Firgof Umbra
Member
Getting into space:
I'll say it upfront: I'm not a big fan of ground-launched heavy loads. It requires a lot of fuel to do it and I'd much prefer the heavier stuff to be built in space as that'd be a lot cheaper than spending a ton of money on the fuel to get it past the atmosphere and then a lot of additional money to complete its voyage. I think Virgin's WhiteKnight Two is a step in the right direction but can't currently replace the fact that we don't have any way right now to get long range spacecraft into space other than doing ground launches. In order to perform construction operations on a spacecraft thousands of miles above the ground we'll need efficient means of getting people to and from the construction site and a means to keep the site fully staffed and supplied; not to mention getting the parts up there to make our first dock. And in order for any of that to happen, we need better methods of getting small loads up there -- thankfully the private sector have begun to solve this problem as the various X-models NASA has scrapped and pontificated over for a number of years have resulted in 0 engineerable prototypes; though NASA has tried to implement the mid-air boost for quite some time now. Once we can establish a cheap means to get people back and forth, we can then proceed to start building these big ships in space where they -should- be being built instead of building them on the ground and -then- having to boost them to orbit; it's simply more cost-effective. Other corporations such as the Ansari corporation are vying to get into the commercial transport of packages into and from space and will have the capability to crew their ships in as few as four years. All in all, things are picking up in this sector finally and with that, the viability of building a long-range ship increases, though we'll have to investigate how to construct things properly in space and such a vessel could take a considerably longer period of time to produce due to the number of persons necessary and the relative lack of transportation-able craft. Hopefully the private sector will continue to drive this area as long as NASA continues to oversee and regulate where it can the construction and feasibility of these craft.
Propulsion:
In so few words, the future of space propulsion is not firmly vested in chemical rockets but we may have to settle with them for now. You may have heard of Hall effect thrusters seeing usage in NASA's program in deep space satellites; Ion engines. These are tidy, energy-efficient little buggers, but insufficient for a large cargo-toting vessel. Without divvying into the Orion project ( Nuclear Pulse Propulsion; using a nuclear weapon as a means of propulsion ) and other such largely untested means of transportation ( yes, I have seen the RDX demo of the Orion system; I still require to see a nuclear pulse before I will consider it a more feasible transportation method; for the curious, here it is: http://www.youtube.com/watch?v=E3Lxx2VAYi8 )there are a variety of propulsion methods which address the two chief concerns with propulsion in interplanetary space travel: Longevity and Power.
Conventional and even newer Hybrid and Tripropellant rockets all arrive at the same problem when it comes to long-term missions: it takes too much fuel to get somewhere far away in a reasonable time frame. Given current specifications, the VASIMR ( Variable specific impulse magneto-plasma rocket ) is the current top-tier solution for interplanetary travel on a budget. The VASIMR excels at operating in a high power environment and is efficient enough that it could fire for up to days at a time. It's Delta-V is greater than 100 km/s; it's 'real thrust' mainly limited by the source of power. The optimal set up for a VASIMR would be to be linked to a Fission reactor due to its generous output of energy. However, the VASIMR and other prototypes are not quite yet ready for production ( the first finished product of its kind will be completed next year to be hooked up to the ISS so that it may self-boost ) so exploration beyond Mars is currently simply too expensive at this time due to ceiling budgetary constraints in the engines' respective laboratories and budgetary constraints at NASA. As such, in order to proceed to Mars and beyond without blowing a ton of cash on building a new chassis to hold a vast quantity of fuel, supplies, and equipment, we'd need to either attach exterior fuel pods and service the craft in space or refuel the space shuttle while it is on its mission. As it would be impractical to fire separate 'fuel pods' into space, pursuing other options such as more fuel-efficient engines or engines which use a fuel source which can be extracted from common stellar objects would be the most long-term and short-term cost effective option. VASIMR is an optimal solution for this problem as it could operate on hydrogen, helium, or deuterium; hydrogen being able to be found on nearly any stellar object in the solar system. For instance, we could fuel the spacecraft with enough fuel to get to the moon, use hydrogen from smelted regoliths to fully 'tank up' the spacecraft, and then it can go on its way with as little fuss as possible; potentially allowing the craft to swap its tanks out on the ISS with larger capacity tanks fit for the task thus further saving fuel costs.
