Trunkneck’s Blog

Cheap, lightweight cameras could help protect mass transit, but would they survive a big costly blast?

That was the question on the minds of Department of Homeland Security Science and Technology Directorate (S&T) scientists and managers watching from behind three feet of reinforced concrete.

Outside was an old public bus, rigged with explosives; a series of baseball-sized video cameras mounted to its walls. Could the images on their memory chips be salvaged by computer engineers? Would they be clear enough to identify the bomber? In this case, of course, the latter question wasn’t much of a mystery.

At the Aberdeen Proving Ground in Maryland, every Army vehicle with wheels or tracks had been tested since World War II, and that’s where S&T’s Homeland Security Advanced Research Projects Agency (HSARPA) was to witness the test bombing.

S&T’s Stephen Dennis explains the idea: DHS wants to develop cameras with memory chips sturdy enough to withstand bombing attacks, fires or floods, but inexpensive enough to use in places where a complete surveillance system wasn’t workable.

DHS’s target price for the cameras was between $150 and $200 a piece, he said.

“These cameras would be used as a means of forensic analysis,” said Dennis. They would not transmit or collect personal information, and would be tamper-proof to prevent someone from ripping one off a wall and, say, posting the images on YouTube. Video from the cameras would be recovered and used by law enforcement only after an incident.

Inside the shelter, the scientists watched a wall of flat screens hooked up to high-speed cameras that ringed the bombing range outside. This was just one test with one bus, representing just one kind of dangerous threat.

“The idea is that the cameras are robust enough to survive the blast from a suicide bomber,” said Dennis.

There had been some talk about what kind of damage the explosive representing this suicide bomber could do. Would it pop the ceiling open like a tin can? Would it split the bus in half?

“3, 2, 1! Boom!!”

Even behind a giant steel plate, the walls of the shelter shuddered. The screens flashed red, and filled with smoky plumes.

Once the smoke cleared and flying debris settled, the group watched workmen as they plugged the ground with colored flags wherever they spotted one of the small cameras. A metal strip from the bus’s shell lay across tree branches a hundred yards away.

“There wasn’t much left of the bus except the wheels and chassis. But the cameras survived, and that was the point.”

Did the cameras’ memory chips survive the blast intact? Fourteen out of 16 did. In our next post, analysis of those suvivors will be described.

NASA’s Swift and Fermi spacecraft are monitoring a neutron star 30,000 light years from Earth that is drawing attention to itself with a series of powerful gamma-ray flares.

“At times, this remarkable object has erupted with more than a hundred flares in as little as 20 minutes,” said Loredana Vetere, who is coordinating the Swift observations at Pennsylvania State University. “The most intense flares emitted more total energy than the sun does in 20 years.”

The star, known as SGR J1550-5418, lies in the southern constellation Norma. It began a series of modest eruptions on Oct. 3, 2008, settled down for a while, then roared back to life on Jan. 22, 2009, with an intense episode.

Because of its rapid-fire outbursts and gamma-ray spectrum, astronomers classify the object as a “soft-gamma-ray repeater” — only the sixth known. In 2004, a giant flare from another soft-gamma-ray repeater was so intense it ionized Earth’s upper atmosphere from 50,000 light-years away.

Using data from an X-ray telescope onboard Swift, Jules Halpern at Columbia University captured the first “light echoes” ever seen from a soft-gamma-ray repeater. Images acquired when the latest flaring episode began show what appear to be expanding halos around the source. Multiple rings form as X-rays interact with dust clouds at different distances.

Scientists think the source of the flares is a spinning neutron star–the superdense, city-sized remains of a supernova. Although only about 12 miles across, a neutron star contains more mass than the sun. This particular neutron star is believed to be a “magnetar,” a neutron star with an incredibly intense magnetic field.

A popular theory of soft-gamma-ray repeaters holds that flares are caused by “starquakes” in the outer rigid crust of the magnetar. As a magnetar’s colossal magnetic field shifts, it strains the crust with monstrous magnetic forces, often breaking it. When the crust snaps, it vibrates with seismic waves like in an earthquake and emits a flash of gas

No one is really certain of the details, however, and much work remains to be done to understand these powerfully hyperactive stars.

NASA’s Fermi Gamma-ray Space Telescope, launched in June 2008, is ideal for this work. “The ability of Fermi’s gamma-ray burst monitor to resolve the fine structure within these events will help us better understand how magnetars unleash their energy,” said Chryssa Kouveliotou, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Ala. The object has triggered Fermi’s gamma-ray burst monitor more than 95 times since Jan. 22nd.

