Zack Schools Thomas Foulds Drew Staples Geetesh Devineni. Helium-3 Mining Ops

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1 Helium-3 Mining Ops The primary purpose of this mission to Titan is to mine He-3 from the atmosphere of Saturn. He-3 is an essential piece in a specific fusion process that, when reacted with Deuterium, yields He-4 and Hydrogen -1 plus power. Not only is the output high compared to other power generation processes, but there are no other byproducts. For example, the byproducts of fission include protons, neutrons, radiation, etc. Neutrons are bad because they bump into other substances and make them potentially radioactive. This is hazardous to human health and is not favorable in the long run when using fission. Fusion is both clean and more powerful and therefore makes it the perfect solution for humanities growing power needs. Deuterium is found on Earth in small amounts and can be processed into heavy water. (Used in nuclear reactors) The only problem is that He-3 does not exist anywhere on Earth and this makes safe fusion impossible without outside sources of Helium-3. This isotope of helium is found on the Moon, but in VERY SMALL amounts making large scale fusion processes based on exported helium from the Moon an inefficient process. The other sources of Helium-3 include the Jovian planets; Jupiter, Saturn, Uranus, and Neptune. Jupiter is the closest and has a very large amount of He- 3, but it has problems that make it difficult for us to access this valuable substance. Jupiter is the biggest planet in our solar system and that means it has the biggest gravity well, making continuous retrieval of He-3 more of a hassle than a profitable enterprise. Jupiter also has a very strong electromagnetic field which generates radiation in its vicinity; bombarding Jupiter s moons with lethal doses. Only the farthest of Jupiter s moons are not affected by strong radiation, meaning it s safe for humans to live there without shielding. This combination renders Jupiter a bad choice for a permanent mining colony. Saturn has a considerable amount of He-3 in its atmosphere that would greatly benefit the fusion process. Saturn also has Titan, which is the closest thing to Earth that deep into the solar system. It has a considerable amount of atmosphere and therefore is easier for humans to live on. There are also plenty of interesting chemicals and substances that are useful for humans to utilize, so Titan is a viable option for a base for helium operations. Our other options include hollowed out asteroids as bases in orbit. The main focus of our mission is to find a viable way to mine and transport helium throughout the solar system. Given the details by 2070; both Mars and the Moon have fusion reactors, while the asteroid belt and Titan do not. Since the crew will be living in orbit around Titan, the surface will be used by the unmanned machines to gather resources and conduct experiments. Once we obtain the helium, it will be

2 shipped out to wherever it is needed such as Mars or the Moon. However, the main and default shipments will go directly to the moon. This is because there is already a trace amount of He-3 on the Moon, which has been the basis for their fusion reactor, so they will already have facilities for processing the helium and preparing it back to shipment to re-enter the atmosphere of Earth. This is also due to the unique conditions required to ship the He-3 back from Titan to the Moon. It will be dangerous and inefficient for humans to participate in the trips to Saturn to retrieve the He-3. Therefore, unmanned spacecraft will be used to bring back the He- 3 to orbit where they will be launched through our coil gun. (More info later) The spacecraft will have to be light, but will have to have strong enough propulsion to make repeated trips through Saturn s immense gravity well. The spacecraft will also have the ability to manufacture its own fuel by using the hydrogen and helium-4 from the atmosphere of Saturn in the form of a Nuclear Thermal Rocket. However, if the supplies somehow run short, then the rocket can be equipped with another propulsion system that can utilize hydrocarbons. The reason for this is that Titan is very rich in hydrocarbons; it practically has an ocean of them in abundance. This would not be as efficient as an NTR, but that is why it is a secondary form in case the primary fails. If there is space on the main carriers, then multiple spacecraft could be utilized to increase the amount of He-3 shipped out. The largest construction project of the mission is the massive coil gun that will be built and sustained in orbit around Titan. It will serve as our method to getting the He-3 from Saturn to our side of the solar system. The coil gun will be in orbit because it would be more efficient than on Titan. In Titan, the coil gun would have to be located in a dug out area, which would take way too much work and way too long. Also, continuous use and the effects of Titan s weather on the machine would lead to more problems. But in orbit, friction would be reduced and the extreme low temperature of space would cause a measure of superconductivity, resulting in maximized efficiency. The coil gun is about 1.5 km long, which is really massive by anyone s standards.. However, this huge size is necessary in order to achieve the acceleration needed to launch an object from Titan s orbit back to the Moon. The basic idea behind a coil gun is to use electromagnets to launch a ferromagnetic projectile at very high velocities. A coil gun can have a single stage, meaning it has one electromagnet, or it can have multistages, meaning it has more than one electromagnet triggered in series. It is called a coil gun because the electromagnet is in the shape of a coil of wire, whose purpose is to induce a magnetic field in order to propel the projectile forward, similar to a solenoid. Our aim is to construct one that tops out at around 20 km/s. The contemporary ones have reached speeds at around 3 km/s, however in around year; one can

