Solar wind density, speed, and energy flux measurements by PSP during Encounter One (from October 31, 2018 00:00:00 to November 12, 2018 00:00:00 UTC). First panel: QTN electron density. Second panel: proton bulk speed. A red horizontal line (V_p = 300 km s⁻¹) is plotted forreference. Third panel: solar wind energy flux W. Fourth panel: solar wind energy flux normalized to one solar radius (black) with a red horizontal line ( W m⁻²) superimposed for reference. The heliocentric distance (in units of the Solar radius R_⊙) is indicated at the top of the first panel and the black vertical line denotes the perihelion of the PSP orbit.