Europa mission that could blast off in the mid-2020s, while ESA aims to launch its JUpiter ICy moons Explorer (JUICE) mission —which would study the Jovian satellites Callisto and Ganymede in addition to Europa — in 2022.
These compounds may reveal that extraterrestrials have disastrously altered their planets, scientists added.
To detect biomarkers, or signs of life, on distant worlds, scientists have often focused on molecules such as oxygen, which theoretically disappears quickly from atmospheres unless life is present to provide a constant supply of the gas. By looking at light passing through atmospheres of alien worlds, past studies have suggested future instruments such as NASA’s James Webb Space Telescope could detect telltale traces of oxygen.
But the search for extraterrestrial intelligence (SETI) has mostly concentrated on “technosignatures,” such as radio and other electromagnetic signals that alien civilizations might give off. Now researchers suggest that searches for atmospheric biomarkers could also look for industrial pollutants as potential signs of intelligent aliens.
Astronomers at Harvard University focused on tiny, superdense stars known as white dwarfs. More than 90 percent of all stars in the Milky Way, including our own sun, will one day end up as white dwarfs, which are made up of the dim, fading cores of stars.
Though white dwarfs are quite cold for stars, they would still be warm enough to possess so-called habitable zones — orbits where liquid water can exist on the surfaces of circling planets. These zones are considered potential habitats for life, as there is life virtually everywhere there is liquid water on Earth.
The scientists examined how Earth-size planets in the habitable zones of white dwarfs might look if they possessed industrial pollutants in their atmosphere. They focused on chlorofluorocarbons (CFCs), which are entirely artificial compounds, with no known natural process capable of creating them in atmospheres.
CFCs are nontoxic chemicals that were once used in hairspray and air conditioners, among many other products, before researchers discovered they were causing a hole in Earth’s ozone layer, which protects the planet from dangerous ultraviolet radiation.
“Very hairy extraterrestrials may be a little easier to detect,” joked lead study author Henry Lin, a physicist at Harvard.
CFCs are strong greenhouse gases, meaning they are very effective at absorbing heat. This means that if CFCs are in the atmosphere of a distant Earth-size planet, they could alter a white dwarf’s light when that world passes in front of that star — enough for the $8.8 billion James Webb Space Telescope (JWST), which is due to launch in 2018, to detect them.
In addition, the researchers noted that CFCs are long-lived molecules, capable of lasting up to about 100,000 years in atmospheres. This means they could even serve as markers of long-dead alien civilizationsThe investigators simulated the amount of time it would take JWST to detect the fluorocarbon CF4 and the chlorofluorocarbon CCl3F in the atmosphere of an Earth-size planet in the habitable zone of a white dwarf. They modeled concentrations of these gases 100 times greater than the highs currently seen on Earth.
The scientists found it would take JWST three days of looking at such a white dwarf to detect signs of CF4, and only a day and a half for CCl3F.
“The most exciting aspect of the results is that within the next decade we might be able to search for excessive industrial pollution in the atmospheres of Earth-like planets,” study co-author Abraham Loeb, a theoretical astrophysicist and chair of Harvard’s astronomy department, told Space.com.
Ironically, “aliens are often referred to as green little creatures, but ‘green’ also means ‘environmentally friendly,’” Loeb said. “Detectable CFC-rich civilizations would not be ‘green.’”
The scientists did caution that it would take much longer to detect these industrial pollutants than it would biomarkers such as oxygen, which JWST could find after about three hours of looking at such a planet. Astronomers should only attempt to discover technosignatures such as CFCs if initial searches for fundamental biomarkers like oxygen were successful, the research team suggested.
The astronomers cautioned it would be 100 times more difficult to detect industrial pollutants on planets orbiting yellow dwarf stars like the sun, making such searches beyond the capabilities of JWST. It would also take an unrealistically long time to detect CFC levels on alien planets that match those currently found on Earth, Loeb said.
One potentially sobering future discovery might be of alien worlds that possess long-lived industrial pollutants such as CFCs but no longer have any short-lived biomarkers such as oxygen.
“If we find graveyards of other civilizations, most rational people would likely get engaged in protecting the Earth from a similar catastrophe,” Loeb said.
