However, most of the biomass is in the form of fuelwood and agricultural and animal wastes. As noted above, fuelwood can no longer be thought of as a 'renewable' resource in many areas, because consumption rater have overtaken sustainable yields. Although worldwide reliance on all these sources has been growing by more than 10 per cent a year since the late s, it will be some time before they make up a substantial portion of the world's energy budget. Renewable energy systems are still in a relatively primitive stage of development.
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, we 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. In some locations the mantle interface material KREEP is accessible at the surface; this rock is rich in incompatible elements like phosphorus, potassium, rare earths and radioactives.
Low Earth orbit takes anywhere from 9.Technology initiated by Space Exploration is often today driven by terrestrial mass market sectors.
A study analyzing the find, published in the journal Nature Communications, suggested that multiple lineages of unknown, now-extinct humans may have existed side-by-side in Asia eons before the arrival of modern humans approximately 40, years ago.. The Penghu 1 mandible, jaw and teeth in various orientations. (Y. Kaifu et al./ CC BY NC SA ). Informal communications may tarnish a company's reputation. For example, if an employee addresses a customer in an email, "Hey Linda," this simple informal salutation may be perceived as too. A surfeit of information and advertising messages are two of the major disadvantages of mass communication. Exposure to inappropriate content is a consideration as well. Mass communication tools provide powerful and voluminous outreach but also pose potential hazards. The offerings from mass.
While early space scientists and engineers expected that space exploration would have positive impacts on humanity, they could not have foreseen all the specific social and economic benefits To a great extent, the benefits from space.
Note: But, before we begin looking at it, first of all, we repeat again and again: do not blindly believe anything or merely take in on faith. What is said here is just a particular way to look at things, but it does not imply that you are forced to agree with anything said here, or anywhere for that matter.
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