3 assume more advances can be made in efficiency. This velocity would give the shipment around 2 years to reach Earth from Titan and a little bit shorter to reach the Moon. One important consideration would be the position of the orbital satation in relation to the coilgun at the time of each firing. The electromagnetic pulse generated by such a large linear inductance motor would be enough to take out most of the sensitive electronics on the station if it was too close. It would be optimal if the station and the launch unit were on opposite sides of Titan whenever the unit was fired. The conditions must be very careful inside the containers to hold the helium. The basic outline of the container will be an outer shell that contains a vacuum, with another layer in between for insulation. The insulation will be provided by the hydrogen gathered by our unmanned spacecraft from the atmosphere of Saturn. This will keep the helium very cold to keep it in its current phase throughout the shipment. The innermost container (for the helium) will hold about 200 L of Helium. We had a few options of choosing the phase of helium through which we wanted to transport it as; solid, gas, or a liquid. However, compressing helium to each of the phases is very tough as the container itself needs to have constant pressure to keep the helium from exploding through an explosive phase change. We ruled out the solid phase because helium in solid form acts like a super fluid, while still retaining its crystal form. We also ruled out storing the helium as a super fluid because inside a container it would just escape and all the precious He-3 would be lost into space. Therefore, we decided that our container would have to have a pressure of 2.5 MPa and a temperature of about 5 K. These figures would be very improbable to reach; however, records have shown that pressures up to 200 or 300 MPa have been reached so it s definitely possible to reach MPa. Another reason we chose these conditions is that the liquid form of helium-3 has a very high safe range where it would change into other phases. The only problem is maintaining these specific temperatures. If the temperature various enough to cause a phase change or unstable changes, then the whole container would explode causing an immense explosion. Compressed gas could also be used and it would be relatively cheaper and easier to contain than fluid helium. However, the downside is that it offers less of a yield because helium gas has a lot less density than liquid helium, even if it is compressed to a high pressure. If we used compressed gas instead of liquid, we would consider pressures and temperatures of the container around.75 MPa and 10 K. This is fairly close as we can get before helium-3 turns into a liquid. Using the ideal gas law, we can find out exactly the mass of helium-3 obtained using 200 L of the substance collected. The total yield is about 5400 g or 5.4 kg in mass of helium-3. Current estimates are that

4 a kg of helium-3 would be worth around $5.7 million, which, over time, would cover the initial costs of setting up the coil-gun and our whole mission. Our containers will also have to have some sort of ferromagnetic casing to make them launch-able. Also, the shielding should be minimal since the container will be layered. We re also launching through the asteroid belt, but the odds of hitting some asteroid are very minimal, so it should be safe to keep launching with only minimal thrusters on each canister. The time in between shipments would actually be 2 years between each container launched. There could be multiple launches throughout the year; only limited by how swiftly the helium could be collected. However, this would be very inefficient in the beginning years of the program; it would be the ultimately goal however. The main coil gun would ideally be set up in around 5-10 years, depending on various factors like availability of materials. So, shipments would actually start arriving by 2082 or so. The maximum time between any shipments would be 2 years, and that depends on how many containers launched. Our spacecraft also has to be specially designed to suit Saturn s atmosphere. Spacecraft nowadays are made of materials that are usually alloys made out of different materials. These materials (used to make the alloys) include: titanium, aluminum, and magnesium. These metals are used because they are comparably light and relatively durable. They are also ductile and can be formed into many different shapes, which is very useful for spacecraft. They can also withstand heavy pressures, which will be very useful for our spacecraft since Saturn is mainly composed of a thick and heavy atmosphere. Other materials considered and are still being developed for practical uses involve a variety of man-made plastics and synthetic materials. These can be carbon nano-tubes, types of fibers, and carbon based plastics. Even stronger materials include aramid and glass substances that have a very high durability and a very low weight factor. This makes them ideal for uses in engineering. These can also be used on our spacecraft. The actual mining of helium-3 begins with the spacecraft sucking up the Saturn air around it by using a vacuum-type mechanism. This collected air will then be shifted to an onboard centrifuge, which will be calibrated carefully to handle and separate gases. The helium-3 will then be shifted to our special container, and the rest of the useful gases will be used for propulsion (covered above). The aircraft will need to be semi-autonomous for a few reasons. One, it cannot be fully manually controlled because of the time lag in between for light to travel back

5 and forth. It has to be semi-automated because it is the best combination of both human innovativeness and computer technology. The part of autonomy will make the regular tasks easier and efficient for collecting the helium-3. There will need to be communications systems on board in order to receive commands and send back data back to Earth. Therefore, a combination of lasers and radio waves will be used for communication. Manned control of the spacecraft was ruled out immediately due to the potential loss of human life in such unsafe conditions. To contain all these instruments, survive the Saturn atmosphere, and have enough propulsion to make repeated trips through Saturn s gravity well, the spacecraft will need to be fairly large. It will somewhere in between the size of an actual spacecraft and the size of an unmanned probe. More likely, it will be closer to the size of an actual spacecraft. Another current estimate elaborates on a space shuttle cargo full of helium-3 from the moon; it would be enough to fulfill the U.S. s energy needs up to a full year. A space shuttle s cargo can hold probably a city bus. This of course is more immense than the 5.4kg of helium-3 delivered by the initial container. But, by the time fusion has spread across the world and the operation on the Moon has been set up. There will be ample time to increase our operation to a much larger scale of mining and shipping. All we need is time, and the Moon can provide some of that time due to its own supply of helium-3 (even if it is small, it can still last for awhile). Other options to increase efficiency include the spacecraft containing multiple tanks, which would practically multiply our output of helium-3 by ridiculous numbers. Another option is to up our operation to include even more spacecraft and with each new addition and even more additions of tanks, our production of helium-3 will eventually be enough to satisfy the world s growing fusion reactor and even power needs. A coil-gun of our size will consume an immense amount of power. We were thinking around a few terawatts of power, which is very high cost. But power requirements can be alleviated by including solar elements and maybe even wind power from Saturn s atmosphere. These again are future options to consider for growth and economy. Our motto is to start out small; a coil-gun here and a spacecraft there, but eventually to grow exponentially with each additional unit. Shipments of helium-3 can be

6 expected to reach the moon by around It will take about 10 years (maximum number) for the coil-gun to be assembled and it takes around 2 years for a container to reach the Moon. So for now, humanity will have to be a little patient.

7 Sources: -power point from class on nuclear reactions - -Alex Matta

4.8 Space Research and Exploration. Getting Into Space

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