Why not. <br /><br />Silylene suggested, jokingly on another thread, that we should redirect Titan closer to Saturn to take advantage of its tidal forces to heat up Titan. That’s what motivated me to start this thread. I can't go back to see if this topic has been discussed before so if it was then here it is again. <br /><br />As soon as we get to Mars we would have already developed the VASMRI engines, nuclear engines and ion engines. This may make Jupiter about a six to nine months drive with faster transportation. Some of these engines could be sent out to adjust the path of some of the smaller satellites of these gas giants. Have them redirect the orbital path of some of these planet sized moons by crashing some of these smaller satellites into them. This would enable these worlds to take more advantage of the Tidal forces closer in, therefore melting Europas ice caps or warming Titans atmosphere. Radiation shields would have to be made strong enough to live on the surface of these worlds, but Europas Oceans would be a great place to live for aquatic life.<br /><br />I proposed, years ago, to crash a projectile into Europa prior to a when a probe gets there, aim for a soft spot to break the ice so a submersible could be injected under the ice sheet. A 5,000-Kilogram projectile traveling at 50,000 mph carries a lot of kinetic energy. <br /><br />I understand that Terraforming another world would not be an easy task and may not be doable within a hundred years, but it is another way to expand human’s evolution within our Solar system. The material to do this with, comets and asteroids are presently in orbit around these gas giants. <br /> <div class="Discussion_UserSignature"> Ron Bennett </div>
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The amount of energy required to move a planet sized moon is insane. I don't know the numbers, exactly. But its INSANE. I mean like the Earths energy supply for a million years.
That was an expected thought. You’re right it would take a lot of energy. The closer in the orbits of these moons the greater the amount of energy it would take to redirect there paths. For instance after redirecting a Satellite like Phoebe for ten years with several nuclear planted engines it crashes into Titan. There is a lot of energy stored in a retrograde 150 kilometer Satellite like Phoebe. We could break Phoebe up and through smaller sections of it at Titan so we don't rip Titan apart.<br /><br />Look how much energy was in the 12 kilometer Shoemaker-Levy 9 comet that crashed into Jupiter. <div class="Discussion_UserSignature"> Ron Bennett </div>
Here is some facts about Shoemaker-Levy 9 comet<br /><br />http://www.isc.tamu.edu/~astro/sl9/cometfaq2.html<br /><br /><font color="yellow">Just before the the first comet fragment hit Jupiter, Zdenek Sekanina wrote that based on Hubble Space Telescope observations in early July 1994 the fragments had effective diameters generally between 1 and 2 kilometers: "Although the evidence points to an apparently continuing disintegration of the large fragments in numerous discrete events, objects a few km across still seem to have been present in early July, and the temporal variations in the effective diameters are likely to be primarily a rotational effect of strongly irregular shape." [58] Would some of the fragments remain intact and create large fireballs or would the comet nuclei shatter before they reached Jupiter? Perhaps both were true. Some fragments created large fireballs that rose above the limb of Jupiter and left giant dark marks on the planet, while other fragments seem to leave little trace of their impact.<br /> <br />Fragment A struck Jupiter with its kinetic energy equivalent to about 225,000 megatons of TNT creating plume which rose about 1000 km above the Jovian cloudtops. It was not long before the Hubble Space Telescope images of the fireball and impact site of fragment A were downloaded by thousand of observers. Many were surprised to see any effects from Earth. "We were thinking that we were going to have to go in with a microscope and you know stretch the image as hard as we could to pull out anything, but its just blasting away at us...unbelievable." - Hal Weaver <br /><br /></font> <div class="Discussion_UserSignature"> Ron Bennett </div>
The largest impact of the kind you are proposing that comes to mind is the collision of a Mars-sized object into a very young Earth to create the Moon. This is the currently favored "Giant Impact" theory of lunar creation and has been much studied in computer simulation. I haven't read extensively about it, but in what I have read I haven't seen any mention of a large change in Earth's orbit as a result of this enormous collision. <br /><br />It seems that the prospect of colliding an object into a comet or asteriod to create a minute change in trajectory, which translates into a signifcant change in position over large distances, is a much more feasable undertaking than changing the orbit of a body with a relatively small radius orbit. I can envisage an impact so powerful that the orbiting body is destroyed and reduced to pieces... which <i>continue in the same orbit as the original body</i>! <br /><br /> <div class="Discussion_UserSignature"> </div>
