Science of Life in Solar System
There will come one day in the future. Relatively and astronomically speaking, it might come sooner than we think. It could happen way before we realize that there is no turning back. The day when Mother Earth will simply say, Sorry guys, I have no more energy to sustain this kind of life anymore, and when most of the biodiversity cocoons on Earth will reach the ultimate hazard and start imploding back into themselves. Air and water pollution will help a lot, and not even the planet's regular motions will be able to take us into another interglacial cycle. It is as much inevitable as what we are going to do next. We will take a long look toward the stars and say, "Well, we have to do this sooner or later. It's time to leave the Earth. Time to jump into Christopher Columbus's shoes again. And find the new home."
But we will not get far. There will be no warp drives, "phasers on stun", robots, AIs, or artificial gravity like in sci-fi blockbusters, and there will be no scientific breakthroughs that will bring Moon or Mars gravity to the comfortable number of 1. No, we will be completely helpless in all our efforts to terraform other planets and gas giants' moons. Not at first. Or fast. Or to make large asteroids rotate. Or to initiate Mars' core to fire its lost magnet. Or to make Venus act a little less than hell.
No, there are good chances that this day will catch us completely unprepared, and we will be forced to, like Columbus, make one giant step into the unknown. And learn on the way.
This journey will definitely be very difficult in the beginning, but like any other endeavor, after the first steps, it will become handy and enjoyable. So let's think and see where we could go, how we will survive, and what we will become after a few or more generations. Let's start our travel from the Sun with Mercury as our first stop. Or, to be precise, we could skip this stop altogether. Mercury is almost gravitationally locked by the Sun, meaning that its three days last almost two planetary years. That is bad, as during the daylight, temperatures go toward 400°C, while the other side of the planet goes deep below -100°C. Perhaps we should wait for the Sun to completely lock the planet and hope that we can build some domes within the narrow ring between the day and night with the hope that a couple of suitable terrains will be able to provide normal temperatures.
However, creating settlements on the surface of orbital bodies assumes condemning future colonists with severely lower gravity than Earth's (~0.38 for Mars and ~0.17 for the Moon). As much as I like the plot and the described humans who were born in colonies in 'The Expanse' franchise, created by Daniel Abraham and Ty Franck, to date there has been no sustainable research on how low gravity affects the human body in the long term. From what we know, it causes bone demineralization, muscle atrophy, immune system problems, and other complications throughout the body. We simply can't test low gravity on animals or humans here on Earth, and what might happen to various systems—including reproduction—at the moment is in the realm of (scientific) guesses. But, logically speaking, on a planet surface with lower gravity, evolution would probably modify the human body, as on Mars, for example, we would not need that amount of muscle activity to support simple things, like walking around or lifting heavy things. For the same reasons, the human heart doesn't need to work that hard in order to cope with gravity force and pump the blood to the farthest cell. If you add NASA research on the ISS, which hints that astronauts can grow up to 3 percent taller during the time spent living in microgravity, it is more than a valid assumption that future colonists living on the Moon or asteroid belt, like Detective Miller from Ceres or Rocinante executive officer Naomi Nagata, would indeed grow around 7 feet or more and be very thin.
So there you go; if you plan to move to Mars, you can, with a decent amount of certainty, count on the fact that your descendants will not look anything like you. If you will be able to make kids at all. In a natural way, that is.
Well, whatever happens with gravity difficulties and other hazards of moving to the surface, we still have one more option. To build orbital stations, space harbors, construction sites, and all other types of settlements around Solar System planets and moons. Rotational wheel stations, just like those from Kubrick/Clarke's space odyssey from '68 (a very nice year), would be able to resemble 1g with centripetal acceleration. How big the station would be in radius and how many rotations per minute is necessary to create Earth-like gravitational force can be calculated with a relatively simple equation: a=ω2r, (a-9.81 m/s2, ω-angular velocity, and r-radius of the station). There is a very nice calculator made by Theodore W. Hall you can try and see the real numbers. Perhaps one more hidden advantage of building orbital cities is in the fact that, well, we would not need rockets to lift off the planet or to take down all those gravity wells every time we want to visit relatives who live on another planet or moon. Building space docks and air locks are way simpler and not that dangerous compared to entering Earth's or Mars's atmosphere at 20,000 kph.
