RECYCLING ROCKET EXHAUST - Revision history

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 *Other nations trying to assist in peace making will have the task of making reasonable analysis of the likelihood of Russia and Ukraine abiding by terms reached at any stage of negotiations and advising negotiations to bring about a successful end to fighting.
 *Ukraine's help in setting up SBSP is desirable but Russia's help is especially needed because the international treaties needed for SBSP should be written to work with enemies being parties to the treaty forswearing use of the technologies for warlike purposes and verifying each other's compliance.  Unfortunately, the attitude of Putin and the Russian leadership make cooperation with a good enemy and the whole notion of industrialization of the moon seem unlikely.  We should not quit without an attempt.
-*China requires a different approach.  A big concern of the People's Republic is that factions of the population take the opinion that the communist party government is illegitimate and even occasionally voice that opinion.  The communist party leadership correctly interpreted the Tiananmen protests as a the first step in a change of government if they were to have done nothing.  The nationalist Chinese on Taiwan could offer to help stabilize dissident groups by encouraging them to diplomatically word their grievances and plead for practical relief while acknowledging the legitimacy of the current government.  They could do this with trained teams of diplomats visiting groups in the People's Republic and promoting the benefit of a stable government as opposed to the chaos that can be expected in a violent change of government, acceptance of the devil one knows rather than the unknown devil to come.  Teams of two trained Taiwanese with PLA armed guards and a logistics support crew could be convincing.  The idea that even the Taiwanese oppose violent overthrow of the communist government would make quite an impression.  In return the People's Republic would agree to no invasion of Taiwan or use of violence to take over Taiwan.  The People's Republic could become the best authoritarian government that it can be.  The population of mainland China would have more of its needs met.  Taiwan would still be safe behind the navies of the USA and Australia.  The People's Republic suspects the nationalists on Taiwan of fomenting rebellion on the mainland.  Another rebellion on the mainland would not only hurt the mainland population, it would hurt the world economy.  We do not need to know if the communist party's suspicions are justified.  Openly and actively opposing rebellion would answer such suspicions.  Give peace a chance.
+*China requires a different approach.  A big concern of the People's Republic is that factions of the population take the opinion that the communist party government is illegitimate and even occasionally voice that opinion.  The communist party leadership correctly interpreted the Tiananmen protests as a first step in a change of government if they were to have done nothing.  The nationalist Chinese on Taiwan could offer to help stabilize dissident groups by encouraging them to diplomatically word their grievances and plead for practical relief while acknowledging the legitimacy of the current government.  They could do this with trained teams of diplomats visiting groups in the People's Republic and promoting the benefit of a stable government as opposed to the chaos that can be expected in a violent change of government, acceptance of the devil one knows rather than the unknown devil to come.  Teams of two trained Taiwanese with PLA armed guards and a logistics support crew could be convincing.  The idea that even the Taiwanese oppose violent overthrow of the communist government would make quite an impression.  In return the People's Republic would agree to no invasion of Taiwan or use of violence to take over Taiwan.  The People's Republic could become the best authoritarian government that it can be.  The population of mainland China would have more of its needs met.  Taiwan would still be safe behind the navies of the USA and Australia.  The People's Republic suspects the nationalists on Taiwan of fomenting rebellion on the mainland.  Another rebellion on the mainland would not only hurt the mainland population, it would hurt the world economy.  We do not need to know if the communist party's suspicions are justified.  Openly and actively opposing rebellion would answer such suspicions.  Give peace a chance.
 *I hope and pray enough talented people of goodwill will be able to bring some sort of solution to our political troubles.  I know that some groups in war have done terrible things, killing large numbers of people who had not been threatening them with violence.  If it is considered impossible to make necessary treaties that can be depended upon, industrial development of the moon will need to wait until such treaties are possible.

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 *A zeroth step in building a SBSP system is verifying the technologies. Step 0.1 is committing to all that is necessary for the whole chain of steps to work and finally start producing revenue. Within step 0.1 there are agreements among nations to share the financing, engineering, hardware building, electrical power sales arrangements, and revenue.
