= Solution
Retain the unchanged-<angular momentum> assumption of the preceding part. The initial <orbit> has radius $r_o=6400+500=6900\,\mathrm{km}$, and the desired <pericentre distance> is $r_p=6400+100=6500\,\mathrm{km}$. Using $r_p=r_o/(1+e)$ gives
$$
e=\frac{6900}{6500}-1=\frac4{65}.
$$
The required fractional increase in initial <kinetic energy> is therefore
$$
\boxed{\frac{\Delta K}{K_0}=e^2=\frac{16}{4225}
\simeq0.00378698=0.378698\%.}
$$
Here $\Delta E=\Delta K>0$ because the instantaneous kick does not change <potential energy>. Since the initial total <orbital energy> is $E_0=-K_0$, an alternative convention for the requested fractional <energy> change gives
$$
\boxed{\frac{\Delta E}{|E_0|}=+0.00378698,\qquad
\frac{\Delta E}{E_0}=-0.00378698.}
$$
The total <orbital energy> becomes less negative. Explicitly specifying its denominator avoids interpreting a positive <energy> input as a decrease of <energy>.
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