My last three posts were about plans for setting up a permanent base on the Moon. I mentioned that NASA is more focused on a major mission to Mars than going back to the Moon. Before he left office, President Obama made the declaration that the Moon is not a “planned” destination for U.S. astronauts. However, there are signs that some people at NASA are not ready to write off missions to the Moon.
       In a speech in 2010 at the Kennedy Space Center in Florida, President Obama laid out his vision of the next stage of NASA space exploration. With respect to a mission to the Moon, Obama said that “We have been there before.” Instead of President Bush’s plan for going to the Moon to test technology and to mine for ice and minerals before attempting a mission to Mars, Obama said that NASA should send a mission to an asteroid in the 2020s and send a mission directly to Mars in the 2030s.
       Last summer, the National Research Council issued a report calling for a reconsideration of a lunar base before sending a mission to Mars. Their report said “It was clear to the committee from its independent analysis of several pathways that a return to extended surface operations on the moon would make substantial contributions to a strategy ultimately aimed at landing people on Mars.”
        The chief of human exploration for NASA does not believe that it will be possible to launch a direct nine hundred day mission to Mars as President Obama proposed. He believes that it will be necessary to use a base on the Moon to convert ice into oxygen and hydrogen which can then be used to fuel a Mars mission. He said “If propellant was available from the moon, this could dramatically lower the mass needed from the Earth for a NASA Mars mission.”
       Senior officials at NASA have given signs of renewed interest in a lunar base but they have to tread softly in promoting such a mission for political reasons. NASA officials have begun talking about an “Evolvable Mars Campaign.” They acknowledge the challenges involved in getting to Mars and express doubts that the U.S. will be willing to spend the resources needed for a direct to Mars Apollo-type mission. Going back to the Moon before Mars would allow time to work out a lot of technical issues and test a lot of technology. The Moon is only a few days away and emergencies could be much more easily dealt with.
       On the political front, a Moon-then-Mars plan would garner much more interest in Congress for funding than the asteroid-then-Mars current plan. European nations as well as Japan are interested in going to the Moon and the U.S. could lead an international effort. Without strong U.S. involvement, other nations may turn to China which has major plans for lunar exploration. This would not be of benefit to the U.S. Private space companies are also keen to participate in lunar exploration.
       I believe that there is a very strong case to be made for going back to the Moon before considering a manned mission to Mars.

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Part Three of Three Parts:
        In the first part of this post, I talked about the NASA focus on visiting Mars and suggestions by a conference on lunar exploration that visiting and setting up a manned base on the Moon before a Mars mission would make more sense. In Part Two, I discussed some of the technologies that could be used to construct and supply a lunar base. Today, I am going to talk about locations for a lunar base. When considering the location for a lunar base, there are four main things that need to be considered.
       The lunar base will need a source of power. Of course, a nuclear fission reactor could be brought from Earth but that would be a heavy load and uranium fuel would also have to be brought from Earth. The best source of energy would be solar power. However, the sun shines on the lunar surface for two weeks and then the surface is dark for two weeks for most of the Moon. Although battery research is advancing rapidly, it might not be possible to sustain a lunar base for two weeks on batteries. Some analysts believe that one of the lunar poles would be best for locating the first base. The tilt of the axis of the Moon to its orbital plane is only 1.5 degrees so sunlight would be continuously available at the poles.
       Communications with the Earth would be critical for a lunar base. While a polar base would be best for power, an equatorial base would be best for communications. However, it should be easy enough to put a few satellites in orbit around the Moon to relay communications reliably from a polar lunar base.
        Proximity to useful resources will also be a must for a lunar base. Water especially will be important both for life support on the base and to separate into hydrogen and oxygen as a source of fuel for rockets. It has been estimated that as much as forty billion dollars worth of rocket fuel could be generated per year at a lunar base. Fortunately for a polar lunar base, there should be a lot of frozen water in the deep dark craters at the Moon’s Poles. Unlike craters nearer the lunar equator, the sun never shines down into such craters.
       And, finally, the ability to travel easily over the lunar surface will be important for a lunar base. While both poles of the Moon would be suitable from the standpoint of sunlight for power and ice for water, the north pole of the Moon is much flatter and smoother than the south pole so the north pole of the Moon turns out to be the best option for the first lunar base.
