Parker Solar Probe: A Mission to Touch the Sun

On August 12, 2018, Parker Solar Probe (PSP) began its seven-year exploration of the inner heliosphere and the Sun's corona. Using specially designed systems to protect from the Sun's intense environment and power the spacecraft, PSP has already provided game-changing insights into coronal heating, the source of the solar wind, and how the solar wind is propagated into the interplanetary medium to interact with Earth. More than a decade in the making, PSP was designed, built, operated and managed by The Johns Hopkins University Applied Physics Laboratory (JHU/APL) as part of NASA's Living With a Star program. PSP launched into a solar orbit, and used a Venus gravity assist to lower the orbit perihelion to complete the planned solar encounters (where the solar distance is less than 0.25 AU), currently with perihelion as close to the Sun as 0.17 AU. PSP will use six more Venus gravity assists over the next six years to reduce its perihelion from 0.17 AU to 0.046 AU in the last three encounters. During solar encounter, measurements to characterize the in situ environment will be made by four instrument suites: FIELDS (electromagnetic fields), SWEAP (solar wind plasma), ISOIS (energetic particles) and WISPR (imaging of the coronal structure). We discuss the scientific motivation for PSP and the instrument suite used to make these ground-breaking measurements. We describe the development of PSP since inception in 2007, the extreme environments to which the observatory is exposed and how these environments drove design, technologies that enable the mission, and the final configuration of both the mission and the observatory. Finally, we give an account of post-launch commissioning and operations in early orbits, and an assessment of observatory performance over these first orbits.