A spring-activated door protects IDEXThe Interstellar Dust Experiment (IDEX) instrument collects and analyzes interstellar dust and interplanetary dust particles found in our solar system to better understand their compositions, the speeds they travel, their concentrations within our solar system, and their interactions with the solar wind.’s sensor head from contamination while it is being integrated into the spacecraft and during launch. In space, the door swings open permanently, allowing interstellar and interplanetary dustThe small particles of solid matter that are believed to originate from comets and asteroids found between planets in a system. to flow into the instrument.

The collected dust passes through three sets of charged grids toward an impact target plate coated with pure gold. The grids prevent charged particles, electrons, and ions, from entering the instrument.

In a process called impact ionizationThe process by which ions are produced, typically occurring by collisions with atoms or electrons ("collisional ionization") or by interaction with electromagnetic radiation ("photoionization")., the dust crashes into the gold-coated target at a high speed, smashing the dust grains into their composite ions – tiny, charged particles. These fragments then spray upwards and are directed through an opening at the center of the gold target to a detectorAn instrument which is used to discover that something is present somewhere, or to measure how much of something there is. that counts the number of ions that are received.

The ringed structure surrounding the instrument and shield-like reflectronA device used in the particle-detection instrument to improve the velocity measurements it makes. It uses an electric field to reflect ions back through a space, effectively lengthening their path and correcting for small differences in their energies, resulting in sharper and more precise time-of-flight measurements. at the top of the assembly use electric fields to keep the ions from escaping and direct them towards the detector. This also works to form a simple timeA measure of the flow of events.-of-flight (ToF) system by timing how long it takes the ionAn atom that has become electrically charged by the gain or loss of one or more electrons. to reach the detector after impact ionization. Scientists use the amount of time and distance traveled from the target, up to the electric field and down to the detector to identify what elements the dust particles were made of. The heavier fragments (ions) of the dust move slower than smaller fragments, which means they are heavier elements such as iron and silicon. Faster ones are lighter elements, such as helium or hydrogen.

The final detector below the center counts the number of tiny dust particles collected by IDEX by measuring the amount of electrical charge they carry. Because space dust ions are so tiny, even a group of 1000 would not have a big enough charge for a sensor to pick up, so the charges need to be multiplied, or increased, to be detected.

 This detector consists of a series of specially designed, electrically charged perforated disks, called dynodes, that have peaks and valleys surrounding each tiny hole. As the ions come through the opening in the middle of the gold target, they contact a peak of the diskThe visible surface of the Sun (or any heavenly body) projected against the sky. that increases the ion’s charge and funnels it through the hole in the valley to the next disk where the charge is multiplied again as it meets the next peak. The ion is passed through the other disks like a pinball hitting bumpers, increasing its charge as it continues. By the time the particle reaches the final detector surface, the charge is large enough that it can be sensed and counted.

The impacts on IDEX’s gold-coated target leave a residue that can contaminate future collection of data. IDEX periodically on a previously set schedule heats up the target to high temperatureA measure of the average random speeds of the microscopic particles in a substance. that gets rid of this residue.

Learn more about idex

IDEXThe Interstellar Dust Experiment (IDEX) instrument collects and analyzes interstellar dust and interplanetary dust particles found in our solar system to better understand their compositions, the speeds they travel, their concentrations within our solar system, and their interactions with the solar wind. reveals the compositionThe specific components or “ingredients” that make up a substance or type of matter. of the interstellar and interplanetary material locked in the dust grains. This helps gives scientists critical insight on the formation and evolution of matter both inside and outside our solar neighborhood. Composition data from IDEX also links the makeup of interstellar dustTiny particles of solid matter found in the interstellar medium that are believed to be formed from supernova star events that result in the formation of stars and planetary systems, including those found in our solar system. with the composition of interstellar neutrals (ISNs) and pickup ions (PUIs) measured by IMAP-Lo, CoDICE, and SWAPI.

Understanding the number of particles of space dust in a certain area of the sky, along with their composition, informs scientists how much of each type of elemental material is out there in various regions of our universeThe totality of all space and time; all that is, has been, and will be..

Meet the Team

IDEX was built and tested at the Laboratory for Atmospheric and Space Physics (LASP) at University of Colorado, Boulder under instrument lead Mihaly Horanyi.

Playing a role in the incredibly successful IDEX dust testing campaigns has been a highlight in my career. Testing like we fly required pushing the accelerator to its extremes for hypervelocity interstellar-like dust grains. The magnitudeAn astronomical measurement of an object's brightness; larger magnitudes represent fainter objects. of IDEX and the team's precision was seen in all aspects, including using almost every inch of test chambers for this large instrument. Go IDEX, go IMAP! 

 - John Fontanese, Former IMPACT Dust Accelerator Operator, IDEX