
IMAP-Lo Instrument
The IMAP-Lo instrument collects, counts, categorizes, and maps invisible particles called interstellar neutral atoms (ISN) and energetic neutral atoms (ENAs) of energies less than 2 kiloelectron volts (keV). Detectors inside the instrument are used to determine the direction the particles came from, as well as their energy levels. IMAP-Lo is mounted on a pivot platform that allows it to adjust its field-of-view to capture data across almost the entire sky.
How It Works
Particles enter the IMAP-Lo instrument through the ring-shaped collimator into the sensor head that includes the electrical systems. The collimator only lets particles from a narrow range of directions pass through it. Directionality for mapping the particles coming from the heliosphere and the nearby interstellar medium is determined by where in the sky the instrument is facing. Mounted on a pivot platform, the IMAP-Lo’s field-of-view can be adjusted remotely to collect data over nearly 100% of the sky.
An electrified deflector shield surrounds the entire sensor head and prevents low-energy charged solar particles from entering the collimator. The collimator directs the incoming particles towards an electrified surface made of a special material that converts the neutral particles into negatively charged ions. A ring of magnets is also used to deflect electrons out of the way.
The newly charged ions are funneled into an electrostatic energy analyzer, or ESA. This part of the instrument consists of two electrically charged plates that allow only ions of specific energy levels to be passed through the analyzer’s uniquely shaped channel and towards the next sensor. Ions that are too high of an energy crash into the outer plate of the channel, ions with too low of energy crash into the inner plate of the channel.
The ions that fall into that specific energy range, or passband, then reach the time-of-flight (ToF) sensor. The ToF sensor uses the time needed for an ion to travel between two foil surfaces. Scientists can use this timing of particles at a specific passband energy to determine the velocity of the particle. The combination of velocity and energy determine what type of particle it is, such as whether it is helium, oxygen, or hydrogen.
Explore the IMAP-Lo Model
How We Use IMAP-Lo Data
Using the energy levels of the converted ISN and ENA particles and the direction they entered IMAP’s collimator, scientists can create a map using color-coded pixels that shows the origin of the different particles from the heliosphere, as well as their energetic levels. Using the ToF sensor data, scientists like IMAP-Lo lead Nathan Schwadron can also map the type, or species, of particle, helping us to understand better the composition of the heliosphere protecting our solar neighborhood, as well as the composition and flow direction of the interstellar medium where the two entities interact with each other.
Meet the Team
The IMAP-Lo instrument was built at University of New Hampshire in Durham, New Hampshire. The team is led by Nathan Schwadron, who also serves as a deputy Principal Investigator for the IMAP mission. The IMAP-Lo team also has collaborators from Southwest Research Institute (SwRI) in San Antonino, TX, the University of Bern, Bern, Switzerland, Princeton University in Princeton, NJ, and Johns Hopkins University APL in Laurel, MD. The pivot platform for IMAP-Lo was built by the Sierrra Space Aerospace Company and is managed by the Johns Hopkins University APL.
The extreme efforts put forth by the team at SwRI to overcome many design challenges to get one of the most technically complicated parts of the instrument, the Conversion Surface and ESA, done on schedule was nothing short of a triumph.
- David Heirtzler, System Engineer, IMAP-Lo
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IMAP-Lo Team
Front row left to right: Todd Jones, Isabella Householder, Colin Frost, Ben Bergan, David Heirtzler, Phil Demaine, Skylar Vogler, Naoufal Souitat
Back row left to right: Aaron Bolton, Stan Ellis, Nathan Schwadron, Jay Rushforth