For years, mysterious dark matter has eluded scientists, and now, a new study shows there may be less of it to find.
Using a century-old equation, scientists have found that the Milky Way galaxy holds half as much dark matter — the invisible stuff believed to make up a sizable chunk of the universe — as scientists had previously thought.
By calculating the speed of stars throughout the galaxy and conducting a detailed study of the Milky Way’s outer edges, a team of astronomers in Australia determined that the amount of the unseen dark matter in the galaxy is just 80 billion times the mass of the sun — half the mass of recent estimates.
In the 1950s, scientists determined that galaxies contain more matter than the human eye can see. The everyday material humans can see is made of baryonic matter, and it contains protons, neutrons and electrons. Scientists think dark matter may be composed of baryonic matter, nonbaryonic matter or a mixture of the two. Several possibilities for the material have been raised in recent years.
“Stars, dust, you and me — all the things that we see — only make up about 4 percent of the entire universe,” study lead author Prajwal Kafle, from the University of Western Australia, said in a statement. “About 25 percent is dark matter, and the rest is dark energy.”
Kafle and his team utilized the most up-to-date measurements of the galaxy. The measurements of the outer edges of the galaxy included more detailed studies than previous observations had. Then, the team used a technique developed by British astronomer James Jeans in 1915, long before researchers had envisioned dark matter.
In determining that the Milky Way contains less dark matter than previously thought, Kafle and his fellow researchers gained insight into a problem that theorists have been struggling with for almost 20 years.
“The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter Theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don’t see that,” Kafle said. “When you use our measurement of the mass of the dark matter, the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see — the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf [Spheroidal] galaxy.”
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.
After decades of wondering why young massive stars don’t blow away the gas surrounding them, astronomers have finally found a process that explains how these stellar youngsters hang on to their gassy envelopes.
This star type — more than 10 times the mass of the sun and most active in ultraviolet light — begins shining as a gigantic gas cloud collapses, fusing hydrogen into helium and igniting the star’s nuclear engine. The new research shows that this gas accretion continues even as the star shines, counteracting the stellar radiation that “pushes” against the gas.
A new model reveals that the gas falls unevenly onto the star and also clumps into spiral “filamentary concentrations” because there is so much gas in a small area. When the star moves through the spirals, these filaments absorb the ultraviolet radiation the star emits, protecting the surrounding gas. Once the absorption stops, the gas nebulas shrink. [Top 10 Star Mysteries]
“These transitions from rarefied to dense gas and back again occur quickly compared to most astronomical events,” Mac Low, a curator in the American Museum of Natural History’s Department of Astrophysics and co-author of the paper, said in a statement. “We predicted that measurable changes could occur over times as short as a few decades.”
Massive stars only influential not only when they are alive but also when they die. When a star of this size finishes burning the elements inside it, this triggers a massive collapse and explosion known as a supernova. These explosions created all elements in the universe that are heavier than iron, making Earth and other rocky planets possible.
Young massive stars have been closely studied for decades. Nobody could figure out why the gas around them didn’t blow away, however, as simpler models used previously implied that the gas would expand and dissipate.
The new models, based on observations from the Karl G. Jansky Very Large Array (VLA) in New Mexico, suggest that there are many small ionized hydrogen regions around these stars. The accretion process on the star kept going even after the hydrogen hotspots had formed, which was the opposite of what astronomers expected. Using models, astronomers then supposed that the gas falls unevenly on the star, creating the filaments.
Researchers came to this conclusion after using VLA observations of Sagittarius B2, a huge gas and dust cloud almost 400 light-years away from the center of the Milky Way galaxy. Between observations made in 1989 and 2012, researchers spotted four ionized hydrogen or HII regions getting brighter.
“The long-term trend is still the same, that HII regions expand with time,” said study leader Christopher De Pree, an astronomer at Agnes Scott College. “But in detail, they get brighter or get fainter and then recover. Careful measurements over time can observe this more detailed process.”
The research was recently published in Astrophysical Journal Letters and is also available in preprint form on Arxiv.
Astronomers have found what appears to be one of the oldest known stars in the universe.
The ancient star formed not long after the Big Bang 13.8 billion years ago, according to Australia National University scientists. The star (called SMSS J031300.362670839.3) is located 6,000 light-years from Earth and formed from the remains of a primordial star that was 60 times more massive than the sun.