NASA’s Wind satellite, the joint NASA-Japan Suzaku mission, and the European Space Agency’s INTEGRAL satellite also have detected flares from SGR J1550-5418.

Space dust annoys astronomers just as much as the household variety when it interferes with their observations of distant stars. And yet space dust also poses one of the great mysteries of astronomy.

“We not only do not know what the stuff is, but we do not know where it is made or how it gets into space,” said Donald York, the Horace B. Horton Professor in Astronomy & Astrophysics at the University of Chicago.

A Hubble Space Telescope image of the Red Rectangle, approximately 2,300 light years from Earth in the constellation Monoceros. What appears to be the central star is actually a pair of closely orbiting stars. Particle outflow from the stars interacts with a surrounding disk of dust, possibly accounting for the X shape. This image spans approximately a third of a light year at the distance of the Red Rectangle.

But now York, the University of Toledo’s Adolf Witt and their collaborators have observed a double-star system that displays all the characteristics that astronomers suspect are associated with dust production. The Astrophysical Journal will publish a paper reporting their discovery in March.

The double star system, designated HD 44179, sits within what astronomers call the Red Rectangle, an interstellar cloud of gas and dust (nebula) located approximately 2,300 light years from Earth.

One of the double stars is of a type that astronomers regard as a likely source of dust. These stars, unlike the sun, have already burned all the hydrogen in their cores. Labeled post-AGB (post-asymptotic giant branch) stars, these objects collapsed after burning their initial hydrogen, until they could generate enough heat to burn a new fuel, helium.

An artist’s rendition of the possible appearance of the double star system in the Red Rectangle nebula. The details of the image follow the observations that a team of astronomers at the University of Toledo and the University of Chicago has made using the 3.5-meter telescope at Apache Point Observatory in New Mexico. The image spans a distance of approximately 1 astronomical unit (93 million miles, the average distance between the Earth and sun).

Dust in the solar wind

During this transition, which takes place over tens of thousands of years, these stars lose an outer layer of their atmosphere. Dust may form in this cooling layer, which radiation pressure coming from the star’s interior pushes out the dust away from the star, along with a fair amount of gas.

In double-star systems, a disk of material from the post-AGB star may form around the second smaller, more slowly evolving star. “When disks form in astronomy, they often form jets that blow part of the material out of the original system, distributing the material in space,” York explained.

This seems to be the phenomenon that Witt’s team observed in the Red Rectangle, probably the best example so far discovered. The discovery has wide-ranging implications, because dust is critical to scientific theories about how stars form.

“If a cloud of gas and dust collapses under its own gravity, it immediately gets hotter and starts to evaporate,” York said. Something, possibly dust, must immediately cool the cloud to prevent it from reheating.

The giant star sitting in the Red Rectangle is among those that are far too hot to allow dust condensation within their atmospheres. And yet a giant ring of dusty gas encircles it.

Witt’s team made approximately 15 hours of observations on the double star over a seven-year period with the 3.5-meter telescope at Apache Point Observatory in New Mexico. “Our observations have shown that it is most likely the gravitational or tidal interaction between our Red Rectangle giant star and a close sun-like companion star that causes material to leave the envelope of the giant,” said Witt, an emeritus distinguished university professor of astronomy.

Some of this material ends up in a disk of accumulating dust that surrounds that smaller companion star. Gradually, over a period of approximately 500 years, the material spirals into the smaller star.

Bipolar behavior

Just before this happens, the smaller star ejects a small fraction of the accumulated matter in opposite directions via two gaseous jets, called “bipolar jets.”

Other quantities of the matter pulled from the envelope of the giant end up in a disk that skirts both stars, where it cools. “The heavy elements like iron, nickel, silicon, calcium and carbon condense out into solid grains, which we see as interstellar dust, once they leave the system,” Witt explained.

Cosmic dust production has eluded telescopic detection because it only lasts for perhaps 10,000 years—a brief period in the lifetime of a star. Astronomers have observed other objects similar to the Red Rectangle in Earth’s neighborhood of the Milky Way. This suggests that the process Witt’s team has observed is quite common when viewed over the lifetime of the galaxy.

“Processes very similar to what we are observing in the Red Rectangle nebula have happened maybe hundreds of millions of times since the formation of the Milky Way,” said Witt, who teamed up with longtime friends at Chicago for the study.

