[extropy-chat] stardust at home

spike spike66 at comcast.net
Sat Jan 21 23:52:27 UTC 2006

bounces at lists.extropy.org] On Behalf Of Robert Bradbury
Subject: Re: [extropy-chat] stardust at home

On 1/21/06, Amara Graps <amara at amara.com> wrote:
Generally, an average of 40 tons per day of extraterrestrial material
falls to the Earth...

...Wow, that much!  I didn't realize it was that high but I have been
thinking about this since I pointed out somewhere that  many space
exploration missions, e.g. the Pluto mission, are actually disassembling the

Robert that little bit leaving and even that 4e7 kg/day incoming
is negligible compared to the 6e24 kg upon which we shuffle about
in our tragically short few years of human existence.

  ... Spike, isn't this going to end up changing the Earth's orbit because
we are getting heavier?...  

The total mass doesn't matter.  We pick up a little momentum from
some of the stuff, lose a little to some of it.  I haven't calculated,
but my intuition guesses that it nearly balances.

... how much would we have to lighten the Earth on a yearly (daily) basis to
enlarge our orbit as the Sun expands to a red giant and thus maintain the
planet in a habitable zone ... 

Why would we want to drag the entire rock?  Make a number of
habitable microplanets, download ourselves into those and
blast them out as quickly as we can make them.  As we do,
we carry off momentum and the enormous rock we call earth
will slip a little closer to the sun, but there is time
before sol goes red giant.  Assuming we get busy.  {8-]

Robert your notion of a Matrioshka Brain is still one of
the most stunning insights ever seen on this list.  Don't
lose sight of that jewel of an idea.

... How much power will we need?  How many active fusion reactors?  How many
mines hauling mass out of the ground?  How long before the Earth starts
turning into swiss cheese?  Etc. etc.

Fusion reactors?  We already have a really good one.  We
use mirrors to reflect photons from the sun directly west.  The
entire earth is turned into an enormous photon rocket,
gradually picking up angular momentum and thus spiralling
slowly away from the sun.  

That was a joke of course.  We would move earth little further
from the sun with this scheme, but the real reason to do 
this would be to increase the rotation rate of the planet.  Once
we spin it up to about a milliradian per second, from its current
~72 microradians per second, stuff at the equator becomes
nearly weightless.  That is a good starting point for taking
material off of the planet.

As we do, of course, it takes angular momentum with it,
so we must make up the difference with mirrors reflecting
sunlight west.  In doing this, we will have created a
the equivalent of a solar powered orbit ascent vehicle.

Of course we would also sling our atmosphere into interplanetary
space, resulting in suffocation of all lifeforms.  But at least
it cleanly solves the problem of excess carbon dioxide and freon 
in the atmosphere.  


ps HEY cool!  This is starting to sound like the good old 
ExI chat that I knew from years ago.  {8-]

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