Newsgroups: alt.sci.planetary
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: Venus question
Date: Sun, 8 Mar 1998 05:08:28 GMT

In article <01bd4a34$5a301fa0$c2e728c3@default>,
Aldrin <moony@easynet.co.uk> wrote:
>Is it at all feasible, given the intense pressure and heat etc.., that one
>day a 'Mars pathfinder' type mission could be carried out on the surface of
>Venus, or is it just not possible?

It's not utterly impossible but it's formidably difficult.  The pressure
is no big deal; the problem is the heat.  To date, Venus-surface probes
have all died when their electronics got too hot.  Building electronic
systems that can run at Venus-surface temperatures is seriously hard, and
cooling the electronics package to more manageable temperatures is
effectively impossible.  It would probably take major new technology to
make it work.  The incentive to develop this is lacking; Venus seems to be
a pretty worthless place.  Someday, but not soon.
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Terraforming Venus with controlled Asteroid Strikes
Date: Sat, 7 Aug 1999 18:11:48 GMT

In article <7oeqiq$q1i$1@news2.inter.net.il>,
Oren Ben-Kiki <oren@capella.co.il> wrote:
>At any rate, I originally thought vaguely of the algae getting rid of the
>unwanted elements in the atmosphere by some form of waste product which will
>sink in the atmosphere and stay stable at a lower lever (ideally, on the
>surface itself). This doesn't have to be a simple compound - after all,
>plants on earth produce a lot of stable complex C/H/O compounds; the trick
>is to find a sulfur one to fit the bill - that is, one which wouldn't
>recombine with the oxygen "too quickly".

Unfortunately, at Venus-surface temperatures, there are *no* carbon
compounds which are likely to be stable enough... especially in 60atm
of oxygen!  *1atm* of oxygen is nasty on most organics, as witness the
Apollo fire.  60atm is much, much worse.

Besides, *we* can't live in 60atm of oxygen either.

It's necessary to convert the oxygen, as well as the carbon, into some
other form.  That's considerably harder.

Carbonate rock is what was used on Earth.  (Earth has about as much CO2 as
Venus, but it's mostly in limestone rather than loose in the air.)  Alas,
to get that you need liquid water on the surface.

(The fundamental difference between the two planets is that Earth was cool
enough for water to stay liquid while the CO2 was being converted to
carbonate rock.  Venus's oceans boiled before the conversion got very far.)

>I don't know whether this makes any biochemical sense. As an extreme
>example, I bet bucky balls with trapped sulfur atoms would fit the bill...

Buckminsterfullerene is fairly stable as carbon goes, but in 60atm of pure
oxygen, no.

The sulfur is not a significant problem, by the way; there just isn't all
that much of it, and we can find something for it to combine with.  The
CO2 is the hard part.
--
The good old days                   |  Henry Spencer   henry@spsystems.net
weren't.                            |      (aka henry@zoo.toronto.edu)

From: henry@spsystems.net (Henry Spencer)
Newsgroups: alt.war.nuclear,sci.space.tech,sci.physics
Subject: Re: Anti Matter(lowering Venus atmospheric pressure with nuclear)^
Date: Thu, 16 Sep 1999 03:40:56 GMT

In article <37E01910.F660ED06@wzrd.com>, Ra  <nospam@wzrd.com> wrote:
>> about a hundred *kilograms* of CO2 per *square centimeter* of surface.  If
>> you could wave a magic wand and liquefy all of it, the average depth of
>> the resulting liquid-CO2 ocean would be about a kilometer! ...
>
> umm.... oops. I haven't done any math, or anything like that. It was
>just an idea.

I admit, I was somewhat startled by the numbers myself when I worked them
out -- hadn't figured it that way before -- and I had to check them
several times to convince myself they were right.

> I was thinking that the liquid CO2 (that isn't used for water) could be
>stored until it could somehow be put into orbit or another use for it
>could be found...
> Maybe the carbon could be used for carbon fiber type materials? ...

Steve Gillette (sp?) has pointed out that this is a really huge amount of
carbon, much the largest supply of it in the inner solar system, and it
really would be nice if it were kept in some accessible form rather than
blown off into space or otherwise destroyed.  We might have a use for it
someday.
--
The good old days                   |  Henry Spencer   henry@spsystems.net
weren't.                            |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Terraforming Venus
Date: Thu, 6 Jul 2000 14:59:17 GMT

In article <3964402D.64BD3A54@bigpond.net.au>,
David Sander  <surfren@bigpond.net.au> wrote:
>Venus' atmospheric pressure needs to come way down, and the best way to
>do that is to separate the carbon from the oxygen from the atmospheric
>CO2...

