THE TRANSFORMATION OF MANKIND TO INTER-PLANETARY VIEW (4) Elon Musk (Beginning here) HOW TO REDUCE THE PRICE OF DELIVERING TONS ON MARS BY 5 MILLION PERCENTAGES It is not easy to reduce the price of a ticket to Mars to the specified amount, since we need to reduce the cost of traveling by 5 million percent. This can be described as an improvement of 4 and a half orders of magnitude. It is not simple. This seems almost impossible, but there are ways to do this.
There are key elements needed to improve by 4.5 orders of magnitude. Most of them are associated with the full reuse of components - an approximate reduction in cost by 2 to 2.5 orders of magnitude. The remaining two orders can be achieved by refueling in orbit, fuel production on Mars, and choosing the right fuel.
COMPLETE RE-USE To make the flights to Mars possible in a large enough to create an autonomous city scale, it is critically important to completely re-use. In fact, it is very difficult. It is very difficult to achieve the reuse of components even of the orbital system, and the calls become much larger for a system that will travel to another planet.
You can use any mode of transport as an example of the difference between reusable and expendable systems. A car, a bicycle, a horse, if they were a one-time use - almost no one would use them, they would be too expensive. However, with frequent flights, you can take a plane, the cost of which is $ 90 million, and right now buy a Southwest airline ticket from Los Angeles to Las Vegas for $ 43, including taxes. If the plane was used once, the ticket price would be $ 500,000 for the flight. Right here we see an improvement in value by 4 orders of magnitude.
Alas, but re-use will not give such a result when flying to Mars, because you can use the spaceship system much less times. The minimum distance between Earth and Mars is only every 26 months. That is, you can reuse the spacecraft only every two years.
REFUELING IN ORBIT You will have to use an accelerator and a fuel tank often. Therefore, it makes sense to bring the spacecraft into orbit with empty tanks. If you have large enough tanks to fill them with accelerators and a tanker, being in orbit, you can increase the payload of the spacecraft, and when it goes to Mars, you will have a very large payload.
Therefore, refueling in orbit is one of the key elements. Without refueling in orbit, you will have a cost that is big by half the order. Since each order is a power of ten, the lack of refueling in orbit will increase the ticket price by about 500 percent.
The advantages of refueling in orbit:.
The lack of refueling requires a rocket with 3 steps and increases the size and cost by 5-10 times.
The distribution of the required output load for many starts significantly reduces the development cost and compacts the schedule 3. In combination with reuse, refueling allows you to replace the exponential increase in cost by geometric.
Also refueling in orbit will allow us to use much smaller missiles and reduce development costs, although it is already quite large. However, to build anything larger 5-10 times the size is much more difficult.
Moreover, the sensitivity to the parameters of the accelerator stage and the tank decreases. If one of the elements does not fulfill its function, it can be compensated by one or two additional flights to refuel. It is very important to reduce the sensitivity of the system to performance shortcomings.
MANUFACTURE OF FUEL ON MARS Fuel production on Mars is also very important. Again, if we do not do this, the cost will rise by half a dozen. It would be absurd to build a city on Mars, if the spacecraft were sent to Mars and did not return to Earth. You would have a vast cemetery of space ships, you would have to do something with them.
Advantages of fuel production on Mars:.
It makes possible the re-use of ships and allows people to easily return to Earth.
Provides the use of resources available on Mars.
Delivery of fuel from the Earth will require 5 times more fuel consumption for its delivery.
There is no sense in leaving the spacecraft on Mars, you want to build a fuel factory on Mars, and send them back. On Mars, it's easy to get, because it has an atmosphere of carbon dioxide, there is water ice in the soil, and with H2O and CO2 you can get methane and oxygen.
RIGHT FUEL Choosing the right fuel is also important. There are three main options, and each has its own advantages.
First, kerosene, or rocket kerosene, is essentially a highly purified form of jet fuel. It allows you to keep the size of the rocket small, but it is quite expensive. Its reuse potential is lower. It is difficult to produce on Mars, since there is no oil there. Its specific energy is good enough, but not outstanding.
Hydrogen, although it provides a very high impulse, is very expensive, and it is very difficult to store it in liquid form, not allowing boiling, since the temperature of liquid hydrogen is very close to absolute zero. Consequently, the required equipment will be huge, and the energy needed to produce and store hydrogen on Mars will be very large.
Picture 1. Comparison of kerosene fuel, hydrogen / oxygen system and cryogenic system methane / liquid oxygen (Deep-Cryo Methalox) Therefore, considering the overall optimization of the system, it is clear that the winner is methane. Methane will require 50 to 60 percent of the energy on Mars to refuel from the storage, and the technical requirements are much simpler. So we think that methane is better than anything else.
At first we thought that the use of hydrogen makes sense, but eventually came to the conclusion that the best way to optimize the cost ratio per unit of mass when flying to Mars and back is the use of a fully methane system, a technically cryogenic system of methane-liquid oxygen.
Whatever system is developed, whether it will be developed by SpaceX or someone else, we listed four key problems that need to be solved in order to obtain a really low cost of sending a ton of cargo to the surface of Mars.
ARCHITECTURE OF THE SYSTEM (5) Figure (2 - Ed. ) Describes the complete architecture of the system. Rocket accelerator and spacecraft take off and take the spacecraft into orbit. Then the accelerator returns quickly to the ground within 20 minutes. He can then pick up the version of the space-ship-tanker, which is similar to the KK, but the hermetic and unsealed volumes are filled with tanks with fuel. This will also reduce the cost of development, initially considerable.
Then the tanker with fuel rises from three to five times to fill the spacecraft tanks in orbit. When the tanks are filled, and the cargo is transferred and the time of minimal rapprochement with Mars comes, which occurs once in 26 months, the spacecraft leaves.
Over time, spacecraft will be many. Perhaps up to 1,000 ships or more will be in orbit. The Martian colonial fleet will depart simultaneously.
It makes sense to collect spacecraft in orbit, because this is two years, and you can use accelerators and tankers very intensively. The reuse of the spacecraft will be less, since 12-15 flights will take 30 years or so. Therefore, you want to maximize their useful load and use accelerators and tankers as many times as possible. So, the ship goes to Mars, it is refueled, and sent back to Earth.
Rice. 2 System Architecture. The ultimate goal: 1000 accelerator uses, 100 tanker uses, 12 spacecraft uses The ship will be relatively small in comparison with the interplanetary ships of the future. However, it should hold about 100 people in a sealed section, carry luggage and do not require sealing materials for the construction of a plant for the production of fuel and everything else, from metallurgical plants and pizzeria to anything, we need to transport a lot of cargo.
The turn of an autonomous city or civilization on Mars will be a million people. When flying every two years and the ship's capacity of 100 people, this is 10 000 flights. Consequently, 100 people per ship is the correct estimate, and we can increase the passenger section, and carry 200 or more people to reduce the cost per person.
However, 10,000 flights are a lot, so it will really take about 1,000 spaceships.
How long does it take since the first ship was sent to Mars? Probably from 20 to 50 Mars meetings with the Earth, that is, the achievement of a fully autonomous civilization on Mars will take from 40 to 100 years.
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