Well, I started this post with travel from the Sun, and perhaps now is the time to move further from Mars. So, let's see what is beyond the Goldilocks zone and why bother to go to the outer system where the Sun is just one more bright star in the sky. For example, the Sun seen from Titan or any other of Saturn's moons would be smaller in apparent size than Venus seen from Earth. But, we have to conquer that part of the system simply because the water is there. In vast quantities. Just like in the "Leviathan Wakes" prediction, collecting ice from Saturn's rings or from gas giants' moons could be essential for all life throughout the system. And water is everything—the drink, the food, the fuel, the air. In the potential future of habitable solar systems, the large number of spaceships could be giant automated robot-craft that will be 'mining' water in the outer system and delivering it to the settlements. Besides, lots of moons from Jupiter and Saturn could also harbor life domes, and perhaps the most interesting one is Ganymede with its protective magnetic field and layers of oxygen in its atmosphere. ESA has plans to launch a probe toward this mighty, tidally locked, Mars-sized moon, and then we will know much more.
One more region of the system is also extremely interesting, and it is not very far. The asteroid belt between Mars and Jupiter is a place of four protoplanets, or large asteroids: Ceres, Vesta, Pallas, and Hygiea, and more than one million smaller rocks larger than 1 km in diameter. The belt is probably old remains of one potential planet that failed to form due to heavy gravitational attraction from Jupiter, and in the future it will be our endless source for everything we need in the form of raw construction materials and ore. This would probably be the industrial zone of the entire solar system, and there is no doubt that many corporations are already dreaming of getting there before everybody else.
Finally, the last (and the weakest) link in the chain called life in the solar system is traffic and communication. It is obvious that most of interplanetary spacecraft's propulsion has to be nuclear. For all we know today, it is the only way to travel long distances within days and weeks instead of months and years. However, the speed of a spaceship is not really limited by the engine used. We can make a super fast engine that can reach Ganymede within hours, but it will have to use thrust so tremendous, with more than 10g during long acceleration periods, that it could be fatal for most of the people inside. There will also be lots of braking maneuvers while establishing stable orbit, and no centripetal force in the wheels will be able to compensate. And there will be no open deck where you will be free to lean over the fence and empty your stomach into the sea. Well, a vacuum of space in this case. As for the communication, the limit is Einstein and the speed of light, which means, well, no Skyping or internet between Jupiter and Earth. We will have to get back to the old-fashioned mail and all sorts of asynchronous communication.
Life in space will be cruel and harsh but also full of challenges and with no boundaries like we used to have here on the ground. Here we are taking life for granted. We don't appreciate enough simple things like air and water, for instance. In space they will be precious. Maybe this will help us to start worshiping real values instead of superficial ones. Today, on Earth Day, April 22, 2015, and also my son's eighth birthday, at least it is allowed for me to be a little bit more sentimental and hope that this life will come true within the next couple of decades and maybe he will have the chance to celebrate one of his future birthdays in some orbital station around Saturn. If nothing else, the view will be immensely and tremendously beautiful.
Article refs:
* http://www.edenproject.com/, http://en.wikipedia.org/wiki/Eden_Project
** http://smpritchard.deviantart.com/art/Let-s-Go-to-Saturn-311935454
http://www.newscientist.com/article/mg14719910.600-nigel-and-the-space-plants.html
http://blogs.discovermagazine.com/crux/2014/09/08/where-build-off-world-colonies/
http://www.space.com/19116-astronauts-taller-space-spines.html
http://www.engadget.com/2014/04/12/syfy-the-expanse/
http://kokogiak.com/solarsystembodieslargerthan200miles.html
http://en.wikipedia.org/wiki/The_Expanse_(novel_series)
http://spiff.rit.edu/classes/phys211/lectures/orbit/orbit_all.html
http://science.nasa.gov/science-news/science-at-nasa/2003/02oct_goldilocks/
http://en.wikipedia.org/wiki/Ganymede_%28moon%29
http://astrobob.areavoices.com/2012/01/05/what-would-the-sun-look-like/
http://sci.esa.int/iso/29762-new-study-reveals-twice-as-many-asteroids
But we will not get far. There will be no warp drives, "phasers on stun", robots, AIs, or artificial gravity like in sci-fi blockbusters, and there will be no scientific breakthroughs that will bring Moon or Mars gravity to the comfortable number of 1. No, we will be completely helpless in all our efforts to terraform other planets and gas giants' moons. Not at first. Or fast. Or to make large asteroids rotate. Or to initiate Mars' core to fire its lost magnet. Or to make Venus act a little less than hell.
Artificial biodomes of Eden in Cornwall, England*
No, there are good chances that this day will catch us completely unprepared, and we will be forced to, like Columbus, make one giant step into the unknown. And learn on the way.
