|Posted by Rohvannyn on November 2, 2015 at 9:35 PM||comments (0)|
Another approach to addressing CO2 and water vapor in cabin air is a series of reactions discovered by the French Chemist Paul Sabatier during the early years of the 20th Century. In this chemical process hydrogen is reacted with carbondioxide at about 480 degrees F, to yield methane (CH4) and water. The water can then be subjected to electrolysis to yield more hydrogen and free oxygen. The concept of Mars Direct, a plan for reaching Mars from Earth’s surface, is based on this idea.
In order to concentrate the cargbondioxide in our ship or station to make it available for recation, we’d either need to remove it chemically, driving CO2 off the chemical scrubbing agent (such as sodium or Potassium hydroxide) or we could chill cabin air down to dry ice temperatures to freeze out CO2 and moisture as well. We’ve discussed processes such as these in the biodyne article.
Four Moles of H2 (hydrogen gas) reacted with a mole of CO2 require about 320 thousand joules to yield a mole of methane and two moles of water. For a crew of six, we’d be looking at a constant power input of about 600 Watts to drive the Sabatier reaction at 100 percent efficiency. Of course we won’t get that but about 1,500 Watts should be safe. In situations that allow passing behind a planet or shading is available, low temperatures can be achieved by exposing a radiator to vacuum. Even with the “thermos-bottle effect” of space, a relatively few square meters of radiator can provide effective cooling for a small vehicle.
Methane itself can be broken down to yield free hydrogen and carbon graphite. This carbon can be stored as ashe or I suspect we will learn to synthesize carbohydrates from methane and a little oxygen. I suspect we won’t duplicate photosynthesis any time soon but if we can make sugars and starches from methane, through effective waste reduction technology we could continuously recycle air, water, and (most of our food) at moderate energy expense.
If we assume a recycling system in which water is cracked to yield hydrogen and oxygen, carbon dioxide is made to yield it’s oxygen while carbon is incorporated into methane and methane is reduced to pure carbon and free oxygen, we can also think about extracting additional oxygen supplies from asteroid rock. Hydrogen can extract oxygen from many sorts of minerals at high temperature, yielding pure metals and silicon as well as water vapor which can be cooled and cracked to extract oxygen. Some of the oxygen can be combined with the carbon graphite to produce carbonmonoxide (CO) which has been shown to be very effective in extracting metal from rock such as that making up many asteroids.
If therefore we can make our carbohydrates we can greatly reduce the amount of food we must ship to an orbital station or departing space mission while oxygen and water will be continuously recycled, without the need for extensive green house or algae tube arrangements.
|Posted by Rohvannyn on February 14, 2015 at 6:00 PM||comments (0)|
February 13, 2015
This is the beginning of what will hopefully be a series on life support and bioastronautics. The main object is the formulation of possible alternative means of providing low-mass alternatives for private space transports with human crews or colonies in space or on other celestial bodies.
As is well-known, Lithium Hydroxide (LiOH) is commonly used aboard space craft for scrubbing carbon dioxide from cabin air. This is accomplished through the reaction 2(LiOH)+CO2 > LI2CO3+H2O. The lithium compound therefore absorbs carbon dioxide but moistens the air of the cabin. When I was looking at early designs for the Biodyne environment/propulsion system (mentioned elsewhere on this site) during high school and college It seemed obvious that if Lithium metal could be brought on an extended voyage instead of LiOH, it should be possible to assist in the removal of water vapor as well as CO2 from cabin air and the reactions might constitute a power source in the same way that hydrox fuel cells do double duty as water suppliers and generators of DC power. Originally the biodyne was conceived as a set of double-duty reactions which furnishing life support and generating power, could become a propulsive mechanism by using excess power to accelerate reduced end-products out electric rocket engines of some description.
Lithium with a molar mass of 6.941 is about 29 % as massive as LiOH in terms of unit amount needed to absorb a mol of CO2. Lithium burned with oxygen (2Li)+(.5O2) > Li2O can form 2(LiOH) with the addition of 1 H2O molecule. The combination of Lithium metal with pure oxygen however is one of the most powerful reactions known and even LI2O with water is “explosive.” If we could carry forward both reactions safely in a confined space, Metallic Lithium in a pure state might be an optimum reagent on which to base CO2 removal and some drying of atmosphere.