Fantasy speculation can be fun!<br /><br />Heh, we would need big antimatter engine running continuously for decades to spiral Titan in a lot closer (maybe to the orbit Pan currently occupies, that would give a GREAT view of the rings to future Titan colonists, assuming the rings didn't break up entirely - unfortunately I strongly expect to be disrupted).<br /><br />Mimas in its current orbit would be close to a 3:2 resonance in the new Titan configuration, so it should get some interesting tidal warming.<br /><br />I would also spiral Rhea in twice as close as its current orbit, so it would be in a 2:1 resonance with the new Titan. This would warm up Rhea too!<br /><br />With Rhea and Mimas in good resonance spots, this would help warm Titan a lot faster than relying only on tidal influences from Saturn.<br /> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>
The Lunar impact formation with earth, from the little I read about it to, was impacted from the side of Earth, this would change its rotational speed and its angular momentum though its axis off –initially wobble more as it rotates. Still I would think that it did change the orbit more, even though it wasn’t a direct hit. I will try to find if the orbit was changed with their models of the impact that created our comet / asteroid vacuum systems, Moon. Here are some good links. The first two are animations showing the Earth Lunar formation, the second one shows what would have happened as a result of a direct hit.<br /><br />http://pegasus.phast.umass.edu/a101/images/moon_formation_anim.gif<br /><br />http://pegasus.phast.umass.edu/a101/images/moon_formation_anim_headon.gif<br /><br /><font color="yellow">These are results of a lunar-forming impact simulation from Canup and Asphaug 2001. The smaller, impacting object is Mars-sized and impacts the Earth obliquely in a counter-clockwise sense. Most of the impacting object eventually ends up on the Earth, but some fraction of it remains dispersed in a cloud of debris orbiting the planet. Color in the simulation is representative of the degree to which the planetary rock has been heated by the impact. The entire impact sequence covers about 24 hours of simulated time. At the end of the impact, the central Earth has a rotational day of only about 5 hours. Credit: Southwest Research Institute <br /><br />http://spaceflightnow.com/news/n0108/15mooncreate/<br /></font> <div class="Discussion_UserSignature"> Ron Bennett </div>
<font color="orange">Fantasy speculation can be fun!<font color="white"><br /><br />Your right it is fun. Jules Vern would be proud of us.<br /><br /><font color="orange"> Mimas in its current orbit would be close to a 3:2 resonance in the new Titan configuration, so it should get some interesting tidal warming. <br /><br />I would also spiral Rhea in twice as close as its current orbit, so it would be in a 2:1 resonance with the new Titan. This would warm up Rhea too! <br /><br />With Rhea and Mimas in good resonance spots, this would help warm Titan a lot faster than relying only on tidal influences from Saturn.<font color="white"><br /><br />That may work, we can move those smaller moons close enough to Orbit Titan or at the Langrean point between Saturn and Titan, with less energy keeping Titan away from Saturn’s strong magnetic field and a moon there to shield it from some of the plasma in Saturn’s magnetosphere.<br /><br />We may first want to through some matter at Titan to change its angular momentum, increase its rotation around its axis, currently that is 16 Earths days, down to 1 Earth day. If Titan is proven to still have a molten iron core, this may also help create a global magnetic field.<br /> <br />We may want to use the same kind of idea to tarraform Mars. Throw parts of Phobos at Mars to change its angular momentum, if there is enough mass there to do this, from 24 hr 37 min to 12 hrs, possibly re-igniting a Martian global magnetic field. This would be done like spinning a basketball on ones finger. In the process we can try to change its leaning axis from 25.2 degrees to 12.5 degrees. By doing this we would make Mars warmer and help melt the poles, resulting in less migration of water vapor to the poles increasing CO2 into the atmosphere from the south polar region. Phobos is doomed anyway, its going to crash into Mars as a whole or in parts in 30 million years. <br /></font></font></font></font> <div class="Discussion_UserSignature"> Ron Bennett </div>
Hi All,
I'm reading a book on SF worldbuilding which hints that a planet/space body would need to be a certain size before it could maintain (I assume, via it's gravitational strength) an atmosphere.
Is this true? Anyone know how big a planet would need to be in order to maintain an atmosphere or have an idea of where else I could find out?