This journey will definitely be very difficult in the beginning, but like any other endeavor, after the first steps, it will become handy and enjoyable. So let's think and see where we could go, how we will survive, and what we will become after a few or more generations. Let's start our travel from the Sun with Mercury as our first stop. Or, to be precise, we could skip this stop altogether. Mercury is almost gravitationally locked by the Sun, meaning that its three days last almost two planetary years. That is bad, as during the daylight, temperatures go toward 400°C, while the other side of the planet goes deep below -100°C. Perhaps we should wait for the Sun to completely lock the planet and hope that we can build some domes within the narrow ring between the day and night with the hope that a couple of suitable terrains will be able to provide normal temperatures.
2001: A Space Odyssey
Life on Venus is also as impossible as it seems without at least a basic form of terraforming. I keep wondering what exact misfortune or planetary billiard game in the past made Venus the only planet facing upside down compared to all other planets, but whatever it was, followed by another armageddon that left Venus with an extremely severe greenhouse effect, establishing colonies on Venus's surface is a mission impossible. Maybe some floating settlements in the high altitudes can be the way to start, but it's a shame—Venus' extremely suitable gravity, which is almost the same as here on Earth, is the only planet in the solar system that could cause almost no transition or health hazards for the colonists. The sooner we figure out how to get rid of the CO₂ (and use it to make fuel in the process) on a large scale, the better. If we find the way to do it, we will get the Earth twin just in the right neighborhood and with similar gravity. Personally I think terraforming Venus has way better chances to be effectively done than terraforming Mars, simply because in this case we might only need to drop lots of CO₂-eating life forms or chemicals and wait, while on Mars it might be way more complicated.
The first colonies on other solar system planetary bodies, which can be done almost today, could be built on the Moon and Mars. They are both close by and in suitable places, with nearby natural water sources or supplied from Earth. Large dome-based colonies can be able to sustain millions of colonists right away. Yes, they have to be built with radiation shielding, and they would probably be dependent on frequent supplies from Earth in the beginning, but it would be a good start. Just like in the case of the artificial biodomes of Eden in Cornwall and settlements on Mars and the Moon, if we exclude low gravities, they could be able to provide everything needed with a closed biodiversity and a liberty to project the one the colonists will need or want. For example, there could be different domes on Mars, and if you would like to move there with your family, you could be able to choose the climate you used to have here on Earth.
The Expanse, novel series by Daniel Abraham and Ty Franck
However, creating settlements on the surface of orbital bodies assumes condemning future colonists with severely lower gravity than Earth's (~0.38 for Mars and ~0.17 for the Moon). As much as I like the plot and the described humans who were born in colonies in 'The Expanse' franchise, created by Daniel Abraham and Ty Franck, to date there has been no sustainable research on how low gravity affects the human body in the long term. From what we know, it causes bone demineralization, muscle atrophy, immune system problems, and other complications throughout the body. We simply can't test low gravity on animals or humans here on Earth, and what might happen to various systems—including reproduction—at the moment is in the realm of (scientific) guesses. But, logically speaking, on a planet surface with lower gravity, evolution would probably modify the human body, as on Mars, for example, we would not need that amount of muscle activity to support simple things, like walking around or lifting heavy things. For the same reasons, the human heart doesn't need to work that hard in order to cope with gravity force and pump the blood to the farthest cell. If you add NASA research on the ISS, which hints that astronauts can grow up to 3 percent taller during the time spent living in microgravity, it is more than a valid assumption that future colonists living on the Moon or asteroid belt, like Detective Miller from Ceres or Rocinante executive officer Naomi Nagata, would indeed grow around 7 feet or more and be very thin.
Solar System bodies—size comparison
So there you go; if you plan to move to Mars, you can, with a decent amount of certainty, count on the fact that your descendants will not look anything like you. If you will be able to make kids at all. In a natural way, that is.
Well, whatever happens with gravity difficulties and other hazards of moving to the surface, we still have one more option. To build orbital stations, space harbors, construction sites, and all other types of settlements around Solar System planets and moons. Rotational wheel stations, just like those from Kubrick/Clarke's space odyssey from '68 (a very nice year), would be able to resemble 1g with centripetal acceleration. How big the station would be in radius and how many rotations per minute is necessary to create Earth-like gravitational force can be calculated with a relatively simple equation: a=ω2r, (a-9.81 m/s2, ω-angular velocity, and r-radius of the station). There is a very nice calculator made by Theodore W. Hall you can try and see the real numbers. Perhaps one more hidden advantage of building orbital cities is in the fact that, well, we would not need rockets to lift off the planet or to take down all those gravity wells every time we want to visit relatives who live on another planet or moon. Building space docks and air locks are way simpler and not that dangerous compared to entering Earth's or Mars's atmosphere at 20,000 kph.
