Simulators/ Game Room
Polluted stars suggest other Earth-like worlds
Debris could come from an asteroid belt similar to our own
By Andrea Thompson
updated 8:27 p.m. ET, Mon., April 12, 2010
Earth-like planets should be a fairly common feature of other solar systems in our galaxy, a new study of stellar senior citizens suggests.
More than 90 percent of stars in the Milky Way, including our own sun, end their lives as a white dwarfs. Traditionally, these dense stellar remains haven't been the first place that astronomers look for signs of planets outside our own solar system. Instead, exoplanet searches have focused on stars like our own sun.
But tantalizing new results suggest that these elderly stars might also be a rich source of information on the potential for other planetary systems out there in the galaxy.
White dwarfs should essentially be composed of pure hydrogen and helium atmospheres. Any elements heavier than helium ("metals" in astronomical parlance) present in a white dwarf atmosphere have to be pollutants from some external source.
For decades, astronomers attributed this metallic pollution to the interstellar medium, the thin gas that permeates the space between stars. The idea was that white dwarfs were old stars that had been on several orbits around the Milky Way and had picked up bits of the interstellar medium as they went around, explained Jay Farihi of the University of Leicester who studied the white dwarf contamination.
"But it turns out that
[this explanation] doesn't really fit the data," Fahiri told
What's going on
Farihi and his colleagues looked at the positions of these white dwarfs within the Milky Way and estimated whether the impurities they saw in the stars' atmospheres could be explained by sweeping up the interstellar medium.
"And the answer is a resounding 'No, it doesn't make sense,'" Farihi said.
To get a better look at the pollution in the white dwarf atmospheres, Farihi and his colleagues used data from the Sloan Digital Sky Survey, which has taken the spectrum, or light signature, of 1 million cosmic objects.
They found that the types of metals seen in the stellar atmospheres, such as silicon, magnesium and iron, suggest a rocky origin. The exact source of the rocky debris isn't known, but Farihi says there are two possibilities: the debris could come from an asteroid belt similar to our own, which essential represents a planet that didn't form, or the pieces of a shattered planet.
The new work, presented this week at the Royal Astronomical Society meeting in Glasgow, Scotland, indicates that at least 3 percent and possibly as much as 20 percent of all white dwarfs are contaminated by rocky material. This in turn suggests that a similar proportion of stars like the sun, as well as some a little more massive, such as Vega, that eventually become white dwarfs host planetary systems.
Interestingly, there are also indications that some of the rocky material polluting the white dwarfs contained water.
The white dwarfs studied had helium atmospheres, but showed trace amounts of hydrogen, one of the two elements that make up water. If the hydrogen and the metals came from different sources, the stars that contained them both should be rare, Farihi explained. But they were actually fairly common, suggesting that the hydrogen and metals have the same source.
"The rocks that delivered the metals probably delivered the hydrogen," Farihi said. The hydrogen suggests that the minerals that contained the metals also contained water, an essential chemical for life as we know it.
Finding an oxygen signature in the atmospheres of these white dwarfs would help bolster that interpretation, but Farihi says the team would need to use the Hubble telescope to find that signature. They have request time on the space telescope and are waiting to hear back to see if their proposal is granted telescope time.
Doubling space station crew aids research
Cramped living conditions offset by the potential benefits for science
By David Nowak
updated 7:52 p.m. ET March 25, 2009
BAIKONUR, Kazakhstan - The Russian-American team set to blast off to the international space station said Wednesday that doubling the station's permanent crew will make life more cramped but will further scientific research. Russian cosmonaut Gennady Padalka and American astronaut Michael Barratt will be part of the new six-person crew aboard the station, doubling the crew's previous size.
Padalka and Barratt, along with U.S. space tourist Charles Simonyi, blast off Thursday aboard a Soyuz space capsule from Russia's Baikonur cosmodrome in Kazakhstan. At their final news conference, the space travelers said the burden of cramped living conditions and increased workload will be offset by the potential benefits for science. "It makes things more complex, of course," Barratt said.
"But the basic idea is that we need six people to adequately man the station and to get the science out of it," he said, adding the new arrangements would more closely replicate conditions on lunar bases or missions to Mars. Extra flight activity around the craft and additional spacewalks will also complicate their lives, Padalka said.
The crew increase means Simonyi, a Hungarian-born software developer who will spend 13 days aboard the station, is to be the station's last tourist for the foreseeable future. The other seats will be occupied by representatives of Japan, Canada and the European Space Agency — partners of the U.S. and Russia in the station project.
Barratt joked of possible communication hazards with such a diverse crew. "A sentence could start in Russian, end in English, and I'm afraid by the end of our expedition it could also include elements of Japanese and French," he said. Thursday's blastoff will be attended by the crew members' wives, girlfriends and relatives, including Simonyi's wife, Swede Lisa Persdotter.
The U.S. space shuttle Discovery and its seven-person crew was scheduled to undock from the orbiting station later Wednesday and begin its journey back to Earth. Discovery will be bringing back five months' worth of scientific experiments from the station. The shuttle also is bringing back about one gallon (four to five liters) of recycled water made from astronauts' urine and condensation. NASA wants to make sure the water is safe before space station astronauts start drinking it up there.
Mission to save Hubble ready for rollout
Risky mission will overhaul the telescope for the fifth and final time
updated 9:03 p.m. ET March 25, 2009
A long-awaited mission to repair and upgrade the venerable Hubble Space Telescope will get serious next week when the space shuttle Atlantis is scheduled to roll out to Launch Pad 39A at NASA's Kennedy Space Center in Florida.
The high-profile and risky mission will overhaul the telescope for the fifth and final time.
The rollout is slated to start Tuesday when the shuttle begins a 3.4-mile journey to the launch pad aboard a crawler moving at less than 1 mph.
The fully assembled space shuttle, consisting of the orbiter, external fuel tank and twin solid rocket boosters, was mounted on a mobile launcher platform and will be delivered to the pad atop a crawler-transporter. The process is expected to take approximately six hours.
During Atlantis' 11-day mission, the crew of seven astronauts will make the final shuttle flight to Hubble, considered by many to be the greatest telescope ever. During five spacewalks, they will install two new instruments, repair two inactive ones and replace components. The result will be six working, complementary science instruments with capabilities beyond what is now available, and an extended operational lifespan for the telescope through at least 2014.
Scott Altman will be the commander of Atlantis. Gregory C. Johnson will be the pilot. Mission specialists will be John Grunsfeld, Mike Massimino, Megan McArthur, Andrew Feustel and Michael Good.
The mission is riskier than most because the astronauts will not have the safe haven of the international space station (which STS-119 crew members undocked from today) to turn to if their shuttle heat shield is damaged beyond repair as current missions to the station do. NASA will have a second shuttle ready to launch as a rescue ship instead.
The Hubble repair mission also has an added risk because of the Feb. 10 collision between a U.S. Iridium 33 communications satellite and the defunct Russian military communications satellite Cosmos 2251. The mission was at a higher space debris risk to begin with.
Astronomers catch a shooting star for first time
Asteroid likely leftover from rocks that tried and failed to become a planet
By Seth Borenstein
updated 3:11 p.m. ET March 25, 2009
WASHINGTON - For the first time U.S. scientists matched a meteorite found on Earth with a specific asteroid that became a fireball plunging through the sky. It gives them a glimpse into the past when planets formed and an idea how to avoid a future asteroid Armageddon.
Last October, astronomers tracked a small non-threatening asteroid heading toward Earth before it became a "shooting star," something they had not done before. It blew up in the sky and scientists thought there would be no space rocks left to examine.
But a painstaking search by dozens of students through the remote Sudan desert came up with 8.7 pounds (4 kilograms) of black jagged rocks, leftovers from the asteroid 2008 TC3. And those dark rocks were full of surprises and minuscule diamonds, according to a study published Thursday in the journal Nature.
"This was a meteorite that was not in our collection, a completely new material," said study lead author Peter Jenniskens of NASA's Ames Research Center in California. For years, astronomers have been lobbying to send a robot probe to an asteroid, grab a chunk of it and return it to Earth for labs to analyze the material. Instead a piece of an asteroid dropped in their laps and the researchers were able to track where it came from and where it landed.
The asteroid, which mostly burned in the atmosphere 23 miles (37 kilometers) above the ground, is likely a leftover from when chunks of rock tried and failed to become a planet, about 4.5 billion years ago, scientists said.
"This is a look back in time and it came to us," said University of Maryland astronomer Lucy McFadden. She wasn't part of the study, but like four other outside experts praised the findings as important to the understanding of the solar system.
