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Unless I missed your point, that is like witching for water with a devining rod.
Asteroids and comets have very little gravity. so the rod likely will not point due to gravity especially if the pivot point is in free fall.
We can however put telescopes in solar orbit with CCD = charge coupled display. When a directon is viewed a day or two later close objects will have moved with respect to the more distant stars. Most of these will be an asteroid, comet, or space ship. Oculations will be rarely detected by this method, but occulations give valuable information. Neil
Now that I have read several other threads on this topic, I reilize you are thinking six humans instead of three. My guess is we need to wait for SE5 which may be able to flip 150 tons, and could be as long as 200,000 miles. That doubles the speed to get you to Jupiter in 500 days, which leaves more supplies for a stop over, and the return trip which could take more than ten years with bad luck. Three persons in each of two ships means improved safety factors and rescue is possible, if not probable. 200,000 miles means the counter weight needs to be on the Earth side of GEO altitude, so we might shorten SE5 after the Jupiter launch and a few others requiring high speed. The good news is SE5 might be completed as soon as two years after SE3 is complete (one year after SE4) with sufficient demand for heavy lift. Neil
Hi DaytonKitchens: We could have 4 SE = space elevators by 2025, if we get strong and cheap CNT = carbon nano tubes soon. SE 4 could be more than 100,000 miles from center of Earth to the tip. C = 6.28 times 100,000 = 628,000 miles per day. The Sun's gravity will slow the average speed to about 500,000 miles per day for 1000 days = 500 million miles which will get us to Jupiter. About 1500 days to get us to Saturn, instead of Jupiter. SE 4 may be able to flip 100 tons toward the gas giant planets. 100 tons is marginal for that long a manned trip as considerable fuel is needed to make a soft landing on a moon, if the slow down manuver around the gas giant planet is unsucessful. There may not be enough fuel (even with a sling shot manuver around the gas giant) to make the return trip in ten years travel time, which is way too long unless supplies can be produced on that moon = not very likely. We can get there, but surviving the return trip is unlikely. Neil
O'Neill colonies were supposed to be paid for by SPS = solar power satellites, but that idea has been injured by people not wanting the rectenna near their house. If we do SPS, it will likely be unmanned with photovoltaic panels instead of mirrors boiling water. I think O'Neill seriously under estimated the waste heat disposal problem in space. I think the O'Neill colonies also require unobtainium, but CNT = carbon nano tubes may make smaller O'Neill colonies(without SPS) possible, if CNT is cheap and meets the optimistic strength projections.
Two approximately sphere habitats, each with a radius of 100 meters spinning around each other with the help of a two kilometer CNT ribbon tether would be far less costly and would accomodate thousands colonists without the trees, streams and very high ceiling which is mostly wasted space. It would have far less mass than an O'neil colony for 1000 colonists, and thus would be much easier to move around our Solar system. The Stanford torus, and the wheel like "deep Space Nine" are compromise concepts.
The big mirror and louvered mirrors on the spheres may be about as practical as it is with the Stanford torrus, but the waste heat disposal problem will not allow more than a tiny amount of food growing even if the mirrors loose 99% of the sunlight spectrum not useful for photosynthesis. Neil
At least one poster insists that the minimum approach speed for any body (assuming no atmosphere) is the escape velocity which for Mars is about 5 kilometers per second at the surface. If the sphere has some thrust, it can orbit in the upper atmosphere for the several days required to radiate away the kenetic energy at 400 degrees k. That is assuming an aluminum color surface that is 50% illuminated by sunlight 60% of the time, and a night time air temperature of 100 degrees k.
I''ll guess only 10% is lost by convection and conduction, in the upper atmosphere of Mars. I'll guess one milibarr internal pressure is sufficent to keep the sphere shape close enough to avoid hot spots over 410 degrees k. The sphere will rotate due to the air pressure being higher on the side closest to Mars. The rotation will help the sphere keep its shape, and reduce hot spots. I don't think the rotation will be fast enough to stress the sphere significantly, unless the radius of the sphere exceeds one kilometer. The heat energy stored in the N2 = nitrogen is less than the heat energy stored in the faberic = skin of the sphere which is close to negligible compared to the energy that needs to be radiated. This is also true if the sphere has H2 = hydrogen at one millibarr. Considerable thrust will be needed to avoid an excessive decent rate as the "orbital" speed falls below 0.1 kilometer per second. The sphere will loose it's shape (unless the skin is very elastic) as the Mars atmosphere reaches 5 millibarrs if landing is at a low elevation of Mars surface. The loss of shape may not cause any serious mischief. The rotation will slow considerably in the 4 or 5 millibarr atmosphere, but the rotation needs to be slowed to approximately zero for a safe landing.
