Re: USA urges scientists to block out sun

On Feb 2, 2:31 pm, Ian Stirling <r...@xxxxxxxxxxxxxxxxx> wrote:
steve <stephen.colbou...@xxxxxxxxxxxxxxx> wrote:
Well the good news for you is that at one tonne per sqkm = 1 gram per
square metre.

That should make your space shield much more practical- Hide quoted text -

- Show quoted text -

Doh! You're right. I slipped a digit and a factor of 1,000! .

The plastics from which GBO is made are 1.2 metric tons per cubic
meter, so 1 gram per square meter is a thickness of 0.83 mm - that's
830 um - far larger than I was thinking. - Two layers 100 um thick -
one transparent, the other refletive, filled with a veyr low pressure
gas - to create a pressure stabilized structure. At 1/2 gram per sq
meter. A 3 km diameter mirror would then weigh 7 tonnes. 70 tons
would be 16.5 km in diameter. 660 tons 29.1 km diameter. 191,440 of
the larger mirrors would be needed to cover the entire surface of the
Earth. 1,915 mirrors would intercept 1% of the sunlight. Over a 5
year period that's 1 launch per day. With a 30 day turn around,
that's a fleet of 30 of the more massive vechicles.

At $6 billion each that's $180 billion - a far far smaller program.

The system could still beam 300 TW to Earth, which could pay for it
all.



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