Imagine going on vacation and having to bring every single item with you, food, clothing, electricity.... (you get the point), now imagine going on a trip where you need to bring the very air you breathe with you, oh and it costs at minimum $10,000/kilogram to get that material there. This is the challenge that faces the world's space agencies when they consider humans exploring Mars. The most popular solution for reducing the weight of what needs to be shipped is to try manufacturing supplies from resources found on the alien world, this process is referred to as In-Situ Resource Utilization (ISRU). The why of ISRU is pretty understandable, make what you need from what you find around you and make your mission more affordable, the how is a little more difficult to determine, researchers and mission planners must consider a range of potential challenges when providing recommendations for research efforts. Currently NASA is researching the potential of collecting Mars' thin atmosphere and converting the carbon-dioxide and extracting breathable oxygen. This approach requires filtering out atmospheric dust particulates, primarily to avoid jamming the atmospheric collector, instead of focusing on extracting gaseous materials, this author wonders how viable it would be to simple collect the dust and soil that are whipped around Mars as a result of the planet's high speed winds. (As I am unfamiliar with the actual energy demands of extracting the useful elements of Martian dust I am going off of a mechanics question, it could be very likely that the dust question was discounted as a result of the net energy demands of resource extraction vs the energy cost of material capture)
The rational behind designing an extraction system that utilizes air born dust as opposed to more active extraction systems, i.e. digging robots, is to minimize the number of moving parts and as a result the potential points of system failure. A properly designed dust scoop could stand stationary for years or decades slowly accumulating dust and soil picked up by Martian dust storms. The overall design of the dust collector array would need to meet a range of system requirements, including, but not limited to, surviving dust storms where wind speeds could reach 100 kph or more (the highest wind speeds recorded on Mars were measured by the Viking Landers at 100 kph, but there is no guarantee that they have seen the highest wind speeds Mars can produce), the body of the collection system must be able to withstand the weathering forces of Mars' extremely abrasive dust, and most critically the dust collector must be able to extract as much Martian dust and soil for every dollar it would cost to send as a more active excavating robot. Estimating the design requirement of the first constraint is relatively easy, the remaining two, a bit harder, but let's try.
To estimate the median force that the wind would apply on the collector, which for initial calculations we are going to treat the collector as simple wall, namely because that limits the variables and we're only going for the same scale of force, read we are only worried if we are within a factor of 10 of the actual value.
The Equation Used is the Drag EquationV is the velocity of the wind, here calculated for the known worst case scenario, 100 kph or 27.7777 m/s
Holy crap, I have spent a few too many hours on this, I will follow up tomorrow with more, but time to get back to job hunting.
Edit I want to add some links at the bottom that will get added into the rest of this document later.
http://reseauconceptuel.umontreal.ca/rid=1225319082132_1402805076_76755/In%20Situ%20Resource%20Utilization.cmap probably a contender for one of the worst flow charts in history, but it does talk about dust extraction vs air extraction
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110016184.pdf a higher level document on dust extraction utilizing electrical fields
http://www.lpi.usra.edu/lunar_resources/documents/ISRUFinalReportRev15_19_05%20_2_.pdf over view on ISRUs
http://www.spaceclimate.net/ISRU.Chapter.vers7.pdf another ISRU overview
http://iopscience.iop.org/1742-6596/327/1/012048/pdf/1742-6596_327_1_012048.pdf filtering out dust from atmospheric extraction systems
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120001775.pdf powerpoint in PDF format that talks about atmospheric extraction
The rational behind designing an extraction system that utilizes air born dust as opposed to more active extraction systems, i.e. digging robots, is to minimize the number of moving parts and as a result the potential points of system failure. A properly designed dust scoop could stand stationary for years or decades slowly accumulating dust and soil picked up by Martian dust storms. The overall design of the dust collector array would need to meet a range of system requirements, including, but not limited to, surviving dust storms where wind speeds could reach 100 kph or more (the highest wind speeds recorded on Mars were measured by the Viking Landers at 100 kph, but there is no guarantee that they have seen the highest wind speeds Mars can produce), the body of the collection system must be able to withstand the weathering forces of Mars' extremely abrasive dust, and most critically the dust collector must be able to extract as much Martian dust and soil for every dollar it would cost to send as a more active excavating robot. Estimating the design requirement of the first constraint is relatively easy, the remaining two, a bit harder, but let's try.
To estimate the median force that the wind would apply on the collector, which for initial calculations we are going to treat the collector as simple wall, namely because that limits the variables and we're only going for the same scale of force, read we are only worried if we are within a factor of 10 of the actual value.
The Equation Used is the Drag EquationV is the velocity of the wind, here calculated for the known worst case scenario, 100 kph or 27.7777 m/s
ρ is the density of Martian atmosphere 0.02 kg/m^3
A is the area of the collector system.
CD is the coefficient for Drag, which we are assuming is 100%, remember we are looking at the worst case scenario.
When we remove the units we see everything balances out, which is always nice to see.
Holy crap, I have spent a few too many hours on this, I will follow up tomorrow with more, but time to get back to job hunting.
Edit I want to add some links at the bottom that will get added into the rest of this document later.
http://reseauconceptuel.umontreal.ca/rid=1225319082132_1402805076_76755/In%20Situ%20Resource%20Utilization.cmap probably a contender for one of the worst flow charts in history, but it does talk about dust extraction vs air extraction
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110016184.pdf a higher level document on dust extraction utilizing electrical fields
http://www.lpi.usra.edu/lunar_resources/documents/ISRUFinalReportRev15_19_05%20_2_.pdf over view on ISRUs
http://www.spaceclimate.net/ISRU.Chapter.vers7.pdf another ISRU overview
http://iopscience.iop.org/1742-6596/327/1/012048/pdf/1742-6596_327_1_012048.pdf filtering out dust from atmospheric extraction systems
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120001775.pdf powerpoint in PDF format that talks about atmospheric extraction
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