"It's a beautiful example of looking at an earlier stage of planet development that was arrested, halted," said NASA cosmic mineralogist Michael Zolensky, a co-author of the study.
But it also serves as a lesson for the future if this asteroid's big brother comes hurtling toward Earth.
Blowing it up like in the Bruce Willis movie "Armageddon" would not be smart because this type of asteroid turns out to be very much like a "traveling sandpile," Zolensky said. "If you blow it up, all the pieces are heading toward Earth."
Instead, a spaceship-aided nudge would be more effective, said NASA Ames Research Center director Simon "Pete" Worden, another study co-author. He is a longtime advocate of a worldwide program to plan for the threat of asteroids and comets hitting Earth.
"The real important issue is to understand the physics of these objects," Worden said.
There are many different types of asteroids, all classified from afar based on color and light wavelengths. This type is called class F and turns out to be mostly porous and fragile. University of Maryland's McFadden said it is unlikely that a class F asteroid could be any danger to Earth, even if it's bigger, because of its porous makeup which would cause it to break up before hitting.
It was full of metals, such as iron and nickel, and organics such as graphites, Zolensky said. And most interesting is that it has "nanodiamonds." These diamonds are formed by collisions in space and high pressure and they are all over the rocks, making them glitter like geodes, he said. But they are not big.
"If bacteria had engagement rings, these would be the right size for them," Zolensky said.
Triumph of the telescope
Posted: Monday, November 10, 2008 6:12 PM by Alan Boyle
Caltech / Palomar Observatory
Stars whirl over the 200-inch Hale Telescope's dome in a time-exposure photo.
Astronomer George Ellery Hale's decades-long drive to build bigger and bigger telescopes is the stuff that operas are made of. The epic brought him in contact with the richest and smartest people of a century ago ... forced him to struggle against petty jealousies and personal demons ... and led him to grand achievements that some thought were impossible.
"The Journey to Palomar," a PBS documentary premiering tonight, touches upon all those operatic elements while keeping its focus squarely on the quest's deeper meaning: In the first half of the 20th century, telescope-building was the biggest science around.
"This was the equivalent of a moonshot in that time period," historian Kevin Starr explains during the 90-minute documentary.
Today, it's hard to imagine throngs of people turning out to watch a train bearing a boxed-up mirror pass by. But that's what happened when a 200-inch-wide, 20-ton glass mirror blank made its way from New York's Corning Glass Works to the California Institute of Technology in 1936 for grinding and polishing.
It would be another 11 years before the finished mirror was set into the 200-inch Hale Telescope on Mount Palomar - in part because World War II got in the way.
Hale himself never got the chance to look through the consummate cosmic window he helped create. He died in 1938, a decade before the telescope was finished. That may sound like a tragic ending fit for an opera - but Hale's life was no tragedy. He lived long enough to witness a revolution in astronomy that he helped create.
"The Journey to Palomar," the result of five years of work by Los Angeles filmmakers Todd and Robin Mason, touches on the high points and the low points of Hale's life. The documentary also looks beyond Palomar to tomorrow's mega-telescopes. Here are just a few of the high points and low points from the show:
The Hale Telescope on Palomar continues to contribute to astronomy, under management at Caltech. It's no longer the world's biggest optical telescope: That title passed to the Keck I Telescope in Hawaii in 1993. And the astronomical spotlight shines more often nowadays upon the great observatories in orbit, such as the Hubble Space Telescope, the Chandra X-ray Observatory, the Spitzer Space Telescope and most recently the Fermi Gamma-ray Space Telescope.
There are still more great telescopes to come - wonders that Hale could only dream of, ranging from super-sized, high-tech eyes on Earth to the James Webb Space Telescope in deep space. "The Journey to Palomar" shows how Hale set the stage for 21st-century explorations that could someday show us alien Earths and the very edge of the observable universe.
The plan to revive Hubble
Posted: Thursday, October 09, 2008 5:41 PM by Alan Boyle
The Hubble Space Telescope's handlers are weighing a plan to turn on a never-used backup system to restore communications as early as next week. If it works, the world's favorite orbiting observatory could be back in business just a couple of days later. If it doesn't, Hubble could conceivably be worse off than it was before.
The space telescope has been out of commission since Sept. 27, when its command and data-handling system abruptly failed. That forced a postponement of NASA's final Hubble servicing mission, which was due to begin this week with the launch of the shuttle Atlantis. The launch has been put off until next year - to give mission planners time to figure out how to make a fix, and to give Atlantis' crew time to practice the operation.
In the meantime, engineers have a devised a plan to switch Hubble's data-handling functions from the primary system, known as Side A, to the Side B backup system. Side B hasn't been put to the test since Hubble went into orbit in 1990. "The transition to Side B operations is complex," Hubble's managers explained in a mission update released after the breakdown. "It requires that five other modules used in managing data also be switched to their B-side systems."
All the reconfigurations would be made remotely, by beaming commands to Hubble from the ground. Sources familiar with the plans for the switchover note that there's some risk that the Side B systems won't work. There's even a chance that if the A-to-B switch doesn't work, Hubble wouldn't be able to switch back from B to A. That scenario would complicate plans for the eventual repair mission, and thus provides an argument for leaving things alone until Atlantis arrives.
A spare data-handling unit is being tested at NASA's Goddard Space Flight Center in Maryland, where the Hubble operations team is based. Engineers are also analyzing diagnostic data, according to NASASpaceflight.com, an independent Web site that closely follows the space program.
Hubble's managers reviewed the plans for the A-to-B switch today during a round of meetings at Goddard. More meetings are planned on Friday, and NASA Headquarters would review the recommendations on Tuesday, after the federal Columbus Day holiday. If NASA's top officials give the go-ahead, the switchover could take place as early as Wednesday. Science operations could resume a couple of days after the switch has been made. "If Side B goes up, and it's successful, we're looking forward to resuming science observations and coming up with clever programs to fill the time," said Ray Villard, a spokesman for the Baltimore-based Space Telescope Science Institute.
He said the first of Hubble's instruments to be brought back up would be the Wide Field and Planetary Camera 2, or WFPC2. He said reviving Hubble's other working camera, the Near Infrared Camera and Multi-Object Spectrometer, or NICMOS, would be "trickier" because of the camera system's cryogenics. Hubble's Fine Guidance Sensors could conceivably be used for science as well.
Hubble's other two science instruments, the Advanced Camera for Surveys and the Space Telescope Imaging Spectrograph, are currently out of commission and have been slated for repair during Atlantis' visit. Two more instruments, the Wide Field Camera 3 and the Cosmic Origins Spectrograph, are ready for installation.
NASA was already planning to have Atlantis' astronauts do all those upgrades, and change out Hubble's worn-out batteries and gyroscopes as well. Now more complications lie ahead. Will Hubble's handlers go through with the temporary switchover? How will they adjust the spacewalk schedule and the cargo manifest to accommodate the definitive fix for the data-handling system? Stay tuned for next week's episode of "Hubble's Troubles."
Update for 1:30 p.m. ET Oct. 10: The Hubble team had a good round of meetings on the revival plan on Thursday, and it "feels like we're moving in a positive direction," said Ed Campion, a spokesman at NASA's Goddard Space Flight Center. "We're still moving toward doing the Side B transition," he told me.
Another public affairs officer at Goddard, Susan Hendrix, said the discussion touched on the potential risks: "The team thought there was some risk involved, but they thought it was very low," she said. The meetings are continuing, with the aim of making the decision (and the announcement) on Tuesday.
Was Mars wet for a billion years longer?
Scientists think rains and floods persisted into more recent Mars' history
By Andrea Thompson
updated 12:43 p.m. ET Sept. 17, 2008
Parts of ancient Mars may have been wet for a billion years longer than scientists previously thought, a new study of images of the red planet's surface suggests. Along with Earth and the other inner planets of our solar system, Mars formed about 4.5 billion years ago. Scientists have long known that flowing water formed many of the features seen on Mars today, but previous studies suggested that water runoff from precipitation had ceased after the first billion years of Mars' history, called the Noachian Epoch.
But one team of scientists thinks these rains and floods persisted into more recent — geologically speaking — periods in Mars' history. Catherine Weitz, a senior scientist with Planetary Science Institute in Tucson, Ariz., and her colleagues examined close-up images of the plains surrounding the huge Valles Marineris canyon system taken by the HiRISE instrument aboard NASA's Mars Reconnaissance Orbiter (currently still circling the planet). HiRISE can resolve features as small as 3 feet (1 meter) in diameter.
