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Comment Re:oh jeez. (Score 1) 140 140

... Helium .. has roughly half of the lifting capacity of Hydrogen....

not really, the "lifting capacity" is from the difference in mass between lifting gas and surrounding air. Air is ~29 g/mol, so the ratio of lifting capacity of H2:He is

[(29 - 2) / 29] : [(29 - 4) / 29] = 27/25,

works out at 8% difference. The containment vessel's weight is typically more significant than the gas itself in a lighter-than-air craft.

Balloons with He3 give only 3% more lift than He4, lunacy!

Comment Re:No win situation (Score 2) 187 187

Facebook shouldn't be so judgemental, why should people's decision to commit suicide not be honoured? How is "save a few lives" a good thing if those lives are lived by people who don't want to live those lives!

Oh dear /. moderation system is going to call the Samaritans on me now...

Comment The War of the Worlds, Ch. Two: The Falling Star (Score 1) 122 122

An enormous hole had been made by the impact of the projectile, and the sand and gravel had been flung violently in every direction over the heath, forming heaps visible a mile and a half away. The heather was on fire eastward, and a thin blue smoke rose against the dawn. Link here (e.g.)

Comment Re:How surprising... not (Score 2) 110 110

Mars' atmosphere is .. around 20 mBar ..it's near-vacuum. And vacuum makes for a very good thermal insulator.

"For all practical purposes" is not correct. The thermal conductivity of a gas is near-independent of pressure down to very low pressures, until the mean free path of particles becomes large compared to the distance to the solid where the heat gets dumped. 20mBar and the MFP is still tiny.
You need a pretty good vacuum (10^-4mbar or so) in a coffee flask otherwise it doesn't change a thing.

"Mach was the greatest intellectual fraud in the last ten years." "What about X?" "I said `intellectual'." ;login, 9/1990

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