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From: David Hobby
>On 9/5/2013 4:54 PM, Keith Henson wrote:
>> The propulsion lasers to get the parts up to GEO at a cost where the
>> whole thing makes economic sense, those are weapons, game changing
>> weapons. And if I had to bet, it would be for them to be controlled by
>> the Chinese. Keith Henson _
> Now that's a problem with the plan.
> If the lasers could be weapons controlled by one country, I can see
other countries upset enough
to sabotage the whole project. There'd need to be a political solution
that made it clear
the lasers weren't going to be used as weapons by any group short of
most of the UN Security
Council.
John Mankins, one of the big names in power satellite research, told
me that the US would destroy a Chinese propulsion laser before it was
turned on. Covertly.
The head of the Chinese space agency talked to visiting Indians and
proposed they jointly build power satellites.
Would the US destroy an Indian/Chinese propulsion laser?
From: "Dan Minette"
> Do you have any vidios of lasers holding up, say, a 10kg object, for 20
minutes
20 minutes is 1200 seconds. An object falling in a one g field would
be attain a velocity of v=gt or 11760 m/s. Assuming 7.5 km/s exhaust
velocity, the fuel mass to hover that long would be:
1-1/e^(11760/7500) or 79%. So you have a vehicle mass of 2.1 kg, with
7.9 kg of hydrogen
The starting power for the laser would generate g x the mass of the
vehicle, 98 N.
Force being equal to ma where a is v/t for one second for the hydrogen.
98 N = mass per second x 7500 m/s
solving for mass, about 13 gm/s
Ke per second (i.e. watts) of the hydrogen is 1/2 m v^2 or
367,500 W, tapering off over the 20 minutes to 1/5th of that amount.
At $10/watt, this is about 4 million.
How badly do you want to see this demo?
Keith
> and keeping it under control. This would be one of the easy
feasability tests one would do at the start of any serious undertaking.
That would be one of many things that would have to be sucessfully tested
before the project would be deemed even possible.
Dan M.
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