Weitz and her team noticed that light-toned layered deposits in the plains around Valles Marineris had different features from those inside the canyon; these features suggested that water continued to flow on a large scale in these plans after the Noachian, into the Hesperian epoch of Mars, until about 3.7 billion to 3 billion years ago. Phenomena associated with flowing water are called fluvial processes.
"This was a big surprise because no one thought we'd be seeing these extensive fluvial systems in the plains all around Valles Marineris that were formed during the Hesperian Era," Weitz said. "Everyone thought that by then the climate had pretty much dried out." Another recent study suggested that periods of rain and flooding on Mars were longer in duration, not just short bursts, as had previously been thought.
The deposits that Weitz and her team observed outside the canyon showed "a lot of variations in brightness, color and erosional properties that we don't see for light-toned deposits inside Valles Marineris," Weitz said. "This suggests that the processes that created the deposits outside Valles Marineris were different from those operating inside."
Two locations near the canyon had inverted channels, which, on Earth, form when sediment deposits in a streambed over time. After the stream dries up, the softer terrain surrounding the streambed erodes away, leaving the harder, cemented stream sediments forming a ridge above the surrounding terrain.
Other explanations for the deposits, such as explosive volcanism and wind deposition, can't be ruled out, Weitz said, but the distinctiveness of the features suggests a fluvial origin, she added. "What we're seeing tells us that this light-toned layering on the plains was associated with fluvial activity that wasn't occurring just in little pockets over very brief episodes, but rather on a much larger scale for sustained time periods," she added. "For some reason, there was precipitation around Valles Marineris that allowed these systems to form out on the plains." The details of the study are posted online in the journal Geophysical Research Letters.
Scientists turn on biggest ‘Big Bang Machine’
After 14 years of work, atom-smasher comes to life amid hoopla
The eight torodial magnets can be seen on the huge ATLAS detector with the calorimeter before it is moved into the middle of the detector. This calorimeter will measure the energies of particles produced when protons collide in the center of the detector.
By Alan Boyle
updated 6:25 a.m. ET Sept. 10, 2008
After 14 years of preparation, a new scientific wonder of the world opened for business Wednesday with the official startup of Europe's Large Hadron Collider. The $10 billion particle accelerator is the biggest, most expensive science machine on earth, designed to probe mysteries ranging from dark matter and missing antimatter to the existence of extra, unseen dimensions in space.
Scientists, journalists and dignitaries watched from the control room at Europe's CERN particle-physics center on the French-Swiss border, near Geneva, as beams of protons were sent all the way around the collider's 17-mile (27-kilometer) underground ring of supercooled pipes for the first time. "Today is a great day for CERN," the organization's director general, Robert Aymar, told the crowd in the control room as the startup process began.
Controllers checked the alignment of the beam as barriers were removed at each stage of the route. Applause and shouts greeted every report of progress along the 330-foot-deep (100-meter-deep) tunnel — climaxing when the beam made its first full circuit, less than an hour after it was turned on. "It’s a fantastic moment," Lyn Evans, the project leader for the Large Hadron Collider, said afterward. "We can now look forward to a new era of understanding about the origins and evolution of the universe.”
As champagne flowed in the control room and technicians fine-tuned the LHC's supercooled magnets, former CERN chief Luciano Maiani noted that the money spent on the project over 14 years was a mere fraction of the $40 billion that China spent for this summer's Olympic Games in Beijing. "These are the Olympics of science," CERN spokeswoman Paola Catapano replied during a Webcast interview.
Although the actual subatomic collisions aren't due to begin until next month, CERN designated Wednesday's "First Beam" as the official occasion for celebration. For the more than 10,000 scientists, engineers and other workers involved in the project, the Large Hadron Collider represents a revolutionary new research opportunity as well as an unprecedented engineering achievement.
"The combination of the size, scale, complexity and technology — well, the comparison I always use is the pyramids," Peter Limon, a U.S. physicist from Fermilab who played a part in building the device, said during a pre-startup walkthrough. "This is what we do today comparable to the pyramids of 4,000 years ago." The LHC is designed to do things the pyramid's builders never imagined.
Once the machine is in full operation, two streams of invisible protons will be whipped up in opposite directions around an underground racetrack to 99.999999 percent of the speed of light. When the two waves of protons slam into each other, scientists expect particles to melt into bits of energy up to 100,000 times hotter than the sun's core — a state that should replicate what the entire universe was like just an instant after it came into being. How can the Large Hadron Collider possibly perform such feats? That's where the wonder begins.
Going down ...
Although the scale of the project is impressive, these cathedrals are no gleaming shrines to science: Our trip felt more like going into the bowels of a well-worn power plant or subway system. That's because most of the facility was actually carved out in the 1980s for an earlier particle-smasher called the Large Electron Positron collider, or LEP. CERN has spent the past seven years remodeling the space for the Large Hadron Collider.
Steven Nahn, a physicist at the Massachusetts Institute of Technology, conducted research at CERN during the LEP era. "They stole our tunnel, that's the way I see it," Nahn joked as Limon showed us around. For years, Nahn, Limon and thousands of other researchers have pitched in on the design and assembly of the LHC's instruments, forsaking quiet laboratories for the din of the construction site — as well as the occasional industrial mishap.
The LHC tunnel: Misbehaving magnets
To bend those subatomic bullet trains into a circular path requires a chain of more than 1,800 superconducting magnets that have been chilled so close to absolute zero that they're colder than the average temperature of outer space (1.9 degrees Kelvin, or 456.3 degrees below zero Fahrenheit).
Some of those magnets have to be collimated to focus the beams precisely at the ring's four collision points, like a telescope focusing light onto its mirrors. Drawing on its experience from Tevatron, Fermilab was put in charge of providing many of those magnets. But back in March 2007, a design flaw led to a violent breakdown during a cooldown test. The supports that held the magnet in place came loose with a loud bang and a cloud of dust. "Everybody ducked about two seconds after it happened," Limon recalled.
The LHC's scheduled startup had to be delayed 10 months to install and test a fix for the faulty magnets. Even with the fix, there's no guarantee that the magnetic field will always hold. A runaway proton beam could blast right through its helium-cooled pipeline and kill anyone who got in its way. That's why the tunnel is sealed off for each run. If anything goes wrong, a computer-controlled system will shut down the collider and send the errant beam down a blind alley within milliseconds.
However, if everything goes right, each pulse of protons will whip around the ring 11,000 times a second, traveling the equivalent of a trip to Neptune and back before they slam into the protons going the other way at four points around the ring. Four main detectors will watch what happens next.
ATLAS and CMS: What the detectors do
Physicists determined that protons, neutrons and many of the other particles were built up from even more fundamental constituents known as quarks. The particles built up from quarks are classified as hadrons, and that's where the LHC's name comes from: It's a large collider that smashes hadrons together.
So what will come out of those tiny, trillion-degree smash-ups? The LHC will look for exotic high-energy particles that supposedly came into existence just after the big bang — for example, the Higgs boson (which is thought to give other particles their mass) or supersymmetric particles (which may account for much of the universe's dark matter).
These particles can't be detected directly, because they interact so weakly with ordinary matter. Instead, the LHC's detectors will track how those particles decay into more easily detectable particles as they fly out from the collision point. It's like reconstructing the scene of a crime from forensic evidence: Scientists will try to track down the usual suspects (or, they hope, the extremely unusual suspects) by analyzing the subatomic evidence that the culprits leave behind.
To solve their mysteries, the LHC's scientific sleuths will use the latest and greatest tools of the trade, built at a cost of billions of dollars. The two main detectors — ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact Muon Solenoid) — are structured like the layers of an onion to spot different kinds of particles:
Probing the smallest scales of matter requires some of the biggest machines ever devised. ATLAS is the largest of all detectors, measuring 151 feet long and 82 feet high — bigger than your typical apartment building. "It has an awful lot of free space inside," CERN theoretical physicist John Ellis explained. "The reason for that is, they want to be able to measure particles which come out of the collision ... even if the interior of the detector is so clogged with collision products they can't measure them properly there."
Over on the other side of the LHC's ring, CMS takes up less than half as much space as ATLAS but weighs almost twice as much. It contains more iron than the Eiffel Tower, built into alternating magnetized layers with particle detectors like a metallic jelly roll. CMS' built-in magnets and its expensive fine-resolution silicon tracker are part of a different strategy to do the same things that ATLAS does.
"You get big arguments between the ATLAS guys and the CMS guys as to which is the best way to measure these particles," Ellis said. "ATLAS is going to bend them that way, CMS is going to bend them this way, and we'll see in a few years' time which is the better idea."
