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But how big does an asteroid need to be to cause major destruction? The new “Impact: Earth!” asteroid impact effects calculator will help you find out. The interactive web tool, developed by a Purdue University research team led by Jay Melosh, allows anyone to calculate the potential damage caused by a comet or asteroid striking the Earth. Users input information into several parameter fields, such as the diameter and density of the object, its angle of entry, and the location where it will hit. The calculator then estimates the impact consequences, providing information about debris distribution, ground shaking, size of the resulting crater, and whether a tsunami will be generated.

About 50,000 years ago, an asteroid about 164 feet in diameter scooped out the famous Barringer Crater (Meteor Crater) in northern Arizona. The new calculator estimates that if an asteroid twice as large as that one struck about 20 miles outside Chicago, it would generate impact energy equal to about 97 megatons of TNT—igniting a fireball with a 1-mile radius and triggering a magnitude-6 earthquake about six seconds after the impact.

The largest known impact threat in Earth’s near future is the asteroid Apophis, which scientists say has a small chance of striking the planet in 2036. The new calculator will tell you what will happen if Apophis falls in your backyard, Melosh says.

“Impact: Earth” is an update of an earlier impacts calculator that Melosh created with colleagues at the University of Arizona. The new user-friendly version includes more visual components, as well as calculations of tsunamis that would result from ocean impacts. Melosh is also a science team member on NASA’s EPOXI mission, which flew to within 435 miles of the comet Hartley 2 yesterday.

Astronauts lose 1 to 2 percent of their bone mass for each month they spend in space. As far back as the Gemini missions, conditioning exercise regimes have been used to slow the rate of bone loss, but a 2001-2004 NASA-sponsored study showed that crew members aboard the International Space Station (ISS) were still losing up to 2.7 percent of their interior bone material and 1.7 percent of outer hipbone material for each month they spent in space. If ISS crew members lose this much bone density after 4 to 6 months in space, astronauts on long missions to Mars—voyages that could take years—could lose enough bone mass that they suffer fractures while carrying out tasks on the Martian surface.

With stirrups that loop around the feet, the elastic gravity skinsuit is purposely cut too short for the astronaut so that it stretches when put on—pulling the wearer’s shoulders towards the feet. In normal gravity conditions on Earth, a human’s legs bear more weight than the torso. Because the suit’s legs stretch more than the torso section, the wearer’s legs are subjected to a greater force—replicating gravity effects on Earth.

The prototype suit testing took place on parabolic flights that created brief periods of weightlessness. Results showed that the suit successfully imitated the pull of gravity on the torso and thighs, but it did not exert enough force on the lower legs. Researchers are now refining the suit’s design to address this; they also plan to test the suit to see how it performs when worn overnight. Volunteers who wore the suit on the test flights reported that the suit was comfortable and did not significantly restrict movement, which means crewmembers can work and exercise while wearing the suit.

An article on the study will be published in the journal Acta Astronautica.

But a new U.S. Air Force satellite scheduled to launch Saturday night from Vandenberg Air Force Base will provide the first full-time, unobstructed view of both space debris and the hundreds of active satellites orbiting the Earth. The Space-Based Surveillance Satellite (SBSS) spacecraft includes a sensor mounted on a pivoted support that will allow controllers to move the camera quickly without having to reposition the entire spacecraft. Its flexible architecture also provides the option to add more satellites and sensors later.

Pieces of space debris—even objects as small as paint flecks—can pose serious threats to commercial and military space assets, such as satellites that provide communications, navigation, and weather forecasting capabilities.

Until now, the Air Force has relied on a global ground-based network of radar and optical telescopes to monitor about 1,000 active satellites, as well as space debris. But the telescopes only perform during clear conditions and are limited by weather and atmospheric interferences. In addition, not all radar stations can detect objects in deep space orbit—about 22,000 miles above the Earth. With its wide field-of-view, the SBSS will give controllers the ability to find and track objects in deep space more quickly and accurately than previous sensors.

Boeing is responsible for the overall SBSS system, including the ground system and initial mission operations; Ball Aerospace designed the spacecraft and sensor.

Boeing and Ball completed final testing of the SBSS satellite and ground system earlier this week, and the launch is scheduled for 12:41am EDT on September 26 (9:41pm PDT on September 25). Several previous launch dates were delayed this year due to technical issues.

Pulsars are neutron stars that spin rapidly and emit a constant stream of electromagnetic particles ejected from the star's magnetic poles at the speed of light. They were first discovered in 1967 as radio sources that blink on and off at a constant frequency. Pulsars with orbiting companions, called binary pulsars, played a key role in verifying Einstein's theory of general relativity. But the pulsar detected by the Colvins and Gebhardt sits alone with no companion orbiting star, and astronomers believe it could be a recycled pulsar that lost its companion. This makes it particularly interesting to study, as the origin of recycled pulsars is still unknown.