We’ll imagine three chemical reactors which we’ll call A, B and C. B and C are equivalent. In A lithium hydroxide is contained and it removes CO2 from moist cabin air, producing lithium carbonate and additional water vapor (see above reaction.) From A the moister, scrubbed air goes either to B or C in which lithium oxide is contained. Water from air reacts with Li2O to form LiOh and each molecule of LiOH can also absorb an additional molecule of water to form hydrated LiOH. Once the LI2O in B. has been saturated with sufficient water to reach LIOH potential and hydrate same, the flow from A will be routed to C. while B is brought to a temperature of 109 C (228 F) which will drive of the water of hydration from the LiOH. This can be captured and recycled for further use in the life support system. Nonhydrated LiOH would then be transferred to A for further DO2 capture. Of course When C. has been saturated, the flow from A. will shunt back to B.
In this way we can potentially use metallic Lithium for removing CO2 and some of the excess moisture from bacin air and if we’re clever, we might gain an additional power source. The amount of power to be gained from a lithium-Oxygen reaction matched to Human CO2 output is only about 20 % of that forthcoming from H2-O2 fuel cells generating water, assuming 20 liters per day for a 6-person crew. This assumes very high efficiency of energy conversion. When I was in college some success was being had with lithium fuel cells using air as electrolyte. If we had a need for very high temperature on board for some reason, possibly processing sewage, it might be reasonable to burn lithium in pure oxygen in a closed reaction vessel to generate Li2O in a batch which could be transferred to B. or C. or perhaps the reactor could be designed to serve as the B. or C. reactors, needing only a rotating of modules. In the same way A. might be built in the same configuration, removing the need to actually handle the various chemicals except when carbonate must be removed and new lithium inserted.
All of this suggests some interesting areas of small-scale research and as the same reactions work with sodium, it need not be overly expensive.
|Posted by Rohvannyn on October 11, 2014 at 2:05 PM||comments (0)|
Yesterday I read presentation to a 2008 seminar for the American Institute of Aeronautics and Astronautics, called Life Support Systems, Functional stability and Human Control Limitations, an Astrosociological Approach by M. S. Marsh, V. Y. Rygalov and D. M. Livingston. The presentation discussed self-contained ecosystems other than the Earth itself and pointed out that as such systems reach sizes possibly compatible with deep space voyages, they become increasingly unstable because there isn’t the vast inertia we have in Earth’s Biosphere which buffers us from erratic and constant change. It’s also pointed out that as stability decreases the need for intelligent control by human operators increases. (Well Duh!!!) but the point is well-taken. We’re not likely to wrap a greenhouse in cellophane, put it in orbit and expect it, perhaps with a passenger or two inside, to operate more or less smoothly as it might down at ground-level, as part of the Earth system.
One result of this state of affairs is we’ll be more likely to use something like the Biodyne (a rocket system able to use expended water, CO2 etc. for reaction mass) for voyages at least to the nearer planets. We won’t have to worry about recycling air, water or food. With planetary colonies or out-system artificial stations however, one day we’ll need to recycle one way or another and this will likely be the true challenge of interplanetary exploration. The other aspect of the problem set, the sociological part; is the fact that on Earth we seldom used Balanced systems at all. Are water, air, food and power all come from disparate sources and though ultimately tied together on the global scale, can vary constantly and in infinite varieties without one segment needing to refer to any great extent to another. It’s not as if this is a new idea. Anyone who’s planned for a camping trip becomes aware of how much we depend on variety in foods. And we make some gestures at recycling in our c
The real message this astrosociological presentation offers, at least to me, is that in order to become a space faring race we, or at least some of us, must learn to live in a state of Balance, physically, materially and psychically. We need to know more about limiting our needs and desires to what we can produce. We need to balance our energy uses with sources available (living off-grid.) We need to remain increasingly aware of what we use and why. The extent to which we are able to do these things at home will make it more likely that a small group of Earthlings in an intrinsically fragile craft, will someday reach Mars, Jupiter, Pluto? The Oort cloud and eventually, other star systems.