ALICE: The big bang in the machine
ALICE will run for only about a month out of every year, conducting experiments that will require the collider to switch over from smashing protons to smashing lead ions, which are 100 times heavier than protons. The high-energy collisions should blast those ions so thoroughly that, for just an instant, they turn into a plasma of free-flying quarks plus gluons, the particles that usually bind quarks together.
Past experiments indicated that the quark-gluon plasma behaved like a liquid. When ALICE gets up and running, "then maybe we reach the gas phase," said Jurgen Schukraft, CERN's spokesperson for the ALICE experiment. That would be something never before seen in the cosmic scheme of things.
LHCb: The mystery of antimatter
Earlier studies revealed that the particles and antiparticles decayed differently, which runs counter to the idea that matter and antimatter should be in symmetry. LHCb will follow up on those studies, using a battery of high-tech detectors that are lined up on one side of the collision point. Among those instruments are a tracker that can locate particles with a precision of 10 microns, or a tenth the width of a human hair.
Two smaller experiments round out the ring: LHCf, which studies cosmic-ray-like events near ATLAS; and TOTEM, which measures the effective size of protons using a detector near CMS.
The Grid: Getting out the data
Each of the detectors uses "triggers" to pick out the good stuff. Only about 100 events per second are sent to thousands of computers and tape drives at CERN for storage. It's like narrowing down that moon-high stack of CDs to a stack that's only 6 miles high — which is still high enough for a transcontinental jet to run into.
To get the data out to researchers around the world, CERN has set up a multi-tier computer network called the Grid. Digital information goes out to the "Tier 1" data centers on a fiber-optic network at a rate of up to 10 gigabits per second — or roughly 1,000 times the speed of a typical cable Internet connection.
If the system works, it could set the model for future computing — not only for physics but also for other high-end applications such as climate simulation, genetic analysis and petroleum prospecting. Just as the World Wide Web was the best-known spin-off from CERN's LEP experiment back in the 1990s, the Grid could well become the LHC's most visible legacy.
Magnet for innovation
That has sparked more than a few cases of "collider envy" among American researchers, and some worry about the prospects of a reverse brain drain. Michio Kaku, a theoretical physicist at the City College of New York, is already noticing a trend in his colleagues' travel plans.
"They're going where the action is, and that is Europe," Kaku said.
Life’s ingredients may have ‘sprinkled’ on Earth
A component of DNA might survive space and sprinkle onto planets
By Dave Mosher
updated 11:52 a.m. ET Sept. 11, 2007
Some crucial ingredients for life on Earth may have formed in interstellar space, rather than on the planet's surface. A new computer model indicates clouds of adenine molecules, a basic component of DNA, can form and survive the harsh conditions of space, and possibly sprinkle onto planets as the stars they orbit travel through a galaxy.
"There may be only a few molecules of adenine per square foot of space, but over millions of years, enough could have accumulated to help make way for life," said study co-author Rainer Glaser, a molecular chemist at the University of Missouri-Columbia. Glaser and his team's findings are detailed in a recent issue of the journal Astrobiology.
Using computer simulations of the cold vacuum of space, Glaser and his colleagues found that hydrogen cyanide gas can build adenine. Like pieces in a set of tinker toys, hydrogen cyanide serves as adenine's building blocks; the small molecules bond together into chains and, with a little wiggling, eventually assemble into rings.
Although adenine's first ring needs a tiny energy boost from starlight to form, Glaser said the second ring of the molecule self-assembles without any outside help. "When you want to have a reaction, you usually need to heat it up," Glaser said. "It's remarkable to find a reaction that doesn't require activation energy. If you do this reaction in space, this is a huge advantage because it takes a long time for a molecule to be hit by a piece of light."
Seasoned for life? Glaser said adenine's ringed shape helps it absorb and release any excess energy without breaking apart, making it stable enough to form concentrated clouds that planets can drift through. While getting adenine safely onto a rocky planet's surface is a less developed idea, Glaser said many chemists have barely toyed with the notion that life's basic ingredients formed off of the planet's surface.
"We're at a very early stage of anybody even thinking about these things," he said. "The discussion of life's origin has been highly focused on the idea of a warm pool of liquid on the planet's surface." But Glaser said recent discoveries of planets around distant stars is changing that focus. "Chemistry in space isn't the chemistry most of us are trained for," Glaser said. "We should take a much bigger approach: Where are all the chemicals in the galaxy and its solar systems, and what can you do with them?"
Antonio Lazcano, an evolutionary biologist at the National Autonomous University of Mexico who has studied life origins for the past 30 years, said Glaser and his colleagues' work is compelling. "We already know hydrogen cyanide is abundant in interstellar clouds, and it's been suggested that comets can bring some of that material onto planets," Lazcano said. For Glaser and his team's idea to be widely supported, however, adenine needs to be detected in the deep space clouds, Lazcano said. "The likelihood of detection is very small, but it's still possible," he said. "If astronomers can better eliminate background noise, I think we'll have equipment sensitive enough to detect adenine dust clouds."
WILL THE SPACE ELEVATOR RISE?
Pat Rawlings/NASA files
Posted: Friday, July 18, 2008 7:38 PM by Alan Boyle
If space elevators work out the way the idea's advocates hope, sending payloads into orbit would become as routine as, say, sending a shipment on a freight train - except that the train would travel straight up for hundreds or thousands of miles, powered by laser beams.
But will such a "railroad to the sky" ever be built? That's the big question hanging over the 2008 Space Elevator Conference, taking place this weekend on Microsoft's Seattle-area campus. And considering that this is an event primarily attended by elevator enthusiasts, you may find some of the answers surprising.
One of the biggest advocates of the concept, the late science-fiction seer Arthur C. Clarke, said back in 1979 that the first space elevator would be built "about 50 years after everyone stops laughing."
There wasn't much laughing to be heard as the talks got under way today at Microsoft's Redmond conference center (which happens to be a five-minute walk from my newsroom at msnbc.com, a Microsoft-NBC Universal joint venture). Instead, there was a long day's worth of serious talks about way-out subjects such as orbital debris threats and power-beaming lasers.
And there were a lot of predictions: On one end of the scale, Bradley Edwards, president of New York-based Black Line Ascension and one of the pioneers of the space elevator movement, said creating a space elevator would require much less time than 50 years - as long as you had $7 billion to $10 billion to spend.
"It's really a cost issue," he told me. "If you could get the money, you could have one up in probably 12 years, 15 years." On the other end of the scale was Tom Nugent, project manager for Seattle-based LaserMotive, who said the space elevator would never be built, due to technical and safety concerns.
"We don't believe in the space elevator," Nugent told me. The way he sees it, all the activities spawned by the concept merely provide "a useful way to demonstrate our laser power beaming technology." In between those extremes, there's a Japanese technological road map that calls for building a space elevator and a space solar power system by 2030, and a NASA projection that the elevator would take shape in 200 years or so.
Ted Semon, who presides over the Space Elevator Blog, sized up the potential players and concluded that the builder of the first space elevator would likely be either a U.S. industry consortium supported by the federal government - or an alliance involving the governments of Dubai and India. "Dubai could fund it just like that," he told me. "And India would love to jump at the chance to leapfrog China."
Even if you scoff at the starry-eyed vision of riding a ribbon to outer space on a laser-powered lift, the technologies that form the foundation of that vision are far more down to earth - and likely to produce profits long before the space elevator sees the light of day. That's what Nugent and many of the conference's other attendees are going after.
The technological road ahead
The tethers would be sent into orbit aboard a conventional launch vehicle. One set of tethers would be lowered down from the orbiting craft for connection to an "attach point" on Earth's surface - for example, a floating platform in an area of the ocean that's relatively unaffected by weather. Counterbalancing tethers would spool out spaceward.
Those tethers would serve as the "rails" for robots climbing up and down to the orbital transfer station. Proponents say such robots could carry payloads at a cost of $100 per pound or less - compared with current orbital launch costs that range from $2,000 to $60,000 a pound, depending on what is launched and how high it goes. Other types of robots would build up the system and keep it in repair.
You can't really fuel up a robot for this kind of trek to space, so you'd need to find a wireless, tankless way to transmit power hundreds or thousands of miles. That's where the power-beaming systems come in: Laser light from below would be focused on photoelectric cells to keep the robots running, perhaps supplemented by solar power from above.
If those technologies come together, then what? "There are lots of things we want to do in space, but part of the problem is getting there," Edwards said. Cheaper access to space could open the way for space solar-power satellite systems that can beam energy back down to Earth. Elevator operators could send people and payloads to orbital hotels, and then onward to the moon and Mars. The elevators might even revolutionize garbage disposal, Edwards said. "There has been a lot of discussion about using space elevators to take radioactive waste and get rid of it by throwing it into the sun," he said.