Well, I started this post with travel from the Sun, and perhaps now is the time to move further from Mars. So, let's see what is beyond the Goldilocks zone and why bother to go to the outer system where the Sun is just one more bright star in the sky. For example, the Sun seen from Titan or any other of Saturn's moons would be smaller in apparent size than Venus seen from Earth. But, we have to conquer that part of the system simply because the water is there. In vast quantities. Just like in the "Leviathan Wakes" prediction, collecting ice from Saturn's rings or from gas giants' moons could be essential for all life throughout the system. And water is everything—the drink, the food, the fuel, the air. In the potential future of habitable solar systems, the large number of spaceships could be giant automated robot-craft that will be 'mining' water in the outer system and delivering it to the settlements. Besides, lots of moons from Jupiter and Saturn could also harbor life domes, and perhaps the most interesting one is Ganymede with its protective magnetic field and layers of oxygen in its atmosphere. ESA has plans to launch a probe toward this mighty, tidally locked, Mars-sized moon, and then we will know much more.
One more region of the system is also extremely interesting, and it is not very far. The asteroid belt between Mars and Jupiter is a place of four protoplanets, or large asteroids: Ceres, Vesta, Pallas, and Hygiea, and more than one million smaller rocks larger than 1 km in diameter. The belt is probably old remains of one potential planet that failed to form due to heavy gravitational attraction from Jupiter, and in the future it will be our endless source for everything we need in the form of raw construction materials and ore. This would probably be the industrial zone of the entire solar system, and there is no doubt that many corporations are already dreaming of getting there before everybody else.
"Day the Earth Smiled", Cassini photo of Saturn on July 19, 2013
Finally, the last (and the weakest) link in the chain called life in the solar system is traffic and communication. It is obvious that most of interplanetary spacecraft's propulsion has to be nuclear. For all we know today, it is the only way to travel long distances within days and weeks instead of months and years. However, the speed of a spaceship is not really limited by the engine used. We can make a super fast engine that can reach Ganymede within hours, but it will have to use thrust so tremendous, with more than 10g during long acceleration periods, that it could be fatal for most of the people inside. There will also be lots of braking maneuvers while establishing stable orbit, and no centripetal force in the wheels will be able to compensate. And there will be no open deck where you will be free to lean over the fence and empty your stomach into the sea. Well, a vacuum of space in this case. As for the communication, the limit is Einstein and the speed of light, which means, well, no Skyping or internet between Jupiter and Earth. We will have to get back to the old-fashioned mail and all sorts of asynchronous communication.
Life in space will be cruel and harsh but also full of challenges and with no boundaries like we used to have here on the ground. Here we are taking life for granted. We don't appreciate enough simple things like air and water, for instance. In space they will be precious. Maybe this will help us to start worshiping real values instead of superficial ones. Today, on Earth Day, April 22, 2015, and also my son's eighth birthday, at least it is allowed for me to be a little bit more sentimental and hope that this life will come true within the next couple of decades and maybe he will have the chance to celebrate one of his future birthdays in some orbital station around Saturn. If nothing else, the view will be immensely and tremendously beautiful.
Article refs:
* http://www.edenproject.com/, http://en.wikipedia.org/wiki/Eden_Project
** http://smpritchard.deviantart.com/art/Let-s-Go-to-Saturn-311935454
http://www.newscientist.com/article/mg14719910.600-nigel-and-the-space-plants.html
http://blogs.discovermagazine.com/crux/2014/09/08/where-build-off-world-colonies/
http://www.space.com/19116-astronauts-taller-space-spines.html
http://www.engadget.com/2014/04/12/syfy-the-expanse/
http://kokogiak.com/solarsystembodieslargerthan200miles.html
http://en.wikipedia.org/wiki/The_Expanse_(novel_series)
http://spiff.rit.edu/classes/phys211/lectures/orbit/orbit_all.html
http://science.nasa.gov/science-news/science-at-nasa/2003/02oct_goldilocks/
http://en.wikipedia.org/wiki/Ganymede_%28moon%29
http://astrobob.areavoices.com/2012/01/05/what-would-the-sun-look-like/
http://sci.esa.int/iso/29762-new-study-reveals-twice-as-many-asteroids