Some things we can try; Install flow meters for water and electricity in your home so you can know first hand when you use the most of each and why. Honda has a co-generative home generator system, the Micro Combined Heat and Power or MCHP, which can give you 900 Watts of power and heat water or air at the same time. Let’s some of us make a commitment to own this or a comparable system some day. Even planning your shopping to limit trips to once per week or ten days, not so much to save gas, though that’s a factor; but to learn to plan your meals over a period of time so if pressed you could spend a month away from the store. All of these are disciplining exercises for the future, not to ultimately limit ourselves as human beings but to take back control from the utilities, the market and Society in general. The greatest freedom comes from intelligent choices and in order to free our race from a single planet, a process in a sense reversing that transition from hunter gatherer to farmer, me must at the same time relinquish much of the convenience offered by the City and reclaim the autonomy, self and small group reliance of the wanderer.
Compost heaps, recycling centers and thrift stores. But Balance in the larger sense is left to the benevolence (we hope) of our planet’s ecological system.
|Posted by Rohvannyn on February 8, 2013 at 1:30 PM||comments (0)|
Here is a message from my friend Eric:
Ever hear of http://deepspaceindustries.com ?
Their team is quite a read. You and I would fit in there, somewhere. I heard about them when I was on http://slashdot.org after following a link about a group that wanted to fab, that is 3D print, habitats on the moon or asteroids, out of moon or asteroid materials. I think this group would be interested in your writing and blog.
I originally thought "another group of crazies." Then I got real interested when they were talking about their micro gravity foundry stuff. I had known about a strange substance, nickel carbonyl. It's a volatile liquid at room temperature. It is more of a physical compound than a chemical compound in my opinion. Take metallic nickel expose it to pure carbon monoxide, optimally at 130 degrees C., the carbon monoxide molecules, four, surround the nickel atom and produce a complex. There appears to be no oxidation or reduction for this to happen.
Shine your laser focus onto a build platform in this gas and voila the heat cracks the nickel carbonyl back to a spot of pure nickel metal and carbon monoxide gas. The carbon monoxide is free to go react with more nickel metal source material away from the build area. So the metal appears on the build platform as drawn by the laser's focus.
Where do you get all this nickel? chunks of metallic asteroids of course. Well, you might say, meteorites and asteroids, if they are metallic are iron-nickel alloy. All this iron is going to get in the way isn't it? No. Iron also forms a carbonyl also, but at a higher temperature. It's created and destroyed in a steel mills blast furnace.
It's almost like photosynthesis, that is, water vapor and carbon dioxide gasses plus sunlight forms carbohydrate, trees. It's not exactly like photosynthesis but similar in the sense that in this space filled with carbon monoxide, you can mine metal from rocks and adjacent in this atmosphere you can deposit in a very controlled way that very pure metal.
Let's start a company to do this. We will call it United Monoxide or Union Monoxide. Ha Ha! I didn't invent that name. It came from the Fire Sign Theater guys spoofing Union Carbide or someone else responsible for the Bhopal chemical disaster.
Oh by the way nickel carbonyl is the most toxic known industrial chemical. This stems from high volatility, boiling point 38 Degrees C. and it's reactivity. It lasts in air about one minute. That means the concentration drops by one over e in a minute. It has a musty swampy odor. If you smell it, at low ppm levels, you will likely die soon.
Toxicity comes from the hydrolysis of nickel carbonyl where you get poisoned by the released carbon monoxide and the released nickel, a heavy metal.
The way to deal with the extreme toxicity of this stuff is to never have much of it around. Only enough is needed to make a small amount of the vapor in a small chamber. Where it is used immediately after it forms. None of the nickel carbonyl is purchased or stored. It just forms when the warmed metal is in a carbon monoxide atmosphere. This uses up the carbon monoxide as the carbonyl forms. When the carbon monoxide is used up the the production of carbonyl stops. The carbon monoxide reappears where heat from the laser forms metallic nickel. That consumes the nickel carbonyl and the released carbon monoxide is free to react with the raw material nickel again.
So the process can be run in a fairly safe way if the nickel carbonyl is never allowed to accumulate beyond a few milligrams while the process is running. When shutting down the process, the raw nickel is cut off from the carbon monoxide and cooled. The laser continues to run to burn out the remaining nickel carbonyl in the build chamber. The build chamber is pumped out, mostly carbon monoxide gas, for later reuse. The build chamber is then opened and vented. The tiny residual of nickel carbonyl in the build chamber will quickly drop to sub parts per billion in a minute or two.
I don't know if your browser will find all the text on the deepspaceindustries.com web site but some how you will probably find a way to explore it fully.
