MIT researchers are putting a tiny gas-turbine engine inside a silicon chip about the size of a quarter. The resulting device could run 10 times longer than a battery of the same weight can, powering laptops, cell phones, radios and other electronic devices.
Their microengine is made of six silicon wafers, piled up like pancakes and bonded together. Each wafer is a single crystal with its atoms perfectly aligned, so it is extremely strong. [...] They make 60 to 100 components on a large wafer that they then (very carefully) cut apart into single units.
Inside a tiny combustion chamber, fuel and air quickly mix and burn at the melting point of steel. Turbine blades, made of low-defect, high-strength microfabricated materials, spin at 20,000 revolutions per second -- 100 times faster than those in jet engines. A mini-generator produces 10 watts of power. A little compressor raises the pressure of air in preparation for combustion. And cooling (always a challenge in hot microdevices) appears manageable by sending the compression air around the outside of the combustor.
"So all the parts work.... We're now trying to get them all to work on the same day on the same lab bench," Epstein said. Ultimately, of course, hot gases from the combustion chamber need to turn the turbine blades, which must then power the generator, and so on. "That turns out to be a hard thing to do," he said. Their goal is to have it done by the end of this year.
Now the geeks will covet gasoline laptops to go along with their electric cars! But obviously this is not nearly as cool as powering your cellphone on human blood.
Previous studies have investigated the use of magnets to accelerate satellites to the high speeds required for launch. But most have focused on straight tracks, which have to gather speed in one quick burst. Supplying the huge spike of energy needed for this method has proven difficult. The advantage of a circular track is that the satellite can be gradually accelerated over a period of several hours.And, when writing about anything, never forget to trot out someone willing to use The T Word:
The tunnel would direct the cone to a ramp angled at 30° to the horizon, where the cone would launch towards space at about 8 kilometres per second, or more than 23 times the speed of sound. A rocket at the back end of the cone would be used to adjust its trajectory and place it in a proper orbit.
Anything launched in this way would have to be able to survive enormous accelerations -- more than 2000 times the acceleration due to gravity (2000g). This would seem to be an obstacle for launching things like communications satellites, but Fiske points out that the US military uses electronics in laser-guided artillery, which survive being fired out of guns at up to 20,000g. [...]
If the ring launched hundreds of satellites a year, it would be cheaper than conventional rocket launches. With 300 launches per year, the team estimates the ring could put payloads into orbit for $745 per kilogram. If the launch rate reached 3000 launches per year, they calculate that would drop to $189 per kilogram. Today, it costs more than 100 times that to send payloads into space.
Although Epstein is sceptical about the prospects for such a ring, he cautions that if built, the ring itself could become a target for attacks. This is because of its potential for use as a weapon, launching missiles that could reach anywhere in the world. "The ring then becomes one of the most important targets on the planet," he told New Scientist.