“We call industrial pollution a biomarker for intelligent life, but perhaps a civilization much more advanced than us with their own exoplanet program will classify industrial pollution as a biomarker for unintelligent life,” Lin said.
However, if astronomers discover a world heavy with CFCs that exists outside the habitable zone of its star, that could mean an extraterrestrial civilization may have intentionally “terraformed” that planet, making it livably warmer “by polluting it with greenhouse gases,” Loeb said. Scientists have previously suggested terraforming Mars by warming and thickening the Red Planet’s atmosphere so that humans can roam its surface without having to wear spacesuits.
Researchers announced their discovery of the deep watery ocean on Enceladus on Thursday (April 3) in the journal Science, confirming suspicions held by many scientists since 2005, when NASA’s Cassini spacecraft spied geysers of ice and water vapor erupting from Enceladus’ south pole.
The discovery vaults Enceladus into the top tier of life-hosting candidates along with Europa, an ice-sheathed moon of Jupiter that also hosts a subterranean ocean. Both frigid satellites bear much closer investigation, researchers say.
“I don’t know which of the two is going to be more likely to have life. It might be both; it could be neither,” study co-author Jonathan Lunine of Cornell University told reporters yesterday (April 2). “I think what this discovery tells us is that we just need to be more aggressive in getting the next generation of spacecraft both to Europa and to the Saturn system once the Cassini mission is over.”
Cassini arrived in orbit around Saturn in 2004 and is currently scheduled to go out in a blaze of glory in September 2017, when it will dive headlong into the giant planet’s thick atmosphere.
Enceladus’ geysers blast material hundreds of miles into space, offering a way to sample the moon’s subsurface ocean from afar. (Researchers think the ocean is feeding the geysers, though they can’t be sure of this at the moment.)
Cassini has already done some of this work with its mass spectrometer, detecting salts and organic compounds — the carbon-based building blocks of life as we know it — in Enceladus’ plumes during flybys of the moon.
But Cassini’s mass spectrometer can detect only relatively light organics. A follow-up mission to Enceladus should sport a more advanced and more sensitive version of this instrument that could spot a wider range of organics, Lunine said.
“You could actually do this by making flybys of Enceladus, the way that Cassini does now,” he said. “I think you could learn quite a bit about the organic inventory in the plume by flying this device.”
Interestingly, astronomers announced in December that they had discovered plumes of water vapor erupting from Europa’s south polar region as well. So that moon’s ocean could be sampled during flybys, too — perhaps by a mission called the Europa Clipper.
NASA is developing the Europa Clipper as a concept mission at the moment. Recent estimates have pegged the mission’s cost at around $2 billion. That’s pretty steep in these tough economic times, so a scaled-down version might have the best chance of getting it off the ground, NASA officials have said.
Enceladus and Europa aren’t the only icy moons that harbor subsurface oceans; Jupiter’s enormous moon Ganymede also has one, for example. But Ganymede’s appears to be sandwiched between layers of ice, while the seas of Enceladus and Europa are in contact with rocky seafloors, making possible all sorts of interesting chemical reactions, researchers say.
The oceans soured into a deadly sulfuric-acid stew after the huge asteroid impact that wiped out the dinosaurs, a new study suggests.
Eighty percent of the planet’s species died off at the end of the Cretaceous Period 65.5 million years ago, including most marine life in the upper ocean, as well as swimmers and drifters in lakes and rivers. Scientists blame this mass extinction on the asteroid or comet impact that created the Chicxulub crater in the Gulf of Mexico.
A new model of the disaster finds that the impact would have inundated Earth’s atmosphere with sulfur trioxide, from sulfate-rich marine rocks called anhydrite vaporized by the blast. Once in the air, the sulfur would have rapidly transformed into sulfuric acid, generating massive amounts of acid rain within a few days of the impact, according to the study, published today (March 9) in the journal Nature Geoscience.
The model helps explain why most deep-sea marine life survived the mass extinction while surface dwellers disappeared from the fossil record, the researchers said. The intense acid rainfall only spiked the upper surface of the ocean with sulfuric acid, leaving the deeper waters as a refuge. The model could also account for another extinction mystery: the so-called fern spike, revealed by a massive increase in fossil fern pollen just after the impact. Ferns are one of the few plants that tolerate ground saturated in acidic water, the researchers said.
