This week’s haul includes a rocket engine that breaks the laws of physics, a look at the serious side of putty, and astronauts who are about to go fishing for space junk with the help of a century-old fish net company. These are no fish tales!
British inventor Roger Shawyer caused a stir in 1999 when he invented a propulsion engine that seemed to violate Newton’s third law of motion stating that for every action in nature there is an equal and opposite reaction. But his Electromagnetic Drive uses massless microwaves pushing on the walls of a special cavity to move it along directly without anything coming out at the other end, like, say, from a rocket engine. Things got weirder this November when NASA announced that Shawyer’s drive really works. Writing in the Journal of Propulsion and Physics, the team reported that “in spite of the apparent lack of a propellant or other medium with which to exchange momentum,” the test design was “capable of consistently generating force.” If true, Shawyer calculated that his drive could get us to Mars in just 10 weeks. Not so fast, says Brian Cassenti, an expert in advanced propulsion systems. He says that while “peer review is important … it does not mean, however, that the reviewers consider the results valid.” Says Cassenti: “If the results are valid, it definitely points to new physics. Newton’s laws have already been shown not to apply at high relative speeds — where special relativity applies — in large gravitational fields, and with very small-scale molecules. But Newton is still mostly right.”
Researchers working at the University of Houston have developed a new thermoelectric compound of niobium, iron and antimony that more efficiently converts heat directly into electricity. “The majority of industrial energy input is lost as waste heat,” the team reported in the Proceedings of the National Academy Sciences. “Converting some of the waste heat into useful electrical power will lead to the reduction of fossil fuel consumption and CO2 emission.” Thermoelectric materials take advantage of heat flowing from hotter to colder areas. They use this flow to generate electricity. The team reported it was “able to demonstrate an output power density of 22 watts per square centimeter, far higher than the 5 to 6 watts typically produced,” according to a news release.
As it so happens, Silly Putty has a serious side. Scientists in Jonathan Coleman’s nanotechnology lab at Trinity College Dublin have discovered that a pinch of graphene transforms the addictively squeezable substance popular with preschoolers (and invented in a GE lab) into a pressure sensor that they say is 10 times as sensitive as other nanocomposite sensors. Mixed with putty, graphene creates a conducting network. When the substance, which its inventors call G-putty, is stretched or molded, that network breaks apart, but not for long. That separation creates strong electrical resistance, and because of the putty’s low viscosity, the graphene flakes can move quickly back into place, reforming the network. “It’s a self-healing phenomenon,” Coleman says. His team wired the G-putty and placed it on a student’s neck, where it picked up minutely detailed carotid pulse signals. When affixed to the student’s chest, it detected his respiratory rate. And when attached to the wee legs of a spider — because why wouldn’t you attach it to a spider? — the putty was even able to track its footsteps. Medical applications could include continuous-monitoring devices and alternatives to unwieldy cuffs currently used for blood-pressure readings. More details about the substance appear in Nature magazine.
Scientists at Cornell University engineered a soft prosthetic hand that allowed a robot to feel three different tomatoes and select the ripe one. They said that embedding optoelectronic strain sensors into the hand enabled the robot to “feel its surroundings internally, in much the same way humans do.” The research was published in the journal Science Robotics. “Most robots today have sensors on the outside of the body that detect things from the surface,” said the lead author, Huichan Zhao. “Our sensors are integrated within the body, so they can actually detect forces being transmitted through the thickness of the robot, a lot like we and all organisms do when we feel pain, for example.”
Japan has blasted a space junk collector to the International Space Station. The device, which reportedly was made with the help of a century-old net company, will use an “electrodynamic tether” harnessing the planet’s electromagnetic field to fish the remains of rockets, satellites and other space debris out of the orbit and push them into the atmosphere, where it will burn up. Scientists estimate some 100 million pieces of junk have accumulated in space since Sputnik first circled the planet in 1957.