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[img]http://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Lunar_base_concept_drawing_s78_23252.jpg/800px-Lunar_base_concept_drawing_s78_23252.jpg[/img]In-situ resource utilization, to summarize, is 'using the resources available on other planets or moons to help accomplish a mission'. ISRU is being looked at from a spectrum of angles for a variety of missions. In Mars' case, the ISRU research is focused primarily on providing rocket propellant for a return trip to Earth or for use as fuel on Mars. The Sabtier reaction is the most typical of these researches which produces methane at a suitable grade to be a propellant via electrolysis; its proposal aided by the fact that hydrogen is the only thing which must be brought from Earth for the process to function makes it a fantastic 'first step' in harvesting and retrieving valuable, mission-critical, materials. The Moon has also many ISRU scientists working to produce resources from the moon; there are over fifteen proposals alone just for oxygen extraction. As for fuel, the moon's highlands contain anorthite which is similar to bauxite -- an aluminum ore -- which, produces pure aluminum, calcium metal, oxygen, and silica glass when smelted. It is estimated that the moon contains between 1 and 3 million tons of Helium 3 (which has a number of good points over deuterium and tritium) on the moon, which could, in the future, power a fusion reactor on-board the spacecraft and provide ample thrust to future spacecraft equipped the varying sorts of high-power-demanding engines with radiating waste; of course this is a long-term goal. For a more scaled back viewpoint of potential IRSU as regards to propulsion and exploration on the Moon, oxygen could be extracted for life support needs and as a propellant oxidizer which could potentially scale down by a small margin the total weight of fuel required on-board the craft. In addition if a Mass Driver were built (which NASA would prefer) then 'packets' of resources could be sent back to Earth without the need of spacecraft; thus further making independent a Moonbase colony.
Less-than-optimal:
If neither of these options is viable then less-than-rapid engines will have to be approached. Excluding VASIMR, Hall effect engines, the MOA, Ion Drives, and the Nuclear Thermal Rocket are viable alternatives. The Hall effect, MOA, and Ion drives are the most matured technologies of the batch; though the NTR is an available alternative it was aborted before due to thermal and vibration concerns when running the engine at high thrust levels. All of these are less-than-optimal solutions due to being unable to effectively scale to moving a large mass without a large power source; even though they would all be able to go faster than most rockets would in the scope of a long-term mission, short-term missions make these less-attractive unless budgetary constraints were a non-issue. In addition all of these excepting the Ion Drive are non-field-tested so we would need to facilitate a testing in space to ensure the reliability of these systems in addition to working them into the spacecraft's design.
Living in Space:
Assuming all goes well you now have a spacecraft which can go places in the solar system. Now you run into some more mundane problems: What do you eat, how do you recycle, and how do you keep your body in good enough order that when you arrive at your destination you're fit enough to actually do something outside of a wheel-chair. Space-Adaption is a chief concern among these but is dwarfed by the question of what do you eat? A long voyage, say to Mars, requires a significant amount of the cargo to be invested into rations; even if they are mostly nutrients only and conservatively packed. A more optimal solution would be to produce the food on-board the craft itself thus reducing the required cargo in foods though not totally replacing them. Growing plants in space is not the easiest thing to do. There are a number of problems that must be solved before it becomes reliable enough to expect your project to bear fruit; plants suffocating on their own emissions for instance. An experiment in 2003 on-board the ISS proved that plants can flourish and since then there have been a variety of proposed solutions for long-term space flight, enough that the technology could be considered mature enough to expect it to be a part of the official components aboard whatever long-voyage spacecraft would be launched. There's also the issue of life support but the plants help here as well, converting expelled carbon dioxide into oxygen once more which is then cycled back into the craft, receiving hydration from the crew and the supplies brought, and being given nutrition through a variety of proposed solutions ranging from the recycling of excrement and waste goods into simple fertilizers to artificial soils to simple liquid/non-Newtonian tank solutions; finally receiving light from overhead lamps powered by exterior solar cell batteries.
