Solution
= Solution
Setting $1/r\to0$ in <11/b> gives the asymptotic <speed>
$$
\boxed{v_\infty=\sqrt{22^2-\frac{2(1.32712\times10^{11})}{1.5\times10^9}}\simeq17.52\,\mathrm{km\,s^{-1}}.}
$$
The radicand is positive, so the ideal probe has positive total <mechanical energy> and escapes the <Sun>. The later dust-cloud model takes this limiting <speed> as its initial <speed>.