Image Credit: NASA, Karen Teramura, UH IfA, 2015.
As a materials chemist I am interested which materials are used in certain items. So, recently watching the series Star Trek: Voyager has led me to the question which materials are used in space flight in science fiction series. Also, will we ever have access to those materials?
Let us start with a brief introduction about where we are today. The International Space Station (ISS) or the Orion spacecraft that is currently developed by NASA contain a wide range of materials for different tasks. Nevertheless, the ISS modules, especially their hulls, consist mainly of an aluminum-copper alloy called 2219-T6 aluminum alloy. It has an aluminum content of about 91 to 94 % making aluminum the major element on the ISS. This aluminum alloy posseses high strength, but also low weight, two important properties for space flight.
If not aluminum-copper alloy, what are starships like Voyager or the Enterprise made of? In Star Trek the fictional alloys ”duranium” and ”tritanium” are used for the construction of starship hulls. They are suitable for this task due to their extreme hardness. Nevertheless, it is not clear which metals these alloys contain. Could they have been developed from the 2219-T6 aluminum alloy used on the ISS?
Star Wars is much less clear on the materials used in spacecrafts or the Death Star. For this reason, it has often been assumed that materials known today are employed. When calculating what it would cost to build a Death Star, ifls supposed that it consists of the same materials as the aircraft carrier USS Ranger. This would mean that the Death Star is mainly constructed from steel (or iron) which is a strong material, but much heavier than aluminum-based alloys. However, since a Death Star would be constructed in space and is not meant to land on planets, its weight would be less important.
There is one technology Star Wars is more clear about. Its spacecrafts use an ion propulsion drive for their sub-light engines, also called thrusters. This technology has been used by NASA since the 1960s and new engines will be a vital part of future space missions, for example to Mars. Ion propulsion works by ionizing a gas, normally xenon. Positively charged xenon ions are created and accelerated towards a negatively charged grid (an electrode with holes). They leave the engine as an ion beam which produces thrust. This technology can provide higher speeds while using less material than chemical propellants.
This leads us to the faster-than-ligh-speed engines. They are called Hyperdrive in Star Wars and Warp Drive in Star Trek. Here, Star Wars is again more vague on the materials used. In Star Trek the material ”dilithium” is essential for the function of the Warp Drive. In reality, dilithium is a molecule composed of two lithium atoms. While it has been speculated that dilithium could also refer to an unknown isotope of the element lithium, it was shown in Start Trek: The Next Generation that dilithium is an element with the chemical symbol Dt and the atomic number 87 which belongs to francium in reality.
We should not forget other possibilities for space travel, like the Stargate, a device that can create artificial wormholes for instant transport to other planets in the Stargate series. It is constructed from ”naquadah”, a superheavy metal that does not naturally occur in our solar system. This element has been indicated to belong to the so-called island of stability. The stability of elements heavier than uranium decreases with increasing atomic number. But some very heavy elements with a ”magic” number of protons and neutrons are predicted to temporarily reverse this trend and show a greater stability. These elements are expected to occur from the atomic number 120. The heaviest element discovered by humans so far is oganesson with the atomic number 118.
So, maybe we are not too far from naquadah and Stargates after all…