Question 6: The inside pressure needs to be about 6 millibars to retain approximately sphere shape at landing in the 5 milibarr surface pressure. The internal pressure will drop as the sphere cools to perhaps 210 degrees k after landing. 6 millibars may stress the faberic dangerously while the sphere is radiating kenetic energy at 400 degrees k with an outside pressure of perhaps 0.1 milibarr.
High wind speed will deform the sphere considerably after landing. I can't prove any of this with math, so I may be dead wrong. Neil
Brutal chemistry may be the way to go. The hydrogen beam can heat the upper atmosphere to 600 degrees c in the volume filed with iron dust from an iron-nickel asteroid that vaporized in the atmosphere of Venus, recently.
According to the old Analog arcticle the energy of all the sunlight that falls on Venus in 600 years is needed to free all the carbon from the carbon dioxide, so we are looking at 6 million years if we can delver 1% of the sunlight to the algae which uses 1% of that energy. Unless the asteroid dust is extremely fine, it may take just as long with the hydrogen beam. Getting the high speed hydrogen to react with the carbon monoxide that is diluted with lots of carbon dioxide may happen only 1% of the time, before the gases cool below the reaction temperature.
I presume we would be using hydrogen beams as reaction mass to propel space craft = an ion engine? if this is easy and efficient with present technology. We can't let humans breath air with more than a few parts per million of carbon monoxide, as it is very toxic. Neil
Personally, I would be nervous living in a dome with a thin hostle atmosphere outside, but some Mars colonists will want to visit, work or even sleep under a dome. 100 kilometer domes may be possible with CNT = carbon nano tubes, but we can't make 1/10 th kilometer domes of CNT on Earth at present. Building big domes on Mars will be more difficult than Earth inspite of 1/3 gravity. Stress free glass is an exacting process which is why it is expensive. If you also want high transparency the cost is even higher. We may be thinking a meter thick glass for resaonable safety. Thinking a 4 psi mostly oxygen atmosphere instead of 15 psi on the dome will help considerably. Neil
Hi commador: I don't know the math, but I think you are about right, however, the 50 tons shrinks rapidly, if we jutson the external tanks at a higher altiude. Perhaps best is a one ton motor which could assist in the shuttle lift off and slow the deceleration of the tank after it is released from the shuttle. NASA is reluctant, because even minor design changes can adversely affect the shuttle in unexpected ways, so good engineering is to insist on extensive and expensive testing even for minor changes. Neil
S =1/2at squared = 5 times 10 billion meters = 50 million kilometers, which is about the half the distance between each of the 4 inner planets, in a favorable lineup. The acceleration is slightly more than one g, which should be doable contineously with an advanced fusion motor. The square root of 10 billion is 100,000 seconds = 27.777 hours. Besides accelerating 3 times to visit 4 planets we need to decelerate 3 times = 166 hours which is 2 hours short of one week, so a month total allows an average about 6 days lay over and manuver time at each planet. It will not take much longer to visit the remaining 5 planets, because of the wonder of square law = less than a year even with least favorable allignment, and stopovers at several moons. Neil
Hi Austin Stanley: I agree. The small amount of residual hydrogen in the crust of Venus will be even more difficult to free after there are hundreds of meters of dead algae covering most of the surface, as well other solid minerals. The sequestered sulpheric acid produces free hydrogen when mixed with free metals, and this often frees the water which the acid has captured. Large quantities of sulphates may, however, be a nuisance as most of them are at least slightly soluable in water. Hydrogen will be difficult to transport from elsewhere in the solar system as it melts at 10 degrees k and boils at about 30 degrees k even at 60 atmospheres pressure.
My guess is the hydrogen particle beam mentioned early in this thread delivers huge amounts of unneeded energy along with a tiny amount of hydrogen, most of which will escape unless it is combined with something. Hot carbon normally takes oxygen from water steam to make carbon monoxide. Is there a practical way to reverse the reaction (very large scale) so the the hydrogen beam coverts the carbon dioxide to water and soot = free carbon?
It may be more practical to make lots of unwanted steam (from excess comets)early in the terraforming even though that means more off planet shades are needed to offset even worse green house conditions, much of the hydrogen will be lost from the upper atmosphere plus even more free oxygen to cause mischief. As you mentioned carbon is stable in a rich high pressure oxygen atmosphere below about 1000 degrees k = 727 c = 1340 f. Perhaps that is a bit too hot to avoid oxidizing carbon? In any case, Venus has lightening which will occasaionally ignite the piles of dead algae, which will blow about in even a slight wind, until it is cool enough to make mud.
According to the old analog article, the atmosphere of Venus has as many tons of Nitrogen as Earth's atmosphere, but it may not have enough hydrochoric acid = HCl to make a salty ocean which can support coral reefs. The sodium will be far below the dead algae, but the fertilizer may have enough sodium as a contaminant. Making Venus a lot like Earth involves many details, many of which with far exceed the total efforts of humans thoughout the history of Earth. Neil
Hi grypd: what is a soletta?