Where are those technologies today?
Edwards pointed to advances in carbon nanotube fabrication, which he saw as essential for space elevator construction. "That's the only thing that's strong enough," he said. He hailed advances that have brought new records for nanotube length as well as new methods for spinning nanotube fibers.
"Some of the work being done is now becoming a business," Edwards said. Nanotubes are already being woven into the marketing hype for bikes as well as golf clubs, and Edwards predicted that a technological tipping point could come sometime in the next year.
Are nanotubes safe? A recent study raised health questions about the stuff but Edwards said the safety concerns were not as serious as some have made them out to be, particularly for space applications.
Ben Shelef, director of the Spaceward Foundation, was hopeful that the nanotube hurdle would be overcome sooner than the skeptics think. "While we're definitely not there, we're not a factor of 50 away. We're a factor of 10 away," he said.
Shelef previewed Spaceward's plans for the fourth annual Space Elevator Games, a double-header competition that focuses on super-strong tethers as well as power beaming. This year, NASA is offering $4 million in prizes for the winners of the games' ambitious contests, and Spaceward is organizing the contests on NASA's behalf.
To take the top tether prize, the winning team will have to develop a material that can take more stress than the other competitors' offerings, and also best a "house tether" that has a 50 percent weight advantage. Eleven teams have signed up for the power-beaming competition, which involves sending a beam-powered robot up a 0.6-mile-long (1-kilometer-long) tether suspended from a helicopter. If the robot completes the required length with an average speed of 6 feet (2 meters) per second, it would be in the running for a $900,000 prize. If the average speed reaches 16 feet (5 meters) per second, the prize rises to $2 million.
Shelef said the tentative plan is to conduct the games at Arizona's Meteor Crater in mid-October, but the timing and the venue are still subject to change. So far, none of the teams has satisfied any of the requirements for a prize, and as a result NASA hasn't paid out any money in the Space Elevator Games. That may change this year, Shelef said. "This is going to be the first year, I think, where [each] team's main enemy is the other teams," he said. Just this week, LaserMotive announced that it satisfied the power-beaming contest's requirements in a treadmill test. However, the company is expected to face stiff competition from last year's favorites, including the University of Saskatchewan Space Design Team.
If a viable power-beaming system could be developed, it would find almost immediate application. The U.S. military has talked about using beam power to energize balloon-based observation platforms or robotic drone aircraft. Point-to-point power beaming could cut down on risky fuel resupply missions in combat zones. Beyond the battlefield, NASA could conceivably use power-beaming stations to boost rovers or bases on the moon or Mars. And beaming power down to Earth is key to the space solar power systems I've already mentioned.
So ... will it ever rise?
Ivan Bekey, president of Virginia-based Bekey Designs, said that last point was a potentially fatal flaw for the space elevator concept. "We've got a very fundamental problem for which I have seen no engineering or cost analysis to solve," he said.
Edwards said there were potential solutions to the debris-collision problem, such as repositioning the elevator's Earth station, which would in turn move the system's tether out of the path of the occasional piece of space junk. However, he conceded that more analysis was needed. "There's no funding," he said, "and this is a real falling-down for the entire program."
Edwards said several new initiatives were in the works to pool together information and raise public awareness, including a Space Elevator Wiki and a Japanese movie titled "Space Elevator: The Future as Foreseen by Scientists." You can watch a trailer for the movie (in Japanese) as well as a mini-interview with Edwards (in English).
Edwards also hopes to see the rise of a Florida theme park celebrating the space elevator concept. Visitors to the attraction would take a ride on a virtual space elevator to a virtual space station, all enclosed within a 10-story-high structure. Edwards said the land has already been selected for the facility, outside Orlando, and he's working on getting the first $300,000 in seed capital by Nov. 30.
Volcanoes on Mercury solve 30-year mystery
NASA spacecraft’s first flyby yields new info about innermost planet
By Andrea Thompson
updated 6:23 p.m. ET, Thurs., July. 3, 2008
A NASA spacecraft's first flyby of Mercury has yielded a wealth of information about the innermost planet, some of which confirms volcanism occurred there, settling a longstanding debate. Information about such planetary mysteries as Mercury's magnetic field and geological history also has flooded in. "We're really pleased," said Sean C. Solomon of the Carnegie Institution of Washington, principal investigator for the Messenger probe. "[The data] gives us a lot to chew on."
Messenger (short for MErcury Surface, Space ENvironment, GEochemistry and Ranging) made its debut flyby of Mercury on Jan. 14, passing about 124 miles (200 kilometers) over the planet's surface. The spacecraft's instruments took a closer look at the areas seen by the Mariner 10 mission in 1974 and 1975, which imaged about 45 percent of the planet's surface, as well as an additional 21 percent of the surface never before seen by a spacecraft. In a collection of 11 papers detailed in Friday's issue of the journal Science, mission scientists presented the preliminary findings of the initial flyby.
Volcanism or impact melt?
The resolution of the Mariner 10 images as well as the angle of sunlight illuminating the features prevented scientists from determining which geological mechanism had created the plains on Mercury. "That created a stalemate for basically 30 years," until Messenger arrived on the scene, said science team member James Head of Brown University.
The angle of the sun's light on Mercury's features this time around yielded more detail and evidence pointing to volcanic activity. False-color images of the plains and presumed volcanic features showed that they had an orange tint and were "distinctly different from [their] surroundings," Head said.
Messenger images of the Caloris basin, the youngest-known impact basin on Mercury, showed smaller craters within the impact basin that had been filled in with material, "and if you had impact melt [as with the lunar breccia], that wouldn't happen," explained Johns Hopkins University's Scott Murchie, a co-investigator for the Mercury Dual Imaging System.
The small craters likely were the result of impacts in the basin long after it was formed. Later still, volcanic eruptions spewed lava across the basin, all but erasing the smaller craters. Head said this was "clear evidence that you're looking at lava flows."
Messenger also took images of what scientists think is a shield volcano, which are large with gently sloping sides, within the basin. Head said he knew volcanism was behind the smooth plains on Mercury as soon as the image of the volcano was beamed back to Earth: "This was really like a smoking gun."
The volcano is about 60 miles (95 kilometers) in diameter, bigger than the state of Delaware. "This is a big sucker," Head said. Messenger also confirmed that the surface of Mercury is very low in iron, though the planet's high density implies that its core is very iron-rich. Head said this implies that Mercury formed slightly differently from the rest of the inner planets. The processes that formed the planet would have been the same, "it's just that the outcomes were so different," he told Space.com.
Messenger found more of these faults than Mariner 10 originally did, suggesting that the strain from the planet's contraction was at least one-third greater than scientists originally thought, one of the Science papers stated. Essentially, as the hot, dense core cooled, some of the material would have solidified, sinking toward the center of the planet, forming an inner, solid core. When most solids cool, they also contract. In the case of Mercury, the planet's diameter was only decreased by about one-tenth of 1 percent, but in geologic terms, "it's a pretty big shrinkage," Solomon said.
When Messenger settles into orbit around Mercury in 2011 and gets a closer look at the escarpments, they may serve as "a record we can read" to determine when and how much contraction took place, and whether it happened continually and gradually or occasionally sped up, Solomon said. Scientists will also be able to use variations in crater density across the surface to date the sequence of geological events. "The longer a surface sits out there, the more cratered" it becomes, Solomon explained, so more cratered surfaces should be older formations.
Above the surface
During its flyby, Messenger took measurements of the magnetic field, and the results suggest that like Earth's field, Mercury's is largely dipolar (or like having a giant bar magnet stuck inside the planet). But Mercury's magnetic field is much weaker than the one that surrounds our planet.
"Mercury's field is a smaller version of the Earth's," Solomon said. Because the field is weak and Mercury is so close to the sun, the solar wind pushes the planet's magnetosphere very close to its surface on the side facing the sun, while on the side opposite the sun, the magnetosphere is very elongated.
In fact, "the solar wind gets very close to Mercury's surface some of the time," occasionally even hitting the surface, Solomon told Space.com. When the solar wind hits Mercury's surface, it sputters particles off into the magnetosphere. Messenger detected these ionized atoms as it sailed through the magnetosphere; it found silicon, sodium, sulfur and even water ions surrounding the planet.
Voyager 2 confirms solar system is dented
Spacecraft reached southern edge of the solar system after 7 billion miles
By Jeremy Hsu
updated 3:25 p.m. ET, Wed., July. 2, 2008
Voyager 2's journey toward interstellar space has revealed surprising insights into the energy and magnetic forces at the solar system's outer edge, and confirmed the solar system's squashed shape. Both Voyager 1 and Voyager 2 continue to send data to Earth more than 30 years after they first launched. During the 1990s, Voyager 1 became the farthest manmade object in space.