And do *what* with them?  You can't just leave them together; carbon is
intensely flammable, possibly even explosive, in 90atm of oxygen.  So are
people.  You have to get *rid* of most of the oxygen somehow.  That's hard.
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

From: "Paul F. Dietz" <dietz@interaccess.com>
Newsgroups: sci.space.policy
Subject: Re: Terraforming Venus
Date: Thu, 06 Jul 2000 19:07:58 -0500

Dr John Stockton wrote:

> This amount of carbon, ignited in stoichiometric oxygen, should
> produce a substantial bang of the order of 1E11 megatons, which should
> be enough to remove most of Venus' atmosphere in a flash.

No -- the energy is too little (otherwise a carbon/LOX fueled
SSTO would be trivial.)

Moreover, even if you were to blow Venus's atmosphere off the
planet into solar orbit, there's so much of it that the solar
wind could not blow it into interstellar space before it
reaccreted onto Venus or (worse) onto the Earth.

	Paul

Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Terraforming Venus
Date: Fri, 7 Jul 2000 01:29:46 GMT

In article <1Iex+BG2lQZ5EwyI@merlyn.demon.co.uk>,
Dr John Stockton  <jrs@merlyn.demon.co.uk> wrote:
>...that of Venus must weigh over 4E17 tons, of which over 1E17 tons is
>carbon.  This amount of carbon, ignited in stoichiometric oxygen, should
>produce a substantial bang of the order of 1E11 megatons, which should
>be enough to remove most of Venus' atmosphere in a flash.

Alas, not so.  I don't have numbers handy for the exhaust velocity of
C+O2, but even assuming 100%-efficient conversion of thermal energy into
kinetic energy, this doesn't work.  The heat of formation of CO2 from its
elements is about 400kJ/mole, about 9MJ/kg, equivalent to the kinetic
energy of about 4km/s.  Venus's escape velocity is over 10km/s.
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Terraforming Venus
Date: Fri, 7 Jul 2000 11:46:25 GMT

In article <396560FA.F96B3B@austin.rr.com>,
Richard Hendricks  <rahendric@hotmail.com> wrote:
>You could use asteroids to plow parts of the atmosphere off...

This has been looked at.  Apparently it does not really work very well, at
least not for a relatively large planet like Venus.

--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

From: "Paul F. Dietz" <dietz@interaccess.com>
Newsgroups: sci.space.policy
Subject: Re: Terraforming Venus
Date: Fri, 07 Jul 2000 05:41:20 -0500

John Galt wrote:

> I read somewhere that it should be possible to dump a bunch of algae into
> Venus' atmosphere and that would do the trick. Scientists proved that algae
> could thrive in the conditions found on Venus. Algae would eventually
> convert the carbon dioxide into breathable oxygen, and that it would
> eventually rain and produce oceans on Venus.

This doesn't work, for rather obvious reasons we've
been discussing.

	Paul

From: "Paul F. Dietz" <dietz@interaccess.com>
Newsgroups: sci.space.policy
Subject: Re: Terraforming Venus
Date: Fri, 07 Jul 2000 18:56:43 -0500

Andy wrote:

> yes, but the question which generated the "for obvious reasons"
> reply wasn't about humans. It was about algae (and by inference
> other simple life forms).

The obvious reason is that the biomass gets oxidized back to CO2
long before more than a small fraction of the CO2 is separated.
Think of what happens to dead algae falling into an atmosphere
of 89 bars CO2, 1 bar oxygen, and a surface temperature close
to that of today's Venus.

	Paul

Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Terraforming Venus
Date: Sun, 9 Jul 2000 17:54:11 GMT

In article <8k9h1n$ofe$1@news1.xs4all.nl>, BigPilot <nospam@hotmail.com> wrote:
>O'Neil colonies are unrealistic as they would cost gigantuous amounts of
>money and only 10.000 people would be able to live there anyway. Purely from
>an economic standpoint it isn't going to work and therefore will never
>happen.

"Never" is a long time.  Only a few centuries ago, crossing the Atlantic
(one-way) with minimal homesteading supplies required the Plymouth Rock
colonists to spend their entire life savings *and* go deep into debt.
Somewhat later, the Mormons merely had to spend their entire life savings
to move from the eastern US to Utah.  One of my great-grandfathers came
from Europe to North America as a child, with not the slightest chance
he'd ever go back; one of his sons, late in life after retirement, visited
Europe for a *vacation*.  We are already richer than our ancestors'
wildest dreams.

>Terraforming is cheaper, easier and can be done simply by employing
>lifeforms.

If that were *true*, it would have considerable advantages.  Trouble is,
*it's not true*.  Neither Venus nor Mars can be terraformed just by
throwing algae at them, even if you assume genetically-tailored algae.
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.science
From: henry@spsystems.net (Henry Spencer)
Subject: Re: terraforming venus
Date: Sat, 28 Oct 2000 18:48:25 GMT

In article <8tcsa6$1ns4$1@si05.rsvl.unisys.com>,
Helge Moulding <hmoulding@excite.com> wrote:
>How much carbon would one need to terraform Venus? It's my impression
>that almost all life on Earth depends on an abundant supply of carbon.
>Most of it is fixed in the ground.

