Introducing the Volatile Sampler and Volatile Analyser
There is no atmosphere around the Moon which means that volatiles such as hydrogen and water can easily escape. However, some volatiles can become trapped between and within grains of dust. There are also some places on the Moon known as Permanently Shadowed Regions (PSRs) that never see sunlight so they act as cold traps for water ice to form. By sampling these volatiles we can understand how much there is, and perhaps where they come from. It is thought that the solar wind brings some volatiles to the lunar surface, while impacts from asteroids or comets could also bring large deposits of volatiles.
There has been a lot of interest in finding water on the lunar surface as it could be used to support future missions to the Moon and beyond. For example, water could be used for hydration for crew, it can insulate habitats from radiation, but it could also be used as rocket propellant. Water is made from hydrogen and oxygen (H2O), which when separated and burned makes a clean propellant. Generating propellant on the lunar surface would mean we wouldn’t need to bring it all with us from Earth, and it would make a sustainable lunar base possible.
There are going to be a number of prospecting missions in the coming years which will search for water on the lunar surface. These missions will help validate the remote sensing data we already have, and provide more information on how the water is stored so we can extract it more efficiently. The LUVMI-X rover is a prospecting rover concept, which is designed to sample lunar soil and identify what volatiles may trapped within it. A drill known as the Volatile Sampler (VS) works alongside the Volatile Analyser (VA) to sample the lunar material and release the volatiles for analysis.
The VS is comprised of an auger shell and an internal heating rod. As the drill moves deeper into the lunar soil, the auger shell can remove any of the displaced material to the surface. Meanwhile, some material will remain trapped within the hollow drill bit. This material is heated up by the heating rod which releases the volatiles, which can then be detected by the mass spectrometer inside the VA.
The mass spectrometer included in the VA design derives its heritage from other spaceflight mass spectrometers developed at the Open University. Previous versions of the design were used with the Ptolemy instrument for the Rosetta mission to a comet, and the GAP instrument for the Beagle 2 mission to Mars. It is a miniature Ion Trap Mass Spectrometer (ITMS) which can identify a wide range of molecules.
The ITMS instrument is being developed at the Open University. The ITMS works by allowing volatiles into a small cavity formed by three metal electrodes at the heart of the device. Then, electrons are fired into the cavity, they strike the molecules to create ions. Different voltages are applied to the electrodes to deflect specific ions into a detector to create a mass spectrum of molecules present. Unionised molecules are vented out into space so there isn’t a build-up of pressure inside the instrument. The measurements obtained by the instrument could be used to help identify deposits of water on the lunar surface, and provide a guide for future water extraction missions.