science fiction has told us again and again,we belong out there, among the stars. but before we can build that vast galacticempire, we’ve got to learn how to just survive in space. fortunately, we happen to live in a solarsystem with many worlds, large and small that we can use to become a spacefaring civilization. this is half of an epic two-part episode thati’m doing with isaac arthur, who runs an amazing channel all about futurism, oftenabout the exploration and colonization of space. make sure you subscribe to his channel.
this episode is about colonizing the innersolar system, from tiny mercury, the smallest planet, out to mars, the focus of so muchattention by elon musk and spacex. in the other episode, isaac will talk aboutwhat it’ll take to colonize the outer solar system, and harness its icy riches. you can watch these episodes in either order,just watch them both. at the time of this video, humanity’s colonizationefforts of the solar system are purely on earth. we’ve exploited every part of the planet,from the south pole to the north, from huge continents to the smallest islands.
there are few places we haven’t fully colonizedyet, and we’ll get to that. but when it comes to space, we’ve only takenthe shortest, most tentative steps. there have been a few temporarily inhabitedspace stations, like mir, skylab and the chinese tiangong stations. our first and only true colonization of spaceis the international space station, built in collaboration with nasa, esa, the russianspace agency and other countries. it has been permanently inhabited since november2nd, 2000. needless to say, we’ve got our work cutout for us. before we talk about the places and ways humanscould colonize the rest of the solar system,
it’s important to talk about what it takesto get from place to place. just to get from the surface of earth intoorbit around our planet, you need to be going about 10 km/s sideways. this is orbit, and the only way we can doit today is with rockets. once you’ve gotten into low earth orbit,or leo, you can use more propellant to get to other worlds. if you want to travel to mars, you’ll needan additional 3.6 km/s in velocity to escape earth gravity and travel to the red planet. if you want to go to mercury, you’ll needanother 5.5 km/s.
and if you wanted to escape the solar systementirely, you’d need another 8.8 km/s. we’re always going to want a bigger rocket. the most efficient way to transfer from worldto world is via the hohmann transfer. this is where you raise your orbit and driftout until you cross paths with your destination. then you need to slow down, somehow, to gointo orbit. one of our primary goals of exploring andcolonizing the solar system will be to gather together the resources that will make futurecolonization and travel easier. we need water for drinking, and to split itapart for oxygen to breathe. we can also turn this water into rocket fuel.
unfortunately, in the inner solar system,water is a tough resource to get and will be highly valued. we need solid ground. to build our bases, to mine our resources,to grow our food, and to protect us from the dangers of space radiation. the more gravity we can get the better, sincelow gravity softens our bones, weakens our muscles, and harms us in ways we don’t fullyunderstand. each world and place we colonize will haveadvantages and disadvantages. let’s be honest, earth is the best placein the solar system, it’s got everything
we could ever want and need. everywhere else is going to be brutally difficultto colonize and make self-sustaining. we do have one huge advantage, though. earth is still here, we can return wheneverwe like. the discoveries made on our home planet willcontinue to be useful to humanity in space through communications, and even 3d printing. once manufacturing is sophisticated enough,a discovery made on one world could be mass produced half a solar system away with theright raw ingredients. we will learn how to make what we need, whereverwe are, and how to transport it from place
to place, just like we’ve always done. mercury is the closest planet from the sun,and one of the most difficult places that we might attempt the colonize. because it’s so close to the sun, it receivesan enormous amount of energy. during the day, temperatures can reach 427c, but without an atmosphere to trap the heat, night time temperatures dip down to -173 c. there’s essentially no atmosphere, 38% thegravity of earth, and a single solar day on mercury lasts 176 earth days. mercury does have some advantages, though.
it has an average density almost as high asearth, but because of its smaller size, it actually means it has a higher percentageof metal than earth. mercury will be incredibly rich in metalsand minerals that future colonists will need across the solar system. with the lower gravity and no atmosphere,it’ll be far easier to get that material up into orbit and into transfer trajectoriesto other worlds. but with the punishing conditions on the planet,how can we live there? although the surface of mercury is eitherscorching or freezing, nasa’s messenger spacecraft turned up regions of the planetwhich are in eternal shadow near the poles.