Now you have some variety in your food intake and have potentially downsized both food cargo requirements and life support systems. Though there are a variety of novel systems to continue to add to the efficiency of the life support systems aboard a long-range craft, I would encourage you to investigate them yourself rather than make this post needlessly long. With food and air considered solved, you still need to recycle your materials -- such as fluids. Crew aboard the ISS recently tested a prototype filtration system which converts liquid waste back into drinkable water and though the resulting fluid is said to be tasteless and recharging the system has broken down a number of times, leading many to believe it is not ready for a long-range journey. Without the aid of an integrated filtration system which converts waste material back into something usable there will be a lot of 'bunk weight' aboard the craft which will either have to eventually be dumped or stored. Still, more primitive systems could be used here to filter liquid and solid wastes; though the results in cases may potentially be less-than-sparkling over time. Sweat and other bodily fluids could also be recycled through an astronaut's jumpsuit and used to cool the body. The current solution to recycling water aboard a standing crew with a multi-month mission is this diagram for the ECLSS aboard the ISS, the following being a simplified diagram of the process:
Assuming that water and food are taken care of there's still the issue of bodily health. Space-Adaption is the top-ranked issue but following in its footsteps are cosmic radiation, psychological and social disorders, and numerous interpersonal relationship issues which must be addressed and sorted before such a mission should be attempted. The degeneration of tissues due to the lack of the pull of gravity; much of our internal systems are regulated by gravity though they do not stop working in zero gravity. Cosmonauts and Astronauts aboard the ISS for only months at a time return home with majorly atrophied musculature and bone density; such that it potentially takes weeks even for a person considered 'in good shape' to regain the use of their legs. Without the effects of gravity, much of our postural and locomotive muscle groups aren't used in the same fashion we used them on earth; as a result some of our traditional muscles atrophy rapidly. Endurance fibers used to maintain posture are replaced by twitch fibers insufficient for heavy labor. Bone tissue is lost at approximately 1.5% per month especially in the hip region. Elevated blood calcium levels from the lost bone result in calcification and kidney stones and it is unknown whether the bone ever recovers completely. Eventually, with current technology, after an extended period of time in space an individual may simply be unable to survive Earth's gravity over time.
Given that a mission to Mars would with current technology best take several weeks even with the latest in propulsion and power generation technology, the mission a potential two weeks, and a return trip another set of several weeks the issue rapidly becomes a major problem, especially if the Heart begins to degenerate (currently being investigated). To combat SA, astronauts are currently given an exercise ritual which keeps their muscles stimulated and their bones stressed enough that they don't atrophy so much over time and a variety of fluid and dietary regimens to help keep everything intact. The solution to these problems is difficult and though many researchers are constantly proposing possible systems no consensuses have been met on any official level. Combating space adaptation may be the final issue humanity may have to overcome to voyage in space for any extended period of time; it is the weakest link of the chain.
This is not the end of problems observed from returning astronauts. Several studies of tests taken on the astronauts on their first days back from space showed "dramatic changes in their immune system" and experiments are ongoing to determine whether this is also an autonomic difficulty or a depression of the immune system due to unusual lack of stimulus.
In addition to the autonomic problems aboard a spacecraft, there are also fungal and bacterial problems to consider. Over a long period of time it is conceivable that a form of mold may spread somewhere aboard the ship and must be dealt with. This is a new issue and has been only thinly explored, but NASA'S LOCAD department is working on a way to detect molds and fungus aboard a spacecraft passively.
Beyond the physical problems there are also sociological and psychological issues which have to be examined before a mission would ever launch; things such as how to best handle the monotony of a cramped space which is far more functional than aesthetic with food that would be mostly bland and liquids that would taste stale and how to handle relationships on-board the craft over months of time become important questions. Again, there are a number of proposed solutions hanging in limbo but none have been completely evaluated due to the public's general lack of interest in near-term interplanetary space travel.
All of this and a bag of cosmic radiation while you're drifting around in space getting to your next destination (which there are again a variety of solutions for; for example lining the vessel with a thin membrane of lead and silicon which could also double as a solar panel array) Speaking of getting to your next destination.