This is exciting stuff.
|Posted by Rohvannyn on February 6, 2013 at 3:35 AM||comments (0)|
When I was six I remember my cousin Dave Ville telling about a dream he had one night about being in Red China. He said there were bombs which followed everyone around and if you said or did anything wrong, you’d get blown up. Dave said he got killed right away and had evidently lain dead for a while then at the end of the dream there were a lot of bright lights and things looked “real pretty.” There may’ve been more to the dream but this was the gist.
What did all of this mean? Perhaps just a manifestation of the pervasive fear of Communism common to most of us from the ‘50s through the ‘70s, followed with a hope for the Day of Judgment which might reverse death for the Just? Who knows? My cousin’s dream has just been something I’ve recalled from time to time when contemplating what it might be like to live in a totalitarian society. It was just a 13-year-old boy’s fantasy of course and no nation could actually have bombs following their citizens around.
Alas, things change though, and fantasies sometimes come true. For all of the bashing George W. Bush got during his terms as president (and I am no particular admirer of Past President Bush) I think it’s chillingly fascinating that the president who has actually deployed drone missiles (possibly the ultimate in automatic weapons) is held to be a liberal and a champion of human rights. And now we are told American citizens are subject to robot bombing, even without evidence. Is there any difference at least at the higher levels, between a war-mongering militarist fundamentalist and a war-mongering humanist, social agendaist or does it all have to do with who holds the reins (or the remote control?) I think most of us wanted a change in ’04 and we got one sort of, but is anything improving or were we better off with what we had?
|Posted by Rohvannyn on January 24, 2013 at 12:10 PM||comments (1)|
Yesterday at work I got three versions of basically the same E-mail entitled "Lean For Dummies." A very brief inspection I gave the first iteration indicated that employees in our agency were invited to join an online chat group centered around a book by the same name which presumably deals with issues such as diet and exercise. I didn’t check further versions since in my opinion the first one should have been deleted prior to sending.
No, I don’t have anything particularly against either dieting or exercise. I try to indulge in both from time to time. The thing that angers me is this use and overuse in contemporary culture of book titles of the form …For Dummies. I never read such books and don’t believe anyone else should, in fact I think those who do read such books are probably the audience the authors are seeking. No, that’s not really fair. I am afraid that a lot of people allow themselves to be called condescending names and allow themselves to think of themselves in diminishing terms because they don’t possess much self esteem which is certainly unfortunate but does not mean the persons in question are stupid, unable to speak or clothes maniquins which so far as I know are the three common definition for the term dummy.
|Posted by Rohvannyn on January 17, 2013 at 12:30 PM||comments (0)|
The other day I ran across a blog in which some interesting points were made concerning interstellar voyages with human crews. The blogger stated that we generally assume interstellar flights necessarily require recycling of food and other supplies needed to sustain life and that to fly between the stars would require onboard farming. He then went on to give some figures he’d found concerning the mass of a shipboard farm able to sustain a crew of say 20 persons and showed that for the same mass, a very adequate supply of food could be carried on board to sustain crew members for 20 years. At first I responded mentally that water at least would be recycled and we’d likely use some advanced chemical process to convert waste water and CO2 into carbohydrates, perhaps with an energy efficiency of 10 % or more. From there nitrogen fixing bacteria could be used with sugar feed stock to synthesize proteins etc.
On second consideration though I realized most of this wasn’t really necessary. If each member of a 20 person crew uses per day, ten kilos of food, water, clothing and medical supplies for twenty years they’d consume about 3,000 tons of supplies which might be deep frozen, vacuum dried, fresh water, off-the-shelf clothing, whatever. If once consumed this mass wcould be turned into reaction mass for an advanced plasma rocket with an optimum exhaust velocity, there’d be enough propellant here to accelerate 1,000 tons of ship to maximum flight delta-V. Given an exhaust velocity of .25 light speed this kind of mass ratio would enable a starship to reach 40 % light speed for an average mission velocity of 20 % light speed and a trip to Alpha Centauri lasting about 20 years. Of course plasma engines such as this aren’t trivial to build but there’s no teheoretical reason why they might not be possible some day.