Each spacecraft has now crossed the edge of the solar system, known as termination shock, where the outbound solar wind collides with inbound energetic particles from interstellar space. The termination shock surrounds the solar system and encloses a bubble called the heliosphere.
"The solar wind is blowing outward trying to inflate this bubble, and the pressure from interstellar wind is coming in," said Edward Stone, physicist and Voyager project scientist at Caltech in Pasadena, Calif. He and other researchers published a series of studies in the journal Nature this week that detail the Voyager findings.
This way and that
Comparing the Voyager 1 crossing in December 2004 with the Voyager 2 crossing in August 2007 allowed scientists to confirm that the second sibling actually crossed the termination shock and passed into the heliosheath, an outer layer of the heliosphere. But Voyager 2 also carries more working instruments that show the termination shock in full detail. "We're actually seeing the shock for the first time," said John Richardson, principal scientist for Voyager's Plasma Physics instrument at MIT in Cambridge, Mass.
Voyager 1's plasma detector failed after it passed Saturn, so Voyager 2 provided the first glimpse of what happens to the solar wind's energy as it slams into interstellar space. The solar wind travels outwards from the sun at supersonic speeds, and at temperatures near 17,540 degrees Fahrenheit (10,000 degrees Kelvin). Scientists had predicted that the solar wind would simultaneously slow down and heat up to a temperature near 1.8 million degrees F (1 million degrees Kelvin), but instead found that it reached just 180,000 degrees F (100,000 degrees Kelvin) at the solar system boundary.
Hitching a ride
"Somehow the solar wind knows the shock is coming before it gets there, and theory says that shouldn't be," Richardson noted, adding that the solar wind speed drops from its supersonic speed of about 248 miles per second (400 km/s) to 186 miles per second (300 km/s) even before hitting the edge of the solar system. That speed falls more noticeably to about 93 miles per second (150 km/s) after the termination shock.
Even as researchers continue parsing the Voyager findings, both spacecraft plow onward toward deep space — and beyond all expectations of their original mission. "My guess is five to seven years to reach interstellar space," Stone said. "There's a very good chance that Voyager I will send the first data back from there."
Saturn mission goes into overtime
Cassini orbiter begins two-year extension, focusing on moons and equinox
updated 8:08 p.m. ET, Tues., July. 1, 2008
The multibillion-dollar Cassini orbiter has officially ended its four-year primary mission to Saturn — ushering in a two-year extended mission that will focus on the ringed planet's mysterious moons. The primary mission began when the spacecraft entered Saturnian orbit on July 1, 2004 (or June 30 in some time zones). Cassini produced the first pictures that pierced the haze surrounding Titan, Saturn's biggest moon. The orbiter also sent down a European-built piggyback lander called Huygens, which beamed back pictures from Titan's surface. The Cassini-Huygens observations revealed that Titan was laced with hydrocarbon seas and channels.
Cassini also discovered geysers of ice spewing from Enceladus, another Saturnian moon that may harbor subsurface oceans and perhaps even life. Titan and Enceladus are the primary targets for Cassini's extended mission, which NASA approved in April. Cassini will also monitor seasonal effects on Titan and Saturn, explore Saturn's magnetic field and witness Saturn's equinox on Aug. 11, 2009, when sunlight will pass directly through the plane of the planet's rings.
The spacecraft's new agenda has been dubbed the Cassini Equinox Mission in honor of the astronomical event, which occurs roughly every 15 years. Cassini's $3.3 billion primary mission was funded by NASA, the European Space Agency and the Italian Space Agency. NASA is picking up the bill for the $160 million extension. Officials have said the mission could be extended yet again if Cassini was still in good working order in mid-2010.
"We've had a wonderful mission and a very eventful one in terms of the scientific discoveries we've made, and yet an uneventful one when it comes to the spacecraft behaving so well," Bob Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory, said in a statement. "We are incredibly proud to have completed all of the objectives we set out to accomplish when we launched. We answered old questions and raised quite a few new ones, and so our journey continues."
JPL said that Bob Pappalardo, a geologist at the lab in Pasadena, Calif., would step into the role of Cassini project scientist for the extended mission. He replaces Dennis Matson, who will be turning his focus to future flagship space missions, according to NASA. Carolyn Porco of the Colorado Space Science Institute, leader of Cassini's imaging team, said that the orbiter was "a robust and capable craft and will continue its work with ease."
"To explore a planetary system very much unlike our own is an occasion like no other," she said in a statement. "It has been hard going and exhausting for sure, but in return we have been rewarded beyond all imagining. Without equivocation, we on Cassini can proudly proclaim: Mission accomplished!"
Mars' two-faced nature may have been caused by a giant kick in the head, according to a new study.
Recent evidence suggests the vast disparity seen between the northern and southern halves of the planet is caused by the long ago impact of a gigantic space rock into Mars.
The finding, based on a survey of the red planet's gravity and topography, provides the first convincing support for the idea that the red planet is the site of the largest impact crater in our solar system. The collision that caused the scar would have occurred more than 3.9 billion years ago, the researchers said, around the time an even larger asteroid is thought to have struck Earth, forming our planet's moon.
"This impact is really one of the defining events in Mars' history," said MIT postdoctoral researcher Jeffrey Andrews-Hanna, who led the new study with MIT geophysicist Maria Zuber and NASA Jet Propulsion Laboratory researcher Bruce Banerdt. "More than anything this has determined the shape of the planet's surface. Mars would not be the planet it is today if this hadn't occurred."
Scientists have been scratching their heads trying to explain the differences between the two sides of Mars for about 30 years. The northern hemisphere of the planet is smooth and low, and some experts think it may have contained a vast ocean long ago. Meanwhile, the southern half of the Martian surface is rough and heavily-cratered, and about 2.5 miles to 5 miles (4 km to 8 km) higher in elevation than the northern basin.
Scientists first proposed the idea of a space rock impact to explain the difference in 1984, but for a long time this hypothesis had less support in the field than a competing idea, that internal processes, such as the convection of heat through the mantle, created the different features.
"In the past it has been thought that it just doesn't look like an impact crater," Andrews-Hanna said. "The outline just looked irregular, not circular."
By combining detailed topographical data from the Mars Global Surveyor mission with measurements of the variations in the planet's gravitational field made by the Mars Reconnaissance Orbiter satellite, Andrews-Hanna and his team assembled a map of the Martian surface before volcanic eruptions added layers and obscured the boundary between the hemispheres. The map revealed a stunning elliptical basin shape covering about 40 percent of Mars' surface.
"This was a kind of surprising result," Andrews-Hanna said. "What we noticed is that the dichotomy boundary around the planet was actually smooth and regular. We tested to see if we could fit this with any shape, and it just so happens that it's almost perfectly fitted by an ellipse. There's only one process that's known to make an elliptical depression like that, and that's a giant impact."
The discovery helps to overcome a major criticism of the space rock impact suggestion, that there is not enough visual evidence to support it.
"This is the one thing that nobody had seen before," Andrews-Hanna told SPACE.com. "One of the main arguments against the giant impact hypothesis was that it doesn't look like an impact basin, therefore that's not a good solution. Now we can say that all the evidence we have available to us is pointing toward a giant impact. We can't disprove the other hypotheses, but I think it becomes a challenge now for those hypotheses to explain the feature."
The elliptical crater the study revealed is roughly 5,300 miles (8,500 km) across and 6,600 miles (10,600 km) long, about the size of the combined area of Asia, Europe and Australia. That makes this crater about four times larger than the next-biggest impact basins known, the Hellas basin on Mars and the South Pole-Aitken basin on the moon.
The research changes the debate about the two faces of Mars, but doesn't settle the question forever.
"I think it's an important step forward, but it's not the last word," said Jay Melosh, a planetary scientist at the Lunar and Planetary Lab at the University of Arizona, who was not involved in the new study. "It certainly makes the impact scenario look a lot more plausible than it did before. It's a very strong argument in favor of the giant impact, but there is still no proof."
In order to prove the features seen on Mars are the result of a space rock smash and not some other event or process, scientists would need to find rocks or minerals that could have formed only as the result of an impact.
"If you have a big impact it changes the rocks in characteristic ways," Melosh said. "Minerals like quartz are changed into a form that only occurs at high pressure. It's that kind of change we use on Earth to verify whether impact craters are caused by an impact or something else. If they are right we should be able to find evidence in Martian rocks."