There is little exchange between the biosphere's carbon and the stuff
fixed in limestone, though.  The biosphere doesn't need a lot compared
to what's in Venus's atmosphere.

>>Well, first ask yourself why it needs a 24-hour "day"
>
>I'm not even suggesting 24 hours. Something around 30 hours may be
>acceptable for most terrestrial life. The point is that terrestrial
>life, for the most part, requires a day-night cycle to thrive...

Nope.  Check out the plants and animals that live in the Arctic, where
sunlight is continuous in summer and nonexistent in winter.  It's an
issue but shouldn't be a huge one.

A day that almost matches the terrestrial one may actually be a worst
case.  Humans, in particular, probably cannot generally adapt to a 30h
cycle.  (A 28h cycle has been tried:  some people can adapt, but many
can't.)  In some ways it's better to have a longer day/night cycle that can
be independent of the sleep/wake cycle.  If you can't have something that
closely approximates 24h, it might be better to have a day that's a full
growing cycle long, so you don't have to worry about how crops will
handle a long night.  Depends on what it does to weather, though.

>I wonder if bringing Iapetus down within the Roch limit would do the
>trick: spin up Venus as the tides rip the moon apart, then toss the
>individual chunks of ice down with the right English to add their
>remaining energy to the rotation.

Nope.  Tangential impacts by several of the largest asteroids -- much
larger than Iapetus, and moving much faster than an orbit -- wouldn't give
a decent day.  (It's been looked at.)

>>   As to the magnetic field, good point, but we don't need a magnetic
>>field to shield the Earth from radiation - that's done almost entirely
>>by our atmosphere.
>
>I thought that a major Solar storm would be deadly to the Earth's
>surface, even with our atmosphere, if we didn't have our magnetic
>field. Enough charged particles make it through regularly to break
>down power transmission and wreck radio communications.

The problems with power are because of the magnetic field being kicked
around, not because of the particles themselves.  The communications
difficulties are similar, I believe.  Our atmosphere gives us 10t/m^2
of shielding, equivalent to 10m of water or 4-5m of rock, and would be
quite adequate even in the absence of the field.  (Earth's magnetic
field probably is relatively ineffective as shielding while it reverses,
which it does periodically.)  Radiation levels would probably go up
some, but it wouldn't be catastrophic.

There is little or no magnetic shielding near Earth's magnetic poles, and
those areas remain habitable (well, as habitable as the polar regions get).
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.science
From: henry@spsystems.net (Henry Spencer)
Subject: Re: terraforming venus
Date: Tue, 31 Oct 2000 06:05:29 GMT

In article <8tl8s4$1gst$1@si05.rsvl.unisys.com>,
Helge Moulding <hmoulding@excite.com> wrote:
>>There is little exchange between the biosphere's carbon and the
>>stuff fixed in limestone, though.  The biosphere doesn't need a
>>lot compared to what's in Venus's atmosphere.
>
>Really? I thought most of our limestone is the product of our
>biosphere: weathered out of the atmosphere, and converted to
>CaCO3 by ocean critters...

My (dim) recollection is that much of the carbonate rock is thought to
have been laid down by purely chemical processes in the ocean, before life
became a large-scale participant.

The point remains, though, that *today* there is little exchange between
the two.  The carbonate rock stays carbonate rock, it doesn't exchange
carbon with the biosphere to any great extent.

>...I'm kinda assuming that a
>terraformed Venus is intended to be a living planet, not an
>expensive toy that requires continual external maintenance.

It's quite likely to need some external maintenance... just like buildings
and cities.  For example, there is no obvious way to get any sort of plate
tectonics going, and that complicates matters a bit.

>Once you're on Venus's surface, how are you getting back off?

Any number of ways.  A civilization which can terraform Venus is not going
to have any great problem with that.

>...Without a plentyful supply of
>petroleum, you won't be building a lot of chemical rockets, I think.

LOX/LH2 doesn't need petroleum.  Nor does LOX/hydrocarbon, really --
petroleum is just the most convenient source of hydrocarbons.  Ammonia
and hydrazine are not petrochemicals and make quite reasonable fuels,
as do the alcohols.  These things need hydrogen, but terraforming Venus
absolutely requires importing a whole bunch of hydrogen anyway.

In a pinch you can always use LOX/CO, although its performance is not
great, and that you can make starting with nothing but CO2.

>Without rotation, you can't build the old space elevator.

Not a classical space elevator, no.  Rotating tethers in orbit will work
just fine, though, as will dynamically supported towers and a number of
other variations.
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)