Now we come to another common assumption regarding interstellar travel, that we’d accelerate half the trip, decelerating the second half. There’s a problem with this due to the dreaded Interstellar Hydrogen that physics professors love to offer as definite proof that interstellar travel is impossible. If a very powerful matter beam could be employed to accelerate a ship to maximum velocity fairly near to Sol however, the ship might actually decelerate most of the way to the destination System.
What I have in mind is a four-month boost at one Gravity, during which time incinerated and perhaps ionized human waste, discarded fabrics, exhaled CO2 and waste water would be dribbled out in front of the craft as dynamic shielding. This would carry our ship to a point about 400 Billion miles distant from Earth and a velocity of .40 of light. At this point the jets would turn on, powered possibly by lasers from synchronized stations orbiting the sun and the jet itself would provide shielding as well as braking. The jets, though throwing only about five grams per second, would consume energies in the billions of kilowatts and should be sufficient to sweep the space ahead of the ship of hydrogen atoms as well as more significant particles and bits of debris.
In closing we’ll stipulate that we’ve talked only of drinking water in our mass calculations and we’d likely reclaim moisture exhaled into the cabin air for washing. We could even have a pretty big swimming pool during much of the voyage by using our water stores in a centrifugal tank to provide recreation as well as storage. Our deceleration would only be .02 G after the initial boost phase from Sol but with clever design of a ship able to stay snug behind it’s self-generated plasma shield a reasonably comfortable and fairly spacious accommodation could be provided for 20 or so crew personel in a starship of dry weight 1,000 tons.
|Posted by Rohvannyn on December 10, 2011 at 3:40 AM||comments (0)|
This entry will deal with teleportation among other things and the connections between ideas and events which can make life so interesting and sometimes surprising. The Christmas of 1965 saw me residing 2,400 miles from my home, going to a boarding school in Washington State while my parents and younger sister lived in Ann Arbor Michigan where we owned a dry cleaning plant. Flying home on the Eve of Christmas, I fell into conversation with a young man, one of my seatmates who was also flying to Detroit with his wife and baby daughter. We discovered a shared interest in science fiction books and movies as well as space travel. He introduced me to the idea of matter transmission as a way of traveling in space. He said one might turns one's body into light then travel at the speed of light and turn oneself back into matter at the receiving station.
A couple of years previously I'd run across a similar idea on Superman (the daily half hour drama, not the cartoon), in which the Professor finds a way to send people over the telephone since your body is mostly empty space. "Why thank you Professor," Lois Lane coos. A few days after my flight I was again to hear about matter transmission in a somewhat more memorable fashion.
A year before Star Trek began we had something called Lost in Space, a one-hour SF serial on Wednesday night. Scientific exactitude or realism was almost totally absent but some fascinating things, at least for us kids, happened and it was expected to outlast Star trek. The episode which aired the Wednesday after Christmas of 1965 was Number 16 and showed the younger of the Robinson family, Will and Penny, playing with some equipment left behind by an alien race called the Sargons. One item turned out to be a matter transmitter which allowed Will to travel back to earth and return (just barely) before the machine blew up.
From that time on the idea of being somehow "transported" on a laser or maser beam became something of an obsession and the Star Trek phenomenon of course lent further fuel to that fire. One afternoon in sixth grade I designed a sheet metal robot directed by clock work mechanisms, and a matter transmitter. (A highly productive day I thought.) My matter transmitter worked by vibrating something, a piece of wood, a mouse, a human being apart with powerful ultrasonic noise, and the resulting atoms or subatomic particles being directed into the path of a laser beam which was supposed to sweep the particles along like silt in a river current. It was hoped that when the beam reached it's destination the assemblage would somehow just reconstruct itself into a solid body. (Well I was only eleven and much of my scientific preparation had been obtained watching Felix the Cat and My Favorite Martian.)
In truth I had no real idea how transmission was accomplished. I guess I thought that if one could somehow capture and examine the waves emanating from a TV transmitting station, one would see pictures which swept through the air to land in our home sets. It wasn't until the summer following my
9th Grade year when among 20 or so books I read Arthur C. Clarke's fascinating Profiles of the Future that I understood through analogy with television, how a matter transmitter or teleporter might at least in theory, work. As Clarke pointed out, pictures and sounds are not sent via radio waves. What are sent are the patterns from which pictures and sounds can be constructed.
