Choose any infinite set $A\subseteq\mathbb N$ such that $\mu^+(A)=0$. Enumerate both $A$ and $B=\mathbb N\setminus A$ as 
\begin{align*}
A&=\{a_1<a_2< \dots < a_n < \dots\}\\
B&=\{b_1<b_2< \dots < b_n < \dots\}
\end{align*}
Then you can definite the function $f\colon\mathbb N\to\mathbb N$
\begin{align*}
f(b_k)&=b_{k+1}\\
f(a_1)&=b_1\\
f(a_{k+1})&=f(a_k)
\end{align*}
for $k=1,2,\dots$. It is clear that $f$ is a bijection.

For this function $f$, the set of the rocket elements is $B$ and the asymptotic density of this set is equal to one.