The Chicxulub impact devastated the Earth with more than just acid rain. Other killer effects included tsunamis, a global firestorm and soot from burning plants. [The 10 Best Ways to Destroy Earth]
The ocean-acidification theory has been put forth before, but some scientists questioned whether the impact would have produced enough global acid rain to account for the worldwide extinction of marine life. For example, the ejected sulfur could have been sulfur dioxide, which tends to hang out in the atmosphere instead of forming aerosols that become acid rain.
Lead author Sohsuke Ohno, of the Chiba Institute of Technology in Japan, and his co-authors simulated the Chicxulub impact conditions in a lab, zapping sulfur-rich anhydrite rocks with a laser to mimic the forces of an asteroid colliding with Earth. The resulting vapor was mostly sulfur trioxide, rather than sulfur dioxide, the researchers found. In Earth’s atmosphere, the sulfur trioxide would have quickly combined with water to form sulfuric acid aerosols. These aerosols played a key role in quickly getting sulfur out of the sky and into the ocean, the researchers said. The tiny droplets likely stuck to pulverized silicate rock debris raining down on the planet, thus removing sulfuric acid from the atmosphere in just a matter of days.
“Our experimental results indicate that sulfur trioxide is expected to be the major sulfide component in the sulfur oxide gas released during the impact,” Ohno told Live Science in an email interview. “In addition to that, by the scavenging or sweeping out of acid aerosols by coexisting silicate particles, sulfuric acid would have settled to the ground surface within a very short time,” Ohno said.
A study of teeny-tiny meteorite fragments revealed that two essential components of life on Earth as we know it, could have migrated to our planet on space dust.
Researchers discovered DNA and amino acids components in a smidgen of a space rock that fell over Murchison, Victoria, in Australia in September 1969. Previous studies of the meteorite revealed organic material, but the samples examined then were much larger. This study would lend more credence to the idea that life arose from outside of our planet, researchers said in a statement.
“Despite their small size, these interplanetary dust particles may have provided higher quantities and a steadier supply of extraterrestrial organic material to early Earth,” said Michael Callahan, a research physical scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. [5 Bold Claims of Alien Life]
Amino acids are the basis of proteins, which are structures that make up hair, skin and other bits of living creatures. DNA is a molecule that contains information on building and running an organism.
Meteorites such as Murchison are rare types of space rocks: the carbonaceous chondrites make up less than 5 percent of meteorites found on Earth, NASA said. Further, the molecules discovered in these space rocks are usually in miniscule concentrations of parts-per-million or parts-per-billion.
These factors have researchers questioning how significant the carbon-rich rocks themselves were in bringing life to Earth. Space dust, however, is more plentiful as it is constantly available from comets and asteroids shedding debris in their travels through the solar system.
The Murchison study (a proof of concept for further work, the researchers say) found life’s building blocks in a sample that weighed about the same as a few eyebrow hairs. The 360-microgram sample was about 1,000 times smaller than a typical sample analyzed by researchers.
Samples from space
This micro-sample required a more sensitive technique than usual to extract the information scientists needed. A nanoflow liquid chromatography instrument organized the molecules, which were then ionized with a nanoelectrospray for analysis in a mass spectrometer.
NASA and other agencies have dealt with small sample sizes before, such as on the Stardust mission that collected particles from Comet Wild-2 and returned them to Earth in 2006. Researchers anticipate the techniques they are using today could be used for other missions in the solar system, especially for sample-return missions.
“This technology will also be extremely useful to search for amino acids and other potential chemical biosignatures in samples returned from Mars and eventually plume materials from the outer planet icy moons Enceladus and Europa,” said Goddard astrobiologist Daniel Glavin, who was co-author on the research.
The study, led by Callahan, was recently published in the Journal of Chromatography A.
A NASA asteroid-hunting spacecraft has opened its eyes in preparation for a renewed mission, beaming home its first images in more than 2.5 years.
The Near-Earth Object Wide-field Infrared Survey Explorer spacecraft, or NEOWISE, has taken its first set of test images since being reactivated in September after a 31-month-long hibernation, NASA officials announced today (Dec. 19). The space agency wants NEOWISE to resume its hunt for potentially dangerous asteroids, some of which could be promising targets for future human exploration.