“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” lead scientist Stefan Keller, of the ANU Research School of Astronomy and Astrophysics, said in a statement. “This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars.” [See amazing photos of supernova explosions]
Scientists think SMSS J031300.362670839.3 is probably at least 13 billion years old, though they do not know its exact age, Anna Frebel, an MIT astronomer associated with the research, said
Keller and his team found that the star actually has an unexpected composition. Astronomers thought that primordial stars — like the one that SMSS J031300.362670839.3 formed from — died in huge supernova explosions that spread large amounts of iron throughout space.
However, the new observations have shown that SMSS J031300.362670839.3′s composition harbors no iron pollution. Instead, the star is mostly polluted by lighter elements like carbon, ANU officials said.
“This indicates the primordial star’s supernova explosion was of surprisingly low energy,” Keller said. “Although sufficient to disintegrate the primordial star, almost all of the heavy elements such as iron, were consumed by a black hole that formed at the heart of the explosion.”
The scientists also found that the early star’s composition is very different from the sun.
“To make a star like our sun, you take the basic ingredients of hydrogen and helium from the Big Bang and add an enormous amount of iron — the equivalent of about 1,000 times the Earth’s mass,” Keller said. “To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon. It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”
Because of its low mass, the star, located in the Milky Way, has a long lifetime, Anna Frebel, an MIT astronomer associated with the research, told Space.com via email.
Keller and his team found SMSS J031300.362670839.3 by using the ANU SkyMapper telescope. SkyMapper is surveying the sky at the Siding Spring Observatory in Australia to produce the first-ever digital map of the sky in the Southern Hemisphere. They confirmed their observations using the Magellan telescope in Chile.
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 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.
Their observations suggest that the space cloud will be completely ripped apart over the next year as it swirls closer to the galactic drain.
Most galaxies are thought to have enormous black holes at their center, and the one at the middle of the Milky Way — roughly 25,000 light years from Earth — has a mass about four million times that of the sun. [Milky Way's Black Hole Rips Apart Gas Cloud (Video)]
Scientists first spotted a gas cloud accelerating toward our galaxy’s supermassive black hole in 2011. Data from 2004 show that the cloud was once shaped like a circular blob, but the intense gravitational forces of the black hole have now stretched it spaghetti-thin, researchers say.
Their new observations were made this past April with the European Southern Observatory’s Very Large Telescope (VLT) in Chile. The cloud’s light becomes more difficult to spot the more it gets stretched, but a 20-hour exposure with the VLT’s special infrared spectrometer, called SINFONI, allowed scientists to measure the cosmic body getting closer to its doom.
Scientists still don’t know where exactly the gas cloud came from, but they say the new observations rule out some possibilities.
“Like an unfortunate astronaut in a science fiction film, we see that the cloud is now being stretched so much that it resembles spaghetti,” Stefan Gillessen, of the Max Planck Institute for Extraterrestrial Physics in Germany, who led the observing team, said in a statement. “This means that it probably doesn’t have a star in it. At the moment we think that the gas probably came from the stars we see orbiting the black hole.”
At its closest approach, the grossly stretched cloud is a little more than 15 billion miles (25 billion km) from the black hole itself — about five times Neptune’s distance from the sun, the researchers say. This is dangerously close considering the black hole’s humongous mass, and the cloud, Gillessen says, is “barely escaping falling right in.”
Gillessen and colleagues say the head of the cloud has already whipped around the black hole and is speeding back in our direction at more than 6.2 million mph (10 million km/h), roughly one percent the speed of light. The tail is following at a slower pace (about 1.6 million mph, or 2.6 million km/h).
“The cloud is so stretched that the close approach is not a single event but rather a process that extends over a period of at least one year,” Gillessen said in a statement.
The new observations will be detailed in the Astrophysical Journal. Scientists plan to intensely monitor the region throughout the year to watch as the cloud gets completely torn apart — a rare opportunity to test theories about how black holes pull in mass.
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.”
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.”
NASA’s bold plan to drag an asteroid into orbit around the moon may sound like science fiction, but it’s achievable with current technology, experts say.
President Barack Obama’s 2014 federal budget request, which will be unveiled today (April 10), likely includes about $100 million for NASA to jump-start an asteroid-capture mission, U.S. Senator Bill Nelson (D-FL) said last week.
The plan aims to place a roughly 23-foot-wide (7 meters) space rock into a stable lunar orbit, where astronauts could begin visiting it as soon as 2021 using NASA’s Space Launch System rocket and Orion capsule, Nelson said.