I'm reading a book on SF worldbuilding which hints that a planet/space body would need to be a certain size before it could maintain (I assume, via it's gravitational strength) an atmosphere.
Is this true? Anyone know how big a planet would need to be in order to maintain an atmosphere or have an idea of where else I could find out?
Re:
Rather than try to Move Titan, what a herculean task that would be, your other suggestion might make a bit more sense, from a doable standpoint. Crash a small asteroid into Europa to make a hole then park a nuclear reactor next to the hole to keep it open while we install a cap that allow us to enter and leave when we wish. Then build aquatic habitats in the waters of Europa. I'm betting there is life there, but if not we can import some of ours for food for us.
If we don't find a way to FTL travel to other stars and move our population out into the Galaxy, then these kinds of things might be worth trying. But only if the human race ends up being stuck in this one little solar system.
rlb2":2ywtmzi0 said:
Rather than try to Move Titan, what a herculean task that would be, your other suggestion might make a bit more sense, from a doable standpoint. Crash a small asteroid into Europa to make a hole then park a nuclear reactor next to the hole to keep it open while we install a cap that allow us to enter and leave when we wish. Then build aquatic habitats in the waters of Europa. I'm betting there is life there, but if not we can import some of ours for food for us.
If we don't find a way to FTL travel to other stars and move our population out into the Galaxy, then these kinds of things might be worth trying. But only if the human race ends up being stuck in this one little solar system.
tjlotfi":184lae1v said:
Whether a body can retain an atmosphere depends on several things.
Mars' diameter is about 6800km (4200mi) and its mass is just about 10% that of Earth's. As you know, it has a thin atmosphere primarily comprised of CO2. Its atmosphere is only about 1% that of Earth's.
Mars has no appreciable magnetosphere, which as allowed the solar wind to strip Mars of its atmosphere over time.
By comparison, Titan, Saturn's largest moon has a diameter of 5150km (3200mi) and a mass about 2% of Earth's, yet its atmosphere is 1.2 times more dense than Earth's, and the atmospheric pressure is 1.6 times greater than Earth's at Sea Level.
Titan does not generate its own magnetosphere, but Saturn induces one around it.
Other factors to consider would be whether or not a planet (or moon) replenishes its atmosphere (via biology or vulcanism), its proximity to its host star (density and velocity of its stellar wind), its surface temperature and atmospheric composition.
A short answer would be that the "smallest" body we know of with a significant atmosphere (at least 40% of Earth's) would be one that has only 2% of Earth's mass and 41% of its diameter, but as you see, a lot of things decide whether a body of any size and mass can retain an atmosphere.
I don't know why anyone would consider "terraforming" these satellites, since it would require such huge amounts of energy and god-like engineering. All the Jovian moons are bathed in lethal radiation, and I don't think any amount of terraforming can cure that problem. We can build cities and colonize them, for sure, but I don't see the point of terraforming any world other than Mars and perhaps Venus.
Has anyone considered the lethal radiation that bathes the Jovian Galilean satellites? I don't think any kind of terraforming would solve that problem, unless you could develop an incredibly thick atmosphere, and I'm not sure that even that would be enough protection. Saturn's radiation belt is not as bad, but it's even colder in that part of the solar system, so terraforming such worlds as Titan would involve unimaginable amounts of energy. Maybe someday, when we have god-like engineering capabilities and limitless amounts of power at our disposal, but one wonders if it would be worth the effort and resources when you could build a rotating space habitat out of a hollowed-out asteroid and make a world to order.
Re: Re:
You must mean this little solar system:
http://en.wikipedia.org/wiki/List_of_So ... ts_by_size
But honestly, we are never ever going to try and convert other worlds into new earths. Look at the vast mass of the earth and the tiny, tiny TINY amount of living area it provides. No more than a greenish scum on its surface.
For the effort it would take to turn any of these worlds even into a very small, very inhospitable earth we could smelt down the mass of one of these worlds into a city with a thousand times the livable surface area of the earth that provides fully controlled environments.
For some reason talk of colonizing the solar system always seems to come down to bashing rocks together. That is certainly a good way of discovering fire, but the future human race is going to be a totally different type of caveman.
I think the real attraction of terraforming is that people like to entertain solutions that require vast amounts of energy if this avoids direct human labour applied to every square foot. This is because what people really want is unexplored wilderness with clean air ready to be breathed, to set bare feet where no one has set foot before. Unfortunately this is a dream we will have to give up if we ever intend to colonize space.