Witt (Ph.D.,’67) and York (Ph.D.,’71) first met in graduate school at Chicago’s Yerkes Observatory, where Lew Hobbs, now Professor Emeritus in Astronomy & Astrophysics, had just joined the University faculty. Other co-authors include Julie Thorburn of Yerkes Observatory; Uma Vijh, University of Toledo; and Jason Aufdenberg, Embry-Riddle Aeronautical University in Florida.

The team had set out to achieve a relatively modest goal: find the Red Rectangle’s source of far-ultraviolet radiation. The Red Rectangle displays several phenomena that require far-ultraviolet radiation as a power source. “The trouble is that the very luminous central star in the Red Rectangle is not hot enough to produce the required UV radiation,” Witt said, so he and his colleagues set out to find it.

It turned out neither star in the binary system is the source of the UV radiation, but rather the hot, inner region of the disk swirling around the secondary, which reaches temperatures near 20,000 degrees. Their observations, Witt said, “have been greatly more productive than we could have imagined in our wildest dreams.”

Even in space, someone has to clean the bathroom. Good housekeeping is essential when you’re living in the close quarters of a tightly-sealed spaceship for months at a time. To make this possible, NASA scientists have developed a tricorder-like device called “LOCAD-PTS” that can track down microscopic bacteria and fungi. It helps astronauts do their chores–no Howitzer required.

“The crew of the space station works hard to keep things clean,” says Norm Wainwright, principal investigator for LOCAD-PTS (Lab-On-A-Chip Application Development Portable Test System) at the Marshall Space Flight Center. “Our instrument tells them where to focus their efforts.”

Strange, but true: LOCAD works using enzymes from the immune system of a horseshoe crab. Astronauts swab a surface with a high-tech Q-tip, insert a sample into the LOCAD device, and crab-chemistry does the rest. In less than 15 minutes, the LOCAD test system tells the crew if they’ve got some cleaning to do.

During March to May 2007, astronaut Sunita “Suni” Williams proved LOCAD’s adeptness at detecting gram negative bacteria in the space station’s Node 1 and US Lab.

Sign up for EXPRESS SCIENCE NEWS delivery
In June and September 2008, a station crew tested a second type of LOCAD cartridge, designed to detect fungi. First, they tested Node 1 and found it virtually fungi-free.

That sounds like great news, but it didn’t help the LOCAD scientists prove the abilities of the new cartridge.

So just a couple of weeks ago, astronaut Sandy Magnus decided to play hard ball. She thought of a place that would surely be a fungi factory – the spot where crewmembers put their feet to brace themselves while working on their laptops.

Wrong. Clean.

A determined fungi-finder, Magnus tried another location. She went to the “gym,” where station astronauts ride a modified exercise bike and a treadmill to combat the muscle weakening effects of microgravity. To keep themselves from floating up off the bicycle seat while pedaling, the sweaty space cyclers hold onto hand brackets.

You guessed it — fungi are thoroughly enamored with an oft-sweaty surface. LOCAD ratted out some hand bracket fungi.

“The fungi posed no immediate health concern to the crew,” says Maule, LOCAD-PTS project scientist. “But Magnus called to Houston to say, ‘Tomorrow I’m going to give those brackets a good cleaning.’ That’s just what we want — the intuitive reaction ‘I need to clean that.’”

In years to come, spacecraft cleanliness will be a critical issue for another reason: “One of the key scientific goals for NASA’s future Constellation missions beyond low Earth orbit will be to prepare to search for life on Mars,” says Maule.

All humans carry stowaway microbes around with them on their skin, microbes that shouldn’t be allowed to contaminate Mars samples. On the other hand, they don’t want to bring unwanted alien life forms back into the spacecraft.

“The crew will need a way to monitor themselves before and after EVA [extra-vehicular activity],” says Maule. “LOCAD is ideal for that purpose. We’ve used it successfully during EVA tests on the ground.”

The LOCAD team has also conducted several tests in the US Quest airlock, the conduit from the interior cabin to the outside of the space station where the crew “camps out” overnight and depressurizes before venturing outside. LOCAD proved the airlock to be pretty clean in general, but showed that the handle to the airlock entrance harbored gram negative bacteria. Bacteria on a surface like the airlock handle would be a concern if crew members were about to embark on a sample collecting excursion on Mars.

It would seem that finding fungi onboard the ISS is just the beginning for LOCAD. There are chores to be done … and the whole solar system awaits.