“The spacecraft is in excellent health, and the new images look just as good as they were before hibernation,” Amy Mainzer, principal investigator for NEOWISE at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. [Photos: Asteroids in Deep Space]
“Over the next weeks and months we will be gearing up our ground-based data processing and expect to get back into the asteroid-hunting business, and acquire our first previously undiscovered space rock, in the next few months,” Mainzer added.
NEOWISE began its scientific life as WISE, which launched to Earth orbit in December 2009 on a 10-month mission to scan the entire sky in infrared light. WISE catalogued about 560 million celestial objects, ranging from faraway galaxies to nearby asteroids and comets, NASA officials have said.
WISE ran out of hydrogen coolant in October 2010, making two of its four infrared detectors inoperable. But NASA didn’t shut the probe down at this point; rather, the agency granted a four-month mission extension known as NEOWISE, which focused on hunting asteroids. (The satellite could still spot nearby objects with its other two detectors, which did not have to be super-cooled).
NEOWISE discovered more than 34,000 asteroids and characterized 158,000 space rocks before being shut down in February 2011, NASA officials said.
And the spacecraft is now gearing up for another three-year space-rock hunt, partly to help find potential targets for NASA’s ambitious asteroid-capture project. This “Asteroid Initiative,” which was announced in April, seeks to drag a near-Earth asteroid to a stable orbit around the moon, where it would be visited by astronauts using the agency’s Space Launch System rocket and Orion crew vehicle.
The plan represents a way to meet a major goal laid out by President Barack Obama, who in 2010 directed NASA to get astronauts to a near-Earth asteroid by 2025, then on to the vicinity of Mars by the mid-2030s.
NEOWISE employs a 16-inch (40 centimeters) telescope and infrared cameras to find previously unknown asteroids and gauge the size, reflectivity and thermal properties of space rocks, NASA officials said.
“It is important that we accumulate as much of this type of data as possible while the spacecraft remains a viable asset,” said Lindley Johnson, NASA’s NEOWISE program executive in Washington. “NEOWISE is an important element to enhance our ability to support the [asteroid] initiative.”
The explosive collisions of icy comets with planets and moons generated the vital building blocks of life, spreading these necessary ingredients throughout the solar system, researchers say.
“The important implication is that the complex precursors to life are widespread, thus increasing the chances of life evolving elsewhere,” study co-author Mark Price, a space scientist at the University of Kent in England, told SPACE.com.
Comets are known to possess organic compounds. Scientists have long suggested that comets helped bring the ingredients of life to the early Earth. [7 Theories on the Origin of Life]
Astronomers have detected ammonia and other compounds in comets such as Halley’s Comet that are the precursors of amino acids, the basic components of proteins. Indeed, the simplest amino acid, glycine, was recently discovered in samples of the Comet 81P/Wild-2 collected by NASA’s Stardust spacecraft.
However, more complex amino acids are needed for life. Computer models from physical chemist Nir Goldman at the Lawrence Livermore National Laboratory in California suggested impacts could form complex amino acids, and Price and his colleagues set out to replicate these simulations, while astrobiologist Zita Martins at Imperial College in London and her colleagues helped look for any resultant amino acids.
“Impacts are ubiquitous in the solar system — we see impact craters on every solid surface in the solar system,” Price said. “Due to gravity, we know these impacts must occur at very high velocities, kilometers per second. During such impacts, pressures and temperatures get very high, providing an environment that can induce chemical changes in target and projectile materials. One such change is that simple molecules can become more complicated ones.”
In experiments, the researchers fired steel projectiles at speeds of up to 16,000 mph (25,200 km/h) at ice mixtures similar to ones found in comets. The targets could be difficult to work with — “a mix of carbon dioxide ice, ammonia and methanol gets extremely cold, minus 80 degrees Celsius (minus 112 degrees Fahrenheit), and handling the ices and containers meant using several layers of clean gloves, face masks and coveralls,” Price said. “Even so, this still resulted in frostbitten fingers!”
The results included several amino acids, including L-alanine, an important component of proteins on Earth. Martins, Price, Goldman and their colleagues detailed their findings online Sunday (Sept. 15) in the journal Nature Geoscience.
Price cautioned, “We have not created life. Not even close. What we have done is demonstrate a process that takes molecules that were present at the time of the birth of the solar system and made them into molecules that are required for life. It’s like taking simple LEGO bricks and sticking two together. You are a long way from building a house, but it is a start.”