While challenging, the mission is definitely doable, said Chris Lewicki, president and chief engineer of billionaire-backed asteroid-mining firm Planetary Resources. [NASA's Asteroid-Capture Plan (Video)]
“Return of a near-Earth asteroid of this size would require today’s largest launch vehicles and today’s most efficient propulsion systems in order to achieve the mission,” Lewicki, who served as flight director for NASA’s Spirit and Opportunity Mars rovers and surface mission manager for the agency’s Phoenix Mars lander, wrote in a blog post Sunday (April 7).
“Even so, capturing and transporting a small asteroid should be a fairly straightforward affair,” Lewicki added. “Mission cost and complexity are likely on par with missions like the [$2.5 billion] Curiosity Mars rover.”
Spurring solar system exploration
NASA’s idea is similar to one proposed last year by scientists based at Caltech’s Keck Institute for Space Studies in Pasadena.
The Keck study estimated that a robotic spacecraft could drag a 23-foot near-Earth asteroid (NEA) — which would likely weigh about 500 tons — into a high lunar orbit for $2.6 billion. The returns on this initial investment are potentially huge, the researchers said.
“Experience gained via human expeditions to the small returned NEA would transfer directly to follow-on international expeditions beyond the Earth-moon system: to other near-Earth asteroids, [the Mars moons] Phobos and Deimos, Mars and potentially someday to the main asteroid belt,” the Keck team wrote in a feasibility study of their plan.
The mission would also help develop asteroid-mining technology, advocates say, and advance scientists’ understanding of how our solar system took shape more than 4.5 billion years ago.
Asteroids “probably represent samples of the earliest matter that was made available to form our solar system and our Earth,” Caltech’s Paul Dimotakis, a member of the Keck study team, told SPACE.com in February.
“We learned a lot about the moon by analyzing the moon rocks that Apollo astronauts brought back,” he added. [NASA's 17 Apollo Moon Missions in Pictures]
Asteroids are fascinating for lots of reasons. They contain a variety of valuable resources and slam into our planet on a regular basis, occasionally snuffing out most of Earth’s lifeforms. How much do you know about space rocks?
Unmanned probes have successfully rendezvoused with asteroids in deep space multiple times. Japan’s Hayabusa craft even snagged pieces of the near-Earth asteroid Itokawa in 2005, sending them back to our planet for study.
But bagging an entire asteroid and dragging it to our neck of the cosmic woods is unprecedented, and it presents several daunting challenges.
For example, the target asteroid will be spinning, which doesn’t make for a smooth ride to lunar orbit. After the spacecraft captures the asteroid and brings it into a hold of sorts, the space rock will have to be de-spun, likely with thrusters, Dimotakis said.
“You might use reaction jets to take out most of it [the spin],” he said. “You would give you yourself a lot of time to do this, because there’s no second chance in any of this.”
Further, bringing the asteroid onboard greatly increases the spacecraft’s mass, making propulsion and navigation much more difficult. And precise navigation will definitely be required to deliver the space rock to its desired orbit, Dimotakis said (though he also stressed that any asteroid chosen would pose no danger to humanity even if it somehow struck our planet).
But ion thrusters like the ones powering NASA’s Dawn mission to the huge asteroid Vesta and dwarf planet Ceres should be muscular enough to make the journey, likely taking a few years to reach the asteroid and somewhat longer to come back. And the asteroid-laden probe could probably still be guided with great care, he added.
“My guess is that all of these are not insurmountable challenges, and you would be able to calibrate yourself after you snagged it and adjust your controls,” Dimotakis said.
Choosing a target
Perhaps the biggest challenge of the entire mission is picking a suitable space rock to retrieve, Lewicki wrote in his blog post.
The Keck study recommends going after a carbonaceous asteroid packed full of water and other volatiles. Carbonaceous asteroids can be very dark, and it’s tough to spot and characterize a 23-foot asteroid in the vast depths of space whatever its color.
So both Lewicki and Dimotakis stressed the importance of searching for potential asteroid targets sooner rather than later. Planetary Resources plans to begin launching a line of small prospecting space telescopes in 2014 or 2015, and these “Arkyd-100″ craft could aid NASA’s mission, Lewicki wrote.
Dimotakis, for his part, is engaged in a follow-up to the Keck study that’s looking for potential targets in observations made by current telescopes.