 *For high specific impulse, large, thrusters for orbital stabilization of the moon orbiting fuel depot, the reaction mass should be oxygen plasma since oxygen is readily available on the moon.
-*'''Transportation:''' For East-west roads on the moon the pavement could be graded regolith or sintered, and perhaps glazed, bricks separated by sifted regolith. There could be an East-West awning over the road held up by a row of pillars and made of aluminum sheet or aluminized glass sheet or material of suitable alloy containing some proportions of aluminum, silicon, magnesium, calcium, titanium or whatever available material is found to be most economic for the use.  The pillars would separate the Northern lane from the Southern lane.  There could be solar cells for charging batteries or recharging fuel cells that are swapped, spent for charged, by passing vehicles.
+*'''Transportation on the lunar surface:''' For East-west roads on the moon the pavement could be graded regolith or sintered, and perhaps glazed, bricks separated by sifted regolith. There could be an East-West awning over the road held up by a row of pillars and made of aluminum sheet or aluminized glass sheet or material of suitable alloy containing some proportions of aluminum, silicon, magnesium, calcium, titanium or whatever available material is found to be most economic for the use.  The pillars would separate the Northern lane from the Southern lane.  There could be solar cells for charging batteries or recharging fuel cells that are swapped, spent for charged, by passing vehicles.
 *The vehicles might be walking vehicles (four or more legged) that wear space suits holding one percent of an Earth atmosphere pressure of nitrogen thus eliminating the need for a gas tight rotary seal around wheel axles that would otherwise be necessary to prevent wheel lubricant (and all other lubricants inside the space suit) from evaporating into the vacuum.
 *Alternatively, wheels could be outside of the pressure containing suit and supported by magnetic bearings, instead of a typical greased axle bearing, with only electric wire connections to the inside of the vehicle.  The key to economic remote-controlled equipment on the moon is long-lived equipment.

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 *If acceleration in the tube averages about 30 meters per second squared then the tube on Luna needs to be about 48.3 kilometers (30 miles) long.  I find "30 meters per second squared for 30 miles for orbital speed" easy to remember.   A rocket-sled can use one of various deceleration techniques to use fuel recycling. A free flying rocket continues on in orbit to an orbiting depot where another tube would exist for providing delta v to deorbit and return to the moon with the deceleration rocket exhaust recycled to rocket fuel on the depot.  For orbital stabilization the orbiting depot would need large, high specific impulse electric thrusters with low thrust to weight ratio which are possible with various technologies. The mystery to me is why these technologies have not been already employed, since they were all available since 1985.  The low thrust to weight ratio for the orbital maintenance thrusters on the orbiting fuel depot would not be something people would strive to achieve.  It would be a natural result of releasing a weight constraint in design and using every means possible to increase exhaust velocity.
 *The horizontal acceleration of a rocket in a tube should start with electric acceleration of a movable launching pad for the first 4% or so of orbital velocity.  The moving start of the rocket prevents the rocket exhaust from having too much erosive effect on the tube, prevents excessive pressure build-up behind the rocket, prevents the rocket from flying in its own exhaust, provides ullage thrust for the start of the rocket engines and a portion of mission delta v.  A larger diameter section of tube to collect exhaust behind the launch spot may also be desired.  Six feet larger in diameter than the rocket should be about the minimum diameter for the launching tube to provide the clearance to avoid the rocket smashing into the tube wall.  Rocket scientists can calculate whether the tube needs to be larger at some parts of the tube to accommodate the volume of exhaust. As the rocket continues down the tube at increasing speed, the mass of exhaust gas deposited in the tube per unit length decreases.  So, the diameter of tube needed to accommodate the exhaust gas decreases with distance traveled in the tube to where it is less than the diameter needed to avoid crashes into the tube wall.
-*Recycling rocket exhaust provides a way of storing the electrical energy needed for launch of a cargo carrying rocket.  The energy is stored as rocket propellant.  That compares to the use of the amount of energy for achieving orbit as electricity in the short time that it takes a rocket to accelerate to orbital speed (about 56 seconds), a task that is undemonstrated and, I feel quite confidant, would require much more expensive infrastructure.