The researchers suggest that icy impacts — whether from icy comets against rocky planets or rocky or icy bodies against icy surfaces such as the moons of Jupiter and Saturn — could have manufactured complex organic molecules.
“As impacts occur everywhere we look, this implies that complicated molecules are also widespread throughout the solar system,” Price said. “We have managed to generate a result that may increase the chance of life being present in an environment outside of the Earth, such as under the ice of Enceladus or Europa.”
Future research can analyze what other compounds might form during such impacts — for instance, whether complex molecules can be altered into even more complex molecules.
The dwarf planet Ceres, which orbits the sun in the asteroid belt between Mars and Jupiter, is a unique body in the solar system, bearing many similarities to Jupiter’s moon Europaand Saturn’s moon Enceladus, both considered to be potential sources for harboring life.
“I think of Ceres actually as a game changer in the solar system,” Schmidt said.
“Ceres is arguably the only one of its kind.”
The innermost icy body
When Ceres was discovered in 1801, astronomers first classified it as a planet. The massive body traveled between Mars and Jupiter, where scientists had mathematically predicted a planet should lie. Further observations revealed that a number of small bodies littered the region, and Ceres was downgraded to just another asteroid within the asteroid belt. It wasn’t until Pluto was classified as a dwarf planetin 2006 that Ceres was upgraded to the same level.
Ceres is the most massive body in the asteroid belt, and larger than some of the icy moons scientists consider ideal for hosting life. It is twice the size of Enceladus, Saturn’s geyser-spouting moon that may hide liquid water beneath its surface.
Unlike other asteroids, the Texas-sized Cereshas a perfectly rounded shape that hints toward its origins.
“The fact that Ceres is so round tells us that it almost certainly had to form in the early solar system,” Schmidt said. She explained that a later formation would have created a less rounded shape.
The shape of the dwarf planet, combined with its size and total mass, reveal a body of incredibly low density.
“Underneath this dusty, dirty, clay-type surface, we think that Ceres might be icy,” Schmidt said. “It could potentially have had an ocean at one point in its history.”
“The difference between Ceres and other icy bodies [in the solar system] is that it’s the closest to the sun,” Castillo-Rogez said.
Less than three times as far as Earth from the sun, Ceres is close enough to feel the warmth of the star, allowing ice to melt and reform.
Investigating the interior of the dwarf planet could provide insight into the early solar system, especially locations where water and other volatiles might have existed.
“Ceres is like the gatekeeper to the history of water in the middle solar system,” Schmidt said.
Studying the surface
As large as Ceres is, its distance has made it a challenge to study from Earth. Images taken by the space-based Hubble Space Telescope provided some insight to its surface, but to be sighted, features could be no larger than 25 kilometers (15.5 miles) in diameter.
Several round circular spots mar the terrain, features which Schmidt said could be any one of a number of geologic terrains, including potentially impact basins or chaos terrains similar to those found on Europa. The largest of these, named Piazzi in honor of the dwarf planet’s discoverer, has a diameter of about 250 km (155 miles). If this feature is an impact basin, it would have been formed by an object approximately 25 km (15.5 miles) in size.
But for Schmidt, this is another possible indication about the dwarf planet’s surface.
“It doesn’t mean that Ceres hasn’t been hit by something bigger than 25 kilometers,” she said. “It just means that whatever is going on on Ceres has totally erased [the topographic signature of that event].”
Ceres may have suffered major impacts, especially during periods of heavy bombardment early in the solar system’s history. If the surface contained ice, however, those features may have been erased.
Telescopes on Earth have also been able to study the light reflecting from the planet and read its spectra.
“The spectrum is telling you that water has been involved in the creation of materials on the surface,” Schmidt said.
The spectrum indicates that water is bound up in the material on the surface of Ceres, forming a clay. Schmidt compared it to the recent talk of mineralsfound by NASA’s Curiosityon the surface of Mars. [The Search for Life on Mars (A Photo Timeline)]
“[Water is] literally bathing the surface of Ceres,” she said.
In addition, astronomers have found evidence of carbonates, minerals that form in a process involving water and heat. Carbonates are often produced by living processes.
