How Long-lived Grains Dominate the Shape of the Zodiacal Cloud

Grain-grain collisions shape the 3-dimensional size and velocity distributionof the inner Zodiacal Cloud and the impact rates of dust on inner planets, yetthey remain the least understood sink of zodiacal dust grains. For the firsttime, we combine the collisional grooming method combined with a dynamicalmeteoroid model of Jupiter-family comets (JFCs) that covers four orders ofmagnitude in particle diameter to investigate the consequences of grain-graincollisions in the inner Zodiacal Cloud. We compare this model to a suite ofobservational constraints from meteor radars, the Infrared AstronomicalSatellite (IRAS), mass fluxes at Earth, and inner solar probes, and use it toderive the population and collisional strength parameters for the JFC dustcloud. We derive a critical specific energy of Q^*_D=5×10^5 ±4×10^5 R_met^-0.24 J kg^-1 for particles fromJupiter-family comet particles, making them 2-3 orders of magnitude moreresistant to collisions than previously assumed. We find that the differentialpower law size index -4.2±0.1 for particles generated by JFCs provides agood match to observed data. Our model provides a good match to the massproduction rates derived from the Parker Solar Probe observations and theirscaling with the heliocentric distance. The higher resistance to collisions ofdust particles might have strong implications to models of collisions in solarand exo-solar dust clouds. The migration via Poynting-Roberson drag might bemore important for denser clouds, the mass production rates of astrophysicaldebris disks might be overestimated, and the mass of the source populationsmight be underestimated. Our models and code are freely available online.