  Dark photon dark matter emerges as a compelling candidate for ultralight
bosonic dark matter, detectable through resonant conversion into photons within
a plasma environment. This study employs in-situ measurements from the Parker
Solar Probe (PSP), the first spacecraft to venture into the solar corona, to
probe for DPDM signatures. The PSP in-situ measurements go beyond the
traditional radio window, spanning frequencies between about 10 kHz and 20 MHz,
a challenging range inaccessible to Earth-based radio astronomy. Additionally,
the proximity of PSP to the resonant conversion location enhances the signal
flux, providing a distinct advantage over ground-based observations. As a
result, the PSP data establishes the most stringent constraints on the kinetic
mixing parameter $\epsilon$ for DPDM frequencies between 70 kHz and 20 MHz,
with values of $\epsilon \lesssim 10^{-14}-10^{-13}$. Investigating the data
from STEREO satellites resulted in weaker constraints compared to those
obtained from PSP. By utilizing state-of-the-art solar observations from space,
we have surpassed the cosmic microwave background limits established in the
early universe.