The original material formed with Ceres has mixed with impacting material over the last 4.5 billion years, creating what Schmidt calls “this mixture of water-rich materials that we find on habitable planets like the Earth and potentially habitable planets like Mars.”
A prime site for life?
Water is considered a necessary ingredient for the evolution of life as we know it. Planets that may have once contained water, such as Mars, as well as moons that could contain it today, like Enceladus and Europa, are all thought to be ideal for hosting or having once hosted life.
Because of its size and closeness, Schmidt calls Ceres “arguably more interesting than some of these icy satellites.”
“If it’s icy, it had to have an ocean at some point in time,” she said.
Castillo-Rogez compared Earth, Europa, and Ceres, and found that the dwarf planet bore many similarities to Earth, perhaps more than Jupiter’s icy moon. Both Earth and Ceres use the Sun as a key heat source, while Europa takes its heat from its tidal interaction with Jupiter. In addition, the surface temperature of the dwarf planet averages 130 to 200 degrees Kelvin, compared to Earth’s 300 K, while Europa is a frosty 50 to 110 K.
“At least at the equator where the surface is warmer, Ceres could have preserved a liquid of sorts,” Castillo-Rogez said.
Liquid water could exist at other points on the dwarf planet known as cold traps, shadowed areas where frozen water could remain on the surface. Such icy puddles have been found on Earth’s moon. [Photos: Europa, Mysterious, Icy Moon of Jupiter]
“The chemistry, thermal activity, the heat source, and the prospect for convection within the ice shell are the key ones that make us think that Ceres could have been habitableat least at some point in its history,” Castillo-Rogez said.
The future of Ceres
As scientists develop more information about Europa and Enceladus, there has been a greater call to investigate the two prime sites for life. But Schmidt and Castillo-Rogez think that Ceres could also be a great boon for astrobiology and space exploration.
“It’s not a difficult environment to investigate,” she said. “As we think about the future of landed missions for people and rovers, why not go to Ceres?”
Though it would be more challenging to drill into than Europa, which boasts an icy surface layer, the dwarf planet would make a great site to rove around on. Schmidt also noted that it could make a great launching point when it comes to reaching the outer solar system. Its smaller mass would make it easier to land on — and leave — than Mars, which could make it a good site for manned missions.
“We have such a big planet bias, we have such a bias for things that look exactly like us,” Schmidt said.
“In this kind of special place in the solar system, we have a very unique object that might be telling us a lot about what we don’t know about building a habitable planet.”
NASA’s Dawn mission launched September 27, 2007. It traveled to the asteroid Vesta, where it remained in orbit from July 2011 to July 2012 before heading to Ceres. It is slated to spend five months studying the dwarf planet, though Schmidt expressed hope that the craft would continue working beyond the nominal mission, allowing the team to study the icy body even longer.
Castillo-Rogez pointed out that not only will Dawn reach Ceres in 2015, the European Space Agency’s Rosetta spacecraft will be escorting the comet Churyumov-Gerasimenko around the sun that year, while NASA’s New Horizons mission will be reaching Pluto and its moon Charon.
“’15 is going to be a great year for icy bodies,” Castillo-Rogez said.
“I think when we get to Ceres, it’s just going to be an absolute game changer, a new window into the solar system that we wouldn’t have without going there,” Schmidt said.
3D printing could help the asteroid-mining industry get off the ground.
Billionaire-backed asteroid-mining company Planetary Resources is teaming up with 3D Systems, whose 3D printing technology will help craft components for the Arkyd line of prospecting spacecraft, officials announced Wednesday (June 26).
The collaboration should help Planetary Resources build certain parts of its Arkyd 100, 200 and 300 probes more cheaply and efficiently, officials said. [Planetary Resources' Asteroid Mining Plan (Photos)]
“We are excited to work very closely with Planetary Resources’ engineering team to use advanced 3D printing and manufacturing technologies to increase functionality while decreasing the cost of their Arkyd spacecraft,” 3D Systems CEO Avi Reichental said in a statement.
“In success, we will create the smartphone of spacecraft and transform what has been an old-style, labor-intensive process into something very scalable and affordable that will democratize access to space, the data collected from space and off-Earth resources for scientists and the public,” Reichental added.