What to Do:
So with all those spoken for, now we've got a functional space vehicle which can stand long-term spaceflight with a crew that at the very least can survive in relative comfort for the duration of the journey. But what to do with it? Well, there are a number of exploratory and scientific efforts that become possible but the first immediate, very-long-term, benefit we could return is the launching of a vessel to mine asteroids in the nearby Asteroid Belt, return with potentially thousands of tons of raw materials, and de-orbit those materials to be recovered in the ocean; whereupon the craft could then resupply and re-crew via the ISS and then continue its mining operation.
A 'safer' goal would be to return to Earth tons of lunar regoliths which could then be processed down into other materials. The advantage of space mining is the scale of mining operations; spaceships can carry far more tonnage in materials than any conventional earth-bound vehicle as there is no atmospheric drag or ground friction to compound the problem of acceleration; it merely becomes a matter of mass versus force. However in excelling at this the vessel would be best serviced by being a space-only craft as its scale and weight would require conventional thrusters with several tons of fuel. In addition it could hand these raw materials off to far-orbit stations which could then process the materials into goods in space to produce highly sensitive equipment at a scale which would outweigh the benefits of local Earth production or simply process and then bundle the materials to be retrieved by other spacecraft to be rapidly returned to earth.
Beyond these more than substantial industrial and materials returns, there arise other benefits of note. One such benefit is the establishing of long-range observation stations on the local planets to help expand our early-warning system for inbound extrasolar objects and deal with them accordingly. With no atmosphere to get in the way, high-grade sensors would be able to far more easily pick out inbound objects and plot their trajectory, transmitting coordinates back to Earth of any objects which would be passing close to Earth via a high-intensity laser and high-power radio signal much similar to the lasers currently deployed on the Moon's surface. This would further remove much of the 'fuzziness' on our radar -- especially if we established a network of relay stations all the way out to Pluto's surface -- and add additional layers of protection and time to come up with the best plan possible to deal with any extrasolar threats should the threat arise. This technology could also potentially help us detect undiscovered moons and planetoids which continue to elude our best sensor technologies as well as potentially scope out potential 'breadwinner' asteroids in the asteroid belt and Oort cloud.
Beyond these, the ability to create and analyze chemical reactions and molecular structures in very precise and controlled environments is another big plus. New pharmaceutical drugs could be developed in space; their research and development unhindered by gravity and a variety of exterior forces. These experiments could prove invaluable to understanding fundamental behaviors of chemical compound interactions and the growth and development of such things as protein chains and chemical bonding which have wide and deep applications throughout the pharmaceutical field.
The potential to create what would essentially be solar power plants should also not be overlooked, providing a completely clean alternative to energy production and batteries as well as potentially allowing us to stir innovation in the field of energy storage. With next-generation solar power cells the efficiency of solar power will increase by a significant margin, thus further allowing such solar power plants to gather immense amounts of unharnessed energy and return that to Earth.
You should take this as by no means an exhaustive list of potential applications nor as a real 'proposal' of any sort; you wanted information and here it is. If you'd like to see the actual proposals, go look 'em up; I've been typing for long enough I think. These are just applications we could see within the next ten to fifty years if we start heading into space with actual gusto instead of this 'false start' business we've gotten ourselves into lately. The competition of the ISS should free NASA to begin building its portfolio of space assets to include and incorporate these novel technologies but it will be unable to do so without a budget to test and experiment on. The private sector is still in its infancy and does not have the investors nor the technologies necessary to really kick start this machine to life. What it needs is for these technologies to be carefully compiled and engineered into a solid proposal backed by NASA. Dyson's proposals are simply not enough; as valuable as they are to allowing critical thought to continue on the issue and be continuously brought to light. It needs public interest and industrial interest; and the fact that NASA isn't pursuing these technologies is predominately -due- to a lack of interest. The theories and proposals and working lab-tested solutions are there to be used but nobody's going to do it unless they know that there are people ready to back them; people with deep pockets. Unless NASA gets funding to do this, then they won't, because currently building a long-range spacecraft is simply too expensive -- even with matured VASIMR designs and all the above technologies in place it still will take a lot of time at the drawing board, a ton of equations, and a lot of engineering to figure out exactly what the ship needs, actually build the thing, and actually get it up there, staff it, and get it going on missions -- and to accomplish all of that you need money, time, and materials; all of which end up as money in the long run.
