Integrated Science Investigation of the SunorIS☉IS, is an instrument aboard the Parker Solar Probe, a space probe designed to study the Sun. IS☉IS is focused on measuring energetic particles from the Sun, including electrons, protons, and ions.[1] The parent spacecraft was launched in early August 2018, and with multiple flybys of Venus will study the heliosphere of the Sun from less than 4 million kilometers or less than 9 solar radii.[2][3]
IS☉IS consists of two detectors, EPI-Lo and EPI-Hi, corresponding to detection of relatively lower and higher energy particles.[4] EPI-Lo is designed to detect from about 20 keV per nucleon up to 15 MeV (mega electronvolts) total energy, and for electrons from about 25 keV up to 1000 keV.[4] EPI-Hi is designed to measure charged particles from about 1– to 200 MeV per nucleon and electrons from about 0.5 to 6 MeV, according to a paper about the device.[4]
The shortname includes a symbol for the Sun, a circle with a dot in it: ☉.[1] NASA suggests pronouncing the name as "ee-sis" in English.[5]
By September 2018, IS☉IS had been turned on and first light data was returned.[6]
EPI-Hi includes:[7]
The detectors are solid-state devices.[7]
EPI-Lo includes 8 wedge detectors, fed by 80 separate entrances.[7] These entrances correspond to covering a field of view over almost a full hemisphere.[8]
EPI-Lo can record differential energy spectra for electrons, Hydrogen, Helium-3, Helium-4, Carbon, Oxygen, Neon, Magnesium, Silicon, and Iron.[7]