“We are developing software in collaboration with JPL [NASA's Jet Propulsion Laboratory] that is going to exploit the observational digital record and essentially flag things that could be of interest and might be in this class,” he said. “This has never happened before.”
Still, mission scientists and engineers shouldn’t just sit on their hands until an asteroid selection is made, he added.
It’s important “to start developing the spacecraft before you even know where you’re going,” Dimotakis said. “If you do these things in parallel, then the mission timeline shrinks.”
Mars is farther away than any near-Earth asteroid that NASA would target, but this disadvantage may be outweighed by the greater knowledge scientists have gained of the Red Planet thanks to the many Mars missions that have launched over the years, experts say.
Further, mapping out an asteroid mission is nearly impossible at this point, since NASA does not yet know where it’s going.
“There are still no good asteroid targets for such a mission, a necessary prerequisite for determining mission length and details such as the astronauts’ exposure to radiation and the consumables required,” states a December 2012 report from the U.S. National Research Council (NRC). [How NASA Will Explore Asteroids (Gallery)]
The road to Mars
Landing astronauts on Mars has been the long-term goal of NASA’s human spaceflight program for decades, but the agency’s vision of how to get there was shaken up recently.
NASA had viewed the moon as a stepping stone, working to get humans to Earth’s natural satellite by 2020 under a program called Constellation, which was initiated during the presidency of George W. Bush. But President Barack Obama cancelled Constellation in 2010, after an independent review panel found it to be significantly under-funded and behind schedule.
instead directed NASA to send astronauts to a near-Earth asteroid by 2025, then on to the vicinity of Mars by the mid-2030s. The agency is developing a new crewed capsule called Orion and a huge rocket called the Space Launch System to make it all happen.
The new “asteroid-next” plan has not been enthusiastically embraced by NASA or the broader space community, the NRC report concluded.
“Despite isolated pockets of support for a human asteroid mission, the committee did not detect broad support for an asteroid mission inside NASA, in the nation as a whole or from the international community,” write the authors of the report, which is called “NASA’s Strategic Direction and the Need for a National Consensus.”
A tough proposition
The NRC report was based on research, interviews, site visits and analysis conducted by a 12-member independent committee over the course of about five months in 2012.
One of the people the study team met with was Bill Gerstenmaier, NASA’s associate administrator for human exploration and operations.
Gerstenmaier “talked about how NASA had discovered, in the two years that had elapsed by the time he was speaking to us, just how hard [a manned asteroid mission] was,” committee member and space policy expert Marcia Smith said during a presentation with NASA’s Future In-Space Operations working group on Jan. 30.
“He said in many respects, it’s easier to go to Mars, because we know a lot about Mars,” Smith added. “We know where it is, and we’ve done all these reconnaissance missions already, so we have a knowledge base from which to work in terms of sending humans, whereas no particular asteroid has been selected yet.”
While sending astronauts to an asteroid has never been done before, unmanned probes have successfully rendezvoused with the objects in deep space multiple times.
For example, NASA’s Dawn spacecraft orbited the protoplanet Vesta — the second-largest body in the main asteroid belt between Mars and Jupiter — for more than a year before departing to head to the belt’s largest denizen, Ceres, last September. And in 2005, Japan’s Hayabusa probe plucked some pieces off the near-Earth asteroid Itokawa, sending them back to Earth for analysis.
NASA plans to launch its own asteroid-sampling mission, called Osiris-Rex, in 2016. And two private companies — Planetary Resources and Deep Space Industries — intend to loft reconnaissance spacecraft over the next few years, kicking off an ambitious efforts to mine water, metals and other resources from asteroids.
Scientists would love to be able to rewind the universe and watch what happened from the start. Since that’s not possible, researchers must create their own mini-universes inside computers and unleash the laws of physics on them, to study their evolution.
Now researchers are planning the most detailed, largest-scale simulation of this kind to date. One of the main mysteries they hope to solve with it is the origin of the dark energy that’s causing the universe to accelerate in its expansion.
The new simulation is a project led by physicists Salman Habib and Katrin Heitmann of Illinois’ Argonne National Laboratory, and will run on the lab’s Mira supercomputer, the third-fastest computer in the world, starting in the next month or two. The program will use hundreds of millions of “particles” — elements in the simulation that stand in for small bits of matter. The computer will let time run, and watch as the particles move through space in response to the forces acting on them.