I'll leave this with a few simple diagrams to illustrate that there's more to the Moon than just a neat fuel for nuclear fusion reactors and putting men on mars and developing a colony there is intimidating but not impossible with currently existing technology.
The Soil of Mars:
What could we use these for?
Moon
Oxygen: breathing, synthesis of water, oxidizer for rocket fuel
Silicon: Computer chips
Iron: Strong building material; would weigh very little (copypasta lol, sorry)
Calcium: Can be baked to produce lime (for cement)
Magnesium: Light-weight construction material
Aluminum: Light-weight construction material
Ice: Whoops, forgot this one.
Mars
Oxygen: breathing, synthesis of water, oxidizer for rocket fuel
Silicon: Computer chips
Iron: Strong building material; would weigh approximately the same weight as aluminum on mars as compared to Earth.
Potassium: Synthesis of plant fertilizer
Calcium: Can be baked to produce lime (for cement)
Magnesium: Light-weight construction material
Sulfur: Various chemical processes
Aluminum: Light-weight construction material
Cesium: Construction of some semiconductors and photocells
The propellant I discussed above could be used to power generators. Also, plant material, sulfur, and martian soil along with nitrogen and fertilizer would make usable soil for gardening if we went the terraforming route. If not, we could scale up whatever vegetable production we had onboard the ship and transplant it to the martian soil if we're going to be coming back soon or it's habitat will be fine if we leave it alone for a while (perhaps a bunker of some sort).
Sources:
Ad Astra Rocket Company
VASIMR youtube video demonstration
NASA
Rapid Mars Transits with Exhaust-Modulated Plasma Propulsion: http://ston.jsc.nasa.gov/collections/TRS/_techrep/TP-1995-3539.pdf
Future Propulsion Methods: http://www.nasa.gov/vision/space/travelinginspace/future_propulsion.html
Ion Engine could one day power 39-day trips to Mars: http://www.newscientist.com/article...-day-power-39day-trips-to-mars.html?full=true
How Plants Grow In Space: The Effects of Gravity and Light: http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/How_Plants_Grow_in_Space.html
WAICO experiment page: http://www.nasa.gov/mission_pages/station/science/experiments/WAICO.html
ORZS experiment page: http://www.nasa.gov/mission_pages/station/science/experiments/ORZS.html
The MISSE experiment: http://www.nasa.gov/mission_pages/station/science/misse2009.html
The Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias (Integrated_Cardiovascular) experiment: http://www.nasa.gov/mission_pages/station/science/experiments/Integrated_Cardiovascular.html
ALTEA-Dosi Experiment: http://www.nasa.gov/mission_pages/station/science/experiments/ALTEA-Dosi.html
The effect of long-term microgravity exposure on cardiac autonomic function by analyzing 24-hours electrocardiogram (Biological_Rhythms): http://www.nasa.gov/mission_pages/station/science/experiments/Biological_Rhythms.html
Cardiovascular and Cerebrovascular Control on Return from ISS (CCISS): http://www.nasa.gov/mission_pages/station/science/experiments/CCISS.html
Astronaut's Energy Requirements for Long-Term Space Flight (Energy)http://www.nasa.gov/mission_pages/station/science/experiments/Energy.html
http://www.nasa.gov/mission_pages/station/science/experiments/Lada-VPU-P3R.html
Nutritional Status Assessment (Nutrition) : http://www.nasa.gov/mission_pages/station/science/experiments/Nutrition.html
Surface, Water and Air Biocharacterization - A Comprehensive Characterization of Microorganisms and Allergens in Spacecraft Environment (SWAB): http://www.nasa.gov/mission_pages/station/science/experiments/SWAB.html
Foot Reaction Forces During Space Flight (Foot): http://www.nasa.gov/mission_pages/station/science/experiments/Foot.html
Freeman Dyson
Project Orion: http://www.youtube.com/watch?v=E3Lxx2VAYi8
SPACE.com
French Astronaut Grows Plants in Space: http://www.space.com/scienceastronomy/080304-biolab-experiment.html
Soilphysics.usu.edu
Graphs
University of Wisconsin|Madison: http://fti.neep.wisc.edu/neep602/lectur ... l%26um%3D1
Canadian Space Agency: http://www.asc-csa.gc.ca/images/mars_so ... l%26um%3D1
