IMAP-Hi Technical Overview

The IMAP-Hi instrument consists of an identical pair of imagers that collect, count, measure, and map energetic neutral atoms (ENAs) of energies from 0.4 to 15.6 kiloelectron volts (keV) from two different angles. Together they will be able to image the global sky. consists of two identical, single-pixel high-energy energetic neutral The smallest particle of an element that exhibits the chemical properties of the element. (ENA) imagers mounted at fixed angles of 90 and 45 degrees relative to the spacecraft spin axis. These imagers measure neutral atoms entering our solar system from the outer edge of the The bubble-like region surrounding the solar system inflated by the solar wind, shielding the solar system from interstellar radiation. as they move towards the Sun. The ENA imagers collect the neutral atoms, sort them by type, and then map their incident direction from the outer heliosphere. IMAP-Hi uses a A measure of the flow of events.-of-flight (TOF) section to identify hydrogen (H) and helium (He) and heavier atoms such as carbon (C), nitrogen (N), oxygen (O), and neon (Ne). With each spin of the spacecraft, the imagers sample swaths in the sky that include the From the Earth, the apparent yearly path on the celestial sphere of the Sun with respect to the stars; also, the plane of the earth's orbit. poles and four additional locations in the ecliptic plane. Some low A north-south coordinate measured on the surface of a sphere. It is the angular distance from the equator in the direction of one of the rotational poles and has a range between -90 degrees (south) and +90 degrees (north). regions that contain ENA emissions from the nose and tail of the heliosphere, as well as most of the A predecessor to IMAP, IBEX is studying how our heliosphere interacts with interstellar space. IBEX created the first maps showing the interactions at that border, and how they change over time. Ribbon and Belt, are sampled twice within as little as 1.5 months which allows it to explore short ENA variability.

IMAP’Hi's design and assembly is led by Los Alamos National Laboratory (LANL) in collaboration with Southwest Research Institute (SwRI), University of New Hampshire (UNH), and University of Bern (UBe).

The IMAP-Hi instrument, designed to collect energetic neutral atoms in a high energy spectrum in a clean, white environment. The instrument has a short golden cylindrical – shaped head with an inset ring-shaped collimator entrance surrounding a circular electrical box in its center. The collimator sits several centimeters below the top edge of the collar. A gold circular base supports the instrument head. Electrical wires encircle the space between the base and the bottom of the sensor head.

The IMAP-Hi 45 instrument is shown before installation onto the Interstellar Mapping and Acceleration Probe (IMAP) at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. 

Image Credit: NASA/Johns Hopkins APL/Princeton/Ed Whitman

A diagram of a cross-sectional side view of the IMAP-Hi instrument. It shows the electrified collimator rings and collimator entrance to the inner charge conversion and electrostatic energy analyzer subsystems at the lower end of the instrument. The electrostatic energy analyzer surfaces curve from the inner vertical sides of the instrument toward the center cylinder that houses the time-of-flight sensor foils.

Cross-sectional view of an IMAP-Hi Imager, with black trajectories that highlight the path followed by ENAs. Ambient ions and electrons are deflected before they enter the collimator.