History[ edit ] Pullman advertising poster,depicting a Pullman waiter Prior to the s, the concept of sleeping cars on railroads had not been widely developed. George Pullman pioneered sleeping accommodations on trains, and by the late s, he was hiring only African-Americans to serve as porters.
At lunar takeoff, this tanker would mass tons, but since it is taking off in lunar gravity, it would effectively weigh only about 62 tons. The composite propellant tanks, similar to what will be used for the BFR, would probably mass only 20 tons, leaving 2 tons for the engines, 2 tons for the landing legs, and 6 tons for the rest of the structure, including the cryo-coolers, sunshade and power system.
This provides a structural mass fraction of 8. At this point, Michael porters research project on the do not know the actual cost of the lunar propellants as delivered to the tanker at the lunar base, including the vehicle development costs, but finally we can compare the relative mass of the delivery propellants.
Assuming that we have not underestimated the tanker mass, the delivery propellant mass from Earth to LEO to L1 is Note that this mass difference is about three to four times larger than the typical cost difference of 15— Cost of lunar fuel would include fuel production costs, transport propellant costs, and vehicle operation costs.
Even the cislunar tanker must undergo an aerocapture to return to LEO from L1, while the lunar-to-L1 tanker would encounter only the stresses of thrust and landings.
In addition, propellant at L1 is at least twice as valuable as propellant in LEO, due to the gravitational potential and additional velocity from an Oberth maneuver performed starting at L1.
If future lunar entrepreneurs can beat that price, and if lunar water ice does exist in minable quantities, the lunar fuel production enterprise seems assured. Sales of large amounts of propellant for Mars expeditions would assure a robust human presence on the Moon.
However, to assure that the logistics capability of any cislunar or L1 base will exist, the propellant depot and cargo handling capabilities must be a part of the design of the base from the beginning. Plans for the NASA cislunar base must accept that large propellant depots can be attached to it.
We are getting significant indications of international interest in a lunar base. Why does the cislunar base have to be so small if there is support for it? The solution to this problem is a package deal agreement where there is a combined cislunar, lunar, and fully reusable transport development effort taking place simultaneously, with the international partners providing some of the transport and lunar surface infrastructure, with heavy reliance on commercial launches.
Development would take place so that the first human landings at a lunar base site would take place within a year of the cislunar base completion. The first and most obvious customer is NASA; an orbital fuel depot would allow them to launch satellites on smaller LVs or launch larger satellites, allowing a choice between savings on the LV and increased capabilities on the spacecraft.
Perhaps less obvious, Russia would see a significant benefit from a LEO depot in the plane of the Baikonur launch site. Vehicles would refuel in order to plane-change to an equatorial orbit for GEO deployment.
Further into the future a fuel depot would be essential for the smooth operation of tugs and satellite tenders, serving as a buffer between fuel launches and fuel used in missions.
I think the current leader is Boeing with their in-development ACES vehicle using integrated fluids management.
Hypergolic fuels require a different set of technologies and would most likely require shipping expendable supplies of a pressurant, either nitrogen or helium, but they have a larger potential market right now as hypergolics are typically used for satellite stationkeeping and orbit changes.
The third fuel category is inert gases argon, xenon for ion engines; these can be stored as compressed gases or cryogenic liquids. I think a near-term possibility is simply to ship water. It is dense, relatively inert and can be used as a life support consumable or as a propellant after electrolysis.
It has a high surface tension and can be wicked out of a bulk tank in microgravity without pressurants or membranes. There are cubesat-scale thrusters available today that separate water over time, accumulating a charge of gaseous O2 and H2 using small amounts of power, then ignite that fuel in a high-efficiency engine.
If future satellites were to adopt this technology for RCS and stationkeeping then they could nearly double their Isp while eliminating toxic fuels and cutting down to a single storage tank.
Beyond the near-term possibilities, a water depot operator would be able to buy water from any LEO cargo provider as well as any asteroid mining company, relying on the proven launch capabilities today while safely and cheaply allowing for a riskier but cheaper future supply.
The topic of lunar mining and fuel supply has a rich field of information available and I cannot claim to know all of it, but hopefully this will show how we can begin to harvest most of our propellant instead of shipping it from Earth. First let's establish some basics: I assume that we will develop zero boiloff cryogenic storage, reliable cryogenic fluid transfer and reliable cryogenic engine restart.
Vehicles will be designed to last years, but generally are planned to be replaced every 10 years. Obsolete systems will keep operating until they fail, providing some bonus production capacity.
The Moon's surface gravity is 1. It takes about 1. Only a little more is needed for the poles. Low orbits around the Moon are not stable so you should not park anything important there.
Large amounts of water ice are available at the south pole and most likely at the north pole as well. Plenty of metal oxides are available including iron, aluminum and titaniumbut carbon is rare.Michael Porter designed various vital frameworks for developing an organizations strategy. One of the most renowned among managers making strategic decisions is the five competitive forces model that determines industry structure.
Research design is a pre-planned sketch for the explanation of a problem.
It is the first step to take and the whole research. The School of Social Sciences is an internationally recognised centre of high quality teaching and research. II.—THE MAN WITH THE GOLDEN KEY. The very first thing I can ever remember seeing with my own eyes was a young man walking across a bridge.
He had a curly moustache and an attitude of confidence verging on swagger. SWOT Analysis. A SWOT analysis is a planning tool used to understand the Strengths, Weaknesses, Opportunities, and Threats involved in a project or in a business.
It involves specifying the objective of the business or project and identifying the internal and external factors that are supportive or unfavourable to achieving that objective.
Vimal Shah: “Research Design is a plan of study whether controlled or uncontrolled and subjective as well as objective”.
Ackoff: “It is the process of making decisions before the situation arises in which the decisions are to be carried out after for control”.
Miller: “Researcher Design is a planned sequence of the entire process involved in the conducting of as research study”.