08-02-2005 02:18									#151
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Personally, I like the Stellar Jupiter project: Converting Jupiter into a star to make its moons more habitable. Talk about an arrogant vanity project...

	08-02-2005 02:32									#152
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quote: Originally posted by DRoseDARs Then why'd you ask,"With what?"

I thought you were talking about using an organic process to free CO2.

quote: I can't answer that. Comets are relatively small compared to a planet - even as small as Mars - and we'd need LOTS of them for them to play a significant role in any terraforming project.

That misses the point of my question - how would you get nitrogen from comets at all? Do they have nitrogen?

	08-02-2005 02:33									#153
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quote: As far as talk about living on the surface of Mars, whether they realize it or not, people do so because of that planet's terraforming prospects. People hate the idea of living underground and domes aren't a whole lot better.

People are adaptable, and those who are born on the new worlds will not miss the old one.

I remember a quote from Andromeda where Rebeka 'Beka' Valentine (the pilot), a spacer brat who grew up on starships said (something like) "How can anyone want to live on a planet? It's wet, it's dirty, there's no environmental controls, and how the hell can you sleep knowing there's no ceiling?"

I think that says it all, really.

	08-02-2005 02:35									#154
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quote: Smashing them at Mars.

See above.

	08-02-2005 02:51									#155
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quote: Originally posted by Kuciwalker I thought you were talking about using an organic process to free CO2. That misses the point of my question - how would you get nitrogen from comets at all? Do they have nitrogen?

Yes.

And, you could mine "comets" from the Kuiper belt.

	08-02-2005 04:23									#156
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quote: Originally posted by DRoseDARs As far as subsurface habitation on Mars, it is the safest way to colonize the planet given its lack of a substantial atmosphere (very low air pressure means great stress on any dome; thin atmosphere doesn't burn up incoming material such as meteorites).

I'm puzzled by why pressure domes are regarded as so impractical. Why would that apply to colonising places like mars but not to space stations?

	08-02-2005 04:26									#157
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quote: Originally posted by DRoseDARs Personally, I like the Stellar Jupiter project: Converting Jupiter into a star to make its moons more habitable. Talk about an arrogant vanity project...

*if* a nuclear reaction were somehow triggered in jupiters core, the pressure would expand the planet until it's reduction in density dropped the core temperature and pressure to below that which is needed to sustain fusion. There is a very good reason why brown dwarfs are all brown despite some extremely hot starts when they have a rapid formation.

	08-02-2005 04:32									#158
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quote: Originally posted by Dr Strangelove I hate to burst everyone's bubble, but in addition to supplying enough Oxygen gas to breath and warming the atmopsphere with some sort of "greenhouse gas" there also has to be a generous amount of inert gas, such as Nitrogen, in the atmosphere. If the atmosphere is more than 30% oxygen spontaneous combustion will occur. If the CO2 concentration is too high humans and other animals will be unable to blow off the normal amount of CO2 via respiration. CO2 will build up in their blood and they will die of acidosis. An enormous amount of inert gas is therefore required to dilute the oxygen and the greenhouse gas.

it's not the percentage of oxygen that is important but rather the absolute partial pressure of the oxygen, ditto for toxic effects of CO2.

	08-02-2005 05:35									#159
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quote: Originally posted by Geronimo I'm puzzled by why pressure domes are regarded as so impractical. Why would that apply to colonising places like mars but not to space stations?

Why does the ISS, Mir, or Skylab have such small windows? Why does the Space Shuttle and other craft? Why do airliners? Windows are a weak point in any environment where we need a pressurized cavity to survive. A dome will have lots of windows, if not entirely window with frame. In Mars' low gravity, solid windows (as opposed to inflatible structures some groups have proposed) might be good since they'll resist both the internal pressure and the windstorms of the planets (I'm thinking of the dust, not the force of the Martian wind). However, I'd be more concerned about falling material that survived the fall through Mars' thin atmosphere as well as solar radiation. Exposed structures are just that: Exposed.

More directly answer your question, domed structures would survive better in an environment where there was at least some outside air pressure, even if it isn't up to Earth standard, to counteract the internal air pressure and relieving some of the stress on the material used. Space is a relative vacuum; not external air pressure, the material bares the full brunt of the contained atmospheric pressure.

