
HIT Instrument
The HIT instrument captures very energetic solar particles through a series of apertures, or openings, leading to a series of silicon solid-state detectors that allow scientists to determine the type of particle or species each are, the amount of energy they possess, and the direction they are coming from in our solar neighborhood, the heliosphere.
How It Works
There are 2 sets of 5 apertures, or windows, on opposite sides of HIT’s sensor head, the spaceward facing end of the instrument. The windows are arched in a way that gives each side a more than 90 degree field of view of the sky area it is facing. As the IMAP spacecraft spins, each side scans an entire hemisphere, and combined, they view the entire sky. Particles enter the window that aligns with its direction it was traveling, like entering a building from the side you approach it from. Which opening the particle enters into indicates to scientists where the particle is coming from in our solar neighborhood.
Each set of HIT’s apertures consist of a series of openings covered by different types of thin windows that let particles pass through and an aluminum structure that stop particles. These so-called collimators lead to a stack of detectors at the center of HIT’s head. How much energy the particles have as they enter the windows determines how far they are able to penetrate through the detectors, and the detectors measure how much the particles slow as they pass through.
Explore the HIT Model
How We Use HIT Data
Scientists use the information from HIT in two ways. The first is to map the origin direction and energy level various particles have coming from the heliosphere. The second is to gather information about the charged high-energy particles flowing from the Sun. This helps scientists on the ground be able to monitor one of the most dangerous aspects of space weather that can affect satellites and the safety of astronauts in the event of a solar storm.
Meet the Team
The HIT instrument was built at NASA Goddard Space Flight Center in Greenbelt, MD. The HIT team is led by Instrument Lead Eric Christian, who also serves as a deputy Principal Investigator for the IMAP mission.
It has been a unique experience to take part in all the phases of the HIT experiment development, working with great science and engineering teams on the instrument design, characterization and testing. Seeing our detector finally installed on the IMAP spacecraft was priceless, and the best is yet to come! We can't wait to analyze the first solar particle event recorded by HIT in space!
- Alessandro Bruno, Research Scientist, HIT

Front row from left to right: Teresa Tatoli, Traci Rosnack, Mariana Jeunon Barros Ferreira, Georgia de Nolfo, Jack Letzermiddle
Middle row from left to right: Negeen Saghafi, Kyle Gregory, Eric Christian, Jeff Dumonthier, J. Grant Mitchell, Alessandro Brunoback
Back row from left to right: Miles Smith, Sanetra Bailey Newman, George Suárez, Chris Tiu, Pat Haas, Iker Liceaga Indart, Brian Kittle, Bill Reaves