The heart of a lunar volatiles detector

The heart of the Exospheric Mass Spectrometer (EMS) is visible in this image of the key sensor that will study the abundance of lunar water and water ice for upcoming missions to the Moon.

A similar Mass Spectrometer is also developed for ESA’s Prospect payload package to study lunar water ice. The platform will sample potential resources on the Moon to prepare technologies for future sustainable exploration.

EMS is based on an ‘ion trap’, an ingenious detector device that allows researchers to identify and quantify sample atoms and molecules in a gas and allows to establish a corresponding mass spectrum. Scientists at The Open University and RAL Space are developing EMS under an ESA contract.

Lunar molecules entering the sensor are bombarded by electrons emitted by a heated wire to create ions. The resulting ions are stored within an electric field formed by a set of precisely-shaped electrodes. The ions are then released from this ‘trap’ in order of increasing mass/charge ratio into the detector that identifies and quantifies their chemical makeup.

This will allow the instrument to measure water and other molecules in the very thin atmosphere of the Moon throughout the lunar day to study  a lunar ‘water cycle’ concept.

The PITMS instrument will be part of a lunar lander that will arrive on the Moon on NASA’s Astrobotic M1 mission taking commercial lunar payloads to the Lacus Mortis region in 2021.