Planetary Resources co-founder Peter Diamandis said that the use of 3D printing in the production of the Arkyd spacecraft series could help the company achieve its lofty goals.
“We are absolutely thrilled to partner with 3D Systems, the world’s pioneer and leader in 3D printing and advanced manufacturing, as we pursue our vision to expand the resource base beyond Earth,” Diamandis said in a statement. “3D Systems has a long history of inventing, advancing and democratizing manufacturing – and our vision of mass producing the Arkyd 100, 200 and 300 line will greatly benefit from their thinking and technology.”
Planetary Resources officials hope to launch a series of robotic spacecraft into Earth orbit and, eventually, to near-Earth asteroids in order to mine them for resources such as precious metals and water.
The company, which counts Google execs Larry Page and Eric Schmidt among its investors, hopes its efforts help open up the solar system to further human exploration.
The Arkyd 200 and 300 spacecraft will be able to both search for asteroids and fly toward promising targets for closer inspections. Once an asteroid is spotted, Planetary Resources plans to send a group of about five Arkyds out to the space rock, Diamandis said during a recent Google+ Hangout.
The Arkyd 100, on the other hand, will scout for space rocks from Earth orbit.
The first Arkyd 100 is expected to launch in 2015. Planetary Resources has pledged to make one of these satellites the first publicly accessible space telescope ever sent into orbit. The telescope will search for asteroids and take “space-selfies” crafted from user-submitted photos.
Nearly 15,000 people have contributed more than $1.2 million to help build Planetary Resources’ Arkyd 100 through the crowdfunding website Kickstarter. Planetary Resources’ Arkyd 100 Kickstarter campaign ends on June 30 at 10 p.m. EDT (0200 July 1 GMT). To mark the end if the Kickstarter campaign, Planetary Resources will hold a three-hour webcast Sunday beginning at 6 p.m. EDT (3 p.m. PDT/2200 GMT) to present its asteroid-mining efforts to the public.
If the campaign reaches $1.7 million, Planetary Resources has pledged to create an “Asteroid Zoo” project in cooperation with Zooniverse, a citizen-science website that helps connect the public with projects in different fields. According to the company, the Asteroid Zoo is envisioned to be “a program to allow students, citizen scientists and space enthusiasts to find potentially hazardous asteroids (PHAs) at home and help train computers to better find them in the future.”
“Planetary Resources values the power of the connected mind; when working together, we can accomplish much more than any of us can do alone,” Chris Lewicki, President and Chief Engineer for Planetary Resources, said in a statement. “We’re creating this program to harness the public’s interest in space and asteroid detection, while providing a very real benefit to our planet.”
That conclusion, published in the June 20 issue of the Journal of Physical Chemistry A, was based on a computer model of such an impact’s effect on a comet crystal initially made up of water, carbon dioxide and other simple molecules.
“Comets carry very simple molecules in them,” said study co-author Nir Goldman, a physical chemist at Lawrence Livermore Laboratory in California. “When a comet hits a planetary surface, for example, that impact can drive the synthesis of more complicated things that are prebiotic — they’re life-building.”
The notion that life-building molecules were carried to Earth via comets or asteroids, a hypothesis known as panspermia, has been around for decades. But the idea that the comet impact itself could have created the molecules is newer.
When the Earth was young, comet bombardments may have brought 22 trillion pounds (10 trillion kilograms) of carbon-based material to the planet every year, Goldman said. That would have provided a rich source for the building blocks of life to form. In a separate recent study, scientists zapped a mini-comet in the lab to prove that precursor molecules could form far from Earth. [7 Theories on the Origin of Life]
To test their hypothesis, Goldman and his colleagues used a computer model to simulate a single comet crystal of hundreds of molecules. Comets are mostly “dirty snowballs,” Goldman said, so the simulated crystal started with mostly water molecules, but also included methanol, ammonia, carbon dioxide and carbon monoxide.
The researchers then simulated the effects of the crystal hitting the Earth’s surface at various angles, from crashing into it directly to making a glancing blow. They followed the chemical changes in the crystal for about 250 picoseconds, about the amount of time the system needed to reach a steady state, where the proportion and type of chemicals in the system is stable. The huge jolt from the impact provided the energy needed to make complicated chemicals.
“Certain conditions were a sweet spot for complexity,” Goldman told LiveScience.