StarRider1701":3vg5gnzc said:
You must mean this little solar system:
http://en.wikipedia.org/wiki/List_of_So ... ts_by_size
But honestly, we are never ever going to try and convert other worlds into new earths. Look at the vast mass of the earth and the tiny, tiny TINY amount of living area it provides. No more than a greenish scum on its surface.
For the effort it would take to turn any of these worlds even into a very small, very inhospitable earth we could smelt down the mass of one of these worlds into a city with a thousand times the livable surface area of the earth that provides fully controlled environments.
For some reason talk of colonizing the solar system always seems to come down to bashing rocks together. That is certainly a good way of discovering fire, but the future human race is going to be a totally different type of caveman.
I think the real attraction of terraforming is that people like to entertain solutions that require vast amounts of energy if this avoids direct human labour applied to every square foot. This is because what people really want is unexplored wilderness with clean air ready to be breathed, to set bare feet where no one has set foot before. Unfortunately this is a dream we will have to give up if we ever intend to colonize space.
Something else to consider, if any of these moons harbor even microbial life something like the policy on Star Trek would intervene not permitting us to alter the evolution of life on another world. Or maybe by then the powers that be would just say screw it and bang the rocks together anyway.
Re: Re:
This solar system is very, very tiny when compared with the Galaxy we live in. Ok, to us it seems big now because its the only place we can go. We need to hope that changes at some point in our future, otherwise we will discover the hard way just how tiny this system really is.
There are no other places in our solar system worthy of terraforming. If we live anywhere off Earth in this system, we will be inside a dome or other structure designed to keep the air we need inside and the hostile environment out.
kelvinzero":by5wxumx said:You must mean this little solar system:
http://en.wikipedia.org/wiki/List_of_So ... ts_by_size
I think the real attraction of terraforming is that people like to entertain solutions that require vast amounts of energy if this avoids direct human labour applied to every square foot. This is because what people really want is unexplored wilderness with clean air ready to be breathed, to set bare feet where no one has set foot before. Unfortunately this is a dream we will have to give up if we ever intend to colonize space.
This solar system is very, very tiny when compared with the Galaxy we live in. Ok, to us it seems big now because its the only place we can go. We need to hope that changes at some point in our future, otherwise we will discover the hard way just how tiny this system really is.
There are no other places in our solar system worthy of terraforming. If we live anywhere off Earth in this system, we will be inside a dome or other structure designed to keep the air we need inside and the hostile environment out.
Re: Re:
Actually, the galaxy and the entire universe is also actually very, very tiny.. compared to human exponential growth. If we had FTL and there were an earthlike planet around every single star in the observable universe, we could populate every single one as densely as earth in a mere handful of millennia. That might seem long to you, but it is an eyeblink compared to the age of the universe.
Even if we could get to other solar systems which had earthlike worlds that needed only the most basic terraforming, I dont think they would be good choices to live on. Worlds like Ceres would be far more useful and far more numerous. They have all the resources we need to live, they are much easier to land on and leave, On Ceres you could probably build cities that reached all the way up to orbit. You could put continent-sized solar power collectors in orbit around it. You can live three dimensionally within its entire volume.
About the only thing that Earth has over Ceres is earth-like gravity, for human health. This is a trivial problem compared to interstellar travel, and one we would certainly need to solve first anyway. It isnt even a problem at all to most earthlife, because most earthlife lives in essentially zero-g conditions in earth's oceans. Once we have lived in space for a few hundred years there is no way living down a deep gravity well on a two dimensional surface where everything is heavy and you cannot fly would be seen as anything but as a punishment, and high gravity worlds a prison.
StarRider1701":1n0bulss said:
Actually, the galaxy and the entire universe is also actually very, very tiny.. compared to human exponential growth. If we had FTL and there were an earthlike planet around every single star in the observable universe, we could populate every single one as densely as earth in a mere handful of millennia. That might seem long to you, but it is an eyeblink compared to the age of the universe.
Even if we could get to other solar systems which had earthlike worlds that needed only the most basic terraforming, I dont think they would be good choices to live on. Worlds like Ceres would be far more useful and far more numerous. They have all the resources we need to live, they are much easier to land on and leave, On Ceres you could probably build cities that reached all the way up to orbit. You could put continent-sized solar power collectors in orbit around it. You can live three dimensionally within its entire volume.