       Taking these four factors into account, the rim of the Peary crater near the north pole of the Moon would be a good choice for a lunar base. In addition to continuous sunlight, remote sensing indicates that the floor of the Peary crater contains water ice. It is also smooth which will make it easy for lunar rovers to explore.
Peary Crater in the red circle at the north pole of the Moon:

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Part Two of Three Parts:
        In the first part of this post, I talked about the NASA focus on visiting Mars and suggestions by a conference on lunar exploration that visiting and setting up a manned base on the Moon before a Mars mission would make more sense. Today I am going to go into more detail about technologies that would make that possible and practical.
        It has been suggested that virtual reality could be a powerful tool for planning and training for a permanent manned lunar base. VR could be combined with CAD/CAM, additive manufacturing and 3-D printing for an advanced planning environment to model and perfect the structures needed for a lunar base. Many problems could be explored and solved before setting off for the Moon.
       Up to now, very expensive devices, materials and processes have been developed on a one-off basis for use in space missions. Later, some of these have been adapted for consumer products. One way of reducing the cost of devices, materials and processes for new space missions such as a manned lunar base would be to invert the old procedure and adapt existing consumer products for use in space.
       I have already written about inflatable habitat modules that are being tested on the Internation Space Station. Planners are considering the use of inflatable habitats from Bigelow Aerospace for use on a lunar base. While Biogelow is focused on creating inflatable modules for use in Earth orbit, the light weight, compact shipping configuration and easy setup of these modules make them ideal for the first habitats at a lunar base. Big 3-D printers could be used later to create more permanent and sturdy shelters.
       Human beings have been living on the International Space Station for fourteen years. During that time, the technology necessary for basic life support has been perfected. Water can be efficiently recycled and oxygen balanced with carbon dioxide. Current estimates based on prices charged by SpaceX for cargo delivery suggest that the necessary food and other supplies for a staff of ten at a manned lunar base would cost about three hundred and fifty million dollars a year. Small 3-D printers could be used at the base for the production of small parts to reduce shipping costs.
      Some of the new systems needed for a lunar base do not exist yet but are in development and should be available soon. SpaceX is working on a heavy launch vehicle called the SpaceX Heavy for major payloads and it should be available for use in the near future. Refuelling spacecraft in Earth orbit for missions to the Moon is another possibility that is in development.
       By combining existing off the shelf technologies with new technologies currently under development, it should be possible to build, equip and supply a manned lunar base at a fraction of the cost that would have been required even ten years ago.
Please read Part 3

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Part One of Three Parts:
        The human race has thought about flying to the moon for over a hundred years. About fifty years ago, we did fly men to the moon but then other priorities drew funds away from the space program and we have not sent men there for decades. Right now there is a lot of debate about spending at NASA. There are those that lobby for returning to the Moon and establishing a permanent base. Others want to send men to Mars and set up colonies.
        In 2014, a group of scientists and space enthusiasts met for a conference on lunar exploration. About a year ago, nine of the papers presented at that conference were made available online. One of the papers said that the reason that we have not gone back to the Moon despite repeated calls for lunar missions is that the cost of repeating the Apollo missions would be prohibitive. Estimates of the cost of an Apollo-type government mission to the Moon today are in the neighborhood of one hundred and fifty billion dollars. Today’s entire NASA budget is about twenty billion dollars. Obviously, the money is not available for an Apollo-type mission. The plans outlined by the papers from the conference suggest that it should be possible to return to the Moon by 2022 and set up a permanent manned base for around ten billion dollars.
       There are no current NASA plans to return to the Moon. NASA is planning for manned missions to Mars in the 2030s. But, it would make sense to go back to the Moon to test all the technologies that would be useful for Mars missions before going to Mars. A Mars expedition would take up to nine months while we can reach the Moon in a matter of days. While NASA believes that we can either go back to the Moon or go to Mars but not both in the near future, the conference attendees disagreed and argued that new technologies and private space companies could make it possible to do both.
       China, Russia and the European Union have all expressed an intention to send men to the Moon and set up manned bases. Joining in a multinational effort to set up a manned base similar to the multinational effort that established the International Space Station would make it much cheaper for NASA to send U.S. astronauts to the Moon. In addition, the U.S. would not be left behind in exploration and exploitation of the Moon.