For instance, at pressures of about 360,000 times the atmospheric pressure at sea level and temperatures of 4,600 degrees Fahrenheit (2,538 degrees Celsius), the molecules in the crystals formed complex species called aromatic rings. These types of circular, carbon-based molecules could have been precursors to the letters in DNA.
At higher pressures, the molecules produced methane, formaldehyde and some long-chain carbon molecules.
“Every time there was an impact hard enough to get chemical reactivity, it produced interesting stuff,” Goldman said.
As a follow-up, Goldman and his colleagues want to test different initial chemical concentrations in the comet to see how that affects the formation process.
No way to prove
The findings are fascinating, said Ralf Kaiser, a physical chemist who studies astrochemistry at the University of Hawaii at Manoa.
“It opens another pathway to explain how these biological, or precursor molecules can be formed,” Kaiser, who was not involved in the study, told LiveScience.
The team has shown that such precursor molecules “absolutely could be formed this way, no question,” Kaiser said.
But it’s not all or nothing: Some molecules could have been carried here by comets from outer space, while some formed on impact, and still others formed completely from home-grown materials. The tricky question is to determine what percentage of life’s building blocks arose during each process, Kaiser said.
It is time for the private sector to aid in the search for potentially city-destroying asteroids and meteors, lawmakers said during a hearing Wednesday (April 10).
The House Committee on Science, Space and Technology made the call while hearing from NASA scientists and private-sector asteroid hunters during a hearing entitled “Threats from Space,” with both groups agreeing that something more needs to be done.
“Detecting asteroids should not be the primary mission of NASA,” Rep. Lamar Smith (R-Texas), chairman of the House Committee on Science, Space and Technology, said at the hearing. “No doubt the private sector will play an important role as well. We must better recognize what the private sector can do to aid our efforts to protect the world.” [Meteor Streaks over Russia, Explodes (Photos)]
The meeting Wednesday was the second of three aimed at understanding the threat to Earth posed by asteroids in space. The first hearing took place in late March, and addressed the ways governmental entities, like NASA and the Air Force, are mitigating the risks posed by close-flying space rocks. The meetings were scheduled in response to a surprise meteor explosion over Russia and the close flyby of asteroid 2012 DA14 — both of which occurred on Feb. 15.
Astronomers have mapped the orbits of more than 90 percent of the potentially world-ending asteroids in close proximity to the Earth; however, tracking anything smaller than 0.6 miles (1 kilometer) in diameter is more difficult, said Ed Lu, the CEO of the B612 Foundation, a nonprofit organization in the early stages of building a near-Earth-object-hunting space telescope scheduled for launch in 2018.
“NASA has not even come close to finding and tracking the 1 million smaller asteroids that might only just wipe out a city, or perhaps collapse the world economy if they hit in the wrong place,” Lu said at the hearing.
B612′s space telescope, dubbed Sentinel, will be built to aid in the search for smaller asteroids near Earth. Less than 10 percent of asteroids measuring around 459 feet (140 meters) in diameter have been found, while only 1 percent of all asteroids measuring around 131 feet (40 meters) — or “city killer” range — have been tracked, Lu said.
These city-destroying asteroids are notoriously difficult to track with the ground-based methods used by NASA today because the space rocks are relatively small and dark, said Don Yeomans, the head of NASA’s Near-Earth Object Program.
“A dramatic increase in near-Earth asteroid-discovery efficiencies is achievable using space-based infrared telescopes,” Yeomans said at the hearing.
Searching for space rocks in infrared light — as the $240 million Sentinel is expected to do — could allow astronomers to find a larger number of smaller objects that are too dark to be seen in visible light, Yeomans said.
A space-based asteroid hunter is also helpful because it can seek out space rocks at all hours of the day, as opposed to just at night, Yeomans added.
All of these hunting efforts should be put in place to find near-Earth objects well before they could hit the Earth, the panelists said.
At the moment, we have the technology to deflect an asteroid, but scientists won’t be able to use those methods without ample time to implement them, Michael A’Hearn, an astronomer working with the National Research Council, said at the hearing.
But first, the asteroids have to be found, Lu said.
“You can’t deflect an asteroid that you haven’t yet tracked,” Lu said. “Our technology is useless against something we haven’t yet found.”