This kind of test will have to wait a while until humans can mount missions to Mars to search for these rocks. Scientists would probably need a suite of samples returned from various areas on the planet to be sure, Melosh said.
Modeling the impact
The map created by Andrews-Hanna and his colleagues will be published in the June 26 issue of the journal Nature, along with two other papers that support the Mars findings.
For the latter papers, two groups of researchers used computer models to study the effects such an impact would have had on the planet.
Caltech graduate student Margarita Marinova and planetary scientists Oded Aharonson of Caltech and Erik Asphaug of the University of California, Santa Cruz (UCSC) tested a series of theoretical space rocks approaching Mars with various velocities, energies and sizes. The scientists found that an asteroid about one-half to two-thirds the size of Earth's moon striking Mars at an angle of 30 to 60 degrees could have produced a basin such as the one mapped by Andrews-Hanna's team.
The results help address one of the other main objections to the impact hypothesis — the suggestion that any space rock massive enough to form such a large basin would have melted so much of the planet's surface that all evidence of it would be erased.
"They found, contrary to what was previously thought, that you don't produce that much melt," Andrews-Hanna said. "Most of the melt gets contained in the basin."
Another computer model, by UCSC planetary scientist Francis Nimmo, graduate student Shawn Hart, associate researcher Don Korycansky, and Craig Agnor of Queen Mary University, London, complements these findings.
This group simulated the behavior of the Martian crust during an impact and found that not only could an impact such as the one proposed cause the differences seen in Mars' two halves, it could also explain other features seen on the red planet, such as magnetic field anomalies found in the Southern hemisphere.
Nimmo's model showed how shock waves from the impact on the northern hemisphere would travel through the planet and disrupt the crust on the other side, causing changes in the magnetic field.
"The impact would have to be big enough to blast the crust off half of the planet, but not so big that it melts everything," Nimmo said. "We showed that you really can form the dichotomy that way."
BLACK HOLES FOR BEGINNERS
Posted: Wednesday, June 25, 2008 5:10 PM by Alan Boyle
If big black holes are so scary, why do scientists think it's not a problem to be around teeny-tyny balack holes? Astrophysicist Neil deGrasse Tyson literally wrote the book on"Death by Black Hole," so he ought to know. He also ought to be good at explaining the difference, since he's the director of the Hayden Planetarium at New York's American Museum of Natural History as well as the host of "Nova ScienceNow," the TV magazine show that begins its summer season on PBS tonight.
If you're wrestling with all the claims and counterclaims over matter-gobbling black holes, this is the guy you want on your side.
Tyson, who turns 50 in October, is used to wrestling with scientific puzzlers - and just plain wrestling, for that matter. He was captain of the wrestling team at the Bronx High School of Science as well as editor-in-chief of the school's Physical Science Journal.
More recently, he has wrestled with America's future space policy as a member of several advisory commisions. But you could argue that his most challenging match found him pitted against the scientists and second-graders who are fans of the planet Pluto. Eight years ago, Tyson had to take the heat when the remodeled Rose Center for Earth and Space (which serves as the Hayden Planetarium's home) dropped Pluto from its planet display.
Tyson defended the demotion, saying that the discovery of other icy worlds on the solar system's edge implied that the littlest planet should be reclassified as the biggest member of a new class of celestial objects. In 2005, it turned out that Pluto wasn't even the biggest: Another ice world, eventually dubbed Eris, was found to be even bigger. That set off new rounds of decisions and debates that are still raging.
Tyson says he's taking the subject head-on in a book titled "The Pluto Files," due for publication next year. "It's a study of the public's reaction to the scientific demotion of a planet," he explained in an interview this week.
But enough about Pluto: On tonight's installment of "Nova ScienceNow," Tyson and his team will be wrestling with the mysteries of dark matter as well as the causes of Alzheimer's disease, the scientific methods for detecting fake imagery and the wisdom of crowds." If you miss the show, or if you don't live in an area that gets PBS, you can watch the whole show online beginning Thursday.
About those black holes...
We've known for decades that such things should exist out in the cosmos, based on a reading of relativity theory. There's increasing evidence that supermassive black holes lurk at the core of many galaxies, including our own. And now there's talk that an atom-smasher known as the Large Hadron Collider might blast subatomic particles into each other so energetically they turn into incredibly tiny black holes on Earth.
Is this something we should be worried about? Some people think so, but Tyson has a different view, as reflected in this edited Q&A:
Cosmic Log: You’ve written the book “Death by Black Hole,” and now people have been talking about the black holes that might eat the planet. What can you say about the risks involved, and the different sizes of black holes? Is a microscopic black hole as dangerous as a galaxy-sized black hole?
Tyson: Well, black holes are undeniably scary things. Let’s just start with that fact. They eat what comes near them, and that’s it. Black holes are dangerous. You want to avoid them at all cost. That’s No. 1.
No. 2: Yes, there are black holes of different sizes. The one most commonly discussed is the one that would be the endpoint of the life of a star of very high mass. The sun is not one of those, so the sun will not end its life as a black hole. That’s the most commonly discussed, and that’s what would be the most common in the galaxy. Wherever there was once a high-mass star, there would now be a black hole in its place. You want to map those out, ultimately, and not run into them.
When I say “common,” these types of stars are themselves rare. They’re common for black holes, but they’re rare for a cosmic object. Only one out of 1,000 or even 10,000 stars is a high-mass star. That’s a small fraction of the total.
There’s this other type of black hole that one imagines one might make in a particle accelerator. That’s what you’d call a micro black hole. It turns out that black holes evaporate. That was discovered by Stephen Hawking. The phenomenon is called Hawking radiation in his honor.
The way this happens is kind of cool. The gravitational field is so intense in the vicinity of a black hole that the gravitational energy spontaneously becomes particles, according to E=mc2. They become particles in the field outside the event horizon of the black hole. Gravity extends well beyond the event horizon. So the energy becomes particles, one of those particles escapes, and the other one falls into the black hole. And so, all right, that just took mass away from the black hole. So black holes actually become lighter over time.
Now here’s the catch: The smaller a black hole is, the faster it evaporates. So, micro black holes evaporate practically instantaneously.
There’s this worry that at CERN, they’re going to turn on the accelerator and create states of matter as never before – which is true – at higher energies than ever before – which is true – and possibly produce micro black holes. What happens if one does not evaporate, but just sort of hangs around? Whatever it touches, it eats, then it gets more massive. The more massive it gets, the less likely it will be to evaporate, because they evaporate quickly only when they’re small. This worry that it will create a runaway black hole that will eat the Earth is what some people have been concerned about.
You can do a calculation to show how quickly the black holes will evaporate. You’re sort of protected there. But suppose you made a mistake. There’s a big cost if you made a mistake. The cost is the end of the Earth. However, there’s another separate experiment that’s going on all the time. And that is, there are these mysterious particles in space called cosmic rays, and they hit Earth all the time. They have energies rivaling and exceeding the energies that will be created in this new supercollider, the Large Hadron Collider in Switzerland. They would be making black holes all the time as they slam into our atmosphere.
If the collider were somehow deadly to Earth – so, too, would the rest of these particles striking us from space. Yet, at no time have we had a black hole emergency.
Q: You get all these questions about how the LHC will be producing this phenomenon down on Earth, and people talk about how the black holes would be moving slowly in relation to Earth rather than zooming past like a cosmic ray. The counterargument to that is generally, “Gee, there are so many reactions going on over the history of the universe …”
A: “… that you would catch them.” That’s right. Nature is already conducting this experiment, with Earth as its target. These are the cosmic rays that fly back and forth, whose origin is still a mystery – but we do know they’re there, and we know they’re hugely energetic. It’s that kind of test that gives you the confidence that nothing bad will happen with the Large Hadron Collider.
By the way, it’s not new for people to be concerned when we open up new scientific vistas. Back in the early 20th century, people warned that we shouldn’t split the atom. This was a fundamental building block of nature, and splitting it would be bad. Well, yes, it was bad because we made bombs out of it, but nature was just fine. Nature does it all the time. There was this worry that the atom was someplace we should not go. Yet atomic physics is the foundation of modern technology.
Q: Right. And people talk about the first nuclear detonation, and the concern that that would destroy the world.
A: That it would ignite the atmosphere. So, yes, the fear is understandable if you’re otherwise unfamiliar with a subject. People need to know, however, that the fears are not somehow uniquely applied. There are fear factors at every turn, at every advance in our understanding of the universe. So that should temper the singularity of a person’s concern.
Q: Do you find that’s a particular challenge when you engage the public in scientific discussion? That a little bit of knowledge can be a worrisome thing?
