Thats inefficient, you dont need to cancel the angular momentum as there was no time limit on how long it takes rhe child to enter the sun and there also was not a specified required trajectory. The child can just spiral into the sun
There are no spiral orbits. Canceling the forward motion is exactly what you need to do, to bring down the next periapsis to 0. Now, you can go with a periapsis of about half a million km, because the sun is pretty big, but that is not a significant difference. Getting anywhere near the sun, is the hard part.
Right, I wanted to ask: is that actually the minimum energy to make the child reach the sun? What’s the minimum energy to launch something so it reaches the sun?
The minimum would be something like punting your kid to the orbit of Venus for a gravity assist that takes it to one of the outer planets where another gravity assist can push it to the edge of the solar system.
Out there, the angular momentum of the orbiting child will be very low and can be canceled out by a small thrust.
The child will then fall back into the sun. But this requires remote controlled thrusters strapped to the child. And a life support system if you want your child to actually die by burning in the sun. And then, the child will be well into their teens by the time they reach it.
