Soon everyone will have "google glasses" of some sort that will record everyplace you are and everything you see - sent to the cloud and you can retrieve/delete the recordings at will. This invention seems to be too late for a long run. The science is useful, however.
In most cases, the motion required to respond to an attack is not going to allow for the steady positioning required for a picture except perhaps in out in bright sunlight.
The concept is appealing, the market will see value, the cost will be prohibitive and when the function is really required to be used as intended which probably would involve a darker, less well lit environment and perhaps involving an attack or conflict, the functionality would not be there.
You are right on with that! People who are determined can work through a pepper spray attack. I once had a security firm, and as part of the training you had to restrain and handcuff an assailant who had just pepper sprayed you. We used half strenth spray on the instructor who was demonstrating. Then we used full strength on the students. It was a blast.
Cost is an important consideration. Pepper spray is about $30. And once you use it, it has to be replaced. I'm sure that with GPS, rangefinder, microprocessor, etc, its cost will be way north of $30. Plus, how much is a refill?
So how much is your life worth? Some would say "Priceless", but I don't see many people with a dedicated bodyguard. So cost is an important consideration. Bullets cost pennies, but could be as high as $1.00 each time you shoot one. So even if I have to use 5 shots to bring down an attacker, it's still a pretty good bargain. Add $60 every 5 years to renew my carry permit and it's still a bargain. OK, so the gun cost a lot of money, but some guns are good investments. Pay $400 today and you might get $600 for it in 10 years or less (I have an SP101 I paid $199 for and now is worth $320+). If they can bring this to market for $100 or less with refills at $20 each, they might have something. Otherwise, it's just an Engineering exercise.
On April 15, 2010, President Barack Obama gave a major speech at the Kennedy Space Center in Florida, announcing that the US would send astronauts to Mars by the mid-2030s. But in order to do so, NASA would first need to ramp up its capabilities through missions directed toward "a series of increasingly demanding targets," i.e. asteroids.
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