A small probe is in a circular orbit of radius $h$ around Planet Orb, which has mass $M$ and radius $R \ll h$. The probe shatters, and every fragment leaves at the same speed $v$ in the probe's rest frame, with directions distributed uniformly in the orbital plane. The speed $v$ equals the probe's orbital speed, $\sqrt{GM/h}$. What fraction of the fragments eventually lands on Orb? (Hint: $\cos\delta \approx 1 - \delta^2/2$ for small $\delta$.)