GEO altitude is about 1/2 as high for Mars, so a very large mirror could easily double the average solar flux and supply the extra energy most of the night and part of the day over a million of square miles of the surface of Mars. The catch is the miror needs about 2 million square miles of effective surface. Neil
Hi GCN: Why is there an upper limit on the power in space? If the thrust is 2 million pounds, that accellerates a million pound spacecraft at 2g = 64 feet per sec per sec = 19 meters per second per second? Neil
Hi Kaladasa: I'm inclined to agree, the 2018 date will likely slip eventually, but over optimism has it's rewards. We don't want people thinking they have lots of time to perfect the lifter or the anchor ship nor the big lasers, nor the 840 nanometer photovoltaic panel.
I'm urging a not very useful short slow rotovator of very thin tapered kevar ribbon with a thin coat of not very good CNT and a climber. This will test the laser and climber at LEO, and the transcients generated on the rotovator will give at least a clue about transient which are likely on the 100,000 kilometer ribbon. The climber can lay an almost worthless thread of CNT just to be sure the thread can be attached as expected. Neil
PS: I have absolutely no authority at Liftport, but I do post on their forum frequently. Neil
Hi nickname: I edited my first post to adding hydrogen after Venus was cooled to 200 degrees c to avoid boiling the rain when it hits. The dead algae will insulate the still hot rocks far below, so it may only take 1000 years to get the polar plataus below about 200 degrees c = 392f
The algae breaks the CO2 bonds. I'm thinking cool the poles enough to keep the sulpheric acid liquid. Not nearly cold enough to make dry ice. In the final stages (a million years?) we may have some coral reefs making calcium carbonate out of part of the remaining 5% carbon dioxide. At the cooler temperatures, dead algae burning under ground should be no more problem than old coal mines burning below ground on Earth. Neil
Another possibility for getting the fertilizer, and putting fine dust in the "air" is a large robot machine which contineously circles the Equator of Venus at about 12 kilometers per hour, so it stays where the Sun is directly overhead. It scoops and grinds to a very fine dust which it flings into the air. The strong thermals would carry the dust to the upper atmosphere to fertalize the algae. The poles of Venus have a strong down draft which would be strengthened by the cooling of the poles (the dust and algae shade the poles) so most of the dust would be deposited at the poles. A few thousand miles of snow fence would keep the dust from being blown off the plataus by the gentle surface winds toward the Equator of Venus. When it began to rain acid (1000 years?) the mud would stay where it hit the surface.
The contineous travel of the big machine would (I think) shorten the Venus year by about 1 second per century. A minute bonus. Neil
Hi Austin Stanley: Alchohols, alkyners, ethers, teflon, and so on can also fall with the sulpheric acid into the acquifers of the polar plataus if we can find a convenient way to synthesize these compounds and shade the polar platau completely. Some of my ideas are from a 20? year old Analog science fact article which said, "the carbon dioxide of Venus would make a layer of carbon 600 meters thick covering all the surface of Venus."
I understand diamonds will burn in air much as coal burns. Neil
It appears it will take thousands of year to terraform Venus even if we install sunshades which block 99% of the solar radiation not needed for photosynthesis. We also need to deliver many comets to Venus to supply water and fertilizer for photosythesis in the cool upper atmosphere. The water will be trapped by the sulpheric acid layers, instead of recycling as water does on Earth. A partial solution is to partially terraform = cool, only the Arctic region, first, so the acid falls as rain which can be trapped in aquifers between artificial impervious layers. The dead algae and unused fertilizer will form a very high polar platau, if the crust of Venus is strong enough to support the weight of a very tall plateau. If not, we will get Venus quakes. With the sulpheric acid sequestered, Venus will recycle water much as Earth does. It will take many more thousands of years to lower the carbon dioxide to a percentage which humans can tolerate = about 5% carbon dioxide for genetically altered humans, but hundreds of meters of dead algae mixed with unused fertilizer will make rich top soil.
We can approximately halve the terriforming epic, by building a high platau at both the North and South poles. As the oxygen is freed by photosynthesis, dead algae fires will return the carbon dioxide to the Venus atmosphere, unless we bring many iron asteroids to Venus to absorb the oxygen. Iron oxide will form at much less than one percent oxygen, but dead algae = mostly carbon won't burn at less than about 1% oxygen.
We will have too much oxygen, but we can bring hydrogen to Venus (that has cooled to about 200 degrees c = the boiling point of water at 60? atmospheres) to make more water. Too much water is very unlikely. We will need some sunshades, forever, to keep even the high Arctic plateau at a temperatures tolerable even to genetically altered humans and food crops. Neil
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