        Private space companies are competing to send missions to the Moon. It may be possible to mine helium-3 on the lunar surface which could be used as fuel for nuclear fusion on Earth. Water on the Moon could be mined and broken down into hydrogen and oxygen with solar energy. The hydrogen and oxygen could be used to fuel flight to Mars and other deep space destinations. It also may be possible to mine precious metals from asteroid impact sites.
        Papers from the conference outlined details for the possible construction of lunar colonies. Robotic vehicles could be used to level areas for construction of habitats and installation of solar cells. Buildings could be constructed from lunar regolith with 3-D printing. A functional lunar base could be ready for astronauts when they arrived. At first, there would be small missions with only a few astronauts intermittently resident at a small base but eventually the base would be expanded and permanently occupied. At first, the base would be dedicated to scientific activities but could eventually evolve into a center for commercial activities. There are even suggestions for lunar tourism but I don’t think that that would ever be very popular.
Please read Part Two.

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I have mentioned thermionic power generators that use plutonium-238 to provide power for space probes in past posts. Recently there have been some problems with obtaining sufficient Pu-238 for NASA deep space missions. Nuclear propulsion systems for large spacecraft have also been proposed for decades. With the recent expansion of private space industry, interest in nuclear propulsion has increased. However critics have said that using nuclear power for space propulsion would be too difficult, would take too long and would be too expensive.
      Jeff Bezos, whose fortune comes from his stake in the Amazon company, has a space exploration business called Blue Origin. He recently said, “I think NASA should work on a space-rated nuclear reactor. If you had a nuclear reactor in space—especially if you want to go anywhere beyond Mars­—you really need nuclear power. Solar power just gets progressively difficult as you get further way from the sun. And that’s a completely doable thing to have a safe, space-qualified nuclear reactor.”
       The Los Alamos National Laboratory, NASA and Department of Energy divisions have been working on the idea of nuclear power for use in space vehicles lately. They are focusing on a new generation of small fission reactors that can generation from a hundred watts to a hundred kilowatts of energy. These small reactors are known as KiloPower reactors. They use well know principles in simplified designs with inherent safety features. They are designed to be able to handle the stress of launch as well as operational transients. The feasibility of this approach was shown in 2003 and it is hoped that it will be possible to have a full-scale demonstration in 2017.
       In order to have a reactor operate stably, you want to maintain a steady level of neutron generation. If the reactor starts generating more and more neutrons, the nuclear reactions will increase and the temperature will rise. If the reactor gets hot enough, it can melt down. On the other hand, if the number of neutrons goes down, the nuclear reaction will diminish and less power will be generated. Terrestrial power reactors have sophisticated and complex control systems of moderator rods and cooling fluids that can control the neutron generation and reactor temperatures.
       It is also possible to design reactors in such a way that as the temperature goes up, the power generation goes down automatically and as temperature goes down, power generation goes up. Like the thermostat in a house, this results in maintaining a constant level of operation. The new generation of KiloPower reactors is designed to exploit this type of control.
        The KiloPower design is based on a solid uranium-molybdenum cylindrical core. Heat pipes carry heat to Stirling engines which convert the heat into electricity. The system is designed to be able to recover from large differences between the core output and the conversion module. Various components were developed that would simulate the operation of different parts of the KiloPower system. In one test, a quarter of the thermal energy conversion system was shut down suddenly and the system was able to automatically recover from the mismatch and keep operating. So far, the mechanical tests of components have matched the theoretical results of computer simulations.
        There will be a final test in late 2017 where a live core will be connected via sodium heat pipes to sterling engines. Beryllium oxide rings will surround the core to act as neutron reflectors. The whole assembly will sit atop a test stand in a vacuum chamber. The system will be powered up and, hopefully, generate two hundred and fifty watts of power. The test will assess the startup, operation, stability and shut down of the system.
        If all goes well, it will still take several years for final testing, final design selection and the construction of a fully functional prototype KiloPower system for use in space. The first use being considered for the new KiloPower system is use for a manned Martian expedition. The system will generate forty watts of power that can be used to provided water for the crew and to create fuel for rovers. When the mission ends, the KiloPower system can create rocket fuel to carry the crew back to Martian orbit from the surface.
