Studying Particles blasted from the Sun

The Suprathermal Ion Spectrograph (SIS) is the latest in a long line of pioneering APL energetic particle detectors.

About the Instrument

Instrument Type

The Suprathermal Ion Spectrograph (SIS), flying aboard the European Space Agency and NASA's Solar Orbiter spacecraft, is one of four sensors in the spacecraft’s Energetic Particle Detector suite investigating the suprathermal particles created in solar flares, coronal mass ejections and shocks in the solar wind. The composition of these particles is of particular interest to researchers because it can help to unravel the origins of and acceleration processes in these large solar events. SIS is a highly sensitive mass spectrometer that can determine elements from helium to iron by measuring the particles’ energy as well as velocity by timing how long it takes a particle to move through the instrument.

SIS Instrument
A detailed, 3D rendering of the Suprathermal Ion Spectrograph, showing the two telescopes that funnel particles to the detector.

SIS is the latest in a long line of APL-designed energetic particle detectors, including the Low Energy Charged Particle detectors on the Voyager spacecraft, which are still operating and delivering data from beyond the solar system after more than four decades in space. Its predecessor is the Ultra-Low-Energy Isotope Spectrometer, flying on the Advanced Composition Explorer (ACE) spacecraft.