By the time I was perhaps half way through my Sophomore year I'd visualized a bank of ion sprayers which could build up a variety of objects from supplies of constituent elements. It seemed sort of daunting to try and build up a mammal through such a process but perhaps a machine could someday assemble constituent lying cells all supplied with one's genetic coding, into fully functional bodies. Soon I got the ideas of transmitting the Experience of being somewhere via a remote robot and a wired suit which the stay at home traveler could wear, as well as that of cloning someone at a remote distance and sending the original's brain/mind patterns via a radio signal.
From time to time in college I looked at the idea of what I came to call Pantoformation, or making virtually any shape imaginable by means of magnetically deforming a material or depositing streams of charged atoms or subatomic particles onto a build area in order to made tools, utensils, perhaps entire machines.
Around 1988 I conceived a desire to make objects from plastic, to have a single machine or set of processes which could generate any shape I told it to. I imagined describing a shape into a computer using some sort of drawing program then printing out cross sections of the shape on paper. The sheets of paper would then be scanned with a laser, which would burn holes where black ink existed and leave white areas in tact. The sheets stacked up would form something I thought of as a Brissle Mold which might be parked in a vacuum chamber and molten bronze for instance or even glass might be poured into the tiny vertical channels caused by stacking up the lasered holes in the sheets of paper. We'd then have a skeleton, rather like a sculpted hair brush which could either be dipped into plastic then surface wiped or in the case of the bronze option, placed in a solution and electroplated with aluminum until we had a solid artifact.
These and other notions frequented my thoughts and journal entries for a couple of decades then one day in 2006 while trying to find out if anyone had made any progress building up significant objects by means of ion deposition, I accidentally ran across the concept of fabbing, first selective laser sintering then the Reprap Project and Fused Deposition. Since that time my life hasn't really been the same.
Five days ago a couple of my friends and I completed the first of my
3-D fabbers, something called a Cupcake CNC by Makerbot (http://www.makerbot.com), It works by forcing molten ABS plastic (what Lego Bricks are made from) through a nozzle and building up line by line, sheet by sheet, a solid object. It's quite a way from transmitting human travelers through space to building up small objects with what's essentially a glue gun with an attitude but it's a start.
If we're to have star travel sometime in our future I suspect it might come about through bodies essentially artificial, part machine, part living, transported to distant star systems on relatively slow-traveling spacecraft without need of life support or elbow-room; to be animated at journey's end by means of mind patterns transmitter by laser, perhaps from persons still living as or long after the starship is launched. Will the minds which inhabit these cyborg bodies be the same ones that were transmitted from Earth, the Moon, Mars, wherever Star Fleet Control may be? Perhaps, perhaps not. However, I can say I've never been to the moon but still feel it's worth going even if the other guy gets the ride.
Ultimately a sort of teleportational transmission may achieve us the stars even if all we send of ourselves is our minds. In the meantime though we'll need 3-D fabbers on the Moon, asteroids in space itself to help us manufacture everything from solar arrays to robots which in return build human habitats, power beam projectors to propel our starships, catapults to move materials around the solar system and beyond and the future itself!
|Posted by Rohvannyn on June 24, 2011 at 3:07 PM||comments (0)|
I intended returning to the Moon soon but decided to come much closer to Earth for the next couple of installments. I’ve been taking some vacation time, during which I read an interesting if not outstanding book called Jetpack Dreams; One Man’s Up And Down (but mostly down) Search For The Greatest Invention That Never Was, by Mac Montandon. This discusses the history and current state of the art of the jetpack, called Rocket Belt when I was young and to make a rather winding story direct, we seem today to be about where we were in 1961 or so when I first encountered the idea on a TV show called To Tell The Truth hosted by Bud Collier.
The most significant point I took from Mr. Montandon’s book, largely personal narrative of meetings with the dedicated/obsessed? group of people still trying to fly on peroxide and perseverance, is what a cultural icon the Jetpack is. The fact that we all don’t have one in out garage or coat closet ready to rocket us to the supermarket or office appears to be in the minds of many, a singular example of how science and technology has let us down. This shouldn’t be surprising to me. When I was about fourteen I compiled a list of the things I really, really wanted to know about and work on and the list ran about like this, Building flying saucers, matter transmission, antigravity, lasers, robotics, magnetism, controllable solid fuel rockets, alternative space propulsion/fuels/reactions, telepathy and yes, rocket belts. I’d read in Arthur Clarke’s juvenile primmer Going Into Space that solid propellant rockets wouldn’t be of much significance in space, so of course I wanted to defend them. I was interested in magnetism and lasers partly because I had an idea for ionizing a stream of magnetic material which a laser, sending it toward the moon and allowing a dirigible in the stratosphere, equipped with a powerful electromagnet in it’s belly, to run along the stream to the moon like a trolley on a tramline.