in fact, these areas seem to have water ice,which is amazing for anywhere this close to the sun. you could imagine future habitats huddledinto those craters, pulling in solar power from just over the crater rim, using the reservoirsof water ice for air, fuel and water. high powered solar robots could scour thesurface of mercury, gathering rare metals and other minerals to be sent off world. because it’s bathed in the solar winds,mercury will have large deposits of helium-3, useful for future fusion reactors. over time, more and more of the raw materialsof mercury will find their way to the resource
hungry colonies spread across the solar system. it also appears there are lava tubes scatteredacross mercury, hollows carved out by lava flows millions of years ago. with work, these could be turned into safe,underground habitats, protected from the radiation, high temperatures and hard vacuum on the surface. with enough engineering ability, future colonistswill be able to create habitats on the surface, wherever they like, using a mushroom-shapedheat shield to protect a colony built on stilts to keep it off the sun-baked surface. mercury is smaller than mars, but is a gooddeal denser, so it has about the same gravity,
38% of earth’s. now that might turn out to be just fine, butif we need more, we have the option of using centrifugal force to increase it. space stations can generate artificial gravityby spinning, but you can combine normal gravity with spin-gravity to create a stronger fieldthan either would have. so our mushroom habitat’s stalk could havean interior spinning section with higher gravity for those living inside it. you get a big mirror over it, shielding youfrom solar radiation and heat, you have stilts holding it off the ground, like roots, thatminimize heat transfer from the warmer areas
of ground outside the shield, and if you needit you have got a spinning section inside the stalk. a mushroom habitat. venus is the second planet in the solar system,and it’s the evil twin of earth. even though it has roughly the same size,mass and surface gravity of our planet, it’s way too close to the sun. the thick atmosphere acts like a blanket,trapping the intense heat, pushing temperatures at the surface to 462 c. everywhere on the planet is 462 c, so there’sno place to go that’s cooler.
the pure carbon dioxide atmosphere is 90 timesthicker than earth, which is equivalent to being a kilometer beneath the ocean on earth. in the beginning, colonizing the surface ofvenus defies our ability. how do you survive and stay cool in a thickpoisonous atmosphere, hot enough to melt lead? you get above it. one of the most amazing qualities of venusis that if you get into the high atmosphere, about 52.5 kilometers up, the air pressureand temperature are similar to earth. assuming you can get above the poisonous cloudsof sulphuric acid, you could walk outside a floating colony in regular clothes, withouta pressure suit.
you’d need a source of breathable air, though. even better, breathable air is a lifting gasin the cloud tops of venus. you could imagine a future colony, filledwith breathable air, floating around venus. because the gravity on venus is roughly thesame as earth, humans wouldn’t suffer any of the side effects of microgravity. in fact, it might be the only place in theentire solar system other than earth where we don’t need to account for low gravity. now the day on venus is incredibly long, 243earth days, so if you stay over the same place the whole time it would be light for fourmonths then dark for four months.
not ideal for solar power on a first glance,but venus turns so slowly that even at the equator you could stay ahead of the sunsetat a fast walk. so if you have floating colonies it wouldtake very little effort to stay constantly on the light side or dark side or near thetwilight zone of the terminator. you are essentially living inside a blimp,so it may as well be mobile. and on the day side it would only take a fewsolar panels and some propellers to stay ahead. and since it is so close to the sun, there’splenty of solar power. what could you do with it? the atmosphere itself would probably serveas a source of raw materials.
carbon is the basis for all life on earth. we’ll need it for food and building materialsin space. floating factories could process the thickatmosphere of venus, to extract carbon, oxygen, and other elements. heat resistant robots could be lowered downto the surface to gather minerals and then retrieved before they’re cooked to death. venus does have a high gravity, so launchingrockets up into space back out of venus’ gravity well will be expensive. over longer periods of time, future colonistsmight construct large solar shades to shield
themselves from the scorching heat, and eventually,even start cooling the planet itself. the next planet from the sun is earth, thebest planet in the solar system. one of the biggest advantages of our colonizationefforts will be to get heavy industry off our planet and into space. why pollute our atmosphere and rivers whenthere’s so much more space… in space. over time, more and more of the resource gatheringwill happen off world, with orbital power generation, asteroid mining, and zero gravitymanufacturing. earth’s huge gravity well means that it’sbest to bring materials down to earth, not carry them up to space.
