The Mega Foundation

In the News

March 15, 2005

Robotics
    
A few interesting developments in robotics might be worth noting.
    The Japanese are demonstrating humanoid robots, and are saying that there will be one or more of these in most Japanese households by 2015(!), Washington Post- Japan embraces latest robots. Japan has long been enamored of robots, Japanese Hospitality Robots Debut At World Expo. The article says that robots are already being employed as receptionists, night watchmen, guides, hospital workers, and pets. I might dismiss this as hype, except that three years ago, I would never have imagined that Tommie Jean and I would own and depend upon a robotic vacuum cleaner to sweep our floors. I would have guessed that we wouldn't have bought one until 2015-2020.


  The fellow on the left is targeted for household introduction in 5-to-6 years, Hitachi's humanoid robots can chat, zip around. Another article discusses the rapid displacement of human workers by electronic equivalents... e. g., automated answering systems. Of course, the global economy is generating new jobs to replace those that machines are usurping, as it has done for that past two centuries, but the author argues that the pace is quickening. Still, a principal concern in the 1940's and 1950's was what everyone would do with their leisure time now that machines were taking over everything. Social scientists in the 40's and 50's were anticipating the imminent advent of the 32-hour work-week.
    Meanwhile, DARPA is running their autonomous vehicle road run again this year, Duke University Engineers Join 'Red Team' Robotic Vehicle Team. Last year, none of the entrants finished the course.
    Another interesting concept being advanced is that of a "space blimp" that would use solar-powered ion engines (?!) to accelerate a helium-filled flying wing into orbit, Orbital Airship.Ascenderthumb.gif (16257 bytes)
    I have major questions about this. The highest altitudes that present-day balloons can reach is about 125,000 feet (~25 miles or 40 kilometers). At that altitude, atmospheric pressure is about 1/300th what it is at at sea level, or about 2.5 mm. of mercury. Apparently, this concept is based upon deploying a much lighter "blimp" from a "dark sky station" at this 40 kilometer altitude. Conventional ion engines couldn't begin to operate at the atmospheric pressures at 40 kilometers. They would require pressures 3-to-4 orders of magnitude lower than this... pressures of the order of 10-3 to 10-4 which would be found at altitudes of 95 to 110 kilometers.(350,000 to 400,000 feet). However, the ionosphere starts at 40 kilometers. One idea I entertained in 1956 was the notion of trying to generate an "ion wind", in which ions accelerated in air would bump neutral air molecules, herding them forward. In this manner, I thought that it might be possible to accelerate a space vehicle in the ionosphere. However, one problem with this would seem to me to be that if buoyancy gave you enough lift to support the vehicle, it couldn't go very fast because of atmospheric drag. Of course, an inflatable flying wing could generate lift through its forward motion, but it would take quite a bit of push to support it against the pull of gravity. Still, if an "ion wind" could be generated by accelerating positive ions already in the ionosphere, exhaust speed could be very low, and ionic thrusts could be relatively high. 
    But there's another problem that seems insuperable to me. As the speed of the vehicle increased, the stagnation temperature of the air would rise as it does with nose cones. Long before you ever got to orbital speed, the gossamer-thin plastic that enclosed the helium would melt. Lift depends upon momentum transfer, mv, which increases in proportion to speed, but stagnation temperatures increase as the square of the speed, ½mv2. In order to get the lift needed to overcome the gravitational pull, the ship would face energy levels and temperature typical of rocket flight. (Centrifugal force goes up as the square of the speed, so at half the orbital speed of 5 miles a second (8 kilometers a second), the "space blimp" would still weigh 3/4ths of what it would on the ground. And at half the orbital speed, stagnation temperatures would be several thousand degrees.) (Since the accelerating blimp has to pass through all the speed levels up to orbital speed, it's going to have to experience these temperatures before it can attain orbit. And if there's so little air that won't be any heating, there's also no air to provide buoyancy.)
    Finally, the Methuselah Mouse Prize now exceeds $1,000,000, Anti-aging prize tops $1 million. This is wonderful news because it relates directly to the delay, and hopefully, to the prevention and cure of cancer, Parkinson's Disease, Alzheimer's Disease, and so forth and so on.

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