The Einstein@Home project, based at the University of Wisconsin's Center for Gravitation and Cosmology and the Max Planck Institute for Gravitational Physics, was started in 2005 to search for gravitational waves in data from the Laser Interferometer Gravitational-Wave Observatory (LIGO) at Caltech. In March 2009, the program expanded its search mission to look for signals from radio pulsars in data from Arecibo, the world's largest and most sensitive radio telescope. Currently, about 500,000 volunteer computers help analyze data for Einstein@Home (an average of two computers per volunteer). The pulsar finding is the first genuine astronomical discovery by a public volunteer computing project.

Last week, a study of distributed computing applied to the problem of protein-folding found that computers are no replacement for human thinking and insight.

"No matter what else we find out about it, this pulsar is bound to be extremely interesting for understanding the basic physics of neutron stars and how they form," said James M. Cordes, professor of astronomy at Cornell University.

A paper on the discovery was published today in Science Express.

Click to launch the photo gallery

From its orbit several hundred miles above the Earth's polar regions, the spacecraft scans strips of the sky, always staying over the day-night dividing line. Every 11 seconds, an infrared-sensitive digital camera takes a snapshot over the entire sky.

WISE has already observed more than 100,000 known and previously unseen asteroids. Most of these are located in the asteroid belt between Mars and Jupiter, but some are near-Earth objects that pass relatively close to the Earth. The telescope's infrared vision also enables it to detect the glow of brown dwarfs, objects with masses between that of planets and stars, and it can also see the brightest of ultra-luminous infrared galaxies.

Less than two months after its December 2009 launch, WISE detected its first comet (named the WISE comet) orbiting about 109 million miles from Earth. Because they are rare in the inner solar system region, comets aren't as easy to find as asteroids. But WISE's powerful telescope is expected to find up to dozens of new comets, which will give astronomers new numbers to crunch in determining the probability of one coming close to Earth's orbit.

WISE will now begin a second full scan of the sky to reveal even more objects and to detect any changes that have occurred since the first survey. In about three months, this second survey will end when the block of solid hydrogen coolant that chills the instrument's detectors runs out. In May 2011, the astronomical community will have access to the first release of WISE data, which will include over a million images that help researchers catalog astronomical objects and answer questions about how planets, stars, and galaxies develop and evolve.

The new bug is the first with complete resistance to the parasite -- and it passes that gene on to its children

For years, researchers have tried to engineer mosquitoes so that they're immune to the parasite that carries malaria -- a single-celled organism called Plasmodium. But previous attempts only succeeded in destroying about 97 percent of malaria parasites in mosquitoes' bodies. The difference between 97 and 100 percent might seem negligible, but Michael Riehle, who led the new study, says that 3 percent means the difference between success and failure. "If you want to effectively stop the spreading of the malaria parasite, you need mosquitoes that are no less than 100 percent resistant to it," he said.

In the new study, Riehle's team designed a piece of genetic information that inserts itself into a mosquito's genome. When the researchers fed malaria-infested blood to the modified mosquitoes, the Plasmodium parasites did not infect a single animal in the study. And once the anti-malaria molecule is injected into the mosquito's eggs, the next generation then carries the altered genes and passes it on to future generations.

The team also found that the anti-malaria molecule shortened the mosquito's lifespan, which minimizes chances that the malaria parasite will develop. Wild mosquitoes typically live for 2-3 weeks, but the malaria parasite needs 12-16 days to develop within the mosquito before it can be transmitted back to people. "The oldest mosquitoes are responsible for most malaria transmission, so reducing the lifespan of the mosquito can reduce or eliminate the number of people the mosquito can infect," said Riehle.

The malaria parasite is carried by the female Anopheles mosquito. When transmitted to a human, the parasite travels first to the liver and then on to the bloodstream, where it reproduces and destroys red blood cells. An estimated 250 million people contract malaria each year, and about 1 million die -- many of them children. There are currently no effective or approved malaria vaccines, although a few have been tested. Riehle says that even if a vaccine were developed, distribution would be a major challenge.

According to Riehle, completely eradicating the malaria parasite carried by mosquitoes requires three things: the ability to engineer the mosquito, finding genes or molecules that can kill the malaria parasite, and giving the modified mosquitoes a competitive advantage so they can replace the wild population. The first two components have been accomplished, but Riehle says the third represents a bigger hurdle. "A lot of research is being done now to give the mosquitoes fitness advantages so that they can replace the wild populations," he said. "But it's probably at least a decade away, and if this is ever used for malaria control it will take several years for population replacement to actually occur."

Riehle stressed that complete blockage of the malaria parasite is essential to any future control strategy -- if some of the parasites slip through the mechanism, then the next generation will likely be resistant to it. "If you release the mosquito and within two or three generations, it's no longer resistant to the malaria parasite, then you're back where you started," he said.

The genetically altered mosquitoes from the new study are being held in a secure lab environment that ensures they won't escape. Once researchers find a way to replace wild mosquito populations with lab-bred ones, the altered genes will hopefully spread through the natural population. If the approach ultimately succeeds, malaria could be a disease of the past.

The results of the new study were published today in the journal Public Library of Science Pathogens.