Hi,

>Rachel wrote:
>Interresting, this is the first I've heard of anyone wanting to terraform
>Venus. Seems like it would be a lot more work than Mars would be (aside from
>the gravity calculations you provided). So, cooling Venus...would you think
>something like the "Soletta" as represented in the Mars books by Robinson to be
>an option to shade the planet and allow it to cool?

It would be a LOT easier to terraform Venus than Mars, in terms of
energy (a calculation I will be posting soon - I'm currently working on
Galactic maps). Venus only needs to be cooled down, then some of the
atmosphere to be compressed and stored in a gas cylinder type
structure. Then large amounts of Deutrium to be transported from
Jupiter. All this will still need less energy than moving large chunks
of mass to Mars. Also, the high-density mass just isn't freely
available in our solar system to add to Mars. Most of it is already
part of the terrestrial planets or has fallen into the gas giants. This
will require significant energy to extract. There is not enough mass in
the asteroid belt.

The hard part about terraforming Venus is the technology. More research
is needed into cooling the atmosphere.

Small hollow, highly reflective spheres, with a density equal to 1.5
atmospheres. They can be made here on Earth then sent to Venus by
rocket, where they are dumped in the upper atmophere. Because they have
a low density (compared to the atmosphere), they will sit above the CO2
and reflect light back into space. The atmosphere will cool and the
pressure reduce enough for the first colony to arrive. The colony can
then start compressing the atmosphere while, building greenhouses.
When the atmospheric pressure falls below 1.5 atmospheres the spheres
will fall to the ground and be covered by soil (dust or organic), and
their reflective function will stop. Also, if the rocket explodes on
take-off (from Earth) they will all fall to the ground and be buried by
soil.

The spheres will need to be resistant to corrosion by Sulfuric acid,
which exists in the upper Venusian atmosphere.

>if Venus could be cooled, cleaning the CO2 with algae and lichen and
>progressing to more complex plants could be possible, and would
>provide oxygen at the same time for a breathable atmosphere.

A future terraforming problem for Venus will be too much Oxygen.
Generally, organic matter will spontaneously combust at 0.25
atmospheres. Large amounts of Deutrium will be needed to reduce the
partial pressure of Oxygen, by forming water. Plants don't like high
levels of Deutrium, so the release of Deutrium will need to be
carefully balanced. This is why Deutrium will need to be transported to
Venus, instead of just hurled into the atmosphere uncontrolled.

>I think it would be much more difficult to convince most people that Venus,
>rather than Mars would be the best option in our solar system for
>terraforming...at least going on everything I've heard up to this point on
>terraforming...it's almost totally linked to Mars.

It is hard to convince people. You wouldn't believe how many have
written and told me off. Without logic and unable to back up their
ideas they blindly swear Mars is the only option. I can't believe how
closed-minded people can be. Terraforming is linked to Mars too much,
thanx to Kim Stanley Robinson. The Red/Green/Blue Mars series was a
work of pure Fiction, not a scientific paper. Most people can't move
beyond the theme of the books to realise they're just that, books,
stories. If people want to talk about the reality of terraforming then
they'll need to be realistic.

>well, since mars wouldnt be terraformed UNTIL we hit it with Iron

No. Moving Iron to Mars is part of the terraforming process.
Terraforming encompases all the changes to a planet. It is not limited
to adding plants, or changing the atmospheric constituents. It also
includes adding mass.

>I would assume we're doing this so it could hold an atmosphere?

Yes

>why would we have to slow the chunks down?

Most of the additional mass will come from the outer solar system, at
least outside Martian orbit. The delta-v, the difference in velocity,
will be very high and all of the masses will hit from one side of the
planet, the outer side. (Note: I'm talking about the direction the
masses will hit, which is independent of the planets rotation).
Individually, each mass will have a minor effect on the planets orbit.
Remember we're talking about a mass (in total) larger than Mars itself.
So it's not hard to imagine, the combined force of all these masses
will be enough to knock Mars out of its orbit. Certainly enough to
create a wobble in rotation, which will have a chaotic effect on
seasons and weather patterns later on.

Also, what if they miss? You'll then have a high-veocity mass hurtling
towards the inner solar system. Hopefully it would hit the sun, but
worse, it could take an unstable orbit and eventually hit an inner
planet, with disaterous effect.

>I think Mars has been hit by enough meteors and asteroids already.

A vast majority of the meteors that have hit Mars have come from the
nearby asteroid belt. They have low delta-v's and enter a degrading
orbit before hitting the surface. They circle the planet a few times
before hitting, and can hit from any direction. As their impacts are
multi-directional, their combined effect on the planets orbit is (very)
roughly evened out.

>changing their orbits isn't *that* hard.

No, it's not hard, and we have the technology to do it now. But it
takes a LOT of energy and coordination.

>but the real question is, why terraform?

Practice! We, as a species run a serious risk of extinction when
Betelguese goes supernova.

>because it would take so long to terraform the whole planet. last estimate I
>heard was 100 000 years

Yes, but that's a best guess using current technology.

On Thursday, September 11, 2003, at 12:24 AM, alt_cosmos wrote:

> It would be a LOT easier to terraform Venus than Mars, in terms of
> energy (a calculation I will be posting soon - I'm currently working on
> Galactic maps). Venus only needs to be cooled down, then some of the
> atmosphere to be compressed and stored in a gas cylinder type
> structure. Then large amounts of Deutrium to be transported from
> Jupiter.

Correction, this is all you THINK needs to be done. As with any large,
complex project operating on a poorly understood system, the chances
are excellent that whatever you want to do is a lot harder than you
think.

The materials in one asteroid (the largest ) are sufficient to make
orbital space colonies with ~150 times the surface area of the Earth in
usable real estate. See http://lifesci3.arc.nasa.gov/SpaceSettlement/
for details.

Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html

Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.

alt_cosmos wrote:

> It would be a LOT easier to terraform Venus than Mars, in terms of
> energy (a calculation I will be posting soon - I'm currently working on
> Galactic maps).

:-) Yeah? Have you even begun to consider the energy required to spin Venus
up to something terrestrial? Or are you contemplating sealed habs with
day/night shows? And therefore why not just make orbital spun ones?

> Venus only needs to be cooled down...

Interesting use of the word "only". I can't wait to see a timescale for this.

> then some of the
> atmosphere to be compressed and stored in a gas cylinder type
> structure.

Some?

Get real. Venus is a hell hole. I can see limited habs floating at around
the fifty km altitude, relying on solar energy, reasonable pressures and
temperatures close to what we're used to. But the surface is well
off-limits while economics has anything to do with it.

Andy G