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IMAP (Interstellar Mapping and Acceleration Probe) is a mission in NASA's STP program to monitor the interactions between solar wind and the interstellar medium in the outer solar system from the Sun-Earth L1 point. It will sample, analyze, and map particles streaming to Earth from the edges of interstellar space.

The IMAP mission will help researchers better understand the fundamental mysteries that occur at the boundary of the heliosphere, a sort of magnetic bubble surrounding and protecting our solar system. This region is where the constant flow of particles from our Sun, called the solar wind, collides with material from the rest of the galaxy. This collision limits the amount of harmful cosmic radiation entering the heliosphere. IMAP will collect and analyze particles that make it through.

Another objective of the mission is to learn more about the generation of cosmic rays in the heliosphere. Cosmic rays created locally and from the galaxy and beyond affect human explorers in space and can harm technological systems, and likely play a role in the presence of life itself in the universe.

The spacecraft will be positioned about 1.5 million kilometers away from Earth towards the Sun at what is called the first Lagrange point, or L1. This will allow the probe to maximize use of its instruments to monitor the interactions between solar wind and the interstellar medium in the outer solar system.

IMAP was selected in June 2018 following an extensive and competitive peer review of proposals submitted in late 2017. The mission is cost-capped at $492 million, excluding cost for the launch vehicle. The mission will carry 10 science instruments provided by international and domestic research organizations and universities.

Following instrument suite is onboard:

  • IMAP-Lo is a single-pixel neutral atom imager mounted on a pivot platform. It delivers (1) energy and angle-resolved measurements of Interstellar Neutral (ISN) atoms (H, He, O, Ne, and D) tracked over >180 in ecliptic longitude and (2) energy resolved global maps of ENA H and O.
  • IMAP-Hi consists of two identical, single-pixel high energy ENA Imagers that measure H, He, and heavier ENAs from the outer heliosphere.
  • IMAP-Ultra images the emission of Energetic Neutral Atoms (ENAs) produced in the heliosheath and beyond, primarily in H atoms between ~3 and 300 keV, but also sensitive to contributions from He and O.
  • MAG - The IMAP magnetometer (MAG) consists of a pair of identical triaxial fluxgate magnetometers based on the Magnetospheric Multiscale (MMS) magnetometers, for which UCLA built 4 electronics units and 9 fluxgate sensors. On IMAP, the magnetometers are both mounted on a 1.8 m boom to reduce the impact of the magnetometer on spacecraft design
  • SWE (Solar Wind Electron) instrument measures the 3D distribution of SW thermal and suprathermal electrons from 1 eV to 5 keV.
  • SWAPI (Solar Wind and Pickup Ion) instrument measures solar wind H+ and He++ and interstellar He+ and H+ Pickup Ions (PUIs).
  • CoDICE (Compact Dual Ion Composition Experiment) simultaneously measures the 3D velocity distribution functions (VDFs) and ionic charge state and mass composition of ~0.580 keV/q ions in CoDICELo and the mass composition and arrival direction of ~0.035 MeV/nuc ions in CoDICEHi. CoDICEHi also measures ~20600 keV electrons.
  • HIT (High-energy Ion Telescope) measures the elemental composition, energy spectra, angular distributions, and arrival times of H to Ni ions over a species-dependent energy range from ~2 to ~40 MeV/nuc.
  • IDEX (Interstellar Dust Experiment is a high-resolution dust analyzer that provides the elemental composition, speed and mass distributions of Interstellar Dust (ISD) particles.)
  • GLOWS (GLObal solar Wind Structure) instrument measures the heliospheric resonant backscatter glow of hydrogen (the Lyman-α line at 121.6 nm) and helium (at 58.4 nm). GLOWS consists of two separate detectors: LaD and HeD for the two spectral channels.
Nation: USA
Type / Application: Science, Solar
Operator: NASA Goddard Space Flight Center
Power: Solar cells, batteries
Orbit: Sun-Earth L1
Satellite COSPAR Date LS Launch Vehicle Remarks
IMAP (STP 5) - 2025 CC Falcon-9 v1.2 (Block 5) with SWFO-L1, Lunar Trailblazer, GLIDE, Solar Cruiser


Further STP (Solar Terrestrial Program) missions: