Fuel Tanks Integration- an Important Milestone on Our Journey to the Moon
At the beginning of December, the spaceship’s four fuel tanks were integrated into its body. These tanks account for 80% of the initial weight of SpaceIL’s spacecraft.
The fuel tanks were shipped to us from the USA, and first underwent vibration tests that simulate the vibrations that will occur during the launch. Following the successful results, the IAI team in the clean room installed them in the spacecraft. The integration of the remaining components will now continue, and once completed, the spacecraft will be ready to begin the testing phase.
As you can see, the fuel tanks are round, because this shape renders them the most durable and robust, and will allow them to withstand the pressure they will need to endure during the space mission. However, you may be surprised to know that the tanks are made of titanium that is less than 1 mm thick – which means they must be handled delicately, and with extreme caution. Any improper contact may damage them and significantly reduce their durability. The required repair in such a case would be very costly in terms of both time and money.
Which compounds will the fuel tanks be filled with?
Two of the four tanks will be filled with an oxidant – a liquid that is rich in oxygen. The remaining two tanks will be filled with liquid fuel. These are highly toxic substances, and therefore will only be inserted into the tanks in the USA, shortly before the launch, by a team of specialists contracted specifically for this purpose.
The engine we are using is a rocket engine that operates on the gas emitted during combustion.
How is combustion possible in space, where there is no oxygen?
The lack of oxygen in space – an element necessary for combustion, requires using an oxidant in addition to the fuel. The mixing of the oxidant with the fuel under high pressure produces combustion. The gas emitted as part of the combustion process passes through a nozzle – the narrow opening of the engine, where the pressure of the gas is converted into velocity. The gas is emitted through the engine at high speed, and in keeping with the law of conservation of momentum, propels the rocket forward.
A bit about the PMD – Propellant Management Device
There is a system inside the fuel tanks that constrains the splashing of the liquids. When the spacecraft is in motion, the liquids inside the tanks move as well, and may destabilize it. This system restricts this movement, and thus maintains the spacecraft in a stable position during the mission. The system also separates the liquid from the gas inside the tanks, thus preventing the entry of small gas bubbles into the pipes leading to the engine.
This is the first time that a Bi-Propellant rocket propulsion system is being planned and manufactured in Israel, when some of the components are manufactured in IAI (Israeli Aerospace Industries) and others, such as the engines, are being manufactured in cooperation with international companies.
In this picture, in addition to the engines, you also see some other interesting elements:
The orange stripes on the tanks, which are the warmers – a component of the spacecraft’s thermal control system. They are responsible for maintaining the proper temperature of the fuel tanks throughout the mission. These warmers are the product of Israeli R&D, and were developed uniquely and specifically for SpaceIL.
Also, on the right side, you can see the fuel pipes, through which the fuel and oxidant flow – separately, of course, into the engines.
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