About the only thing that Earth has over Ceres is earth-like gravity, for human health. This is a trivial problem compared to interstellar travel, and one we would certainly need to solve first anyway. It isnt even a problem at all to most earthlife, because most earthlife lives in essentially zero-g conditions in earth's oceans. Once we have lived in space for a few hundred years there is no way living down a deep gravity well on a two dimensional surface where everything is heavy and you cannot fly would be seen as anything but as a punishment, and high gravity worlds a prison.
Re: Re:
I suppose that might be true given FTL drive now and unlimited resources to build and crew colony ships. Your point is only valid in the mathematical sense, pure number crunching. Reality is a far different story. First, as MW loves to point out, endlessly and pointlessly, we have not yet discovered FTL drive and may not for a few hundred years. Once we do discover it, it will likely be millennia before we become a significant presence even in this section of this Galaxy. It takes time to build ships, find planets, build colonies, etc.
1. There most certianly is NOT likely to be an Earthlike or easily terraformable planet in every solar system we find.
2. Unless your FTL is instantaneous travel from any point in our Universe to any other point in our Universe, then travelling between stars will take time even moving faster than light.
3. The distances between Galaxies is several orders of magnitude above and beyond merely traveling between stars in this Galaxy.
Sorry kevin, but your point has almost zero validity in any reality outside of pure mathematics.
As for the Dyson Sphere that another poster mentioned, building one is so far outside of our current abilities it almost isn't worth discussion. Which is why no one mentioned it. Building it would require us to move most if not all of the mass in our Solar System to use to create it. Making a mere Ringworld would be easier...
kelvinzero":14ucjgu8 said:
I suppose that might be true given FTL drive now and unlimited resources to build and crew colony ships. Your point is only valid in the mathematical sense, pure number crunching. Reality is a far different story. First, as MW loves to point out, endlessly and pointlessly, we have not yet discovered FTL drive and may not for a few hundred years. Once we do discover it, it will likely be millennia before we become a significant presence even in this section of this Galaxy. It takes time to build ships, find planets, build colonies, etc.
1. There most certianly is NOT likely to be an Earthlike or easily terraformable planet in every solar system we find.
2. Unless your FTL is instantaneous travel from any point in our Universe to any other point in our Universe, then travelling between stars will take time even moving faster than light.
3. The distances between Galaxies is several orders of magnitude above and beyond merely traveling between stars in this Galaxy.
Sorry kevin, but your point has almost zero validity in any reality outside of pure mathematics.
As for the Dyson Sphere that another poster mentioned, building one is so far outside of our current abilities it almost isn't worth discussion. Which is why no one mentioned it. Building it would require us to move most if not all of the mass in our Solar System to use to create it. Making a mere Ringworld would be easier...
Since Space Science and Astronomy is a Science forum, it's not pointless at all, so I will continue to repeat it.
If this were the Science Fiction forum I wouldn't say anything.
If this were the Science Fiction forum I wouldn't say anything.
Hello StarRider1701
I think Im going to withdraw from this conversation because I think you are taking it a bit wrong. However I want to clarify that I do not personally expect FTL to exist and certainly would not speculate on its parameters. My point was that we will always end up being faced with a crowded environment and limited resources, even given the most optimistic assumptions.
As for calling my argument pure mathematics, I choose to take that as a compliment. The last couple of centuries have been a battle between common sense and mathematics, with common sense losing time and time again.
I think Im going to withdraw from this conversation because I think you are taking it a bit wrong. However I want to clarify that I do not personally expect FTL to exist and certainly would not speculate on its parameters. My point was that we will always end up being faced with a crowded environment and limited resources, even given the most optimistic assumptions.
As for calling my argument pure mathematics, I choose to take that as a compliment. The last couple of centuries have been a battle between common sense and mathematics, with common sense losing time and time again.
kelvinzero":w10wiu1y said:
Ah, so you ascribe to the mathematicians solution for population control?!?
Shoot every second (or third) person on the planet. Instant no population problem, solved by mathematics rather than common sense.
Doesn't population solve itself when you reach zero population growth, because the rate of death and birth are equal (almost equal)?
It's more the damage our technology does isn't it?
It's more the damage our technology does isn't it?
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