PSP Dust Impact Orbits

FIELDS TDS dust impact rate along the orbit · ecliptic J2000

Orbit

±5 d ±14 d orbit

Impact rate

raw wav ucc

colour: rate measured / model

Rate curtain above the orbit

Dust model

β source R☉

bound n ∝ r⁻ mass index

Dust cloud in the ecliptic plane Model rate in the strip chart Animated grains (Kepler orbits)

fit this orbit fit all orbits

Impact direction

β-meteoroids bound, circular

Impact arrows along the orbit Impact speed in the strip chart

Scene

linear r log r

Mercury, Venus, Earth orbits Venus flybys Distance rings (ecliptic plane) PSP velocity arrow (blue)

Rates. FIELDS L3 dust (Malaspina et al. 2023): V2 TDS samples with |Peak/RMS| > 100, 8-h bins. raw hits/live time; wav adds wave dead time; ucc adds undercounting. L3 ucc never exceeds 0.108 s⁻¹.

Model. Two populations: bound grains on circular prograde orbits with n ∝ r^−δ, and β-meteoroids leaving the source radius with gravity reduced by (1 − β), n ∝ r⁻²/v(r). Detected rate per population = N · n(r) · |v_rel| · (|v_rel|/50 km s⁻¹)^{3.5 μ}, the last factor from the charge yield Q ∝ m v^3.5 with a cumulative mass index μ. The two normalisations N are fitted to the measured rate; everything else is yours to set.

Mission map. Every encounter as a row against time from perihelion, in the same 8-h bins: the whole mission in one frame. Coloured by rate, or by measured/model once the model is fitted to all orbits — where that residual is not flat, the two smooth populations do not account for what PSP flew through. Click a cell to jump there.

Mission frames. Time from perihelion stacks the encounters; ecliptic longitude asks whether anything stands still in inertial space (a stream, a trail); ecliptic latitude asks where the cloud's midplane is — PSP samples ±3.4° of latitude, so a residual that peaks away from 0° means the symmetry plane is tilted.

Orbital-plane histogram. Every 8-h bin binned into 5 R☉ cells of PSP's own orbital plane (x toward the mean perihelion direction, y prograde in-plane), showing the median rate or the median measured/model there. Cells filled by many orbits average over years; the inner cells are sampled on every pass.

Impact direction panel. Measured: the share of hits on each monopole as a dipole asymmetry, and the fraction of V2 peaks that are positive. Model: the arrival direction −v̂_rel projected on the spacecraft axes (SC Z is sunward), from the L3 attitude. They are different quantities — the comparison asks whether the measured asymmetry turns over when the geometry does, not whether the curves coincide.

Geometry. Heliocentric ecliptic J2000, R☉; +X toward the vernal equinox. PSP from the FIELDS full-mission ephemeris. Grey orbit: no rate.

Rate Impact direction Mission map