+*Recycling rocket exhaust provides a way of storing the electrical energy needed for launch of a cargo carrying rocket.  The energy is stored as rocket propellant.  That compares to the use of the amount of energy for achieving orbit as electricity in the short time that it takes a rocket to accelerate to orbital speed (about 56 seconds).  The task of all electric acceleration to orbital velocity is undemonstrated and, I feel quite confidant, would require much more expensive infrastructure.
 ==Mining the building materials==

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 :National space agencies can learn how to build a [[Thermal Shelter on the moon]] to allow their remotely controlled devices to last longer than two weeks on the moon.
 :However, if they actually start to build something on the moon, there will be people who will want to know what the plans are.
-:To see some discussion of argument in favor of building infrastructure on the moon see [[New moon base concepts]]
+:To see some discussion of argument in favor of building infrastructure on the moon see [[New moon base concepts]].
 ==The benefits to be expected from space bases solar power==
 :    As SBSP built from lunar materials continues to be installed and promoted, starting perhaps about twenty years after the start of building a landing base on the moon, there should be many various uses of electrical power that become practical as the price of the electricity decreases.  Desalination of sea water to irrigate deserts and chemical processing of the material buried in land-fills to remove toxic substances that could enter ground water are possibilities.  The incorporation of Whipple shields of the proper scale to protect SBSP satellites will have the effect of sweeping small debris from the geostationary orbit environment.  Larger pieces of debris will need to be removed on a per each basis, perhaps by solar sail maneuvering satellites dedicated to the task.

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 * After the acceleration tube and fuel depot on the lunar surface are completed, they can be helpful in constructing the exhaust collecting deceleration tube for the lunar orbiting fuel depot.
 *People who were intent on using mass drivers to build space habitats as suggested in "THE HIGH FRONTIER" by Gerard K. O'Neill need not give up hope.  Recycling rocket exhaust to make it possible to build SBSP and space habitats does not preclude perfecting better mass drivers for space transportation.  The more that extraterrestrial resources become available, the more they can be used to develop more advanced technology.
-* The rocket for which exhaust is recycled can burn liquid methane and liquid oxygen.  Then, the Sabatier reaction could be used to add hydrogen to the carbon dioxide at the proper temperature with a proper catalyst to produce methane and water.  That water along with the exhaust water could then be subjected to electrolysis to recover the amount hydrogen added previously and the amount oxygen that originally burned the fuel.  As side benefits the lower exhaust velocity of a methane/lox rocket as compared to a hydrogen/lox rocket would result in cooler exhaust gas to collect and recycle, a smaller fuel tank in comparison to the cargo mass and a less difficult cryogenics problem handling the low temperature liquid fuel.
+* The rocket for which exhaust is recycled can burn liquid methane and liquid oxygen.  Then, the Sabatier reaction could be used to add hydrogen to the carbon dioxide at the proper temperature with a proper catalyst to produce methane and water.  That water along with the exhaust water could then be subjected to electrolysis to recover the amount of hydrogen added previously and the amount of oxygen that originally burned the fuel.  As side benefits the lower exhaust velocity of a methane/lox rocket as compared to a hydrogen/lox rocket would result in cooler exhaust gas to collect and recycle, a smaller fuel tank in comparison to the cargo mass and a less difficult cryogenics problem handling the low temperature liquid fuel.
 * oxygen gas could be used as a heat transport fluid for taking the heat from the captured hot exhaust and transferring it to shaded radiators extending from east to west along with the launch tube.  Oxygen is not the best heat transfer fluid on Earth but on the moon we might take what we can get most cheaply and there is plenty of oxygen available.
 ==Military Considerations==

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 *It may be difficult for people in Ukraine and Russia to imagine cooperating peacefully after the harm and destruction that has been done but if all that can be imagined is continuing war, war will go on for a long time.
 *One does not need to believe Christian teaching to see that it could be a basis for these countries with a history of Christianity to reach a peace agreement acceptable to many of their people.  Scriptures respected by the Jews predate the exclusively Christian scriptures on this point so Zelenski should pay attention as well.
