Pluto Energetic Particle Spectrometer Science Investigation

[2] The spacecraft was launched in 2006, flew by Jupiter the following year, and went onto flyby Pluto in 2015 where PEPSSI was able to record and transmit back to Earth its planned data collections.

[9] One of the expectations that was not confirmed by PEPSSI was that sunlight would make a large bubble of ionized gases around Pluto from its atmosphere.

[10] PEPSSI found that the rate of atmospheric loss was only 0.01 percent of what was anticipated, and the region of interaction with the solar wind was much smaller than expected.

[12] The design avoided using magnets for the time of flight section, which enhanced weight and/or power savings for the instrument.

[12] To meet the low power use and weight requirements, the device made use of application-specific integrated circuits (ASICs).

[14] PEPSSI is based on an instrument that was on board the Discovery program's MESSENGER (planet Mercury orbiter, launched 2004/ended 2015) called the Energetic Particle Spectrometer.

[14] PEPSSI has an enhanced design to reduce weight and power consumption having to do with electron detection, with heritage going back the 1980s and 1990s.