# [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,
http://hypertextbook.com/facts/2005/RandyAbbas.shtml
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
physics.

--
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

```