Dome, Dome on the Range

Jerry Friedman · 16 Jan 2011, 19:44 · from 2011-January.txt.gz

This is the message as the crawl holds it, before anything here touched it. What the conversation shows has been through ingest: transfer encodings decoded, attachments dropped, quote markers repaired, and the archiver’s ? resolved into quotation marks and dashes. Those repairs are judgements and some of them are wrong, which is what this page is for. Email addresses are obscured here as they are everywhere else on the site, so it is before our repairs rather than byte for byte.

From: jerry_friedman at yahoo.com (Jerry Friedman)
Date: Sun, 16 Jan 2011 11:44:04 -0800 (PST)
Subject: (urth) Dome, Dome on the Range
In-Reply-To: <4D32DAD1.1080301 at io.com>
References: <850030.91086.qm at web84105.mail.mud.yahoo.com>
	<261903.11019.qm at web161805.mail.bf1.yahoo.com>
	<980429.72652.qm at smtp820.mail.ird.yahoo.com>
	<4D2EEA53.7030002 at verizon.net> <4D2F1B2B.1010702 at io.com>
	<4D2F20C9.9030809 at verizon.net> <4D2F2C6E.2000907 at io.com>
	<430DCB16D8604E4483F358EC46969D06@jill> <4D2F4939.3010108 at io.com>
	<AANLkTi=Va5L70WEU8f94y-fTj2wXSRRbaxXWigh_P3Ky at mail.gmail.com>
	<4D2F8114.2000401 at io.com>
	<4D2F8433.1020304 at verizon.net><4D2F95AF.9010504 at io.com>
	<4D30B621.9050508 at io.com> <8D13FD44CA76440BBAC21C9A0F5E6E78@jill>
	<48834.67926.qm at web114701.mail.gq1.yahoo.com>
	<4D32DAD1.1080301 at io.com>
Message-ID: <527047.44567.qm at web114703.mail.gq1.yahoo.com>

> From: Jeff Wilson <jwilson at io.com>

> On 1/15/2011 11:51 PM, Jerry Friedman wrote:
> >> From: Gerry Quinn<gerryq at indigo.ie>
> >>  From: "Jeff Wilson"<jwilson at io.com>
> >>
> >>>  It occured  to me at lunch today that a problem with the open air  
>atmosphere
> >> schemes, even  ones that last thousands of years  between refills, is that 
>they
> >> take half to 3/4  the mass of  earth's atmosphere to work. When this does 
>escape
> >>from the  moon,  only small amount of that will also escape from the earth,  
>and
> >> the reset  will eventually come to fall on the earth,  raising its surface 
>air
> >> pressure  accordingly; this is a  serious problem
> > ...
> >
> >> Seriously, will this actually  happen, anyway?  I couldn't find  detailed
> >> references to a  proper calculation, but here are my thoughts:
> >>
> >> If   an atom leaves the top of Lune's atmosphere at lunar escape velocity,  
>the
> >> question of whether it is likely to end up in Urth's atmosphere  on Urth 
>depends
> >> on whether it exceeds Urth escape velocity at this  point (unless it's 
>headed
> >> directly for Urth, which is  unlikely.
> 
> It can escape the moon moving rearward, going into an  elliptcial orbit,

Those seem like two ways of saying the same thing--headed for Urth, going 
backwards
relative to Lune, which puts it into an elliptical orbit that intersects with 
Urth.
 
> > I like it, but you need to add in the orbital  velocity of Lune, which makes
> > molecules substantially more likely to  escape.  (This could actually be a 
>bigger
> > problem than air ending  up back on Urth, where as you note it's not lost.)
> >
> > Also,  molecules that escape from Lune but not the Lune-Urth system will be 
>in
> >  orbits that intersect Lune's orbit where they left it. Except for the  
>relatively
> > small portion aimed at Urth, they're not going to come to  rest on Urth 
until
> > their orbits are modified by collisions with other  molecules or brushes 
with
> > Lune.  I suspect they're a good deal more  likely to come to rest back on 
>Lune
> > than on Urth.
> 
> I considered  that last, but the infalling gas regains the kinetic energy 
> so when it  returns it heats the atmosphere, increasing the rate other 
> gas leaves, so  that much more gas is available to take non-returning 
> paths while  maintaining the same overall rate of depletion.

It just puts back the energy it took out with it, partially compensating for the
evaporative cooling.

> Not to 
> mention all  this gas farting around lunar orbit is a hazard to navigation.

Much like Earth's atmosphere.

Jerry Friedman

An unofficial mirror of a public mailing list · about & removal requests · download the archive · before the list · original archive at urth.net