As the simulation progresses, these bits of matter will clump together under gravity to form larger and larger blobs representing galaxies, galaxy clusters and superclusters. To evolve the universe from the Big Bang 13.7 billion years forward to today, the simulation will take up to two weeks. [Video: Simulation of the Universe from Big Bang to Now]
Testing the theory
The ultimate goal is to compare the best telescope observations of structure in the universe to the structure displayed in the computer model, to test the reigning theory of cosmology.
“We are trying to look for subtle ways in which it’s wrong,” Habib told SPACE.com. “That’s why you need these very high-resolution, very large-scale simulations to see if the observations don’t match the predictions.”
Dark energy is the name given to whatever is causing the expansion of the universe to accelerate. When this acceleration was first discovered in the 1990s, it shocked the science community, because theories predicted the universe’s expansion would be steady or slowing down, because of the inward pull of gravity.
The current reigning theory posits that dark energy is what’s called the cosmological constant, a term Einstein first thought to put into his equations of general relativity to represent the vacuum energy of the universe. Although Einstein ultimately decided not to include the term, scientists later realized that it could explain the current observations of the expansion of the universe.
However, cosmologists aren’t satisfied with this explanation, Habib said.
“It’s just a single number entered as an extra term in the equations,” he said. “The problem is that if you ask what its value should be, it’s enormous — many orders of magnitude bigger than what is actually observed.”
While simulations based on the cosmological constant so far appear to match what’s seen in large-scale observations of the universe, scientists think that next-generation observations may reveal discrepant details.
If a cosmological constant is not to blame for the accelerated expansion of the universe, another possibility is that space contains some other type of mass or energy, such as a field, that is pulling everything apart.
“It’s basically guesswork; it could be like this, or it could be like that,” Habib said. “Either way it’s very interesting.”
The map, which was released Wednesday (Aug. 8), uses new data to reveal the locations of more than a million galaxies over a total volume of 70 billion cubic light-years. (A light-year is the distance light travels in one year — about 6 trillion miles, or 10 trillion kilometers.)
David Schlegel of Lawrence Berkeley National Laboratory in California said this kind of atlas could help scientists get to the bottom of perplexing mysteries such as the invisible, untouchable dark matter and dark energy that seem to be rampant in space.
“Dark matter and dark energy are two of the greatest mysteries of our time,” Schlegel said in a statement issued with the map’s release. “We hope that our new map of the universe can help someone solve the mystery.”
The new data come from the Sloan Digital Sky Survey III (SDSS-III), and they include measurements from the ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which calculates the distances to galaxies as far as 6 billion light-years away and humongous black holes that lie up to 12 billion light-years from Earth.
The SDSS-III project publically released a large amount of its data, including the map, for use by astronomers around the world in their own studies.
“Our goal is to create a catalog that will be used long after we are done,” said Michael Blanton of New York University, who led the team that prepared the data release.
The release contains photos of 200 million galaxies and spectra (measurements where an object’s light is split into its constituent wavelengths) of 1.35 million galaxies.
“We want to map the largest volume of the universe yet, and to use that map to understand how the expansion of the universe is accelerating,” said Daniel Eisenstein of the Harvard-Smithsonian Center for Astrophysics, the director of SDSS-III.
Scientists think the prevalence of dark energy in the universe is the force causing space to accelerate in its expansion to a greater and greater volume.
By linking powerful radio telescopes in Chile, Arizona and Hawaii together, astronomers created a deep-space observing system with 2 million times sharper vision than the human eye, which gave them the most detailed direct view ever of a supermassive black hole inside a galaxy 5 billion light-years from Earth.
The telescopes revealed a fresh look at the quasar 3C 279, a galaxy in the constellation Virgo that scientists classify as a quasar because it shines ultra-bright as massive amounts of material falls into the giant black hole at its core. The black hole is about 1 billion times the mass of the sun, with the linked-up telescopes providing details down to a resolution of 1 light-year or less, researchers said in an announcement today (July 18).
The new view used an astronomy technique called interferometry and marked “a remarkable achievement for a target that is billions of light-years away,” researchers with the European Southern Observatory explained in a statement.”The observations represent a new milestone towards imaging supermassive black holes and the regions around them.”
The European Southern Observatory (ESO) in Chile is home to the Atacama Pathfinder Experiment telescope used in the quasar study. The other two instruments included the Submillimeter Array in Hawaii, and the Submillimeter Telescope in Arizona. [What Does Quasar 3C 279 Really Look Like (Video)]
By linking the three telescopes together, astronomers with ESO, the Onsala Space Observatory and the Max Planck Institute for Radio Astronomy used an observation method called Very Long Baseline Interferometry.
