IDEX (Interstellar Dust Explorer)



Cutaway diagram of the IDEX sensor head, showing the principle of operation.

The Interstellar Dust Experiment (IDEX) is a time-of-flight (TOF) dust impact ionization mass spectrometer that provides the elemental composition, speed, and mass distributions of interstellar dust and interplanetary dust particles. IDEX links the makeup of interstellar dust with the composition of interstellar neutrals and pickup ions (PUIs) measured by IMAP-Lo, CoDICE, and SWAPI.

High-speed impacts with the gold-coated target smashes dust grains into their composite ions, which is called impact ionization. These fragments then spray upwards through the time-of-flight system and are redirected to the detector allowing the elemental makeup of particles to be identified. In this way, IDEX is able reveal the composition of interstellar material locked in dust grains, garnering critical insight on the evolution of interstellar material and the interaction of our heliosphere with its local interstellar neighborhood.

IDEX design and build is led by the Laboratory for Atmospheric and Space Physics (LASP).