Tuesday, July 26, 2011
My thoughts take flight...
[Click here to view the cartoon properly]
Nice one by Abstruse Goose. It brings up the interesting theme - Pace of technological advancement. We are actually advancing at a super fast clip, and all indications are that if you or I are airlifted 100 years into the future, we will be as clueless as people from 1911 would be in the world of 2011. However, mankind has a fascination with flying and with space, and that is where technology appears to have failed us. I mean, where are all the space colonies? If the Mars colonies are still a few decades away that's understandable, but why aren't there at least some astronauts visiting Mars by now? In that context, it appears that we have achieved a big squat zero in aerospace in the 42 years since 1969. Why, the Concorde was a supersonic jet which first flew in - guess the year - 1969, but was actually retired by 2011! So has aerospace failed us? This blogger thinks, maybe its not technology. Maybe its some other force holding us back from spreading our seed in outer space. Allow me to speculate...
Firstly, man has had many significant achievements in aerospace. Its no mean feat that there are thousands of heavier-than-air aircraft criss-crossing the world all the time. Which means not only have we mastered the technology, but we have made it practically safe and commercially feasible to carry millions of people in metal tubes flying at 30,000 feet altitude. Try telling that to a 19th century man. So indeed man has conquered gravity in a way, its only that he has not been able to conquer gravity on a large scale. Think about it, the biggest aircraft to fly has been the Boeing 747 (coincidentally, it made its first commercial flight in 1970!). We all marvel at the 747's size, but seriously, a length of 250 feet? Is that the best we can do? We can build bridges which are dozens of kilometers in length, but 250 ft is great for an aircraft?
Do you remember this iconic image in Independence Day? Why can't we imagine humans to build a similar craft which is maybe 2-3 kms along each dimension (length, breadth, height)? And craft of such scale would be necessary if we want to colonize other planets. Imagine the amount of stuff we would need to carry. Maybe you would get iron and some metals over there, but wouldn't you require lots of other materials to be airlifted? Think plastics, glass, rubber, fabric, organic stuff. Thousands of tonnes - if not millions - would need to be sent across. And what is our current payload limit? 2,000 kilograms is a great deal for space missions. Heck, that's the payload of an average pickup truck back on Earth.
Indeed our problem has been that conventional energy sources seem to have met their match in gravity. 9.8 m/s2 is a lot of acceleration to be facing every second an object is in the air. I haven't done the math, but it would require massive amounts of energy to lift even a thousand tonne object at surface level. Hence we are stuck. The reason why we can't go to Mars using current conventional energy sources is the same reason why we had to retire the space shuttle program: the technology exists, but its just unbelievably expensive!
I think, maybe things could have been different if we had been on a planet with lesser gravity - for example, the moon, which has a sixth the gravity of the earth. But I am not too sure. Maybe its a scale thing. An ant can lift 50 times its own weight, an average human not even one time his/her own weight. Similarly internal combustion engines have proved they can move payloads a few 'x' their weight (think trains), but cannot be expected to *lift* weights of that magnitude (fighting against a super strong gravity instead of a weak friction force). Therefore I am compelled to think the next advancement in space flight may come only when we are able to harness new sources of energy. Nuclear propelled motors? Fuel Cell powered motors? Who knows. But can you imagine the downward thrust that would be required to push up something which spreads a mile across? I am thinking we need even more radical technology. Something which can make the below image possible:
Technology that will allow objects to hover easily without requiring massive, massive downthrust. I am thinking more 'fundamental physics' than 'mechanical engineering'. Go physicists! Give us applications of Higgs boson or some stuff like that which will maybe help us work around / reduce the whole problem of mass itself! This kind of technology I am talking about does not even have primary science backing it up yet, so even if it were ever possible from a physics standpoint, we would still be looking at a few decades to make it practical and feasible. Hope my lifetime is enough!