[ExI] A Geophysics problem

Anders Sandberg anders at aleph.se
Wed Sep 30 13:15:22 UTC 2015

On 2015-09-30 04:30, Keith Henson wrote:
> At peak production about 2 million tons of ionized hydrogen gets
> expended between LEO and GEO every year.

The solar wind has a few atoms per cubic centimeter,
giving me a rough estimate of about 10^-17 kg/m^3.

The volume out to synchronous orbit is 4*pi*(42164e3)^3/3=3*10^23 m^3, 
so the total mass is about 3 million tons. So 2 million tons is actually 
significant... if it was an instantaneous release.

But note that the solar wind is moving: the slow solar wind is moving 
about 400 km/s (and has twice the density as the fast), so over a year a 
mass of pi*(42164e3)^2 * 400e3 * (3600*24*365.24) * 1e-17 = 705 billion 
kg is moving past the geosynchronous orbit.

The hydrogen "pollution" is hence neglible...

...unless funky interactions with the magnetosphere happens. Now, that 
can be complex because of the different locations involved. Keith's 
scheme would deposit hydrogen across the plasma sphere, van Allen belts, 
magnetotail and other structures. As a general rule the protons would 
tend to spiral along the field lines, wobbling north and south if they 
get trapped. I would not expect it to do much more than a slight 
increase of solar activity would do, but maybe if the exhaust has just 
the right energy to get some resonance they might build up, cause 
auroras or do something else nonlinear.

So I would suggest talking to somebody doing space weather or aurora 

Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

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