       If the development of KiloPower reactors is successful, a new generation of MegaPower reactors will be next. These reactors will used on Earth to provide a few megawatts of electricity to remote locations. An air based system will be used for power conversion and heat dissipation.
Artist’s concept of a KiloPower system:

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       I have posted before about the problem with all the space junk in orbit around the Earth. It is estimated that there are over a hundred million pieces of space junk including old satellites, rocket boosters, fragments of rockets, and fragments of metal and paint. About twenty thousand pieces are more than four inches in diameter. One-half a million pieces are between four-tenths of an inch and four inches in size.
       An object, including pieces of space junk, in Earth orbit travels at four miles a second. A fleck of paint traveling at that speed has the same impact as a five hundred pound object traveling sixty miles an hour. So even tiny pieces can inflict significant damage on solar cell panels, penetrate pressurized compartments and even create new pieces of space junk.
        If space launches continue to spew junk into space, at this rate we may reach a point where it is impossible to launch a vehicle to Earth orbit without it being damaged by junk. If we are going to continue to explore and exploit space we have to reduce the production of space junk and find a way to remove it from orbit.
       A few weeks ago I posted a story about an experiment being conducted by the Japan Aerospace Exploration Agency to deal with space junk. The JAXA partnered with a fishing net company to create a tether with woven stainless steel and aluminum wires. The tether was about two thousand three hundred feet long. The intention was to test the idea of attaching a tether to a fragment of space junk and to letting the tether create a drag as it moved though the electromagnetic field around the Earth. As the tether dragged the satellite down, its orbit would decay and it would burn up in the atmosphere.
       The tether was carried aloft by a cargo ship bound for the International Space Station in December. The mission plan called for the tether to be unreeled from the cargo vessel but it apparently failed to deploy as planned.
       A few weeks ago, a JAXA mission tried to use a mini rocket to carry a satellite to orbit. A small, experimental rocket called the SS-520-4 was intended to carry six and half-pound satellite, called TRICOM-1, to orbit but failed. The SS-520-4 rockets have been used to reach six hundred miles above the Earth, known as the edge of space. The SS-520-4 in the failed experiment had an extra stage added that was intended to allow it to carry the attached satellite all the way to Earth orbit.
      Last February, JAXA launched the Hitomi satellite. It was much bigger than earlier Japanese scientific satellites at forty-six feet and two and three quarter tons. The Hitomi satellite was designed to analyze X-rays emitted by black holes and colliding galaxies. Contact with the satellite was lost a month after launch. After efforts to restore communication failed, JAXA abandoned the mission, concluding that the solar panels of the satellite had broken off at their bases.
       The recent failure of these three missions is a serious blow to the JAXA.

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       Last year, I blogged about Moon Express, the first private space company to be licensed for travel beyond Earth orbit by the U.S. government. Moon Express plans a lunar mission in late 2017. Recent developments have certainly been positive for ME.
       Last Tuesday, ME announced that it had raised another twenty million dollars which brings its total fund-raising to forty-five million dollars. Peter Thiel’s Founders Fund, the Collaborative Fund and Autodesk have all contributed.
        Another positive development has to do with the members of the Trump NASA transition team, Charles Miller and Chris Shank, who are advocates of commercial space unmanned and manned ventures. The nominee to head NASA put forward by the new U.S. President, Republican Representative Jim Bridenstine, is also a supporter of the private space industry.
        ME hopes to be able to win the Google Lunar XPRIZE. To win the XPRIZE, the contestant must successfully land a rover on the lunar surface, travel about seventeen hundred feet and radio back high resolution still shots and video from the Moon. The winner of the XPRIZE will receive twenty million dollars. The winner’s mission must take place before the end of 2017. The chairman of ME says that they have all the resources they need for a November or December launch of their Moon mission.
        ME was encouraged by a call last fall from NASA for concepts for private space companies to deliver payloads to the Moon. ME enjoys a public-private partnership with NASA which allows ME to access NASA engineering expertise. ME has licensed Launch Complexes Seventeen and Eighteen at Cape Canaveral.