	08-02-2005 05:37									#160
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quote: Originally posted by Geronimo *if* a nuclear reaction were somehow triggered in jupiters core, the pressure would expand the planet until it's reduction in density dropped the core temperature and pressure to below that which is needed to sustain fusion. There is a very good reason why brown dwarfs are all brown despite some extremely hot starts when they have a rapid formation.

Sorry, I must've forgotten to add the smiley earlier...

	08-02-2005 05:45									#161
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quote: Originally posted by Kuciwalker I thought you were talking about using an organic process to free CO2.

I don't recall if I was, I doubt it and am too lazy at the moment to look, but I'll go ahead and respond. I have my doubts of how effective GM'd life would be in the early stages of a Martian terraforming process. I think what I was talking about earlier was using industrial processes to heat the planet by pumping CO2 into the atmosphere to make the environment more plant-friendly and perhaps start adding oxygen to allow for GM'd insects). I know squat about nitrogen, so I'm not the person to ask. In later stages, if GM'd plant and animal life (those CO2-tolerant insects) has taken root, the plants would slowly begin increasing the oxygen levels on their own if we let them, just as what happened here on Earth. For me it's all about the timing. I just don't think natural processes (bacteria, algae, lichen and so forth) can play that big of a role early on in such a project, not in Human time-scales at least.

quote: That misses the point of my question - how would you get nitrogen from comets at all? Do they have nitrogen?

Again, I'm not the person to ask.

	08-02-2005 06:44									#162
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quote: Originally posted by Geronimo it's not the percentage of oxygen that is important but rather the absolute partial pressure of the oxygen, ditto for toxic effects of CO2.

Yes, and that is also true for breathing. The Oxygen pressure we're used to is only 66% of the pressure at which spontaneous combustion of some materials occurs. Furthermore a pure oxygen atmosphere damages the lungs and eyes. Patients on pure oxygen begin to develop problems with their lungs even within 24 hours.

I wonder what sort of atmospheric pressure Mars is capable of sustaining?

With regards to ionizing radiation, Mars is 1.5 times further from the sun than we are, so I would assume that the intensity of radiation striking Mars' surface would be 40% of that being asorbed by the Van Allen blet or by the Earth. Does anyone know how efficient the Van Allen belt is?

	08-02-2005 06:47									#163
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quote: Originally posted by Geronimo I'm puzzled by why pressure domes are regarded as so impractical. Why would that apply to colonising places like mars but not to space stations?

Space stations are small so they don't have a lot of gravatational pull. It's highly unlikely anything big is going to smash them at high speeds.

Planets are different. They bring down small floating objects from space and they come crashing at a nice, high speed.

	08-02-2005 06:50									#164
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quote: Originally posted by The Mad Monk We'll be doing that with Luna, Mercury, Titan, probably most of the other major moons, and orbitals as well. Why make a special case for Mars?

The cost of doing that is prohibitive, both in terms of energy and monetary.

That's why Mars is good and Luna is bad for any large scale permanent settlement.

	08-02-2005 09:34									#165
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quote: Originally posted by The Mad Monk Colonizing space is not a matter of economics to me, it is a matter of survival. Evolution has clearly demonstrated that the more a species expands, whether geographically, or in terms of habitat or food source, the longer it survives in this universe. We thrive because we have managed to exploit nearly every crack and crevice this planet has to offer. We are immune to most catastrophes this world has to offer, because there is little here now that could hit every region, and every food supply. Still, there are still threats out there, that can kill us off on a planetary scale. The only real long-term countermeasure for this is the same one that has served us so well for so long. Expand into new territories, or as in this case, new worlds.

My thoughts on this exactly. We need to look at long term survival. Colonizing Mars would be a good first step, providing us with valuable terraforming experience... we just need to make sure we don't destroy ourselves in the meantime.

	08-02-2005 09:59									#166
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quote: Originally posted by My Wife Hates CIV all you have to do is push mars towards the sun... just a bit. easy!

If we could somehow devise a way to move a planet the Venus problm would be much easier to solve. Move it out to the same distance from the sun as Earth. Wouldn't the distance from the sun cool surface temperatures, allowing for some of the other terraforming ideas expressed in this thread? Heck, if you could manage to move Venus, you could probably figure out a way to also move Mercury and use it to provide Venus with its very own moon. In effect, we'd basically be creating a spare Earth/Moon system.

