The charged hydrogen and helium (and sometimes larger) particles enter the SWAPIThe Solar Wind and Pickup Ion (SWAPI) instrument collects and counts solar wind particles and pick-up ions (PUIs). instrument parallel to the spin axis of the spacecraft. As IMAP spins in space, solar windA stream of charged particles, mostly protons and electrons, that escapes into the Sun's outer atmosphere at high speeds and streams out into the solar system in all directions. particles are swept into SWAPI through a special opening called “sunglasses.” The opening is covered by a screen with very tiny precise holes that cut down the brightness of the very intense solar wind. The incoming pick-up ions enter the device through the part of the opening which does not have the “sunglasses.”  The charged particles are then guided further into the instrument between two spheres. The paths of the particles are curved by the electrical charge setting on the inside sphere. Particles with energies either larger or smaller than the chosen setting either crash into the metal walls of the instrument or, if they have exactly the right amount of energy, they flow down to hitThe High-energy Ion Telescope (HIT) collects, measures, and maps very energetic particles coming through the heliosphere, as well as those flowing from the Sun. Near real-time energetic particle data collected by HIT will be used to better predict and warn scientists about Earth-bound solar storm activity. a carbon foilA thin layer of carbon that is used for ion and neutral atom detection in space plasma instruments. The foil is made from pure carbon that is arc evaporated onto glass slides that are coated with a surfactant, which allows the foil to slide off the glass.. This impact releases electrons which are then collected by a pair of devices called channel electronA negatively charged elementary particle that normally resides outside (but is bound to) the nucleus of an atom. multipliers. Because electrons are so tiny, even a group of 1000 would not have a big enough signal for a sensor to pick up, so the charges need to be multiplied, or increased, to be detected. Only electrons detected by both channel electron multipliers are counted as incoming ions. This data is then transmitted to IMAP scientists on Earth where it is analyzed to determine the concentrations of helium and hydrogen coming from the Sun and from outside the heliosphereThe bubble-like region surrounding the solar system inflated by the solar wind, shielding the solar system from interstellar radiation..

Learn more about swapi

By graphing the data collected using SWAPIThe Solar Wind and Pickup Ion (SWAPI) instrument collects and counts solar wind particles and pick-up ions (PUIs)., scientists like Dr. Jamie Rankin can determine the amounts of hydrogen and helium ions from the solar windA stream of charged particles, mostly protons and electrons, that escapes into the Sun's outer atmosphere at high speeds and streams out into the solar system in all directions. and the hydrogen and helium pickup ions at various possible energies. From this information, they can then determine the basic information of the solar wind at any moment, such as its temperatureA measure of the average random speeds of the microscopic particles in a substance., densityThe amount of mass or number of particles per unit volume. In cgs units, mass density has units of gm cm-3. Number density has units cm-3 (particles per cubic centimeter)., and speed. Since the pickup ions come in from different directions, those characteristics of the solar wind partially determine the number of pickup ions that can travel in through the solar system to reach IMAP. Most of the pickup ions detected by SWAPI are helium because they are bigger than hydrogen and have more energy to travel upwind into the inner solar system where they can be detected.

Meet the Team

The SWAPI team, led by Dr. Jamie Rankin at Princeton University, is comprised of 25 engineers, scientists, and other supporting roles.