-*Things that a peace treaty might include would be: 1) an agreement to not seek prosecution for war crimes that may have occurred in this invasion by Russia and defense by Ukraine  2) a return to their original countries of anyone captured or deported to another place who is willing to return 3) interviews with any persons unwilling return, which interviews are to be monitored by neutral parties  4) provisions allowing international trade with reasonable cross border shipping procedures to help both countries to return to economic productivity.  There is some potential use to be made of Putin.  He can carry the blame for "Putin's war".  Leave him under house arrest in his dacha outside Moscow with the Kremlin controlling who does or does not visit him.  It does not matter if ruling class in Russia forced this war on Putin or not.  Only Russians can determine if this is practical or not.
+*Things that a peace treaty might include would be: 1) an agreement to not seek prosecution for war crimes that may have occurred in this invasion by Russia and defense by Ukraine  2) a return to their original countries of anyone captured or deported to another place who is willing to return 3) interviews with any persons unwilling return, which interviews are to be monitored by neutral parties  4) provisions allowing international trade with reasonable cross border trans-shipping procedures to help both countries to return to economic productivity.  There is some potential use to be made of Putin.  He can carry the blame for "Putin's war".  Leave him under house arrest in his dacha outside Moscow with the Kremlin controlling who does or does not visit him.  It does not matter if ruling class in Russia forced this war on Putin or not.  Only Russians can determine if this is practical or not.
 *Other nations trying to assist in peace making will have the task of making reasonable analysis of the likelihood of Russia and Ukraine abiding by terms reached at any stage of negotiations and advising negotiations to bring about a successful end to fighting.
 *Ukraine's help in setting up SBSP is desirable but Russia's help is especially needed because the international treaties needed for SBSP should be written to work with enemies being parties to the treaty forswearing use of the technologies for warlike purposes and verifying each other's compliance.  Unfortunately, the attitude of Putin and the Russian leadership make cooperation with a good enemy and the whole notion of industrialization of the moon seem unlikely.  We should not quit without an attempt.

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 :It seems technologically possible to produce a space based solar power (SBSP) system for Earth from lunar materials, but the economics cause difficult constraints and the current geopolitical situation is very difficult.
 *Investment in costly infrastructure is necessary to take full advantage of the potential low cost of achieving orbit from the moon. Many launches to orbit for a large customer are necessary to pay for the infrastructure. So, committing to infrastructure for launching to orbit and the building of SBSP should be a package deal. One or the other by itself or half-way measures do not make much sense.
-*Industrial production of oxygen on the moon with depot storage should be a first step. Then depots orbiting the Earth and moon. This technology is difficult, possible, and certainly possible to get wrong. Then there is the recycling of rocket exhaust into rocket fuel by having the acceleration to orbit on Luna occur in a tube that is horizontal along the equator with the tube in a semicircular cross section ditch in the lunar regolith with an air-lock door at the downrange end of the tube. The air-lock door must be closed after the rocket leaves the tube to allow the rocket exhaust to be captured by vacuum pumps. The regolith on which the tube rests should be built up enough so the craft exiting the acceleration tube misses any landscape features. The rocket flies free down the center of the tube with guidance from RFID tags mounted on the walls. The guidance of a free flying rocket would need to have about the accuracy that is achieved in acrobatic formation flying of jet airplanes. Jet airplanes have routinely flown as close as three feet from wing-tip to wing-tip while in formation flying.  This suggests that three feet clearance between the rocket and the tube walls can provide room in which the rocket can maneuver to avoid hitting the walls.  The choice between rocket-sled cargo launching and free flying rocket is a matter of which technology is most easily verified by development of models on Earth.
+*Industrial production of oxygen on the moon with depot storage should be an early step. Then depots orbiting the Earth and moon. This technology is difficult, possible, and certainly possible to get wrong. Then there is the recycling of rocket exhaust into rocket fuel by having the acceleration to orbit on Luna occur in a tube that is horizontal along the equator with the tube in a semicircular cross section ditch in the lunar regolith with an air-lock door at the downrange end of the tube. The air-lock door must be closed after the rocket leaves the tube to allow the rocket exhaust to be captured by vacuum pumps. The regolith on which the tube rests should be built up enough so the craft exiting the acceleration tube misses any landscape features. The rocket flies free down the center of the tube with guidance from RFID tags mounted on the walls. The guidance of a free flying rocket would need to have about the accuracy that is achieved in acrobatic formation flying of jet airplanes. Jet airplanes have routinely flown as close as three feet from wing-tip to wing-tip while in formation flying.  This suggests that three feet clearance between the rocket and the tube walls can provide room in which the rocket can maneuver to avoid hitting the walls.  The choice between rocket-sled cargo launching and free flying rocket is a matter of which technology is most easily verified by development of models on Earth.
 *If acceleration in the tube averages about 30 meters per second squared then the tube on Luna needs to be about 48.3 kilometers (30 miles) long.  I find "30 meters per second squared for 30 miles for orbital speed" easy to remember.   A rocket-sled can use one of various deceleration techniques to use fuel recycling. A free flying rocket continues on in orbit to an orbiting depot where another tube would exist for providing delta v to deorbit and return to the moon with the deceleration rocket exhaust recycled to rocket fuel on the depot.  For orbital stabilization the orbiting depot would need large, high specific impulse electric thrusters with low thrust to weight ratio which are possible with various technologies. The mystery to me is why these technologies have not been already employed, since they were all available since 1985.  The low thrust to weight ratio for the orbital maintenance thrusters on the orbiting fuel depot would not be something people would strive to achieve.  It would be a natural result of releasing a weight constraint in design and using every means possible to increase exhaust velocity.
 *The horizontal acceleration of a rocket in a tube should start with electric acceleration of a movable launching pad for the first 4% or so of orbital velocity.  The moving start of the rocket prevents the rocket exhaust from having too much erosive effect on the tube, prevents excessive pressure build-up behind the rocket, prevents the rocket from flying in its own exhaust, provides ullage thrust for the start of the rocket engines and a portion of mission delta v.  A larger diameter section of tube to collect exhaust behind the launch spot may also be desired.  Six feet larger in diameter than the rocket should be about the minimum diameter for the launching tube to provide the clearance to avoid the rocket smashing into the tube wall.  Rocket scientists can calculate whether the tube needs to be larger at some parts of the tube to accommodate the volume of exhaust. As the rocket continues down the tube at increasing speed, the mass of exhaust gas deposited in the tube per unit length decreases.  So, the diameter of tube needed to accommodate the exhaust gas decreases with distance traveled in the tube to where it is less than the diameter needed to avoid crashes into the tube wall.

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 ==What goes on now==
 :I have noticed several people simultaneously becoming reluctant to discuss lunar development.  I suspect there may have been a decision that studies of such potential development should be classified.  So, people who might have access to official discussion of such development can no longer openly discuss it.  What can be done while keeping lunar industrial development secret?  Technology verification experiments can be done.  A rocket can fly through a two-mile long tube made of chicken wire and mounting RFID tags.  Scientists can learn how the output of inertial sensors for inertial guidance and data read from RFID tags correlate with maneuvering controls for the rocket.  They learn how the data is a measurement of how straight and level the tube is in order to use such measurements to straighten the tube to be built to actually collect rocket exhaust on the moon.  They can measure the effectiveness of heat transfer by oxygen gas pumped from a storage tank to a heat source and on to a radiator and back to storage with the whole system being in a vacuum tank simulating the moon.  They can test remote controlled devices to assemble a liquid oxygen storage tank, devices to produce oxygen from simulated lunar regolith and store it, devices to haul liquid oxygen to a rocket on a simulated lunar surface and make fluid transfer.  They can test instrument landing systems and ground navigation aids for the rockets that will bring equipment to a lunar base construction site.
 :However, if they actually start to build something on the moon, there will be people who will want to know what the plans are.
 ==The benefits to be expected from space bases solar power==