Of course, I cannot begin to imagine the amount of energy necessary to move entire planets tens of millions of miles. Besides that, I bet that if we ever developed technological sophistication to that degree we could probably find more efficient solutions (maybe even have mastered interstellar flight, which is ultimately necessary to ensure long term survival)

	08-02-2005 10:02									#167
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quote: Originally posted by Urban Ranger The cost of doing that is prohibitive, both in terms of energy and monetary. That's why Mars is good and Luna is bad for any large scale permanent settlement.

Cost prohibitive compared to bombarding Mars with gigatons of frozen gas from 40 AUs out?

	08-02-2005 15:34									#168
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JUST A LITTLE REMINDER of why doing this ASAP is IMPORTANT:

quote: Scientists: Asteroid flyby a once in a lifetime event By Robert Roy Britt SPACE.com RELATED • SPACE.com: Scientists: Asteroid won't hit Earth in 2029 SPACE.com: Asteroid Vesta: The 10th planet? (SPACE.com) -- An asteroid expected to fly past Earth in 2029 will be visible to the naked eye, scientists projected Thursday. It's a once-in-a-millennium event. And you may want to buy plane tickets now, as the flyby will be visible only from Europe, Africa and western Asia. There has been no event like this in modern history. Some people have seen dramatic fireballs created by small space rocks blazing through Earth's atmosphere. And two house-sized asteroids have made closer passes. But they were not visible without telescopes. The 2029 event will be the closest brush by a good-sized asteroid known to occur. The rock will pass Earth inside the orbits of some satellites. No other asteroid has ever been clearly visible to the unaided eye. The asteroid is roughly estimated to be a little more than 1,000 feet (320 meters) wide. It won't hit The rock, catalogued as 2004 MN4, was discovered last June. It was seen again in December, and for a time scientists said it had the highest odds of hitting Earth ever given to a space rock. Subsequent observations refined the future path and eliminated those odds for the 2029 flyby. It won't hit the Moon, either. This week, NASA scientists used new observations from the Arecibo Observatory to further pin down the track of 2004 MN4. On April 13, 2029, it will be about 22,600 miles (36,350 kilometers) from Earth's center. That is just below the altitude of geosynchronous satellites, which hover in fixed perches above the planet to communicate with and collect data on half the globe at all times. Of the ten known closest asteroid flybys, 2004 MN4 is by far the largest object, said Steve Chesley of NASA's Jet Propulsion Laboratory. Only two have come closer, and they were only tens of yards (meters) wide. "All of the others in the top ten were discovered during the close approach, whereas for 2004 MN4 the close approach is predicted well in advance," Chesley said in a telephone interview. Last fall, an even larger asteroid made a notable flyby. That rock, called Toutatis, is about 2.9 miles long and 1.5 miles wide (4.6 by 2.4 kilometers). Its closest approach, widely photographed, was about four times the distance to the Moon. It was not visible to the naked eye. What to expect The asteroid 2004 MN4 is expected to shine like a fast-moving star at magnitude 3.3, Chesley said. That would be easily visible under dark skies without the help of binoculars or telescopes. On this astronomers' magnitude scale, smaller numbers represent brighter objects. The brightest stars and planets have negative magnitudes. The dimmest stars visible under perfect sky conditions away from city lights are about magnitude 6.5. Urban residents may need to get out of town to see the rare event. Chesley said the exact proximity of the object could cause its brightness to vary, but probably only by a few tenths of a magnitude. The asteroid will pass through the constellation of Cancer. Observers with clear skies in Europe, Africa and parts of Asia will be able to see a star-like point of light. "Whether you could see it from the center of London is another matter," said Alan Harris of the Space Science Institute. Harris notes that asteroid Vesta -- 334 miles (538 kilometers) in diameter -- periodically gets as bright as magnitude 5.3, which is visible to the naked eye under very dark sky conditions. "Curiously, Vesta attains this brightness at its opposition in July, 2029, only a few months after the April 2029 apparition of MN4," Harris told SPACE.com. With small telescopes and high-tech tracking software, the asteroid's shape could be evident. "It will be potentially resolvable with small telescopes, but they'll have to be able to track pretty fast," Chesley said. The rock will cover about 42 degrees of sky per hour, slower than a satellite but noticeably quick in the small field of view of a telescope. Rare event On average, one would expect a similarly close Earth approach by an asteroid of this size only every 1,300 years or so, Chesley and his colleagues have determined. 2004 MN4 circles the Sun, but unlike most asteroids that reside in a belt between Mars and Jupiter, the 323-day orbit of 2004 MN4 lies mostly within the orbit of Earth. The 2029 flyby will bend the rock's path and change the circumstances of later close passes to Earth. "However, our current risk analysis for 2004 MN4 indicates that no subsequent Earth encounters in the 21st Century are of concern," according to a statement issued by Chesley and his JPL colleagues Paul Chodas, Jon Giorgini and Don Yeomans. Additional observations in coming months and years could help eliminate the small chances of impacts in years after 2029. Were an asteroid the size of 2004 MN4 to hit Earth, it would cause local devastation and regional damage. It would not be expected to cause any sort of global disruption, experts say.