        ME currently has private contracts for delivering payloads to the Moon. These future missions include delivering the international lunar observatory to the Moon, delivering retroreflector arrays to the Moon to test relativity physics, and delivering human remains and DNA for Celestis, a company that has already sent ashes from a human cremation to the Moon. ME also hopes to get a contract from NASA for lunar payloads.
       Rocket Lab, a New Zealand company that provides rockets for private space missions has been contracted to provide five of their Electron rockets for planned ME missions. Following the use of the Electron rockets, ME plans to shop around for rockets for future missions.
       The goals of ME are to “mine the moon for valuable resources such as helium-3, gold, platinum, iridium, ruthenium, rhodium, palladium, rare earth metals, and water and to help researchers develop human space colonies for future generations.” Helium-3 is rare on Earth but common on the regolith of the Moon from billions of years of bombardment of the solar wind. It is considered to be an excellent fuel for nuclear fusion reactors which are currently under development. There is also water on the moon which could be mined for lunar colonies and could also be separated into oxygen and hydrogen by solar power to use as a fuel for spacecraft.
       ME is just one of several companies that are working to win the XPRIZE, including SpaceIL in Israel, Team Inus in India and Synergy Moon which is an international team. And there are other companies and countries such as China working on mining missions to the Moon. The exploration and exploitation of space is a growth industry.

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       Throughout the more than a century of observation through telescopes and the visits of orbiters and landers, Mars has fascinated the human race. Much smaller than the Earth, the surface area is about equivalent to the land area on Earth. The gravity on Mars is about a thirty eight percent of Earth gravity and the mostly carbon dioxide atmosphere is very thin.
        Although there has been a lot of discussion about visiting Mars and even colonization in the past few years, I have not blogged about it very much. It is true that human beings can walk on the surface of Mars with protection from the low temperatures, low atmospheric pressure and lack of oxygen but it is a very inhospitable place none the less. I honestly believe that the odds of colonization in any meaningful way in the next fifty years are slim to none. Traveling to Mars by current propulsion systems would take months and expose astronauts to the deleterious effects of radiation and zero gravity. In addition to the lack of oxygen and the extreme temperatures, the sand on the surface of Mars contains perchlorates which are very toxic chemical dangerous to human health.
        Even though Mars is a harsh place that would be difficult to get to, individuals and organizations have been hatching plans to send enough people there to found a self-sustaining colony. For the foreseeable future, anyone participating in such an effort will have to accept that it will be a one-way trip and they will die on Mars. Setting aside the technical details of going to Mars and setting up a colony which will be dealt with in future posts, today I am going to talk about some legal issues that will be involved in colonization of Mars.
       While current space treaties say that astronomical bodies in space belong to everyone and cannot be owned by anyone, there is nothing specific in the treaties that prohibits setting up a colony on Mars. There is a strict prohibition against sending weapons of mass destruction into space. And, of course, the colonists could not own the land that they settled on. Otherwise, as long as such a colony did not violate the rest of provisions of the space treaties, it would be legal.
       If colonists arrived on a United States spacecraft, regardless of where it was launched from, they would be subject to U.S. law. With respect to systems of governance of a colony, there could be a variety of choices as long as they do not violate U.S. law. In order to launch a mission into space, you need to apply for a license from the country of origin, the U.S. in this case. Currently, there is no specific license that can be sought for setting up a colony in space. But, considering all the private companies getting into the space industry, that is something that may need to be remedied sooner rather than later.
        There is an unofficial agreement between the signatories of space treaties not to pollute bodies in space. This applies generally to trash and polluting substances but more specifically to not taking Earth microbes to an astronomical body that has conditions that might allow them to survive and spread, competing with and, perhaps, wiping out indigenous life. Ironically, the places on Mars where that would be most applicable such as areas where liquid water are present would also be the areas where it would be most attractive to colonize. It would be best to have some sort of governing legal framework in place before such biological contamination becomes an issue.
        Along with discussions of the technical problems that need to be solved in order to colonize Mars, there also needs to be parallel development of legal frameworks to govern such future colonies.

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Once you go to the trouble of launching a spacecraft, you may be faced with the problem of landing it safely back on Earth or some other astronomical body with an atmosphere. A great deal of effort has gone into perfecting systems to shield spacecraft from the intense heat generated by their rapid penetration of an atmosphere.