A: It can breed fear. A little bit of knowledge about something that people don’t understand, or that is more powerful than they are, can breed fear. And that’s understandable. I’m not critical of the public for that. I’m critical of myself and my colleagues for our efforts to try to create comfort zone around the frontiers of scientific discovery.
Q: I guess that gets right into the show. Do you feel as if you’re making a difference? Have you gotten feedback from the general public?
A: What I get is e-mail and other correspondence from people who say, “I always viewed science as something beyond my ability to understand.” And they see “Nova ScienceNow” as a fun, interesting and entertaining way to become scientifically literate. “Nova ScienceNow” is conceived to bring science to the viewer in such a way that you don’t feel as if you have to take your medicine. It doesn’t mean dumbing it down. It doesn’t mean dropping out all the jargon, to try to simplify things. It just means having fun with the frontier of discovery. I’m there as your guide and as your host. Because I’m a scientist, I have a foot in the scientists’ camp. But I also feel strongly for what’s going on in the mind of the public, so I have a foot in your living room as well.
I see myself as a conduit between you and that frontier that we’re sharing with you. By the way, I’ll get on the scientists’ case for using jargon. I’ll say, “Don’t you mean it’s the blah-bla-blah-bla-blah?” Because I know enough to come at them that way, right? And they’ll say, “Yeah, I guess you could say it that way.” And we just did. So we have fun, and the public sees scientists just having fun.
Q: And you get a sense of the process behind the science.
A: The process. That’s the word. Too many journalists will only report the scientific discovery, leading the public to think that science is all about the discovery, when in fact it’s all about the process. Sometimes it’s long and drawn out. Sometimes there’s no eureka moment at the end of the day. But the scientists love the work, they love the process, they love the quest.
It’s a metaphor for life. People might say, “Oh, when I get my degree…” or “When I get my pay raise…” or “When I retire…” But life happens between now and then, and that’s what you should be paying attention to. As a scientist, so much of your time is spent in the lab, or in the field, or on the computer, trying to grapple with the boundary of ignorance.
Occasionally, you make discoveries that grab something from the unknown and bring it into the world of the known. Then you’ve made a contribution to our understanding of the universe. That doesn’t happen every day.
Q: Dark matter is a perfect example of that – where you have something you know that’s out there, and yet it’s unknown.
A: And it’s still unknown. We do a whole segment showing that we don’t know what it is. Most science programs wouldn’t do that. They’d wait until it was known, and then they’d report the results. We go right in there to this mine that’s more than 2,000 feet below Earth’s surface. You’ve got to go that deep so that the bedrock above you shields the experiment from particles that could masquerade as dark matter.
Particle physicists are confident that dark matter is a new family of exotic particles that do not interact with ordinary matter. But I look at that with the idea that when you’re a hammer, all your problems look like nails. When you’re a particle physicists, the solution to dark matter looks like particles. I try to stay open to what other possible solutions might exist.
Q: Right, and as an astrophysicist, you probably have your own brand of hammer – the idea that dark matter might be MACHOs [massive compact halo objects] rather than WIMPs [weakly interacting massive particles].
A: That’s true. But if I were a betting man, I’d probably give the nod to the particle physicists. I don’t care which it is, as long as it has the right properties. If it works, we’re good.
Q: That brings us around full circle to the Large Hadron Collider. With all this talk about micro black holes, people may not realize that the LHC might detect dark-matter particles.
A: If there are dark-matter particles, they should be within reach of the Large Hadron Collider. So the people at CERN are anxious to be the first to discover dark matter through that means, rather than natural dark matter that happens to be passing through the earth.
Q: I suppose the good thing about the “Nova ScienceNow” format is that you could always come back with an update.
A: Exactly. I think of it as having the style of CBS’ “60 Minutes,” where there are different segments, and I do the parts that lead from one segment to the next – right on down to the Andy Rooney part, where at the end of the show, I give my “Cosmic Perspective.” I offer a point of view that enhances your understanding of where we fit in the universe, drawn on themes that have just appeared on the program.
Q: And as you get closer to Andy Rooney’s age, you can become more and more of a curmudgeon.
A: Ha! I’d have to get bushier eyebrows – and get an old Underwood typewriter. The counterpart would be an old oversized PC, I guess.
REPORT RULES OUT SUBATOMIC DOOMSDAY
Posted: Friday, June 20, 2008 12:57 PM by Alan Boyle
Europe's CERN particle-physics lab has issued its long-awaited report on safety issues surrounding the Large Hadron Collider, the world's biggest and most expensive atom-smasher. Some have feared that when the collider reaches full power, sometime next year, it might create microscopic black holes or other exotic phenomena that could endanger Earth. The new report, like earlier safety studies, rules out the possibility of global danger.
Critics of the collider are pursuing a federal lawsuit challenging the safety claims - and they're likely to continue the doomsday debate even in the wake of this report.
The report's argument follows the basic line used in past reports: Even the most energetic collisions planned for the LHC are far less powerful than cosmic-ray collisions that have been going on for billions of years.
"Nature has already generated on Earth as many collisions as about a million LHC experiments – and the planet still exists," CERN said in itslay-language summary of the report. "Astronomers observe an enormous number of larger astronomical bodies throughout the universe, all of which are also struck by cosmic rays. The universe as a whole conducts more than 10 million million LHC-like experiments per second. The possibility of any dangerous consequences contradicts what astronomers see - stars and galaxies still exist."
The report also delves into the theoretical implications even if it turns out that microscopic black holes may hang around longer than most scientists think, and still ends up ruling out the catastrophic risk. In the stable-black-hole scenario, physicists do not expect the black holes to gobble up matter and grow to a monster size. Instead, they would interact - or not interact - with the particles they came across.
You'll want to start with CERN'S summary document and then check out the full report. The report was reviewed by outside experts, and a separate report lays out what they had to say.
CERN discussed the safety report in a news release today, issued after this week's meeting of the CERN Council. Here's the text:
The news release confirms that researchers will start sending beams through the LHC in August rather than July - but the startup procedure is expected to take months, with actual collisions coming later, and collisions at full power coming later still.
GALAXY GOES ON THE BLACK HOLE DIET
Posted: Thursday, June 19, 2008 7:50 PM by Alan Boyle
The latest X-ray view of a photogenic galaxy shows that the feeding habits of black holes are the same, whether they're 10 times or 70 million times as massive as the sun.
Black holes are thought to come in all sizes, from Supermicro protron size to supermassive galaxy size. But are all black holes alike? Albert Einstein thought so: General relativity suggests that the collapsed singularities are simple things, varying only in how big they are and how much they spin.
Some astronomers have taken issue with Einstein, however. Stellar-mass black holes are in settings that are much different from galaxy-scale black holes, which might lead to differences in diet and behavior: The smaller ones suck in whirling disks of gas from their companion stars, while the bigger ones feed on the material surrounding them at the dense cores of galaxies.
In an effort to shed new light on a black hole's digestive routine, astronomers observed the spiral galaxy M81, about 12 million light-years from Earth, using NASA's Chandra X-Ray Observatory as well as three radio-telescope arrays, two millimeter-wave telescope arrays and the infrared camera at the Lick Observatory.
In a paper due to appear in The Astrophysical Journal, the international research team reports that M81's monster black hole behaves much the same as stellar-mass suckers, in their pattern of activity as well as in the distribution of radiation given off as whipped-up material falls into the singularity.
"This confirms that the feeding patterns for black holes of different sizes can be very similar," Sera Markoff of the University of Amsterdam's Astronomical Institute, the leader of the study, said in aChandra news release. "We thought this was the case, but up until now we haven't been able to nail it."
The study confirms earlier work by Andrea Merloni of Germany's Max Planck Institute for Extraterrestrial Physics and his colleagues: The new model fleshes out the details, using more detailed observations made simultaneously by different telescopes.
X-ray emissions are the hallmark of a black hole's activity, which is why the Chandra observations were key to the latest study. Other wavelengths show up to varying degrees in different regions around the black hole (which emits no radiation on its own):
"When we look at the data, it turns out that our model works just as well for the giant black hole in M81 as it does for the smaller guys," said the Massachusetts Institute of Technology's Michael Nowak, a co-author of the study. "Everything around this huge black hole looks just the same, except it's almost 10 million times bigger."
If astronomers confirm that the model holds true for all black holes, that could help them confirm the existence of a mysterious intermediate class of black holes. Some candidates for the midsize class have already been identified, but researchers are debating whether they're actually black holes or examples of other cosmic phenomena. Closer observations could reveal whether the objects are following the required black hole diet.
Bright Chunks at Phoenix Lander's Mars Site Must Have Been Ice
Image credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University
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