http://www.cnn.com/2005/TECH/space/...asteroid.flyby/

	08-02-2005 16:59									#169
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quote: Originally posted by Urban Ranger Space stations are small so they don't have a lot of gravatational pull. It's highly unlikely anything big is going to smash them at high speeds. Planets are different. They bring down small floating objects from space and they come crashing at a nice, high speed.

Even for a much larger planet like Earth only a negligable fraction of the speed of an object from space that impacts the surface is due to gravitational acceleration by the planet.

Furthermore the incidence of impact is almost entirely a function of volume of space occupied by the target object with gravity playing only minor role. IIRC even massive jupiter experiences only fractionally more impacts than would be expected if it were a nearly massless object of the same size.


Once impact does occur gravitational pull is a huge plus for the inhabitants of the struck sealed atmospheric dome. In the absence of gravity pressure is lost that much faster.

	08-02-2005 17:02									#170
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quote: Originally posted by Wycoff If we could somehow devise a way to move a planet the Venus problm would be much easier to solve. Move it out to the same distance from the sun as Earth. Wouldn't the distance from the sun cool surface temperatures, allowing for some of the other terraforming ideas expressed in this thread? Heck, if you could manage to move Venus, you could probably figure out a way to also move Mercury and use it to provide Venus with its very own moon. In effect, we'd basically be creating a spare Earth/Moon system. Of course, I cannot begin to imagine the amount of energy necessary to move entire planets tens of millions of miles. Besides that, I bet that if we ever developed technological sophistication to that degree we could probably find more efficient solutions (maybe even have mastered interstellar flight, which is ultimately necessary to ensure long term survival)

The exact manner of how to move a planet a considerable distance using currently available technology has already been worked out!

Moving venus further from the sun wouldn't help much unless you moved it quite a bit further out than the earth's orbit simply because Venus has such an intense greehouse effect due to it's ultra thick CO2 rich atmosphere.

On the other hand if you did move it quite a bit further from the sun than the Earth is it might become possible to terraform venus because then it's slow rotational rate will be neutralised somewhat by the possiblity of retaining at least some of it's greenhouse atmosphere so that the night side wouldn't cool so severly as it would at it's current orbital distance if enough greenhouse gasses were removed to allow the day side to reach a habitable temperature.

	08-02-2005 21:12									#171
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quote: Originally posted by Geronimo The exact manner of how to move a planet a considerable distance using currently available technology has already been worked out! Moving venus further from the sun wouldn't help much unless you moved it quite a bit further out than the earth's orbit simply because Venus has such an intense greehouse effect due to it's ultra thick CO2 rich atmosphere. On the other hand if you did move it quite a bit further from the sun than the Earth is it might become possible to terraform venus because then it's slow rotational rate will be neutralised somewhat by the possiblity of retaining at least some of it's greenhouse atmosphere so that the night side wouldn't cool so severly as it would at it's current orbital distance if enough greenhouse gasses were removed to allow the day side to reach a habitable temperature.

That's an interesting artcle, Geronimo... I wonder if it would be possible to quicken the pace of such a project?

	08-02-2005 22:47									#172
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quote: Originally posted by Wycoff That's an interesting artcle, Geronimo... I wonder if it would be possible to quicken the pace of such a project?

It could be sped up considerably by using a more massive asteroid to do the shuttling of orbital energy. Of course the more massive the asteroid is the more work will have to be done early on to get the asteroid moving into position in the first place. I imagine that if we wanted to send very immense asteroids like Ceres or Vesta to do our dirty work for us we would first have to spend a couple hundred years playing cosmic billiards with smaller asteroids to get them moving the right way.

In short, there's no way we could anticipate using this sort of method to move Venus to a terraforming friendly orbit in anything less than thousands or probably millions of years.

	09-02-2005 02:04									#173
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All this shows that asteroids, comets and the Kuiper belt may eventually be man's best friends.