       The most intense heat ever experienced by a spacecraft entering a planetary atmosphere happened when the Galileo probe entered the atmosphere of Jupiter. The heat was twice as intense as the surface of the sun. Special lightweight phenolic carbon heat shields made of fibers in resin matrix were used to protect the probe. Due to planning for missions to land probes on Saturn and Venus, new heat shielding is under development. These new shields will have to be as heat resistant as the phenolic carbon shields but much lighter than the phenolic carbon shields.
        NASA in conjunction with private space industry partners is working on a new Heat-shield for Extreme Entry Environment Technology system. In 2013, the Planetary Science Division and the Space Technology Mission Directorate’s Game Changing Development Program at NASA jointly funded an initial study that lasted a year. In 2014, NASA’s Science Mission Directorate and Space Technology Mission Directorate formally funded a four year program to work on the development of the new HEEET. Bally Ribbon Mills in Bally, PA and Fiber Materials Inc in Biddeford, MA. are the private space industry partners in the HEEET project.
       The HEEET system is based on three-dimensional weaving techniques developed to manufacture carbon composite parts for airplanes. Instead of just bonding layers of two dimensionally woven carbon fibers with resin, the new technique weaves together the two-dimensional layers in the third dimension. Fibers of different composition in yarns of different density are woven together and then infused with resin to bond the fiber matrix together. The NASA scientists have created alternative versions of their new HEEET ablative thermal protection system and tested them for many different entry conditions.
       Depending on the specifics of the mission design, the peak heat-flux possible on a Saturn or Venus mission could be as great as ten thousand watts per square centimeter. The peak pressure could rise as high as ten times the average atmospheric pressure at sea level on Earth. The new HEEET woven material will be able to withstand these conditions while being much lighter existing phenolic carbon heat shielding. In addition to these superior qualities, the woven nature of the HEEET materials will also increase the mechanical strength of the heat shield.
      In 2015, the HEEET team demonstrated the ability to form and infuse with resin a spherical heat shield tile cap of standard design. Current plans call for the HEEET project to delivery technology that can be included in the planning and design stages of new missions.
Artist’s rendering of HEEET weave:

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      One of the big problems for the future of spaceflight is the growing amount of junk in Earth Orbit. The human race is certainly careless about littering space. “Old satellites, spent rocket stages, fragments from disintegration, erosion, and collisions” have produced almost two hundred million pieces of space trash smaller than a half inch, about seven hundred thousand pieces from a half inch to four inches, and almost thirty thousand bigger pieces. The US is tracking about eighteen thousand objects in space, only fifteen hundred of which are operational satellites.
       This space junk threatens existing satellites and it is estimated that if current trends continue, the human race may actually block itself from launching manmade objects into space. There have been suggestions and designs for systems to remove space trash but so far, only a few tests. Ideas include tethers to drag large objects into the atmosphere where they burn up, to nets and robot arms to grab smaller objects in space.
        Scientists at the Japan Aerospace Exploration Agency have just launched a space junk collector on a cargo ship called a “Kounotori” bound for the International Space Station. The new system consists of thin wires of stainless steel and aluminum referred to as tethers. The spacecraft will rendezvous with large pieces of space debris and attach the tether to the object. Then the dangling wires will interact with the electrical field of the Earth and exert a drag on the object. Eventually, the drag from the tether will kill enough of the orbital momentum of the object to cause the orbit to decay and the object to burn up in the atmosphere.
      JAXA worked for ten years to create the new tether system in collaboration with Nitto Seimo, a Japanese fishnet manufacture. The plaiting system of the fishnet company was used to intertwine the thin wires of stainless steel and aluminum which were difficult to work with. The tethers being used in this experiment are about twenty three hundred feet long. However, they will have to be two to four times as long to actually function as intended.
       JAXA would like to put their new tether system into regular operation in about ten years. They have already tested deployment of a thousand foot tether in orbit. They have also tested the way in which the electrical field of the Earth interacted with the deployed tether. The current test consists of the launch and deployment of the new craft that carries and attaches the tethers. The next test will be to test will be to actually attach a tether to a targeted object in space. There are also designs that provide for tethers to be attached to objects in space and then reel them in for capture by the spacecraft.
       There will have to be a lot more work done on the capture of space debris in the near future if we want to keep our path to space open for the future.

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