however, the normal gravity, atmosphere andestablished industry of earth will allow us to manufacture the lighter high tech goodsthat the rest of the solar system will need for their own colonization efforts. but we haven’t completely colonized earthitself. although we’ve spread across the land, weknow very little about the deep ocean. future colonies under the oceans will helpus learn more about self-sufficient colonies, in extreme environments. the oceans on earth will be similar to theoceans on europa or enceladus, and the lessons we learn here will teach us to live out there.
as we return to space, we’ll colonize theregion around our planet. we’ll construct bigger orbital coloniesin low earth orbit, building on our lessons from the international space station. one of the biggest steps we need to take,is understanding how to overcome the debilitating effects of microgravity: the softened bones,weakened muscles and more. we need to perfect techniques for generatingartificial gravity where there is none. the best technique we have is rotating spacecraftto generate artificial gravity. just like we saw in 2001, and the martian,by rotating all or a portion of a spacecraft, you can generated an outward centrifugal forcethat mimics the acceleration of gravity.
the larger the radius of the space station,the more comfortable and natural the rotation feels. low earth orbit also keeps a space stationwithin the earth’s protective magnetosphere, limiting the amount of harmful radiation thatfuture space colonists will experience. other orbits are useful too, including geostationaryorbit, which is about 36,000 kilometers above the surface of the earth. here spacecraft orbit the earth at exactlythe same rate as the rotation of earth, which means that stations appear in fixed positionsabove our planet, useful for communication. geostationary orbit is higher up in earth’sgravity well, which means these stations will
serve a low-velocity jumping off points toreach other places in the solar system. they’re also outside the earth’s atmosphericdrag, and don’t require any orbital boosting to keep them in place. by perfecting orbital colonies around earth,we’ll develop technologies for surviving in deep space, anywhere in the solar system. the same general technology will work anywhere,whether we’re in orbit around the moon, or out past pluto. when the technology is advanced enough, wemight learn to build space elevators to carry material and up down from earth’s gravitywell.
we could also build launch loops, electromagneticrailguns that launch material into space. these launch systems would also be able toloft supplies into transfer trajectories from world to world throughout the solar system. earth orbit, close to the homeworld givesus the perfect place to develop and perfect the technologies we need to become a truespacefaring civilization. not only that, but we’ve got the moon. the moon, of course, is the earth’s onlynatural satellite, which orbits us at an average distance of about 400,000 kilometers. almost ten times further than geostationaryorbit.
the moon takes a surprising amount of velocityto reach from low earth orbit. it’s close, but expensive to reach, thrustspeaking. but that fact that it’s close makes themoon an ideal place to colonize. it’s close to earth, but it’s not earth. it’s airless, bathed in harmful radiationand has very low gravity. it’s the place that humanity will learnto survive in the harsh environment of space. but it still does have some resources we canexploit. the lunar regolith, the pulverized rocky surfaceof the moon, can be used as concrete to make structures.
spacecraft have identified large depositsof water at the moon’s poles, in its permanently shadowed craters. as with mercury, these would make ideal locationsfor colonies. our spacecraft have also captured images ofopenings to underground lava tubes on the surface of the moon. some of these could be gigantic, even kilometershigh. you could fit massive cities inside some ofthese lava tubes, with room to spare. helium-3 from the sun rains down on the surfaceof the moon, deposited by the sun’s solar wind, which could be mined from the surfaceand provide a source of fuel for lunar fusion
reactors. this abundance of helium could be exportedto other places in the solar system. the far side of the moon is permanently shadowedfrom earth-based radio signals, and would make an ideal location for a giant radio observatory. telescopes of massive size could be builtin the much lower lunar gravity. we talked briefly about an earth-based spaceelevator, but an elevator on the moon makes even more sense. with the lower gravity, you can lift materialoff the surface and into lunar orbit using cables made of materials we can manufacturetoday, such as zylon or kevlar.