Here’s how the interferometry method works:
In astronomy, larger telescopes can take sharper pictures or measurements of the universe. The interferometry technique allows astronomers to use multiple telescopes perform as if they were a single telescope, one that is as large as the distance between the different instruments. In Very Long Baseline Interferometry, astronomers seek to maximize the distance between telescopes to create the sharpest views possible.
For the new quasar study, astronomers created a huge triangle of telescopes on Earth using the three different instruments. The distance between the Chile and Hawaii telescopes is 5,870 miles (9,447 kilometers), with the baseline from Chile to Arizona extending across 4,458 miles (7,174 km). The baseline from Arizona back to Hawaii was 2,875 miles (4,627 km).
The telescopes also observed the quasar at extremely short wavelength, making it the shortest wavelength ever observed using such a large baseline array, researchers said.
Altogether, the telescope array was reached a resolution of just 8 billionths of a degree arc in the night sky. For comparison, your closed fist held out at arm’s length covers about 10 full degrees in the sky.
ESO officials said the new look at quasar 3C 279 marks a major step forward for an even more ambitious interferometry-based project called the Event Horizon Telescope. That project aims to combine more telescopes to create an even more powerful very long baseline array, one that could ultimately reveal the shadow of the supermassive black hole at the center of our own Milky Way galaxy.
“The shadow — a dark region seen against a brighter background — is caused by the bending of light by the black hole, and would be the first direct observational evidence for the existence of a black hole’s event horizon, the boundary from within which not even light can escape,” ESO officials said.
A telescope in South America has found tantalizing evidence of primitive galaxies born in the early universe, a find that, if confirmed, would mark the first-ever view of the so-called “dark galaxies.”
Dark galaxies are small, gas-rich objects from the early universe. The existence of such galaxies, which are devoid of stars, but packed with gas, has long been predicted in galaxy formation theories, but direct proof of them has so far remained elusive.
Now, an international team of astronomers may have found dark galaxies by using the light from quasars, the brightest and most energetic objects in the universe, as a guide.
Quasars are powered by enormous black holes that give off huge amounts of energy and light as gas, dust and other material falls into their cores. The astronomers pinpointed the dark galaxies by their glow from the quasars’ light.
“Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it,” study co-author Simon Lilly, of ETH Zurich, an engineering and science university in Switzerland, said in a statement. “We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club.”
In the new study, the scientists were able to glean some preliminary characteristics of the dark galaxies. They estimate that the mass of the gas in such galaxies is roughly 1 billion times that of the sun, which is expected for gas-rich, low-mass galaxies in the early universe. [7 Surprising Things About the Universe]
The astronomers also estimate that star formation in the dark galaxies is suppressed by a factor of more than 100 compared with typical star-forming galaxies at similar stages in their cosmic histories.
In theories of galaxy formation, dark galaxies are thought to be the building blocks of the bright, star-filled galaxies we see today. Some theories state that dark galaxies may have also funneled gas to larger galaxies to form the stars that currently exist.
But dark galaxies are inherently challenging to spot, the researchers said. Since dark galaxies have no stars, they do not emit much light. Astronomers have long attempted to confirm their existence using new techniques that could reveal dark galaxies in the cosmos.
Previous studies of small absorption dips in the spectra of background light sources were thought to have hinted at dark galaxies, but this new study may be the first time that these mysterious objects have been directly detected.
Chasing dark galaxies
Using the European Southern Observatory’s Very Large Telescope (VLT) in northern Chile, the researchers saw the extremely faint fluorescent glow of the dark galaxies. They used the telescope’s FORS2 instrument to map a region of the sky around the bright quasar HE 0109-3518, searching for ultraviolet light that is released by hydrogen gas when it is bombarded with intense radiation.
“After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects,” study lead author Sebastiano Cantalupo, from the University of California, Santa Cruz, said in a statement.
The astronomers found almost 100 gaseous objects within a few million light-years of the brilliant quasar. They eventually narrowed the list to 12, after weeding out objects where the emission might be a product of star formation in the galaxies, rather than from the quasar’s light.
According to the researchers, these objects represent the most convincing detections of dark galaxies in the early universe to date.
“Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds,” Cantalupo said. “With this study, we’ve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas.”