Plus: Could Dark Matter Be Massive?; and Cockroaches to the Rescue
No good spy equipment is worth its salt if it can't disavow its own existence if caught. After all, what's the whole point of espionage if you're going to leave evidence that you were there?
In comes the world's first "biological drone," which avoids capture by degrading naturally but within a predetermined amount of time. Made of a root-like fungal material called mycelium for its body, the drone made its first flight at the International Genetically Engineered Machine competition in Boston recently. Ecovative Design designed the drone's shape, working in collaboration with NASA's Ames Research Center. Before the project, Ecovative Design was known for development of mycelium applications in sustainable packaging and surfboards.
So don't be surprised to see a contraption that looks like a recyclable Starbucks quad-cup holder tray with four beanie propellers.
"No one would know if you'd spilled some sugar water or if there'd been an airplane there," said Lynn Rothschild of the Ames Research Center.
The drone's primitive look is designed to beguile, as its circuits are printed in silver nanoparticle ink and the fungal body has a protective coating of sticky cellulose "leather" sheets grown by lab bacteria. The sheets, in turn, are coated to become waterproof with proteins cloned from the saliva of paper wasps.
The developers' next step is to come up with a way to degrade the drone's sensors using E. coli
bacteria. If they had their druthers, everything about the drone would be able to disintegrate, but alas. "There are definitely parts that can't be replaced by biology," said team member Raman Nelakanti of Stanford University, referring to the propellers, controls, and battery.
Ella Atkins, an aerospace engineer not involved in the project, is excited about the bio-drone but added one potential danger would be premature biological breakdown. "We don't want biodegradable drones to rain down from the sky, and we don't want to litter the land and seas with crashed drones," she said.
Could Dark Matter Be Massive?
Since being postulated in 1932, dark matter has eluded the detection of physicists' most complex and sensitive experiments. While most researchers focus their search on smaller particles, theorists are looking in a completely different direction.
According to physicists, dark matter is an unseen material that creates gravity and prevents our universe's galaxies from dispersing into millions of dissociated pieces. In fact, dark matter's impact on our universe is so great that it could make up nearly 27 percent of its mass (whereas regular matter constitutes a paltry 5 percent).
While modern searches for dark matter have focused on weakly interacting massive particles (WIMPs), the effort hasn't turned up any clues about the nature of this mysterious material. In an attempt to redirect the search for this significant weft in the universe's fabric, a group of researchers now believe dark matter may be built upon macroscopic particles.
"The community had kind of turned away from the idea that dark matter could be made of "normal-ish" stuff in the late '80s," said Glenn Starkman, a University of Cape Town physics professor. "We ask, 'Was that completely correct, and how do we know dark matter isn't more ordinary stuff - stuff that could be made from quarks and electrons?'"
In Starkman's view, strange nuclear matter, like quarks and baryons, could have been made during the birth of the early universe and come together in large arrangements to produce our concept of dark matter. Starkman calls these arrangements macros.
According to this new view, macros would have been created at temperatures hovering around 2.5 trillion degrees Celsius (similar to the temperature at the core of a supernova) and would abide by the following limits:
- A minimum of 55 grams. If dark matter were smaller, it would have been seen in detectors in Skylab or in tracks found in sheets of mica.
- A maximum of 1,024
[DA1] (a million billion billion) grams. Above this, the macros would be so massive they would bend starlight, which has not been seen.
- The range of 1,017 to 1,020 grams per centimeter squared should also be eliminated from the search, the theorists say. Dark matter in that range would be massive and would require gravitational lensing to affect individual photons from gamma ray bursts in ways that have not been seen.
If dark matter is within this allowed range, there are reasons it hasn't been seen:
- At the mass of 1,018 grams, dark matter macros would hit the Earth about once every billion years.
- At lower masses, they would strike the Earth more frequently but might not leave a recognizable record or observable mark.
- In the range of 109 to 1,018, dark matter would collide with the Earth once annually, providing nothing to the underground dark matter detectors in place.
While Starkman's ideas are certainly tantalizing - mostly because they seem to fit into the standard model - it may be a while before his ideas are tested or even taken seriously by his peers. Regardless, Starkman's macros are an intriguing notion that's worth exploring further, even if it's in disbelief.
This article was originally published on Engineering.com and is adapted in its entirety with permission. For more stories like this please visit Engineering.com.
Cockroaches to the Rescue
We at The Light Side feel bugs are cool, when they're not invading your personal space or taking blood from you. They're helping electronics engineers tackle the challenges of design verification, for example
. Then take cyborg cockroaches, this week, which could potentially help humans in post-disaster rescue efforts.
"In a collapsed building, sound is the best way to find survivors," Alper Bozkurt, an assistant professor of electrical and computer engineering at NC State, pointed out. NC State also prefers to call their helpers "biobots" rather than the negative-sounding cockroaches.
Researchers at North Carolina State University have developed technology that sits atop a biobot and controls its movements to hone in on sound sources. Each electronic backpack has a small microphone that can capture sound from any direction to be wirelessly transmitted to first responders and emergency personnel. Also on each backpack are mini-solar panels that collect energy to power the device.
Technology was also developed to keep the biobots "fenced in" within a designated area.
Then, there is what we like to call a super biobot (sorry, NC State), whose electronic backpack contains not one but three
directional mics to detect the direction of sound. Researchers developed algorithms that analyze sound from the mike array to localize the source and steer the biobot in that direction.
"The goal is to use the biobots with high-resolution microphones to differentiate between sounds that matter -- like people calling for help -- from sounds that don't matter -- like a leaking pipe," Bozkurt said.
Biobots can also map out a disaster area as long as they're kept inside the "invisible fence" NC State scientists have created. Keeping the biobots hemmed in at a disaster site and within range of each other forms a mobile wireless network. Research is already underway to develop the next generation of biobot networking and localization technology.
Meanwhile, a separate group of scientists, inspired by the longhorn beetle's ability to shift colors, have designed an ink that they can finely tune to change color upon exposure to ethanol vapor. The ink reportedly is resistant to bleaching when exposed to light, can be applied to hard or flexible surfaces, and can return to its original color -- be it bright green or red.
The ink is based on a new set of color-changing materials known as colloidal photonic crystals; it is also compatible with inkjet printing. The practical application being envisioned is color-changing features on paper money that combat counterfeiting and don't fade when exposed to light and air. Other potential uses of the ink are changing billboards and art displays.