The rocket belt in my mind and those of my friends, would be something that would allow us to cruise pretty much anywhere, I guess more or less like having your own Cessna or one-person copter. We were pretty impatient with sluggish military developers who were limited to 20 MPH speeds and less than 30 seconds of duration. That was okay though because when we got a little money and some junk air tanks etc. we’d make something that really worked! Well why didn’t that happen?
Rocket belts do work though they’re damned dangerous things to use and even if we had packs of enhanced power and endurance it’s hard to see how many people would gain the skill to use them. They work by the decomposition of hydrogen peroxide (H2O2) in a catalytic chamber, generating live steam and superheated oxygen to provide thrust. Peroxide isn’t a particularly powerful fuel and it’s dangerous in and of itself even at room temperature. The real limitation of the near-ground rocket belt though is more basic. I once published some calculations that showed that a rocket hovering just above the ground and using a pretty good propellant such as kerosene and liquid oxygen, would burn up 90 percent of it’s mass in about 17 minutes. The same amount of fuel could easily send the remaining 10 percent into orbit. Rocketing is very expensive in terms of energy and therefore in terms of fuel. For hovering near to the ground, revolving blades are much more energy efficient than jets or rockets.
A middle choice between hovering above the ground and orbiting is the comparatively high trajectory rather like an artillery shell’s path; put on a burst of acceleration initially, coast up, over and down, break your fall at the end of your trip. Next time we’ll look at what are some practical limits of this strategy and see if maybe there is a jetpack in the future of not only some, but with the help of computerization and sophisticated instrumentation, perhaps many?
|Posted by Rohvannyn on June 3, 2011 at 1:11 PM||comments (0)|
The next few entries we’ll devote to a minimal expenditure base on Luna and the investigation of what investments must be made to keep a dozen residents alive for an extended period. Initially I’d like to point out that the recent publicity concerning evidence of water on the Moon and how much closer it brings us to Lunar colonization is perhaps overstated. In the early phases of lunar settlement agriculture will be a marginal proposition and I suspect it will be unwise to use lunar water for propellant manufacture as it is likely to prove a limited and therefore precious resource. It’s also the case that water would appear to be concentrated in the polar regions of the Moon where sunlight may be available most of the time yet not in the concentrations available at the equator. The ability to store heat at high temperature in rock bins and (cold) similarly during the lunar night, offers a potential for using simple and relatively inexpensive heat engines throughout the lunar day/night cycle In the absence of green plants at least initially; there will be found to be advantages in access to very high and very low temperatures.
Anyone who has planted a successful garden knows that there’s a lot more to growing vegetables than simply pushing seeds into any available substrate and pouring water on it. We may be able to farm moon dust but it will need to be inoculated first with a range of fungi and bacteria needed to support growth. Soil has it’s own ecology and this doesn’t develop immediately. We may be able to grow algae in an aqueous environment and this may allow us to mulch prospective soil among other things but growing a sufficient amount to feed everyone in the base will require a good deal of energy and in the absence of a nuclear reactor, will require a good deal of window or plastic film to admit sunlight.
Any plan for a Lunar outpost must depend initially at least; upon food shipped from Earth, probably freeze-dried and possibly mixed with seed and grain for sprouting and bread manufacture. It takes about a half kilo of dry mass food to feed a person for a day so 12 persons will require around 2,200 kilograms per year. Rounding up to 2,500 for packaging and a single Apollo Mission of Old could feed our dozen for a couple of years.
Even totally dry, a food ration has the potential when burned within the body with oxygen; to yield about 1/3 liter of water in the form of exhaled vapor. Cooking oxygen out of Lunar soil and suitably recycling air as well as other metabolic outputs will continuously increase our water supply. In the absence of green plants it will also help us build a feed stock of carbon dioxide which will be useful in a variety of ways. Next time we’ll have a look at building a lunar shelter then we’ll continue to look at the semi-open but potentially closable, life support for permanent residency on the Moon.