one of the greatest threats on the moon isthe dusty regolith itself. without any kind of weathering on the surface,these dust particles are razor sharp, and they get into everything. lunar colonists will need very strict protocolsto keep the lunar dust out of their machinery, and especially out of their lungs and eyes,otherwise it could cause permanent damage. although the vast majority of asteroids inthe solar system are located in the main asteroid belt, there are still many asteroids orbitingcloser to earth. these are known as the near earth asteroids,and they’ve been the cause of many of earth’s great extinction events.
these asteroids are dangerous to our planet,but they’re also an incredible resource, located close to our homeworld. the amount of velocity it takes to get tosome of these asteroids is very low, which means travel to and from these asteroids takeslittle energy. their low gravity means that extracting resourcesfrom their surface won’t take a tremendous amount of energy. and once the orbits of these asteroids arefully understood, future colonists will be able to change the orbits using thrusters. in fact, the same system they use to launchminerals off the surface would also push the
asteroids into safer orbits. these asteroids could be hollowed out, andset rotating to provide artificial gravity. then they could be slowly moved into safe,useful orbits, to act as space stations, resupply points, and permanent colonies. there are also gravitationally stable pointsat the sun-earth l4 and l5 lagrange points. these asteroid colonies could be parked there,giving us more locations to live in the solar system. the future of humanity will include the colonizationof mars, the fourth planet from the sun. on the surface, mars has a lot going for it.
a day on mars is only a little longer thana day on earth. it receives sunlight, unfiltered through thethin martian atmosphere. there are deposits of water ice at the poles,and under the surface across the planet. martian ice will be precious, harvested fromthe planet and used for breathable air, rocket fuel and water for the colonists to drinkand grow their food. the martian regolith can be used to grow food. it does have have toxic perchlorates in it,but that can just be washed out. the lower gravity on mars makes it anotherideal place for a space elevator, ferrying goods up and down from the surface of theplanet.
unlike the moon, mars has a weathered surface. although the planet’s red dust will geteverywhere, it won’t be toxic and dangerous as it is on the moon. like the moon, mars has lava tubes, and thesecould be used as pre-dug colony sites, where human martians can live underground, protectedfrom the hostile environment. mars has two big problems that must be overcome. first, the gravity on mars is only a thirdthat of earth’s, and we don’t know the long term impact of this on the human body. it might be that humans just can’t matureproperly in the womb in low gravity.
researchers have proposed that mars colonistsmight need to spend large parts of their day on rotating centrifuges, to simulate earthgravity. or maybe humans will only be allowed to spenda few years on the surface of mars before they have to return to a high gravity environment. the second big challenge is the radiationfrom the sun and interstellar cosmic rays. without a protective magnetosphere, martiancolonists will be vulnerable to a much higher dose of radiation. but then, this is the same challenge thatcolonists will face anywhere in the entire solar system.
that radiation will cause an increased riskof cancer, and could cause mental health issues, with dementia-like symptoms. the best solution for dealing with radiationis to block it with rock, soil or water. and martian colonists, like all solar systemcolonists will need to spend much of their lives underground or in tunnels carved outof rock. in addition to mars itself, the red planethas two small moons, phobos and deimos. these will serve as ideal places for smallcolonies. they’ll have the same low gravity as asteroidcolonies, but they’ll be just above the gravity well of mars.
ferries will travel to and from the martianmoons, delivering fresh supplies and sending martian goods out to the rest of the solarsystem. we’re not certain yet, but there are goodindicators these moons might have ice inside them, if so that is an excellent source offuel and could make initial trips to mars much easier by allowing us to send a firstexpedition to those moons, who then begin producing fuel to be used to land on marsand to leave mars and return home. according to elon musk, if a martian colonycan reach a million inhabitants, it’ll be self-sufficient from earth or any other world. at that point, we would have a true, solarsystem civilization.
now that you’ve heard how to colonize theinner planets, come on over for part 2, colonizing the outer solar system, and we will startwith the asteroid belt and work our way out the oort cloud.
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